Derivatives - Cash Flow Hedges (Details) - Cash flow hedge - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Derivatives in Cash Flow Hedging Relationships
Accumulated other comprehensive income (loss), unrealized gain (loss) on cash flow hedges	$ 17
After-tax net unrealized gain (loss) anticipated to be reclassified from AOCI to the income statement within next twelve months	69
After-tax net unrealized gain (loss) anticipated to be reclassified from AOCI to the Income Statement over remaining fiscal year	18
After-tax net unrealized gain (loss) anticipated to be reclassifed from AOCI to the Income Statement over next fiscal year	63
After-tax unrealized gain (loss) anticipated to be reclassified from AOCI to the Income Statement after the next fiscal year	$ (64)
Foreign currency forward/option contracts
Derivatives in Cash Flow Hedging Relationships
Maximum length of time hedged in interest rate cash flow hedge	36 months
Interest rate swap contracts
Derivatives in Cash Flow Hedging Relationships
Accumulated other comprehensive income (loss), unrealized gain (loss) on cash flow hedges	$ (114)
Derivative notional amount		$ 700
Additional derivative notional	$ 743