Loans and Allowance for Loan Losses - Aging of Balance of Loans Held for Investment By Class (Details) - USD ($) $ in Millions		Mar. 31, 2019	Dec. 31, 2018
Aging of loans
Current		$ 87,086	$ 86,151
30 to 89 Days Past Due		417	258
90 Days or More Past Due		84	98
Total past due		501	356
Loans held for investment	[1]	87,587	86,507
Loans 90 days or more past due and still accruing		13	23
Commercial
Aging of loans
Current		43,339	43,040
30 to 89 Days Past Due		247	55
90 Days or More Past Due		29	40
Total past due		276	95
Loans held for investment		43,615	43,135
Consumer
Aging of loans
Current		43,747	43,111
30 to 89 Days Past Due		170	203
90 Days or More Past Due		55	58
Total past due		225	261
Loans held for investment		43,972	43,372
Home equity and other consumer loans | Consumer Loans
Aging of loans
Current		5,491	4,893
30 to 89 Days Past Due		29	28
90 Days or More Past Due		13	12
Total past due		42	40
Loans held for investment		5,533	4,933
Residential mortgage | Consumer Loans
Aging of loans
Current		38,256	38,218
30 to 89 Days Past Due		141	175
90 Days or More Past Due		42	46
Total past due		183	221
Loans held for investment		38,439	38,439
Commercial mortgage | Commercial Loans
Aging of loans
Current		15,273	15,333
30 to 89 Days Past Due		22	17
90 Days or More Past Due		4	4
Total past due		26	21
Loans held for investment		15,299	15,354
Commercial and industrial | Commercial Loans
Aging of loans
Current		26,381	26,114
30 to 89 Days Past Due		220	18
90 Days or More Past Due		24	36
Total past due		244	54
Loans held for investment		26,625	26,168
Construction | Commercial Loans
Aging of loans
Current		1,685	1,593
30 to 89 Days Past Due		5	20
90 Days or More Past Due		1	0
Total past due		6	20
Loans held for investment		$ 1,691	$ 1,613

[1] Includes $343 million and $340 million at March 31, 2019 and December 31, 2018, respectively, for net unamortized (discounts) and premiums and deferred (fees) and costs.