Loans and Allowance for Loan Losses - Aging of Balance of Loans Held for Investment By Class (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Aging of loans
Current		$ 87,861	$ 86,151
30 to 89 Days Past Due		339	258
90 Days or More Past Due		268	98
Total past due		607	356
Loans held for investment	[1]	88,468	86,507
Loans 90 days or more past due and still accruing		15	23
Commercial
Aging of loans
Current		43,579	43,040
30 to 89 Days Past Due		130	55
90 Days or More Past Due		218	40
Total past due		348	95
Loans held for investment		43,927	43,135
Consumer
Aging of loans
Current		44,282	43,111
30 to 89 Days Past Due		209	203
90 Days or More Past Due		50	58
Total past due		259	261
Loans held for investment		44,541	43,372
Home equity and other consumer loans | Consumer Loans
Aging of loans
Current		6,129	4,893
30 to 89 Days Past Due		31	28
90 Days or More Past Due		12	12
Total past due		43	40
Loans held for investment		6,172	4,933
Residential mortgage | Consumer Loans
Aging of loans
Current		38,153	38,218
30 to 89 Days Past Due		178	175
90 Days or More Past Due		38	46
Total past due		216	221
Loans held for investment		38,369	38,439
Commercial mortgage | Commercial Loans
Aging of loans
Current		15,753	15,333
30 to 89 Days Past Due		13	17
90 Days or More Past Due		3	4
Total past due		16	21
Loans held for investment		15,769	15,354
Commercial and industrial | Commercial Loans
Aging of loans
Current		26,170	26,114
30 to 89 Days Past Due		117	18
90 Days or More Past Due		215	36
Total past due		332	54
Loans held for investment		26,502	26,168
Construction | Commercial Loans
Aging of loans
Current		1,656	1,593
30 to 89 Days Past Due		0	20
90 Days or More Past Due		0	0
Total past due		0	20
Loans held for investment		$ 1,656	$ 1,613

[1] Includes $342 million and $340 million at June 30, 2019 and December 31, 2018, respectively, for net unamortized (discounts) and premiums and deferred (fees) and costs.