Marketable Securities (Notes)

9 Months Ended

Sep. 30, 2014

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

Marketable Securities

Marketable securities at September 30, 2014 and December 31, 2013 consist of both debt securities issued by investment grade institutions as well as equity securities. The Company also held restricted marketable securities as of September 30, 2014, consisting of the Company's investment in Avalanche common shares (see Note 3), which are subject to customary transfer restrictions until January 2015 under a lock-up agreement with the underwriters of Avalanche's IPO.

The following tables summarize the Company's investments in marketable securities at September 30, 2014 and December 31, 2013.

	Amortized		Unrealized					Fair
At September 30, 2014	Cost Basis		Gains		Losses			Value
Unrestricted
U.S. government and government agency obligations	$	51,059	$	71	$	(1	)	$	51,129
Corporate bonds	696,149		574		(1,131		)	695,592
Municipal bonds	42,756		94		(8		)	42,842
Equity securities	1,166		3,933		—			5,099
	791,130		4,672		(1,140		)	794,662
Restricted
Equity securities	15,000		39,431		—			54,431
	$	806,130	$	44,103	$	(1,140	)	$	849,093
At December 31, 2013
Unrestricted
U.S. government and government agency obligations	$	107,493	$	55	$	(27	)	$	107,521
Corporate bonds	369,321		233		(361		)	369,193
Commercial paper	23,891		53		—			23,944
Municipal bonds	36,935		45		(59		)	36,921
International government agency obligations	2,007		1		—			2,008
Certificates of deposit	7,509		5		—			7,514
Equity securities	1,166		—		—			1,166
	$	548,322	$	392	$	(447	)	$	548,267

The Company classifies its debt security investments based on their contractual maturity dates. The debt securities listed at September 30, 2014 mature at various dates through August 2024. The fair values of debt security investments by contractual maturity as of September 30, 2014 and December 31, 2013 consist of the following:

	September 30, 2014		December 31, 2013
Maturities within one year	$	287,739	$	158,376
Maturities after one year through five years	496,700		383,410
Maturities after five years through ten years	5,124		4,138
Maturities after ten years	—		1,177
	$	789,563	$	547,101

The following table shows the fair value of the Company’s marketable securities that have unrealized losses and that are deemed to be only temporarily impaired, aggregated by investment category and length of time that the individual securities have been in a continuous unrealized loss position, at September 30, 2014 and December 31, 2013.

	Less than 12 Months					12 Months or Greater		Total
At September 30, 2014	Fair Value		Unrealized Loss			Fair Value	Unrealized Loss	Fair Value		Unrealized Loss
U.S. government and government agency obligations	$	1,401	$	(1	)	—	—	$	1,401	$	(1	)
Corporate bonds	343,835		(1,131		)	—	—	343,835		(1,131		)
Municipal bonds	10,502		(8		)	—	—	10,502		(8		)
	$	355,738	$	(1,140	)	—	—	$	355,738	$	(1,140	)
At December 31, 2013
U.S. government and government agency obligations	$	49,241	$	(27	)	—	—	$	49,241	$	(27	)
Corporate bonds	176,140		(361		)	—	—	176,140		(361		)
Municipal bonds	14,431		(59		)	—	—	14,431		(59		)
	$	239,812	$	(447	)	—	—	$	239,812	$	(447	)

Realized gains and losses are included as a component of investment income. For both the three and nine months ended September 30, 2014, total realized gains and losses on sales of marketable securities were not material. For both the three and nine months ended September 30, 2013, total realized gains on sales of marketable securities were $0.5 million and $1.0 million, respectively, and there were no realized losses. Changes in the Company's accumulated other comprehensive income (loss) for the three and nine months ended September 30, 2014 and 2013 related to unrealized gains and losses on available-for-sale marketable securities. For the three and nine months ended September 30, 2014 and 2013, amounts reclassified from accumulated other comprehensive income (loss) into investment income in the Company's Statements of Operations were related to realized gains and losses on sales of marketable securities.