Derivatives - Offsetting Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Offsetting of Financial Liabilities under Master Netting Agreements with Derivative Counterparties
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	$ 72	$ 106
Net Amount of Derivative Liabilities	41	95
Derivatives subject to master netting agreements
Offsetting of Financial Liabilities under Master Netting Agreements with Derivative Counterparties
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	72	106
Gross Amount of Eligible Offsetting Recognized Derivative Assets	31	11
Net Amount of Derivative Liabilities	$ 41	$ 95