Derivative Instruments - Additional Information (Detail) (USD $)			3 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2013 Scenario, Forecast [Member]	Sep. 30, 2014 Scenario, Forecast [Member]
Derivative [Line Items]
Realized and unrealized losses on derivatives classified as cash flow hedges recorded in other comprehensive income (loss)	$ 294,000,000	$ 404,000,000
Estimated loss to be reclassified from other comprehensive income (loss) into earnings			30,000,000	116,000,000
Carrying amount of non-derivative debt instruments designated as net investment hedges	0	0
Fair value of derivatives under collateral agreements in a net liability position	1,100,000,000
Collateral posted by company netted against net liability position	862,000,000
Forward commitments to sell mortgage loans	6,200,000,000
Hedged mortgage loans held for sale	3,100,000,000
Unfunded mortgage loan commitments	$ 4,200,000,000