Fair Value Measurement and Election - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Estimated Fair Value of Loan Portfolio's Net Carrying Value, Percentage		101.00%		101.00%
Assets		$ 205,642		$ 204,875
Loans Receivable, Fair Value Disclosure		221		222
Allowance for Loan and Lease Losses, Write-offs		146	$ 112
Unfunded loan commitments and letters of credit		64,200		67,200
Allowance for unfunded loan commitments and letters of credit		73		71
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		2,100
Interest Rate Lock Commitments [Member]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		36	29
Trading Account Assets [Member] | Commercial and Corporate Leveraged Loans [Member] | Fair Value, Inputs, Level 2 [Member]
Loans Receivable, Fair Value Disclosure		459		356
Loans Held For Sale [Member]
Loans Receivable, Fair Value Disclosure		1,819		3,540
Commercial and Corporate Loans [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Assets				185
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		221		222
Lease Agreements [Member] | Fair Value, Measurements, Nonrecurring [Member] | Other Assets [Member]
Asset Impairment Charges				12
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		2
Other Assets [Member] | Fair Value, Measurements, Nonrecurring [Member]
Asset Impairment Charges		5		36
Building [Member] | Fair Value, Measurements, Nonrecurring [Member] | Other Assets [Member]
Asset Impairment Charges		$ 5		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 18, "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.