Investments (Tables)

6 Months Ended

Jun. 30, 2014

Investments [Abstract]

Summary of contract maturity of available-for-sale securities

The following table summarizes the contract maturity of the available-for-sale securities we held as of June 30, 2014:

One year or less	53	%
After one year but within two years	36	%
After two years but within three years	11	%
Total	100	%

Summary of investments

The following is a summary of our investments (in thousands):

	Amortized		Unrealized					Other- Than- Temporary Impairment		Estimated
June 30, 2014	Cost		Gains		Losses			Loss		Fair Value
Available-for-sale securities:
Corporate debt securities(1)	$	166,635	$	115	$	(39	)	$	—	$	166,711
Debt securities issued by U.S. government agencies (1)		61,421		14		(38	)		—		61,397
Debt securities issued by the U.S. Treasury		9,245		17		—			—		9,262
Debt securities issued by states of the United States and political subdivisions of the states		43,527		17		(42	)		—		43,502
Total securities with a maturity of one year or less		280,828		163		(119	)		—		280,872
Corporate debt securities		173,089		186		(139	)		—		173,136
Debt securities issued by U.S. government agencies		37,048		4		(76	)		—		36,976
Debt securities issued by the U.S. Treasury		1,997		5		—			—		2,002
Debt securities issued by states of the United States and political subdivisions of the states		22,861		68		(40	)		—		22,889
Total securities with a maturity of more than one year		234,995		263		(255	)		—		235,003
Total available-for-sale securities	$	515,823	$	426	$	(374	)	$	—	$	515,875

	Cost			Unrealized							Other- Than- Temporary Impairment				Estimated
June 30, 2014	Basis			Gains			Losses				Loss				Fair Value
Equity securities:
Regulus Therapeutics Inc.		$	15,526		$	41,152		$	—			$	—			$	56,678
Securities included in other current assets			1,269			1,856			—				(1,269	)			1,856
Securities included in deposits and other assets			625			—			—				—				625
Total equity securities		$	17,420		$	43,008		$	—			$	(1,269	)		$	59,159
Total available-for-sale and equity securities		$	533,243		$	43,434		$	(374	)		$	(1,269	)		$	575,034

	Amortized		Unrealized					Other- Than- Temporary Impairment		Estimated
December 31, 2013	Cost		Gains		Losses			Loss		Fair Value
Available-for-sale securities:
Corporate debt securities(1)	$	142,096	$	75	$	(27	)	$	—	$	142,144
Debt securities issued by U.S. government agencies (1)		23,242		22		(16	)		—		23,248
Debt securities issued by the U.S. Treasury		6,239		6		—			—		6,245
Debt securities issued by states of the United States and political subdivisions of the states		8,082		6		(28	)		—		8,060
Total securities with a maturity of one year or less		179,659		109		(71	)		—		179,697
Corporate debt securities		265,969		177		(393	)		—		265,753
Debt securities issued by U.S. government agencies		41,308		3		(127	)		—		41,184
Debt securities issued by the U.S. Treasury		9,062		21		—			—		9,083
Debt securities issued by states of the United States and political subdivisions of the states		14,186		37		(28	)		—		14,195
Total securities with a maturity of more than one year		330,525		238		(548	)		—		330,215
Total available-for-sale securities	$	510,184	$	347	$	(619	)	$	—	$	509,912

	Cost			Unrealized							Other- Than- Temporary Impairment				Estimated
December 31, 2013	Basis			Gains			Losses				Loss				Fair Value
Equity securities:
Regulus Therapeutics Inc.		$	15,526		$	36,570		$	—			$	—			$	52,096
Securities included in other current assets			1,538			618			—				(880	)			1,276
Securities included in deposits and other assets			625			—			—				—				625
Total equity securities		$	17,689		$	37,188		$	—			$	(880	)		$	53,997
Total available-for-sale and equity securities		$	527,873		$	37,535		$	(619	)		$	(880	)		$	563,909

(1) Includes investments classified as cash equivalents on our condensed consolidated balance sheet.

Schedule of investments temporarily impaired

Investments we considered to be temporarily impaired at June 30, 2014 were as follows (in thousands):

			Less than 12 months of temporary impairment					More than 12 months of temporary impairment					Total temporary impairment
	Number of Investments		Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
Corporate debt securities		135	$	130,498	$	(167	)	$	8,342	$	(11	)	$	138,840	$	(178	)
Debt securities issued by U.S. government agencies		12		65,917		(114	)		-		-			65,917		(114	)
Debt securities issued by states of the United States and political subdivisions of the states		12		9,800		(82	)		-		-			9,800		(82	)
Total temporarily impaired securities		159	$	206,215	$	(363	)	$	8,342	$	(11	)	$	214,557	$	(374	)