Derivative Financial Instruments - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Fair value hedges which increase (decrease) the carrying amount of debt	$ 2,000,000	$ (8,000,000)
Amortized of basis adjustments related to fair value hedge relationships	14,000,000	12,000,000
Total accumulated unamortized increase in fair value of hedge	33,000,000	49,000,000
Increases (decreases) in fair value hedges is available for sale of securities	775,000,000	130,000,000
Increase in accumulated unamortized adjustments for fair value hedges as available-for-sale securities	84,000,000	836,000,000
Cash flow hedge relationships extend or mature	July 2036
Income (loss) related to cash flow hedge were amortized to earnings from accumulated other comprehensive income (loss)	(10,000,000)	(17,000,000)
Next twelve months, reclassification of remaining losses to earnings resulting from cash flow hedges	6,000,000
Aggregate fair value of all derivative instruments with credit-risk-related contingent	5,600,000,000	8,700,000,000
Collateral already posted aggregate fair value	5,100,000,000	7,900,000,000
Additional collateral aggregate fair value on return swap	6,000,000
Cash Flow Hedging [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Derivative [Line Items]
Income (loss) related to cash flow hedge were amortized to earnings from accumulated other comprehensive income (loss)	$ (10,000,000)	$ (17,000,000)