FAIR VALUE (Tables)

9 Months Ended

Sep. 30, 2015

Fair Value Disclosures [Abstract]

Financial Assets Measured at Fair Value on Recurring Basis

The following table summarizes our fair value measurements at September 30, 2015 and December 31, 2014, 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)
September 30, 2015
Cash equivalents	$	1,459	$	1,459	$	—	$	—
Debt securities:
U.S. Treasury and other U.S. government corporations and agencies:
U.S. Treasury and agency obligations	328		—		328		—
Mortgage-backed securities	1,567		—		1,567		—
Tax-exempt municipal securities	2,751		—		2,746		5
Mortgage-backed securities:
Residential	13		—		13
Commercial	1,031		—		1,031		—
Asset-backed securities	273		—		272		1
Corporate debt securities	3,339		—		3,334		5
Total debt securities	9,302		—		9,291		11
Total invested assets	$	10,761	$	1,459	$	9,291	$	11
December 31, 2014
Cash equivalents	$	1,712	$	1,712	$	—	$	—
Debt securities:
U.S. Treasury and other U.S. government corporations and agencies:
U.S. Treasury and agency obligations	374		—		374		—
Mortgage-backed securities	1,498		—		1,498		—
Tax-exempt municipal securities	3,068		—		3,060		8
Mortgage-backed securities:
Residential	17		—		17		—
Commercial	843		—		843		—
Asset-backed securities	29		—		28		1
Corporate debt securities	3,718		—		3,695		23
Total debt securities	9,547		—		9,515		32
Total invested assets	$	11,259	$	1,712	$	9,515	$	32

Changes in Fair Value of Assets Measured Using Significant Unobservable Inputs

During the three and nine months ended September 30, 2015 and 2014, 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 September 30,
	2015									2014
	Private Placements			Auction Rate Securities			Total			Private Placements		Auction Rate Securities		Total
	(in millions)
Beginning balance at July 1	$	6		$	5		$	11		$	24	$	13	$	37
Total gains or losses:
Realized in earnings	—			—			—			—		—		—
Unrealized in other comprehensive income	—			—			—			1		—		1
Purchases	—			—			—			—		—		—
Sales	—			—			—			—		—		—
Settlements	—			—			—			—		—		—
Balance at September 30	$	6		$	5		$	11		$	25	$	13	$	38
	For the nine months ended September 30,
	2015									2014
	Private Placements			Auction Rate Securities			Total			Private Placements		Auction Rate Securities		Total
	(in millions)
Beginning balance at January 1	$	24		$	8		$	32		$	24	$	13	$	37
Total gains or losses:
Realized in earnings	(1		)	—			(1		)	—		—		—
Unrealized in other comprehensive income	—			—			—			1		—		1
Purchases	—			—			—			—		—		—
Sales	(17		)	(3		)	(20		)	—		—		—
Settlements	—			—			—			—		—		—
Balance at September 30	$	6		$	5		$	11		$	25	$	13	$	38