Derivative Instruments - Additional Information (Details) € in Millions, $ in Millions, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2021 CAD ($)	Mar. 31, 2021 EUR (€)	Dec. 31, 2018 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net unrealized loss recognized in AOCI	$ (95)	$ 214
Amount of pre-tax losses in AOCI expect to be reclassified into interest expense	8
Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount	124
Interest rate swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount			$ 3,500
Interest rate swaps | Interest expense, net
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net unrealized loss recognized in AOCI			213
Gain (loss) reclassified from OACI to Income	50
Net unrealized loss recognized at settlement				$ 85
Interest Rate Swaps - Period One
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount	3,500
Interest Rate Swaps - Period Two
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount	500
Cross Currency Interest Rate Contract | Fixed Income Interest Rate
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount	5,000				$ 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				$ 400
Cross Currency Interest Rate Contract | Fixed Income Interest Rate | Hedge Funds
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount	$ 1,200					€ 1,108