Derivative Financial Instruments - Cash Flow Hedges (Details) $ in Millions	6 Months Ended
	Jun. 30, 2021 USD ($)
Derivative [Line Items]
Unrealized gain on terminated cash flow hedge remaining in AOCI, before tax	$ 148
Unrealized gain on terminated cash flow hedge remaining in AOCI, net of tax	$ 107
Term unrealized gains reclassified into earnings	4 years
Derivatives designated as hedging instruments | Interest rate swaps
Derivative [Line Items]
Derivative notional amount	$ 5,000
Derivatives net asset fair value	$ 228