Short-term and Long-term Investments, Restricted Deposits (Tables)

12 Months Ended

Dec. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Short-term and long-term investments and restricted deposits by investment type

Short-term and long-term investments and restricted deposits by investment type consist of the following ($ in millions):



	December 31, 2018									December 31, 2017
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	362	$	1	$	(2	)	$	361	$	311	$	—	$	(2	)	$	309
Corporate securities	3,190		8		(52		)	3,146		2,208		12		(10		)	2,210
Restricted certificates of deposit	433		—		—			433		4		—		—			4
Restricted cash equivalents	8		—		—			8		17		—		—			17
Municipal securities	2,196		9		(18		)	2,187		2,085		12		(10		)	2,087
Asset-backed securities	686		1		(4		)	683		437		1		(1		)	437
Residential mortgage-backed securities	452		1		(9		)	444		337		1		(6		)	332
Commercial mortgage- backed securities	366		1		(6		)	361		272		1		(2		)	271
Private equity investments	387		—		—			387		176		—		—			176
Life insurance contracts	128		—		—			128		135		—		—			135
Total	$	8,208	$	21	$	(91	)	$	8,138	$	5,982	$	27	$	(31	)	$	5,978

Schedule of available-for-sale investments in a continuous unrealized loss position

The fair value of available-for-sale debt securities with gross unrealized losses by investment type and length of time that individual securities have been in a continuous unrealized loss position were as follows ($ in millions):



	December 31, 2018										December 31, 2017
	Less Than 12 Months					12 Months or More					Less Than 12 Months					12 Months or More
	Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value
U.S. Treasury securities and obligations of U.S. government corporations and agencies	$	—		$	59	$	(2	)	$	202	$	(1	)	$	222	$	(1	)	$	79
Corporate securities	(27		)	1,389		(25		)	871		(6		)	1,044		(4		)	185
Municipal securities	(4		)	591		(14		)	806		(7		)	943		(3		)	175
Asset-backed securities	(2		)	318		(2		)	168		(1		)	228		—			28
Residential mortgage- backed securities	(1		)	61		(8		)	233		(1		)	109		(5		)	171
Commercial mortgage- backed securities	(2		)	137		(4		)	140		(1		)	112		(1		)	51
Total	$	(36	)	$	2,555	$	(55	)	$	2,420	$	(17	)	$	2,658	$	(14	)	$	689

Contractual maturities of short-term and long-term investments and restricted deposits

The contractual maturities of short-term and long-term investments and restricted deposits are as follows ($ in millions):



	December 31, 2018								December 31, 2017
	Investments				Restricted Deposits				Investments				Restricted Deposits
	Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value		Amortized Cost		Fair Value
One year or less	$	647	$	646	$	205	$	205	$	474	$	474	$	48	$	47
One year through five years	3,026		2,998		351		350		2,424		2,420		88		88
Five years through ten years	2,387		2,362		—		—		1,773		1,779		—		—
Greater than ten years	88		89		—		—		129		130		—		—
Asset-backed securities	1,504		1,488		—		—		1,046		1,040		—		—
Total	$	7,652	$	7,583	$	556	$	555	$	5,846	$	5,843	$	136	$	135