Marketable Securities and Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2017

Notes To Financial Statements [Abstract]

Short-Term And Long-Term Marketable Securities

As of September 30, 2017 and December 31, 2016, 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, 2017	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Commercial paper	$	62,348	$	—	$	—		$	62,348
Corporate bonds	164,661		31		(61		)	164,631
U.S. government agency bonds	7,769		—		(8		)	7,761
U.S. government treasury bonds	78,370		2		(33		)	78,339
Certificates of deposit	3,375		—		—			3,375
Total marketable securities, short-term	$	316,523	$	33	$	(102	)	$	316,454

Long-term

September 30, 2017	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. government agency bonds	$	7,990	$	3	$	—		$	7,993
Corporate bonds	45,815		40		(18		)	45,837
U.S. government treasury bonds	5,025		—		(13		)	5,012
Total marketable securities, long-term	$	58,830	$	43	$	(31	)	$	58,842

Short-term

December 31, 2016	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Commercial paper	$	42,397	$	—	$	(6	)	$	42,391
Corporate bonds	122,788		22		(121		)	122,689
Municipal securities	5,852		—		(5		)	5,847
U.S. government agency bonds	28,903		9		(4		)	28,908
U.S. government treasury bonds	45,146		7		(7		)	45,146
Certificates of deposit	6,000		—		—			6,000
Total marketable securities, short-term	$	251,086	$	38	$	(143	)	$	250,981

Long-term

December 31, 2016	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. government agency bonds	$	6,805	$	—	$	(16	)	$	6,789
Corporate bonds	40,889		8		(85		)	40,812
U.S. government treasury bonds	12,016		5		(16		)	12,005
Asset-backed securities	177		—		—			177
Total marketable securities, long-term	$	59,887	$	13	$	(117	)	$	59,783

Investments Classified by Contractual Maturity Date

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, 2017 and December 31, 2016 (in thousands):

	September 30, 2017		December 31, 2016
One year or less	$	316,454	$	250,981
Due in greater than one year	58,842		59,783
Total available for sale short-term and long-term marketable securities	$	375,296	$	310,764

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation

The following table summarizes the reconciliation of assets measured and recorded at fair value on a recurring basis using significant unobservable inputs Level 3 (in thousands):

	Long-term Notes Receivable
Balance as of December 31, 2016	$	2,047
Additional notes receivable issued	2,000
Accrued interest receivable	54
Change in fair value recognized in earnings	56
Balance as of September 30, 2017	$	4,157

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, 2017 and December 31, 2016 (in thousands):

Description	Balance as of September 30, 2017		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	$	177,486	$	177,486	$	—	$	—
Commercial paper	13,295		—		13,295		—
Short-term investments:
Commercial paper	62,348		—		62,348		—
Corporate bonds	164,631		—		164,631		—
U.S. government agency bonds	7,761		—		7,761		—
U.S. government treasury bonds	78,339		78,339		—		—
Certificates of deposit	3,375		—		3,375		—
Long-term investments:
U.S. government agency bonds	7,993		—		7,993		—
Corporate bonds	45,837		—		45,837		—
U.S. government treasury bonds	5,012		5,012		—		—
Prepaid expenses and other current assets:
Israeli funds	3,310		—		3,310		—
Other assets:
Long-term notes receivable	4,157		—		—		4,157
	$	573,544	$	260,837	$	308,550	$	4,157

Description	Balance as of December 31, 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	$	87,179	$	87,179	$	—	$	—
Commercial paper	2,499		—		2,499		—
Corporate bonds	750		—		750		—
Short-term investments:
Commercial paper	42,391		—		42,391		—
Corporate bonds	122,689		—		122,689		—
Municipal securities	5,847		—		5,847		—
U.S. government agency bonds	28,908		—		28,908		—
U.S. government treasury bonds	45,146		45,146		—		—
Certificates of deposit	6,000		—		6,000		—
Long-term investments:
U.S. government agency bonds	6,789		—		6,789		—
Corporate bonds	40,812		—		40,812		—
U.S. government treasury bonds	12,005		12,005		—		—
Asset-backed securities	177		—		177		—
Prepaid expenses and other current assets:
Israeli funds	2,956		—		2,956		—
Other assets:
Long-term notes receivable	2,047		—		—		2,047
	$	406,195	$	144,330	$	259,818	$	2,047