Fair Value Measurement and Election - Additional Information (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Jun. 30, 2016
Carrying Amount of Loans held for investment Sold					$ 17	$ 185
Estimated Fair Value of Loan Portfolio's Net Carrying Value, Percentage		101.00%	101.00%
Assets		$ 204,875	$ 190,817
Loans Receivable, Fair Value Disclosure		222	257
Allowance for Loan and Lease Losses, Write-offs		591	470	$ 607
Unfunded loan commitments and letters of credit		67,200	66,200
Allowance for unfunded loan commitments and letters of credit		71	66
Cumulative effect of credit risk adjustment	[1]	0
Total Return Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Loans Receivable, Fair Value Disclosure		2,100	2,200
Interest Rate Lock Commitments [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		211	161
Trading Account Assets [Member] | Commercial and Corporate Leveraged Loans [Member] | Fair Value, Inputs, Level 2 [Member]
Loans Receivable, Fair Value Disclosure		356	356
Loans Held For Sale [Member]
Loans Receivable, Fair Value Disclosure		3,540	1,494
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Assets		185	525
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Loans Receivable, Fair Value Disclosure		0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Loans Receivable, Fair Value Disclosure		0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Loans Receivable, Fair Value Disclosure		222	257
Lease Agreements [Member] | Fair Value, Measurements, Nonrecurring [Member] | Other Assets [Member]
Asset Impairment Charges		12	6
Equity Method Investments [Member] | Fair Value, Measurements, Nonrecurring [Member] | Other Assets [Member]
Asset Impairment Charges		8
Other Real Estate Owned [Member] | Fair Value, Measurements, Nonrecurring [Member]
Asset Impairment Charges		2	4
Other Assets [Member] | Fair Value, Measurements, Nonrecurring [Member]
Asset Impairment Charges		36	$ 6
Building [Member] | Fair Value, Measurements, Nonrecurring [Member] | Other Assets [Member]
Asset Impairment Charges		12
Land [Member] | Fair Value, Measurements, Nonrecurring [Member] | Other Assets [Member]
Asset Impairment Charges		4
AOCI Attributable to Parent [Member]
Cumulative effect of credit risk adjustment	[1],[2]	$ (5)

[1] Related to the Company's early adoption of the ASU 2016-01 provision related to changes in instrument-specific credit risk, beginning January 1, 2016. See Note 1, "Significant Accounting Policies," and Note 21, "Accumulated Other Comprehensive (Loss)/Income," for additional information.

[2] Related to the Company's early adoption of the ASU 2016-01 provision related to changes in instrument-specific credit risk. See Note 1, "Significant Accounting Policies," for additional information.