Fair Value Measurements	9 Months Ended
Fair Value Measurements	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Assets and Liabilities Measured at Fair Value on a Recurring and Non-recurring Basis The Company has a cross-currency swap related to its Canadian dollar Medium-Term Notes which were issued in December 2019. The fair value of the swap as a foreign currency exchange derivative is categorized as a Level 2 measurement in the fair value hierarchy and is measured on a recurring basis. As of September 30, 2021 and December 31, 2020, the estimated fair value of the foreign currency exchange derivative asset was $12.8 million and $14.4 million, respectively. Financial Instruments Not Measured at Fair Values The fair value of debt financing is estimated based on the quoted market prices for the same or similar issues, or on the current rates offered to the Company for debt of the same remaining maturities, which would be categorized as a Level 2 measurement in the fair value hierarchy. The estimated fair value of debt financing as of September 30, 2021 was approximately $18.4 billion compared to a book value of $17.8 billion. The estimated fair value of debt financing as of December 31, 2020 was $17.6 billion compared to a book value of $16.7 billion. The following financial instruments are not measured at fair value on the Company’s Consolidated Balance Sheets at September 30, 2021, but require disclosure of their fair values: cash and cash equivalents and restricted cash. The estimated fair value of such instruments at September 30, 2021 and December 31, 2020 approximates their carrying value as reported on the Consolidated Balance Sheets. The fair value of all these instruments would be categorized as Level 1 in the fair value hierarchy.

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.