Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2017

Marketable Securities [Abstract]

Amortized Cost And Fair Value Of Marketable Securities

As of March 31, 2017		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Corporate bonds	$	120,898	$	76	$	(81)	$	120,893
Certificates of deposit		43,198		-		-		43,198
Asset backed securities		37,610		6		(16)		37,600
Commercial paper		17,013		-		-		17,013
U.S. government bonds		16,644		1		(15)		16,630
Agency bonds		4,600		-		(1)		4,599
Total marketable securities	$	239,963	$	83	$	(113)	$	239,933
As of December 31, 2016		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Corporate bonds	$	130,833	$	40	$	(102)	$	130,771
Certificates of deposit		40,400		-		-		40,400
Asset backed securities		27,290		25		-		27,315
Commercial paper		20,228		-		-		20,228
U.S. government bonds		12,244		1		(14)		12,231
Agency bonds		4,600		4		-		4,604
Municipal bonds		1,400		-		-		1,400
Total marketable securities	$	236,995	$	70	$	(116)	$	236,949

Contractual Maturities Of Marketable Securities

As of March 31, 2017		Amortized Cost		Fair Value
Due in one year or less	$	144,581	$	144,547
Due after one year through three years		95,382		95,386
	$	239,963	$	239,933