Fair Value Measurements - Gains (Loss) and Interest Expense on Interest Rate Swap Contracts (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recorded in accumulated other comprehensive loss, net of tax	$ (1)	$ (5)	$ (4)	$ (10)
Interest rate swap
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recorded in accumulated other comprehensive loss, net of tax	2	(11)	(14)	(16)
Interest expense recorded related to interest rate swap contracts	$ 4	$ 0	$ 6	$ 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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-Section 45
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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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