Cash, Cash Equivalents and Investments (Tables)

6 Months Ended

Jun. 30, 2015

Investments, Debt and Equity Securities [Abstract]

Investing in Fixed Income Securities

Cash, cash equivalents and investments as of June 30, 2015 and December 31, 2014 consisted of the following (tables in millions):

	June 30, 2015
	Cost or Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
Cash	$	787	$	—	$	—		$	787
Cash equivalents:
Money-market funds	$	990	$	—	$	—		$	990
U.S. and foreign corporate debt securities	7		—		—			7
Municipal obligations	7		—		—			7
Total cash equivalents	$	1,004	$	—	$	—		$	1,004
Short-term investments:
U.S. Government and agency obligations	$	654	$	1	$	—		$	655
U.S. and foreign corporate debt securities	3,293		4		(5		)	3,292
Foreign governments and multi-national agency obligations	27		—		—			27
Municipal obligations	887		1		—			888
Asset-backed securities	36		—		—			36
Mortgage-backed securities	308		—		(1		)	307
Total short-term investments	$	5,205	$	6	$	(6	)	$	5,205
Other assets:
Marketable available-for-sale equity securities	$	15	$	—	$	—		$	15

	December 31, 2014
	Cost or Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Fair Value
Cash	$	885	$	—	$	—		$	885
Cash equivalents:
Money-market funds	$	1,130	$	—	$	—		$	1,130
U.S. and foreign corporate debt securities	54		—		—			54
Foreign governments and multi-national agency obligations	2		—		—			2
Total cash equivalents	$	1,186	$	—	$	—		$	1,186
Short-term investments:
U.S. Government and agency obligations	$	542	$	—	$	—		$	542
U.S. and foreign corporate debt securities	3,236		3		(5		)	3,234
Foreign governments and multi-national agency obligations	23		—		—			23
Municipal obligations	930		2		—			932
Asset-backed securities	53		—		—			53
Mortgage-backed securities	221		—		(1		)	220
Total short-term investments	$	5,005	$	5	$	(6	)	$	5,004

Unrealized Losses on Cash Equivalents and Investments

Unrealized losses on cash equivalents and investments as of June 30, 2015 and December 31, 2014, which have been in a net loss position for less than twelve months, were classified by investment category as follows (table in millions):

	June 30, 2015					December 31, 2014
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. and foreign corporate debt securities	$	1,718	$	(5	)	$	1,964	$	(5	)
Mortgage-backed securities	169		(1		)	107		(1		)
Total	$	1,887	$	(6	)	$	2,071	$	(6	)

Contractual Maturities of Investments

The contractual maturities of short-term investments held at June 30, 2015 consisted of the following (table in millions):

	Amortized Cost Basis		Aggregate Fair Value
Due within one year	$	1,363	$	1,363
Due after 1 year through 5 years	3,511		3,512
Due after 5 years through 10 years	107		107
Due after 10 years	224		223
Total short-term investments	$	5,205	$	5,205