Derivative Financial Instruments - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Notional value	$ 9,800,000,000
Net derivatives	96,000,000	$ 52,000,000
Estimated accumulated other comprehensive income to be reclassified in next 12 months	18,000,000
Cash collateral held relative to derivative exposure	0	0
Cash collateral pledged	93,000,000	$ 53,000,000
CHICAGO MERCANTILE EXCHANGE
Derivative [Line Items]
Notional value	$ 9,300,000,000
Percent of total notional derivative contracts	95.20%
Amount of variation margin included as settlement	$ (268,000,000)
London Clearing House
Derivative [Line Items]
Notional value	$ 500,000,000
Percent of total notional derivative contracts	4.80%
Amount of variation margin included as settlement	$ 24,000,000