Derivative Instruments - Additional Information (Details) € in Millions, $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2020 CAD ($)	Sep. 30, 2020 EUR (€)	Dec. 31, 2018 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net unrealized loss recognized in AOCI	$ 17,000,000	$ 25,000,000	$ 268,000,000	$ 116,000,000
Amount of pre-tax losses in AOCI expect to be reclassified into interest expense			12,000,000
Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount	98,000,000		98,000,000
Interest rate swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount					$ 3,500,000,000
Interest rate swaps | Interest expense, net
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net unrealized loss recognized in AOCI					213,000,000
Gain (loss) reclassified from OACI to Income			51,000,000
Net unrealized loss recognized at settlement						$ 85,000,000
Interest Rate Swaps - Period One
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount	3,500,000,000		3,500,000,000
Interest Rate Swaps - Period Two
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount	500,000,000		500,000,000
Cross Currency Interest Rate Contract | Fixed Income Interest Rate
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount	5,000,000,000		5,000,000,000				$ 6,754
Cross Currency Interest Rate Contract | Fixed Income Interest Rate | Derivatives designated as net investment hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount					$ 500,000,000				$ 400,000,000
Cross Currency Interest Rate Contract | Fixed Income Interest Rate | Hedge Funds
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount	$ 1,200,000,000		$ 1,200,000,000					€ 1,108