Investments (Fair Values And Gross Unrealized Losses By Credit Rating Category Of Asset Backed Securities) (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	$ 1,558	$ 2,387
Total, Unrealized Losses	(226)	(478)
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	288
Total, Unrealized Losses	(119)
Asset-Backed Securities [Member] | ABS CDO [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	32
Total, Unrealized Losses	(55)
Asset-Backed Securities [Member] | Corporate CDO [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	205
Total, Unrealized Losses	(57)
Asset-Backed Securities [Member] | Auto Loans [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	2
Asset-Backed Securities [Member] | Credit Card [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	2
Asset-Backed Securities [Member] | Small Business/ Student Loans [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	16
Asset-Backed Securities [Member] | Other ABS [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	31
Total, Unrealized Losses	(7)
Aaa [Member] | Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	50
Total, Unrealized Losses	(3)
Aaa [Member] | Asset-Backed Securities [Member] | ABS CDO [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	5
Aaa [Member] | Asset-Backed Securities [Member] | Corporate CDO [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	36
Total, Unrealized Losses	(3)
Aaa [Member] | Asset-Backed Securities [Member] | Credit Card [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	2
Aaa [Member] | Asset-Backed Securities [Member] | Small Business/ Student Loans [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	5
Aaa [Member] | Asset-Backed Securities [Member] | Other ABS [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	2
Aa [Member] | Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	72
Total, Unrealized Losses	(10)
Aa [Member] | Asset-Backed Securities [Member] | ABS CDO [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	5
Aa [Member] | Asset-Backed Securities [Member] | Corporate CDO [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	63
Total, Unrealized Losses	(10)
Aa [Member] | Asset-Backed Securities [Member] | Other ABS [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	4
A [Member] | Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	26
Total, Unrealized Losses	(3)
A [Member] | Asset-Backed Securities [Member] | ABS CDO [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	6
A [Member] | Asset-Backed Securities [Member] | Corporate CDO [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	16
Total, Unrealized Losses	(3)
A [Member] | Asset-Backed Securities [Member] | Other ABS [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	4
Baa [Member] | Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	6
Total, Unrealized Losses	(4)
Baa [Member] | Asset-Backed Securities [Member] | ABS CDO [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	1
Total, Unrealized Losses	(3)
Baa [Member] | Asset-Backed Securities [Member] | Corporate CDO [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	1
Baa [Member] | Asset-Backed Securities [Member] | Other ABS [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	4
Total, Unrealized Losses	(1)
Below Investment Grade [Member] | Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	124
Total, Unrealized Losses	(94)
Below Investment Grade [Member] | Asset-Backed Securities [Member] | ABS CDO [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	15
Total, Unrealized Losses	(52)
Below Investment Grade [Member] | Asset-Backed Securities [Member] | Corporate CDO [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	88
Total, Unrealized Losses	(40)
Below Investment Grade [Member] | Asset-Backed Securities [Member] | Small Business/ Student Loans [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	11
Below Investment Grade [Member] | Asset-Backed Securities [Member] | Other ABS [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	10
Total, Unrealized Losses	(2)
Not Rated [Member] | Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	10
Total, Unrealized Losses	(5)
Not Rated [Member] | Asset-Backed Securities [Member] | Corporate CDO [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	1
Total, Unrealized Losses	(1)
Not Rated [Member] | Asset-Backed Securities [Member] | Auto Loans [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	2
Not Rated [Member] | Asset-Backed Securities [Member] | Other ABS [Member]
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	7
Total, Unrealized Losses	$ (4)