Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Millions		Mar. 31, 2018		Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	[1]	$ 5,112		$ 5,093
Available-for-sale Securities	[2],[3]	30,934		30,947	[4]
Loans Held-for-sale, Fair Value Disclosure		1,428		1,577
Loans Receivable, Fair Value Disclosure		188		196
Other Assets, Fair Value Disclosure				56
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		485		608
Available-for-sale Securities		4,340		4,331
Loans Held-for-sale, Fair Value Disclosure		0		0
Other Assets, Fair Value Disclosure		143		56
Trading Liabilities, Fair Value Disclosure		841		769
Long-term Debt, Fair Value		0		0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		4,610		4,469
Available-for-sale Securities		26,594		26,544
Loans Held-for-sale, Fair Value Disclosure		2,348		2,239
Other Assets, Fair Value Disclosure		0		0
Trading Liabilities, Fair Value Disclosure		880		498
Long-term Debt, Fair Value		9,631		8,834
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		17		16
Available-for-sale Securities		0		72
Loans Held-for-sale, Fair Value Disclosure		41		54
Other Assets, Fair Value Disclosure		418		418
Trading Liabilities, Fair Value Disclosure		16		16
Long-term Debt, Fair Value		1,112		1,058
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		5,112		5,093
Available-for-sale Securities		30,934	[5]	30,947	[6]
Loans Held-for-sale, Fair Value Disclosure		1,428		1,577
Loans Receivable, Fair Value Disclosure		188		196
Servicing Asset at Fair Value, Amount		1,916		1,710
Other Assets, Fair Value Disclosure		143	[5]	56	[6]
Trading Liabilities, Fair Value Disclosure		1,737		1,283
Long-term Debt, Fair Value		209		530
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		485		608
Available-for-sale Securities		4,340	[5]	4,331	[6]
Loans Held-for-sale, Fair Value Disclosure		0		0
Loans Receivable, Fair Value Disclosure		0		0
Servicing Asset at Fair Value, Amount		0		0
Other Assets, Fair Value Disclosure		143	[5]	56	[6]
Trading Liabilities, Fair Value Disclosure		841		769
Deposits, Fair Value Disclosure		0		0
Long-term Debt, Fair Value		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		7,027		7,571
Available-for-sale Securities		26,594	[5]	26,544	[6]
Loans Held-for-sale, Fair Value Disclosure		1,428		1,577
Loans Receivable, Fair Value Disclosure		0		0
Servicing Asset at Fair Value, Amount		0		0
Other Assets, Fair Value Disclosure		0	[5]	0	[6]
Trading Liabilities, Fair Value Disclosure		3,805		4,532
Deposits, Fair Value Disclosure		302		236
Long-term Debt, Fair Value		209		530
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		17		16
Available-for-sale Securities		0	[5]	72	[6]
Loans Held-for-sale, Fair Value Disclosure		0		0
Loans Receivable, Fair Value Disclosure		188		196
Servicing Asset at Fair Value, Amount		1,916		1,710
Other Assets, Fair Value Disclosure		0	[5]	0	[6]
Trading Liabilities, Fair Value Disclosure		16		16
Deposits, Fair Value Disclosure		0		0
Long-term Debt, Fair Value		0		0
US Treasury Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		182		157
Available-for-sale Securities		4,340		4,331
Trading Liabilities, Fair Value Disclosure		698		577
US Treasury Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Available-for-sale Securities		0		0
Trading Liabilities, Fair Value Disclosure		0		0
US Treasury Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Available-for-sale Securities		0		0
Trading Liabilities, Fair Value Disclosure		0		0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Liabilities, Fair Value Disclosure		0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Liabilities, Fair Value Disclosure		1
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Liabilities, Fair Value Disclosure		0
US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Available-for-sale Securities		0		0
US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		238		395
Available-for-sale Securities		249		259
US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Available-for-sale Securities		0		0
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Available-for-sale Securities		0		0
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		123		61
Available-for-sale Securities		636		617
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Available-for-sale Securities		0		0
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Available-for-sale Securities		0		0
Trading Liabilities, Fair Value Disclosure		0		0
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		804		655
Available-for-sale Securities		16		12
Trading Liabilities, Fair Value Disclosure		453		289
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Available-for-sale Securities		0		5
Trading Liabilities, Fair Value Disclosure		0		0
Commercial Paper [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Commercial Paper [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		169		118
Commercial Paper [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		51		56
Trading Liabilities, Fair Value Disclosure		5		9
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Trading Liabilities, Fair Value Disclosure		0		0
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Trading Liabilities, Fair Value Disclosure		0		0
Derivative Financial Instruments, Assets [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		657		802
Derivative Financial Instruments, Assets [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		252		395
Derivative Financial Instruments, Assets [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		2,805		3,493
Derivative Financial Instruments, Assets [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		17		16
Trading Loans [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Trading Loans [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		2,189		2,149
Trading Loans [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		0		0
Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		7		0
Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		0		8
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Liabilities, Fair Value Disclosure		580		408
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Liabilities, Fair Value Disclosure		138		183
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Liabilities, Fair Value Disclosure		3,351		4,243
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Liabilities, Fair Value Disclosure		16		16
Brokered Time Deposits [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits, Fair Value Disclosure		302		236
Estimate of Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		5,112		5,093
Available-for-sale Securities		30,934		30,947
Loans Held-for-sale, Fair Value Disclosure		2,389		2,293
Other Assets, Fair Value Disclosure		561		474
Trading Liabilities, Fair Value Disclosure		1,737		1,283
Long-term Debt, Fair Value		10,743		9,892
Estimate of Fair Value Measurement [Member] | US Treasury Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		182		157
Available-for-sale Securities		4,340		4,331
Trading Liabilities, Fair Value Disclosure		698		577
Estimate of Fair Value Measurement [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Liabilities, Fair Value Disclosure		1
Estimate of Fair Value Measurement [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		238		395
Available-for-sale Securities		249		259
Estimate of Fair Value Measurement [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		123		61
Available-for-sale Securities		636		617
Estimate of Fair Value Measurement [Member] | Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		804		655
Available-for-sale Securities		16		17
Trading Liabilities, Fair Value Disclosure		453		289
Estimate of Fair Value Measurement [Member] | Commercial Paper [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		169		118
Estimate of Fair Value Measurement [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		51		56
Trading Liabilities, Fair Value Disclosure		5		9
Estimate of Fair Value Measurement [Member] | Trading Loans [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		2,189		2,149
Estimate of Fair Value Measurement [Member] | Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		7		8
Reported Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		5,112		5,093
Available-for-sale Securities		30,934		30,947
Loans Held-for-sale, Fair Value Disclosure		2,377		2,290
Other Assets, Fair Value Disclosure		561		474
Trading Liabilities, Fair Value Disclosure		1,737		1,283
Long-term Debt, Fair Value		10,692		9,785
Netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		(2,417)	[7]	(3,102)	[8]
Trading Liabilities, Fair Value Disclosure		(2,925)	[7]	(4,034)	[8]
Netting [Member] | Derivative Financial Instruments, Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		(2,417)	[7]	(3,102)	[8]
Netting [Member] | Derivative Financial Instruments, Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Liabilities, Fair Value Disclosure		(2,925)	[7]	(4,034)	[8]
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		699		700
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		699		700
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0		0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		22,513		22,704
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		0		0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		22,513		22,704
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		0		0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		2,242		2,086
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		0		0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		2,242		2,086
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		0		0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		699		700
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Estimate of Fair Value Measurement [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		22,513		22,704
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Estimate of Fair Value Measurement [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		2,242		2,086
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		57		59
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		0		0
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		57		0
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		0		59
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		874		866
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		0		0
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		874		866
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		0		0
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Estimate of Fair Value Measurement [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		57		59
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Estimate of Fair Value Measurement [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		$ 874		$ 866

[1] Includes trading securities pledged as collateral where counterparties have the right to sell or repledge the collateral of $1,248 million and $1,086 million at March 31, 2018 and December 31, 2017, respectively.

[2] Includes securities AFS pledged as collateral where counterparties have the right to sell or repledge the collateral of $214 million and $223 million at March 31, 2018 and December 31, 2017, respectively.

[3] Text selection found with no content.

[4] Beginning January 1, 2018, the Company reclassified equity securities previously presented in Securities available for sale to Other assets on the Consolidated Balance Sheets. Reclassifications have been made to previously reported amounts for comparability. See Note 9, "Other Assets," for additional information.

[5] Beginning January 1, 2018, the Company reclassified equity securities previously presented in Securities available for sale to Other assets on the Consolidated Balance Sheets. Reclassifications have been made to previously reported amounts for comparability. See Note 9, "Other Assets," for additional information.

[6] Beginning January 1, 2018, the Company reclassified equity securities previously presented in Securities available for sale to Other assets on the Consolidated Balance Sheets. Reclassifications have been made to previously reported amounts for comparability. See Note 9, "Other Assets," for additional information.

[7] Amounts represent offsetting cash collateral received from, and paid to, the same derivative counterparties, and the impact of netting derivative assets and derivative liabilities when a legally enforceable master netting agreement or similar agreement exists. See Note 15, "Derivative Financial Instruments," for additional information.

[8] Amounts represent offsetting cash collateral received from, and paid to, the same derivative counterparties, and the impact of netting derivative assets and derivative liabilities when a legally enforceable master netting agreement or similar agreement exists. See Note 15, "Derivative Financial Instruments," for additional information.