Amounts are comprised of certain investments measured using NAV (or its equivalent) as a practical expedient. These investments have not been classified in the fair value hierarchy. Fair values for bonds are based on market prices supplied by independent sources as of the last trading day. The fair values of mortgages are based on current market yields of financial instruments of similar maturity, coupon and risk factors. Real estate fund values are based on the NAV of the funds that invest directly in real estate investments. The values of the investments have been estimated using the capital accounts representing the plan’s ownership interest in the funds. Of the total, $580 million is subject to redemption frequencies ranging from monthly to annually and a redemption notice period of 90 days (2019 – $606 million). The remaining $124 million is not subject to redemption and is normally returned through distributions as a result of the liquidation of the underlying real estate investments (2019 – $118 million). As at December 31, 2020, there are $32 million of unfunded commitments for real estate investments (December 31, 2019 – $35 million). Infrastructure fund values are based on the NAV of the funds that invest directly in infrastructure investments. The values of the investments have been estimated using the capital accounts representing the plans' ownership interest in the funds. Of the total, $112 million is subject to redemption frequencies ranging from monthly to annually and a redemption notice period of 90 days (2019 – $119 million). The remaining $87 million is not subject to redemption and is normally returned through distributions as a result of the liquidation of the underlying infrastructure investments (2019 – $68 million). As at December 31, 2020, there are $491 million of unfunded commitments for infrastructure investments (December 31, 2019 – $286 million). Private debt fund values are based on the NAV of the funds that invest directly in private debt investments. The values of the investments have been estimated using the capital accounts representing the plans' ownership interest in the funds. Of the total, $154 million is subject to redemption frequencies ranging from monthly to annually and a redemption notice period of 90 days (2019 – $154 million). The remaining $311 million is not subject to redemption and is normally returned through distributions as a result of the repayment of the underlying loans (2019 - $159 million). As at December 31, 2020, there are $533 million of unfunded commitments for private debt investments (December 31, 2019 – $392 million). The investment managers may utilize the following derivative instruments: equity futures to replicate equity index returns (Level 2); currency forwards to partially hedge foreign currency exposures (Level 2); bond forwards to reduce asset/liability interest rate risk exposures (Level 2); interest rate swaps to manage duration and interest rate risk (Level 2); credit default swaps to manage credit risk (Level 2); and options to manage interest rate risk and volatility (Level 2). The Company may utilize derivatives directly, but only for the purpose of hedging foreign currency exposures. As at December 31, 2020, there are currency forwards with a notional value of $1,041 million (December 31, 2019 – $334 million) and a fair value of $73 million (December 31, 2019 – $13 million). The fixed income investment manager utilizes a portfolio of bond forwards for the purpose of reducing asset/liability interest rate exposure. As at December 31, 2020, there are bond forwards with a notional value of  $3,540 million ( December 31, 2019 – $3,269 million) and a negative fair value of  $2 million  (December 31, 2019 – $(72) million). The value of absolute return fund investments is based on the NAV reported by the fund administrators. The funds have different redemption policies with redemption notice periods varying from 60 to 95 days and frequencies ranging from monthly to triennially. The Company's primary investment objective for pension plan assets is to achieve a long–term return, net of all fees and expenses, that is sufficient for the plan's assets to satisfy the current and future obligations to plan beneficiaries, while minimizing the financial impact on the Company. In identifying the asset allocation ranges, consideration was given to the long-term nature of the underlying plan liabilities, the solvency and going-concern financial position of the plan, long-term return expectations, and the risks associated with key asset classes as well as the relationships of returns on key asset classes with each other, inflation, and interest rates. When advantageous and with due consideration, derivative instruments may be utilized by investment managers, provided the total value of the underlying assets represented by financial derivatives (excluding currency forwards, liability hedging derivatives in fixed income portfolios, and derivatives held by absolute return funds) is limited to 30% of the market value of the fund. The funded status of the plans is exposed to fluctuations in interest rates, which affects the relative values of the plans' liabilities and assets. In order to mitigate interest rate risk, the Company's main Canadian defined benefit pension plan utilizes a liability driven investment strategy in its fixed income portfolio, which uses a combination of long duration bonds and derivatives to hedge interest rate risk, managed by the investment manager. At December 31, 2020, the plan's solvency funded position was 47% hedged against interest rate risk (2019 – 45%). When investing in foreign securities, the plans are exposed to foreign currency risk; the effect of which is included in the valuation of the foreign securities. At December 31, 2020, the plans were 33% exposed to the U.S. dollar net of currency forwards (40% excluding the currency forwards), 6% exposed to the Euro, and 14% exposed to various other currencies. At December 31, 2019, the plans were 39% exposed to the U.S. dollar net of currency forwards (41% excluding the currency forwards), 6% exposed to the Euro, and 14% exposed to various other currencies. Additional plan assets information Investments measured at net asset value ("NAV"): (1)  Government & Corporate Bonds: (2)  Mortgages: (3)  Real estate: (4)   Infrastructure: (5)  Private debt: (6)  Derivatives: (7)  Absolute return: (8)