Loans and Allowance for Loan Losses - Loan Losses and Related Loan Balances by Portfolio Segment (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for loan losses:
Individually evaluated for impairment	$ 114	$ 34
Individually evaluated for impairment		34
Collectively evaluated for impairment	606	500
Allowance for credit losses purchased credit-impaired loans	1	3
Total allowance for loan losses	721	537	$ 568	$ 653
Loans held for investment:
Individually evaluated for impairment	833	503
Individually evaluated for impairment		503
Collectively evaluated for impairment	76,431	75,777
Financing Receivable Acquired with Deteriorated Credit Quality Net Not Individually Or Collectively Evaluated for Impairment1	335	524
Total loans held for investment	77,599	76,804
Loans and Leases Receivable Net of Deferred Income and Purchased Credit Impaired Loans	77,263	76,279
Commercial portfolio
Allowance for loan losses:
Individually evaluated for impairment	101	18
Individually evaluated for impairment		18
Collectively evaluated for impairment	550	447
Allowance for credit losses purchased credit-impaired loans	0	0
Total allowance for loan losses	651	465	421	418
Loans held for investment:
Individually evaluated for impairment	525	164
Individually evaluated for impairment		164
Collectively evaluated for impairment	46,143	44,021
Financing Receivable Acquired with Deteriorated Credit Quality Net Not Individually Or Collectively Evaluated for Impairment1	0	0
Total loans held for investment	46,668	44,185
Loans and Leases Receivable Net of Deferred Income and Purchased Credit Impaired Loans	46,668	44,185
Consumer portfolio
Allowance for loan losses:
Individually evaluated for impairment	13	16
Individually evaluated for impairment		16
Collectively evaluated for impairment	36	33
Allowance for credit losses purchased credit-impaired loans	0	0
Total allowance for loan losses	49	49	69	124
Loans held for investment:
Individually evaluated for impairment	307	338
Individually evaluated for impairment		338
Collectively evaluated for impairment	30,288	31,756
Financing Receivable Acquired with Deteriorated Credit Quality Net Not Individually Or Collectively Evaluated for Impairment1	0	0
Total loans held for investment		32,094
Loans and Leases Receivable Net of Deferred Income and Purchased Credit Impaired Loans	30,595	32,094
Purchased credit-impaired loans
Allowance for loan losses:
Individually evaluated for impairment	0	0
Individually evaluated for impairment		0
Collectively evaluated for impairment	0	0
Allowance for credit losses purchased credit-impaired loans	1	3
Total allowance for loan losses	1	3	1	1
Loans held for investment:
Individually evaluated for impairment	1	1
Individually evaluated for impairment		1
Collectively evaluated for impairment	0	0
Financing Receivable Acquired with Deteriorated Credit Quality Net Not Individually Or Collectively Evaluated for Impairment1	335	524
Total loans held for investment		525
Unallocated portfolio
Allowance for loan losses:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	20	20
Allowance for credit losses purchased credit-impaired loans	0	0
Total allowance for loan losses	20	20	$ 77	$ 110
Loans held for investment:
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	0	0
Financing Receivable Acquired with Deteriorated Credit Quality Net Not Individually Or Collectively Evaluated for Impairment1	0	0
Total loans held for investment	0	0
Purchased credit-impaired loans
Loans held for investment:
Loans and Leases Receivable Net of Deferred Income and Purchased Credit Impaired Loans	$ 336	$ 525

The valuation allowance for financing receivables acquired with deteriorated credit quality.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes purchased credit impaired loans.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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