The fair value of our pension plan assets by investment category and the corresponding level within the fair value hierarchy were as follows: (a) No single equity holding amounted to more than 1% of the total fair value. (b) Our corporate bond investments had an average rating of A-. (c) Investments measured at fair value using NAV as a practical expedient are not classified in the fair value hierarchy. The fair value amounts presented in this table for these investments are included to permit reconciliation of the fair value hierarchy to the total plan assets. 93 Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Asset Category December 31, 2020 Cash and equivalents $ 112  $ —  $ 112  $ —  Equity securities (a): U.S. companies 1,137  1,137  —  —  Non-U.S. companies 90  90  —  —  Private equity investments 33  —  —  33  Fixed-income securities: Corporate bonds (b) 3,532  —  3,532  —  Treasury securities 1,129  —  1,129  —  Commingled funds: Equity funds 7,306  —  7,306  —  Fixed-income funds 416  —  416  —  Real estate funds 90  —  —  90  Other investments: Insurance deposit contracts 157  —  —  157  Retirement annuity contracts 38  —  —  38  Total plan assets in fair value hierarchy $ 14,040  $ 1,227  $ 12,495  $ 318  Plan assets measured using NAV as a practical expedient (c): Real estate funds 446  Hedge funds 254  Equity funds 11  Total pension plan assets $ 14,751 