Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2015

Marketable Securities [Abstract]

Summary of Marketable Securities Designated as Available-for-Sale

The following is a summary of marketable securities designated as available-for-sale as of December 31, 2015 and 2014:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
December 31, 2015
Corporate bonds	$	125,132	$	1	$	(304	)	$	124,829
Municipal bonds	16,228		2		(6		)	16,224
Commercial paper	37,236		—		—			37,236
Government securities	8,704		1		(17		)	8,688
Agency securities	7,273		—		(20		)	7,253
Certificates of deposit	2,244		—		—			2,244
Total marketable securities	$	196,817	$	4	$	(347	)	$	196,474
December 31, 2014
Corporate bonds	$	99,592	$	1	$	(119	)	$	99,474
Municipal bonds	18,146		1		(10		)	18,137
Commercial paper	9,196		—		—			9,196
Certificates of deposit	498		—		—			498
Total marketable securities	$	127,432	$	2	$	(129	)	$	127,305

Summary of Amortized Cost and Estimated Fair Value of Marketable Securities by Maturity

The following is a summary of amortized cost and estimated fair value of marketable securities as of December 31, 2015 and 2014, by maturity:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in thousands)
December 31, 2015
Due in one year or less	$	164,147	$	2	$	(221	)	$	163,928
Due after one year	32,670		2		(126		)	32,546
Total marketable securities	$	196,817	$	4	$	(347	)	$	196,474
December 31, 2014
Due in one year or less	$	127,029	$	2	$	(129	)	$	126,902
Due after one year	403		—		—			403
Total marketable securities	$	127,432	$	2	$	(129	)	$	127,305