Fair Value (Tables)

6 Months Ended

Jun. 30, 2013

Financial Assets Measured at Fair Value on Recurring Basis

The following table summarizes our fair value measurements at June 30, 2013 and December 31, 2012, respectively, for financial assets measured at fair value on a recurring basis:

			Fair Value Measurements Using
	Fair Value		Quoted Prices in Active Markets (Level 1)		Other Observable Inputs (Level 2)		Unobservable Inputs (Level 3)
	(in millions)
June 30, 2013
Cash equivalents	$	1,410	$	1,410	$	0	$	0
Debt securities:
U.S. Treasury and other U.S. government corporations and agencies:
U.S. Treasury and agency obligations		571		0		571		0
Mortgage-backed securities		1,440		0		1,440		0
Tax-exempt municipal securities		3,028		0		3,015		13
Mortgage-backed securities:
Residential		28		0		28		0
Commercial		573		0		573		0
Asset-backed securities		53		0		52		1
Corporate debt securities		3,633		0		3,611		22
Total debt securities		9,326		0		9,290		36
Total invested assets	$	10,736	$	1,410	$	9,290	$	36
December 31, 2012
Cash equivalents	$	1,177	$	1,177	$	0	$	0
Debt securities:
U.S. Treasury and other U.S. government corporations and agencies:
U.S. Treasury and agency obligations		618		0		618		0
Mortgage-backed securities		1,603		0		1,603		0
Tax-exempt municipal securities		3,071		0		3,058		13
Mortgage-backed securities:
Residential		34		0		34		0
Commercial		659		0		659		0
Asset-backed securities		68		0		67		1
Corporate debt securities		3,794		0		3,770		24
Total debt securities		9,847		0		9,809		38
Total invested assets	$	11,024	$	1,177	$	9,809	$	38

Changes in Fair Value of Assets Measured Using Significant Unobservable Inputs

During the three and six months ended June 30, 2013 and 2012, the changes in the fair value of the assets measured using significant unobservable inputs (Level 3) were comprised of the following:

	For the three months ended June 30,
	2013								2012
	Private Placements/ Venture Capital			Auction Rate Securities		Total			Private Placements/ Venture Capital		Auction Rate Securities		Total
	(in millions)
Balance at April 1	$	25		$	13	$	38		$	25	$	15	$	40
Total gains or losses:
Realized in earnings		0			0		0			0		0		0
Unrealized in other comprehensive income		(2	)		0		(2	)		0		0		0
Purchases		0			0		0			0		0		0
Sales		0			0		0			0		0		0
Settlements		0			0		0			0		0		0
Balance at June 30	$	23		$	13	$	36		$	25	$	15	$	40

	For the six months ended June 30,
	2013								2012
	Private Placements/ Venture Capital			Auction Rate Securities		Total			Private Placements/ Venture Capital		Auction Rate Securities			Total
	(in millions)
Balance at January 1	$	25		$	13	$	38		$	25	$	16		$	41
Total gains or losses:
Realized in earnings		0			0		0			0		0			0
Unrealized in other comprehensive income		(1	)		0		(1	)		0		0			0
Purchases		0			0		0			0		0			0
Sales		0			0		0			0		(1	)		(1	)
Settlements		(1	)		0		(1	)		0		0			0
Balance at June 30	$	23		$	13	$	36		$	25	$	15		$	40