Allowance for Loan and Lease Losses - Summary of Changes in Allowance for Loan and Lease Losses (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Allowance for Loan and Lease Losses [Roll Forward]
Balance as beginning of the period	$ 5,130
Balance at end of the period	5,416
Total Allowance
Allowance for Loan and Lease Losses [Roll Forward]
Balance as beginning of the period	5,130	$ 4,383
Provision for Loan and Lease Losses	1,469	927
Charge-offs	(1,562)	(1,284)
Recoveries	384	403
Net charge-offs	(1,178)	(881)
Other changes	(5)	(24)
Balance at end of the period	5,416	4,405
Unfunded Lending Commitments Reserve
Allowance for Loan and Lease Losses [Roll Forward]
Balance as beginning of the period	168	113
Provision for Loan and Lease Losses	58	8
Balance at end of the period	226	121
Combined Allowance & Unfunded Reserve
Allowance for Loan and Lease Losses [Roll Forward]
Balance at end of the period	5,642	4,526
Credit Card Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance as beginning of the period	3,654	3,204
Provision for Loan and Lease Losses	1,071	669
Charge-offs	(1,222)	(1,022)
Recoveries	272	303
Net charge-offs	(950)	(719)
Other changes	10	(24)
Balance at end of the period	3,785	3,130
Credit Card Portfolio Segment [Member] | Unfunded Lending Commitments Reserve
Allowance for Loan and Lease Losses [Roll Forward]
Balance as beginning of the period	0	0
Provision for Loan and Lease Losses	0	0
Balance at end of the period	0	0
Credit Card Portfolio Segment [Member] | Combined Allowance & Unfunded Reserve
Allowance for Loan and Lease Losses [Roll Forward]
Balance at end of the period	3,785	3,130
Consumer Portfolio Segment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance as beginning of the period	868	779
Provision for Loan and Lease Losses	229	206
Charge-offs	(291)	(250)
Recoveries	108	91
Net charge-offs	(183)	(159)
Other changes	0	0
Balance at end of the period	914	826
Consumer Portfolio Segment [Member] | Unfunded Lending Commitments Reserve
Allowance for Loan and Lease Losses [Roll Forward]
Balance as beginning of the period	7	7
Provision for Loan and Lease Losses	1	0
Balance at end of the period	8	7
Consumer Portfolio Segment [Member] | Combined Allowance & Unfunded Reserve
Allowance for Loan and Lease Losses [Roll Forward]
Balance at end of the period	922	833
Commercial Banking
Allowance for Loan and Lease Losses [Roll Forward]
Balance as beginning of the period	604	395
Provision for Loan and Lease Losses	171	52
Charge-offs	(48)	(9)
Recoveries	2	6
Net charge-offs	(46)	(3)
Other changes	(15)	0
Balance at end of the period	714	444
Commercial Banking | Unfunded Lending Commitments Reserve
Allowance for Loan and Lease Losses [Roll Forward]
Balance as beginning of the period	161	106
Provision for Loan and Lease Losses	57	8
Balance at end of the period	218	114
Commercial Banking | Combined Allowance & Unfunded Reserve
Allowance for Loan and Lease Losses [Roll Forward]
Balance at end of the period	932	558
Other
Allowance for Loan and Lease Losses [Roll Forward]
Balance as beginning of the period	4	5
Provision for Loan and Lease Losses	(2)	0
Charge-offs	(1)	(3)
Recoveries	2	3
Net charge-offs	1	0
Other changes	0	0
Balance at end of the period	3	5
Other | Unfunded Lending Commitments Reserve
Allowance for Loan and Lease Losses [Roll Forward]
Balance as beginning of the period	0	0
Provision for Loan and Lease Losses	0	0
Balance at end of the period	0	0
Other | Combined Allowance & Unfunded Reserve
Allowance for Loan and Lease Losses [Roll Forward]
Balance at end of the period	$ 3	$ 5