Securities with Unrealized Losses (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Investments, Unrealized Loss Position [Line Items]
Less than twelve months, Fair Value	$ 10,724		$ 1,511
Less than twelve months, Unrealized Losses	436		6
Twelve months or longer, Fair Value	915		40
Twelve months or longer, Unrealized Losses	98		8
Total, Fair Value	11,639		1,551
Total, Unrealized Losses	534		14
Temporarily Impaired Securities
Investments, Unrealized Loss Position [Line Items]
Less than twelve months, Fair Value	10,619		1,511
Less than twelve months, Unrealized Losses	434		6
Twelve months or longer, Fair Value	915		37
Twelve months or longer, Unrealized Losses	98		7
Total, Fair Value	11,534		1,548
Total, Unrealized Losses	532		13
Temporarily Impaired Securities | US Treasury Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than twelve months, Fair Value	1,036
Less than twelve months, Unrealized Losses	47
Twelve months or longer, Fair Value	0
Twelve months or longer, Unrealized Losses	0
Total, Fair Value	1,036
Total, Unrealized Losses	47
Temporarily Impaired Securities | US Government Agencies Debt Securities
Investments, Unrealized Loss Position [Line Items]
Less than twelve months, Fair Value	398		298
Less than twelve months, Unrealized Losses	29		3
Twelve months or longer, Fair Value	264		0
Twelve months or longer, Unrealized Losses	28		0
Total, Fair Value	662		298
Total, Unrealized Losses	57		3
Temporarily Impaired Securities | US States and Political Subdivisions Debt Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than twelve months, Fair Value	12		1
Less than twelve months, Unrealized Losses	0		0
Twelve months or longer, Fair Value	20		24
Twelve months or longer, Unrealized Losses	2		5
Total, Fair Value	32		25
Total, Unrealized Losses	2		5
Temporarily Impaired Securities | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Investments, Unrealized Loss Position [Line Items]
Less than twelve months, Fair Value	9,173		1,212
Less than twelve months, Unrealized Losses	358		3
Twelve months or longer, Fair Value	618		0
Twelve months or longer, Unrealized Losses	67		0
Total, Fair Value	9,791		1,212
Total, Unrealized Losses	425		3
Temporarily Impaired Securities | Asset-backed Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than twelve months, Fair Value	0		0
Less than twelve months, Unrealized Losses	0		0
Twelve months or longer, Fair Value	13		13
Twelve months or longer, Unrealized Losses	1		2
Total, Fair Value	13		13
Total, Unrealized Losses	1		2
Other Than Temporarily Impaired Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than twelve months, Fair Value	105	[1]	0	[1]
Less than twelve months, Unrealized Losses	2	[1]	0	[1]
Twelve months or longer, Fair Value	0	[1]	3	[1]
Twelve months or longer, Unrealized Losses	0	[1]	1	[1]
Total, Fair Value	105	[1]	3	[1]
Total, Unrealized Losses	2	[1]	1	[1]
Other Than Temporarily Impaired Securities [Member] | Asset-backed Securities [Member]
Investments, Unrealized Loss Position [Line Items]
Less than twelve months, Fair Value			0	[1]
Less than twelve months, Unrealized Losses			0	[1]
Twelve months or longer, Fair Value			3	[1]
Twelve months or longer, Unrealized Losses			1	[1]
Total, Fair Value			3	[1]
Total, Unrealized Losses			1	[1]
Other Than Temporarily Impaired Securities [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Investments, Unrealized Loss Position [Line Items]
Less than twelve months, Fair Value	105	[1]
Less than twelve months, Unrealized Losses	2	[1]
Twelve months or longer, Fair Value	0	[1]
Twelve months or longer, Unrealized Losses	0	[1]
Total, Fair Value	105	[1]
Total, Unrealized Losses	$ 2	[1]

[1] Includes OTTI securities for which credit losses have been recorded in earnings in current or prior periods.