Derivative Instruments - Cumulative Fair Value Hedging Adjustments (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Commodity contracts
Assets
Carrying amount of the hedged items	$ 20,100	$ 11,500
Long-term debt
Liabilities
Carrying amount of the hedged items	193,441	177,611
Cumulative amount of fair value hedging adjustments included in the carrying amount of hedged items:
Active hedging relationships	434	3,194
Discontinued hedging relationships	8,916	11,473
Total	9,350	14,667
Long-term debt | Not designated as hedges
Liabilities
Carrying amount of the hedged items	6,400	6,600
Beneficial interests issued by consolidated VIEs
Liabilities
Carrying amount of the hedged items	747	746
Cumulative amount of fair value hedging adjustments included in the carrying amount of hedged items:
Active hedging relationships	0	0
Discontinued hedging relationships	(2)	(3)
Total	(2)	(3)
Investment securities - AFS
Assets
Carrying amount of the hedged items	81,335	139,684
Cumulative amount of fair value hedging adjustments included in the carrying amount of hedged items:
Active hedging relationships	1,420	3,572
Discontinued hedging relationships	579	847
Total	1,999	4,419
Investment securities - AFS | Not designated as hedges
Assets
Carrying amount of the hedged items	$ 12,600	$ 14,500