Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2017

Marketable Securities [Abstract]

Amortized Cost And Fair Value Of Marketable Securities

As of September 30, 2017		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Corporate bonds	$	139,533	$	129	$	(31)	$	139,631
Certificates of deposit		60,473		-		-		60,473
Commercial paper		24,234		-		-		24,234
Asset backed securities		22,476		11		(6)		22,481
U.S. government bonds		16,282		11		(7)		16,286
Treasury bills		10,992		1		-		10,993
Agency bonds		10,989		11		(13)		10,987
Total marketable securities	$	284,979	$	163	$	(57)	$	285,085
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 September 30, 2017		Amortized Cost		Fair Value
Due in one year or less	$	180,221	$	180,236
Due after one year through three years		104,758		104,849
	$	284,979	$	285,085