Commitments and Contingencies - Guarantees (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Jun. 30, 2020	Jan. 01, 2020	Dec. 31, 2019
Other Commitments [Line Items]
Off-Balance Sheet, Credit Loss, Liability, Credit Loss Expense	$ (1)	$ 2
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accounting Standards Update 2016-13 [Member]
Other Commitments [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			$ 0		$ 2
Cumulative Effect, Period of Adoption, Adjustment [Member] | Retained Earnings | Accounting Standards Update 2016-13 [Member]
Other Commitments [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest				$ (18)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Retained Earnings | Other liabilities | Accounting Standards Update 2016-13 [Member]
Other Commitments [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest				$ 25