Available-For-Sale Securities (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Less than 12 months
Fair Value	$ 35		$ 35		$ 164
Unrealized Losses	3		3		8
12 months or more
Fair Value	56		56		53
Unrealized Losses	10		10		10
Total
Fair Value	91		91		217
Unrealized Losses	13		13		18
Pretax charges recognized for "other-than-temporary" declines in the market values of equities securities	1	0	1	0
Corporate bonds
Less than 12 months
Fair Value					54
Unrealized Losses					1
12 months or more
Fair Value					1
Unrealized Losses					0
Total
Fair Value					55
Unrealized Losses					1
Asset-backed Securities
Less than 12 months
Fair Value	3		3		1
Unrealized Losses	0		0		0
12 months or more
Fair Value	19		19		20
Unrealized Losses	4		4		5
Total
Fair Value	22		22		21
Unrealized Losses	4		4		5
U.S. governmental agency mortgage-backed securities
Less than 12 months
Fair Value					51
Unrealized Losses					1
12 months or more
Fair Value					0
Unrealized Losses					0
Total
Fair Value					51
Unrealized Losses					1
Residential
Less than 12 months
Fair Value	2		2		3
Unrealized Losses	0		0		0
12 months or more
Fair Value	15		15		18
Unrealized Losses	3		3		3
Total
Fair Value	17		17		21
Unrealized Losses	3		3		3
Commercial
Less than 12 months
Fair Value	2		2		15
Unrealized Losses	0		0		0
12 months or more
Fair Value	8		8		8
Unrealized Losses	1		1		1
Total
Fair Value	10		10		23
Unrealized Losses	1		1		1
Large capitalization value
Less than 12 months
Fair Value	28		28		36
Unrealized Losses	3		3		5
12 months or more
Fair Value	14		14		6
Unrealized Losses	2		2		1
Total
Fair Value	42		42		42
Unrealized Losses	5		5		6
Smaller company growth
Less than 12 months
Fair Value					4
Unrealized Losses					1
12 months or more
Fair Value					0
Unrealized Losses					0
Total
Fair Value					4
Unrealized Losses					$ 1