Fair Value of Financial Instruments - Narrative (Details) - Fair Value, Measurements, Recurring $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) number	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) number	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) number
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchase price adjustment receivable | $	$ 31		$ 31		$ 14
Purchase price adjustment receivable (gain) loss, fair value adjustment | $	$ (3)	$ (3)	$ (17)	$ 2
Minimum | Level 3 | Variable Interest Entity, Not Primary Beneficiary | Measurement Input, Discount Rate | Valuation Technique, Discounted Cash Flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input, discount rate | number	0.009		0.009		0.014
Maximum | Level 3 | Variable Interest Entity, Not Primary Beneficiary | Measurement Input, Discount Rate | Valuation Technique, Discounted Cash Flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input, discount rate | number	0.10		0.10		0.10