77  /  CP 2018 ANNUAL REPORT For fair value hedges, the periodic changes in values are recognized in income, on the same line as the changes in values of the hedged items are also recorded. For an effective cash flow hedge, the entire change in value of the hedging instrument is recognized in “Other comprehensive income (loss)”. The change in value of the effective cash flow hedge remains in “Accumulated other comprehensive loss” until the related hedged item settles, at which time amounts recognized in “Accumulated other comprehensive loss” are reclassified to the same income or balance sheet account that records the hedged item. Cash flows relating to derivative instruments designated as hedges are included in the same line as the related hedged items on the Consolidated Statements of Cash Flows. Environmental remediation accruals, recorded on an undiscounted basis unless a reliably determinable estimate as to amount and timing of costs can be established, cover site-specific remediation programs. The accruals are recorded when the costs to remediate are probable and reasonably estimable. Certain future costs to monitor sites are discounted at an adjusted risk-free rate. Provisions for environmental remediation costs are recorded in “Other long-term liabilities”, except for the current portion, which is recorded in “Accounts payable and accrued liabilities”. The Company follows the liability method of accounting for income taxes. Deferred income tax assets and liabilities are determined based on differences between the financial reporting and tax bases of assets and liabilities using enacted tax rates and laws that will be in effect when the differences are expected to reverse. The effect of a change in income tax rates on deferred income tax assets and liabilities is recognized in income in the period during which the change occurs. When appropriate, the Company records a valuation allowance against deferred tax assets to reflect that these tax assets may not be realized. In determining whether a valuation allowance is appropriate, CP considers whether it is more likely than not that all or some portion of CP’s deferred tax assets will not be realized, based on management’s judgment using available evidence about future events. At times, tax benefit claims may be challenged by a tax authority. Tax benefits are recognized only for tax positions that are more likely than not sustainable upon examination by tax authorities. The amount recognized is measured as the largest amount of benefit that is greater than 50% likely to be realized upon settlement. A liability for “unrecognized tax benefits” is recorded for any tax benefits claimed in CP’s tax returns that do not meet these recognition and measurement standards. Investment and other similar tax credits are deferred on the Consolidated Balance Sheets and amortized to “Income tax expense” as the related asset is recognized in income. Basic earnings per share are calculated using the weighted average number of the Company's Common Shares (the "Common Shares') outstanding during the year. Diluted earnings per share are calculated using the treasury stock method for determining the dilutive effect of options. Stock-based compensation CP follows the fair value based approach to account for stock options. Compensation expense and an increase in “Additional paid-in capital” are recognized for stock options over their vesting period, or over the period from the grant date to the date employees become eligible to retire when this is shorter than the vesting period, based on their estimated fair values on the grant date, as determined using the Black-Scholes option-pricing model. Any consideration paid by employees on exercise of stock options is credited to “Share capital” when the option is exercised and the recorded fair value of the option is removed from “Additional paid-in capital" and credited to “Share capital”. Compensation expense is also recognized for deferred share units (“DSUs”), performance share units (“PSUs”) and restricted share units (“RSUs”) using the fair value method. Compensation expense is recognized over the vesting period, or for PSUs and DSUs only, over the period from the grant date to the date employees become eligible to retire when this is shorter than the vesting period. Forfeitures of DSUs, PSUs and RSUs are estimated at issuance and subsequently at the balance sheet date. The employee share purchase plan (“ESPP”) gives rise to compensation expense that is recognized using the issue price by amortizing the cost over the vesting period or over the period from the grant date to the date employees become eligible to retire when this is shorter than the vesting period. Earnings per share Income taxes Environmental remediation