Derivatives and Hedging Activities - Credit Derivatives (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	$ 1,414,045,000,000	$ 1,434,396,000,000
Maximum Payout/Notional Amount of Purchased Credit Derivatives	1,490,000,000,000	1,520,000,000,000
Fair Value Asset of Written Credit Derivatives	35,580,000,000	35,960,000,000
Fair Value Liability of Written Credit Derivatives	18,097,000,000	19,741,000,000
Fair Value Net Asset/(Liability) of Written Credit Derivatives	17,483,000,000	16,219,000,000
Offsetting Purchased Credit Derivatives [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	1,280,540,000,000	1,306,234,000,000
Other Purchased Credit Derivatives [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	213,062,000,000	209,710,000,000
0-250 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	1,309,808,000,000	1,315,396,000,000
Fair Value Asset of Written Credit Derivatives	32,185,000,000	32,508,000,000
Fair Value Liability of Written Credit Derivatives	4,644,000,000	4,396,000,000
Fair Value Net Asset/(Liability) of Written Credit Derivatives	27,541,000,000	28,112,000,000
0-250 [Member] | Offsetting Purchased Credit Derivatives [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	1,198,445,000,000	1,208,334,000,000
0-250 [Member] | Other Purchased Credit Derivatives [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	190,998,000,000	183,665,000,000
251-500 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	50,787,000,000	59,804,000,000
Fair Value Asset of Written Credit Derivatives	2,816,000,000	2,837,000,000
Fair Value Liability of Written Credit Derivatives	693,000,000	1,147,000,000
Fair Value Net Asset/(Liability) of Written Credit Derivatives	2,123,000,000	1,690,000,000
251-500 [Member] | Offsetting Purchased Credit Derivatives [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	34,145,000,000	44,642,000,000
251-500 [Member] | Other Purchased Credit Derivatives [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	12,482,000,000	16,884,000,000
501-1000 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	21,181,000,000	24,459,000,000
Fair Value Asset of Written Credit Derivatives	286,000,000	101,000,000
Fair Value Liability of Written Credit Derivatives	1,595,000,000	1,762,000,000
Fair Value Net Asset/(Liability) of Written Credit Derivatives	(1,309,000,000)	(1,661,000,000)
501-1000 [Member] | Offsetting Purchased Credit Derivatives [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	17,939,000,000	22,748,000,000
501-1000 [Member] | Other Purchased Credit Derivatives [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	5,381,000,000	2,992,000,000
Greater than 1000 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	32,269,000,000	34,737,000,000
Fair Value Asset of Written Credit Derivatives	293,000,000	514,000,000
Fair Value Liability of Written Credit Derivatives	11,165,000,000	12,436,000,000
Fair Value Net Asset/(Liability) of Written Credit Derivatives	(10,872,000,000)	(11,922,000,000)
Greater than 1000 [Member] | Offsetting Purchased Credit Derivatives [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	30,011,000,000	30,510,000,000
Greater than 1000 [Member] | Other Purchased Credit Derivatives [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Purchased Credit Derivatives	4,201,000,000	6,169,000,000
0-12 Months [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	291,270,000,000	302,745,000,000
0-12 Months [Member] | 0-250 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	272,975,000,000	286,029,000,000
0-12 Months [Member] | 251-500 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	9,569,000,000	7,148,000,000
0-12 Months [Member] | 501-1000 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	3,133,000,000	3,968,000,000
0-12 Months [Member] | Greater than 1000 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	5,593,000,000	5,600,000,000
1-5 Years [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	1,005,951,000,000	1,039,244,000,000
1-5 Years [Member] | 0-250 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	933,487,000,000	950,126,000,000
1-5 Years [Member] | 251-500 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	30,888,000,000	42,570,000,000
1-5 Years [Member] | 501-1000 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	16,202,000,000	18,637,000,000
1-5 Years [Member] | Greater than 1000 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	25,374,000,000	27,911,000,000
5 Years or Greater [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	116,824,000,000	92,407,000,000
5 Years or Greater [Member] | 0-250 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	103,346,000,000	79,241,000,000
5 Years or Greater [Member] | 251-500 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	10,330,000,000	10,086,000,000
5 Years or Greater [Member] | 501-1000 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	1,846,000,000	1,854,000,000
5 Years or Greater [Member] | Greater than 1000 [Member]
Derivative [Line Items]
Maximum Payout/Notional Amount of Written Credit Derivative	$ 1,302,000,000	$ 1,226,000,000