Derivative Positions (Additional Information) (Detail) - USD ($) shares in Millions, $ in Millions	1 Months Ended	3 Months Ended				6 Months Ended
	May. 31, 2009	Jun. 30, 2015		Jun. 30, 2014		Jun. 30, 2015		Jun. 30, 2014		Dec. 31, 2014
Not Designated as Hedging Instrument [Member] | Trading Activity
Asset Amount Notional From Purchased And Written Interest Rate Swap Risk Participation Agreements		$ 6				$ 6				$ 4
Notional Amount Liability Purchased And Written Interest Rate Swap Risk Participation Agreements		6				6				4
Derivative Financial Instruments, Assets | Not Designated as Hedging Instrument [Member] | Trading Activity
Notional Amount Of Interest Rate Future Derivatives		14,200				14,200				10,300
Notional related to equity futures		1,200				1,200				563
Derivative Financial Instruments, Liabilities [Member] | Not Designated as Hedging Instrument [Member]
Notional Amount Derivative Liability Sale Of Shares		49				49				49
Derivative Financial Instruments, Liabilities [Member] | Not Designated as Hedging Instrument [Member] | Future [Member]
Notional Amount Of Interest Rate Future Derivatives		654				654				$ 791
Derivative Financial Instruments, Liabilities [Member] | Visa Interest [Member] | Not Designated as Hedging Instrument [Member]
Number Of Shares Sold To Selected Financial Institutions	3.2
Interest Income (Expense), Net [Member]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		19		$ 27		38		$ 54
Floating Rate Loans [Member] | Cash Flow Hedging | Interest Income, Interest And Fees On Loans [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		44	[1]	74	[2]	79	[1]	149	[2]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net		$ 9	[1]	$ 44	[2]	$ 134		$ 67

[1] During the three and six months ended June 30, 2015, the Company also reclassified $19 million and $38 million, respectively, of pre-tax gains from AOCI into net interest income. These gains related to hedging relationships that have been terminated or de-designated and are reclassified into earnings consistent with the pattern of net cash flows expected to be recognized.

[2] During the three and six months ended June 30, 2014, the Company also reclassified $27 million and $54 million, respectively, of pre-tax gains from AOCI into net interest income. These gains related to hedging relationships that have been terminated or de-designated and are reclassified into earnings consistent with the pattern of net cash flows expected to be recognized.