Fair Value Measurements - Gains (Loss) and Interest Expense on Interest Rate Swap Contracts (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recorded in accumulated other comprehensive loss, net of tax	$ (1)	$ (5)	$ (5)	$ (15)
Interest rate swap
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recorded in accumulated other comprehensive loss, net of tax	4	3	(10)	(13)
Interest expense recorded related to interest rate swap contracts	$ 4	$ 0	$ 10	$ 0

Amount before tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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