Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Summary of Balances of Cash Equivalents and Investments

The following table presents the balances of assets measured at fair value on a recurring basis, by level within the fair value hierarchy, as of December 31, 2015 (in thousands):

	December 31, 2015
	Total		Level 1		Level 2
Cash equivalents:
Money market funds	$	195,870	$	195,870	$	—
Certificates of deposit		1,622		—		1,622
Short-term investments:
U.S. government agency securities		194,636		194,636		—
Corporate notes and bonds		41,314		—		41,314
Municipal securities		39,853		—		39,853
Certificates of deposit		11,837		—		11,837
Foreign government securities		3,511		—		3,511
Restricted cash		3,015		—		3,015
Total	$	491,658	$	390,506	$	101,152

The following table presents the fair value, by level within the fair value hierarchy, of our cash equivalents and investments as of December 31, 2014 (in thousands):

	December 31, 2014
	Total		Level 1		Level 2
Cash equivalents:
Money market funds	$	98,645	$	98,645	$	—
Foreign government securities		9,035		—		9,035
Certificates of deposit		2,975		—		2,975
Short-term investments:
U.S. government agency securities		118,342		118,342		—
Corporate notes and bonds		78,746		—		78,746
Municipal securities		26,256		—		26,256
Foreign government securities		8,570		—		8,570
Commercial paper		7,987		—		7,987
Certificates of deposit		6,928		—		6,928
Long-term investments:
U.S. government agency securities		63,515		63,515		—
Municipal securities		12,917		—		12,917
Corporate notes and bonds		6,694		—		6,694
Certificates of deposit		200		—		200
Total	$	440,810	$	280,502	$	160,308