Derivative Instruments - Cumulative Fair Value Hedging Adjustments (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Commodity
Assets
Carrying amount of the hedged items	$ 11,500	$ 6,500
Long-term debt
Liabilities
Carrying amount of the hedged items	177,611	157,545
Cumulative amount of fair value hedging adjustments included in the carrying amount of hedged items:
Active hedging relationships	3,194	6,719
Discontinued hedging relationships	11,473	161
Total	14,667	6,880
Long-term debt | Not designated as hedges
Liabilities
Carrying amount of the hedged items	6,600	2,800
Beneficial interests issued by consolidated VIEs
Liabilities
Carrying amount of the hedged items	746	2,365
Cumulative amount of fair value hedging adjustments included in the carrying amount of hedged items:
Active hedging relationships	0	0
Discontinued hedging relationships	(3)	(8)
Total	(3)	(8)
Investment securities - AFS
Assets
Carrying amount of the hedged items	139,684	125,860
Cumulative amount of fair value hedging adjustments included in the carrying amount of hedged items:
Active hedging relationships	3,572	2,110
Discontinued hedging relationships	847	278
Total	4,419	2,388
Investment securities - AFS | Not designated as hedges
Assets
Carrying amount of the hedged items	$ 14,500	$ 14,900