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 value	98,000,000		98,000,000
Interest Rate Swaps - Beginning March 29, 2018
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional value	3,500,000,000		3,500,000,000
Interest Rate Swaps - Beginning September 30, 2019
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional value	500,000,000		500,000,000
Interest rate swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional value					$ 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 AOCI to Income			51,000,000
Net unrealized loss recognized at settlement						$ 85,000,000
Cross currency interest rate contract | Fixed income interest rate
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional value	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 value					$ 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 value	$ 1,200,000,000		$ 1,200,000,000					€ 1,108