Marketable Securities and Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2016

Notes To Financial Statements [Abstract]

Short-Term And Long-Term Marketable Securities

As of September 30, 2016 and December 31, 2015, the estimated fair value of our short-term and long-term marketable securities, classified as available for sale, are as follows (in thousands):

Short-term

September 30, 2016	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Commercial paper	$	19,029	$	—	$	—		$	19,029
Corporate bonds	81,955		18		(29		)	81,944
Municipal securities	9,205		—		(4		)	9,201
U.S. government agency bonds	30,587		24		—			30,611
U.S. government treasury bonds	47,702		31		—			47,733
Certificates of deposits	4,500		—		—			4,500
Total Marketable Securities, Short-Term	$	192,978	$	73	$	(33	)	$	193,018

Long-term

September 30, 2016	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. government agency bonds	$	9,249	$	11	$	—		$	9,260
Corporate bonds	43,101		118		(7		)	43,212
U.S. government treasury bonds	10,027		21		—			10,048
Asset-backed securities	300		—		—			300
Total Marketable Securities, Long-Term	$	62,677	$	150	$	(7	)	$	62,820

Short-term

December 31, 2015	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Commercial paper	$	38,537	$	—	$	—		$	38,537
Corporate bonds	179,765		6		(251		)	179,520
U.S. dollar denominated foreign corporate bonds	510		—		(2		)	508
Municipal securities	14,209		7		(2		)	14,214
U.S. government agency bonds	75,172		—		(53		)	75,119
U.S. government treasury bonds	51,763		1		(81		)	51,683
Total Marketable Securities, Short-Term	$	359,956	$	14	$	(389	)	$	359,581

Long-term

December 31, 2015	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. government agency bonds	$	43,853	$	—	$	(178	)	$	43,675
Corporate bonds	64,012		9		(218		)	63,803
U.S. government treasury bonds	37,673		—		(107		)	37,566
Municipal securities	3,993		—		(2		)	3,991
Asset-backed securities	2,338		—		(3		)	2,335
Total Marketable Securities, Long-Term	$	151,869	$	9	$	(508	)	$	151,370

Investments Classified by Contractual Maturity Date [Table Text Block]

As the carrying value approximates the fair value for our short-term and long-term marketable securities shown in the tables above, the following table summarizes the fair value of our short-term and long-term marketable securities classified by maturity as of September 30, 2016 and December 31, 2015 (in thousands):

	September 30, 2016		December 31, 2015
Due in one year or less	$	193,018	$	359,581
Due in greater than one year	62,820		151,370
Total available for sale short-term and long-term marketable securities	$	255,838	$	510,951

Financial Assets Measured At Fair Value On Recurring Basis

The following tables summarize our financial assets measured at fair value on a recurring basis as of September 30, 2016 and December 31, 2015 (in thousands):

Description	Balance as of September 30, 2016		Quoted Prices in Active  Markets for Identical Assets (Level 1)		Significant Other Observable  Inputs (Level 2)		Significant Other Observable  Inputs (Level 3)
Cash equivalents:
Money market funds	$	92,931	$	92,931	$	—	$	—
Short-term investments:
Commercial paper	19,029		—		19,029		—
Corporate bonds	81,944		—		81,944		—
Municipal securities	9,201		—		9,201		—
U.S. government agency bonds	30,611		—		30,611		—
U.S. government treasury bonds	47,733		47,733		—		—
Certificates of deposits	4,500		—		4,500		—
Long-term investments:
U.S. government agency bonds	9,260		—		9,260		—
Corporate bonds	43,212		—		43,212		—
U.S. government treasury bonds	10,048		10,048		—		—
Asset-backed securities	300		—		300		—
Prepaid expenses and other current assets:
Israeli funds	2,527		—		2,527		—
Other assets:
Long-term notes receivable	2,000		—		—		2,000
	$	353,296	$	150,712	$	200,584	$	2,000

Description	Balance as of December 31, 2015		Quoted Prices in Active  Markets for Identical Assets (Level 1)		Significant Other Observable  Inputs (Level 2)
Cash equivalents:
Money market funds	$	70,148	$	70,148	$	—
Commercial paper	36,887		—		36,887
U.S. government agency bonds	3,599		—		3,599
Corporate bonds	625		—		625
Short-term investments:
Commercial paper	38,537		—		38,537
Corporate bonds	179,520		—		179,520
U.S. dollar denominated foreign corporate bonds	508		—		508
Municipal securities	14,214		—		14,214
U.S. government agency bonds	75,119		—		75,119
U.S. government treasury bonds	51,683		51,683		—
Long-term investments:
U.S. government agency bonds	43,675		—		43,675
Corporate bonds	63,803		—		63,803
U.S. government treasury bonds	37,566		37,566		—
Municipal securities	3,991		—		3,991
Asset-backed securities	2,335		—		2,335
Prepaid expenses and other current assets:
Israeli funds	2,436		—		2,436
	$	624,646	$	159,397	$	465,249