Investments (Tables)

3 Months Ended

Mar. 31, 2016

Investments Debt And Equity Securities [Abstract]

Short-Term and Long-Term Investments in Debt Securities

The Company’s short-term and long-term investments in debt securities are summarized as follows (in thousands):

	Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Balances at March 31, 2016:
Short-term investments:
U.S. government securities	$	45,113	$	19	$	(1	)	$	45,131
U.S. government agency securities		64,442		14		(6	)		64,450
Non-U.S. government securities		4,946		—		(1	)		4,945
Corporate debt securities		56,734		14		(9	)		56,739
Total short-term investments	$	171,235	$	47	$	(17	)	$	171,265
Long-term investments:
U.S. government securities	$	7,412	$	6	$	—		$	7,418
U.S. government agency securities		10,228		5		(3	)		10,230
Corporate debt securities		23,507		28		(15	)		23,520
Total long-term investments	$	41,147	$	39	$	(18	)	$	41,168
Balances at December 31, 2015:
Short-term investments:
U.S. government securities	$	49,036	$	4	$	(45	)	$	48,995
U.S. government agency securities		67,723		1		(30	)		67,694
Non-U.S. government securities		7,303		—		(1	)		7,302
Corporate debt securities		60,290		1		(40	)		60,251
Total short-term investments	$	184,352	$	6	$	(116	)	$	184,242
Long-term investments:
U.S. government securities	$	8,058	$	—	$	(14	)	$	8,044
U.S. government agency securities		14,510		—		(48	)		14,462
Corporate debt securities		24,056		2		(80	)		23,978
Total long-term investments	$	46,624	$	2	$	(142	)	$	46,484

Schedule of Investment in Unrealized Loss Position

The following table summarizes the fair value and gross unrealized losses of investments that are in an unrealized loss position only. The unrealized losses are aggregated by type of investment instrument and length of time that individual securities have been in a continuous unrealized loss position (in thousands):

	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
March 31, 2016:
U.S. government securities	$	6,820	$	(1	)	$	—	$	—	$	6,820	$	(1	)
U.S. government agency securities		27,028		(9	)		—		—		27,028		(9	)
Non-U.S. government securities		4,044		(1	)		—		—		4,044		(1	)
Corporate debt securities		25,472		(24	)		—		—		25,472		(24	)
Total investments	$	63,364	$	(35	)	$	—	$	—	$	63,364	$	(35	)
December 31, 2015:
U.S. government securities	$	48,445	$	(59	)	$	—	$	—	$	48,445	$	(59	)
U.S. government agency securities		71,861		(78	)		—		—		71,861		(78	)
Non-U.S. government securities		5,001		(1	)		—		—		5,001		(1	)
Corporate debt securities		52,571		(120	)		—		—		52,571		(120	)
Total investments	$	177,878	$	(258	)	$	—	$	—	$	177,878	$	(258	)