Investments (Tables)

9 Months Ended

Sep. 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 September 30, 2014:

One year or less	57%
After one year but within two years	32%
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
September 30, 2014	Cost		Gains		Losses			Loss		Fair Value
Available-for-sale securities:
Corporate debt securities(1)	$	205,973	$	153	$	(67	)	$	—	$	206,059
Debt securities issued by U.S. government agencies (1)		51,021		13		(35	)		—		50,999
Debt securities issued by the U.S. Treasury		9,022		18		—			—		9,040
Debt securities issued by states of the United States and political subdivisions of the states		38,134		19		(48	)		—		38,105
Total securities with a maturity of one year or less		304,150		203		(150	)		—		304,203
Corporate debt securities		148,079		55		(345	)		—		147,789
Debt securities issued by U.S. government agencies		55,525		5		(132	)		—		55,398
Debt securities issued by states of the United States and political subdivisions of the states		26,275		41		(77	)		—		26,239
Total securities with a maturity of more than one year		229,879		101		(554	)		—		229,426
Total available-for-sale securities	$	534,029	$	304	$	(704	)	$	—	$	533,629

	Cost			Unrealized							Other- Than- Temporary Impairment				Estimated
September 30, 2014	Basis			Gains			Losses				Loss				Fair Value
Equity securities:
Regulus Therapeutics Inc.		$	15,316		$	32,110		$	—			$	—			$	47,426
Securities included in other current assets			1,269			1,021			—				(1,269	)			1,021
Total equity securities		$	16,585		$	33,131		$	—			$	(1,269	)		$	48,447
Total available-for-sale and equity securities		$	550,614		$	33,435		$	(704	)		$	(1,269	)		$	582,076

	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 September 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		178	$	165,321	$	(397	)	$	9,266	$	(15	)	$	174,587	$	(412	)
Debt securities issued by U.S. government agencies		10		56,358		(167	)		-		-			56,358		(167	)
Debt securities issued by states of the United States and political subdivisions of the states		19		22,661		(78	)		228		(47	)		22,889		(125	)
Total temporarily impaired securities		207	$	244,340	$	(642	)	$	9,494	$	(62	)	$	253,834	$	(704	)