Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2017

Fair Value Measurements

Schedule of assets measured at fair value on a recurring basis

As of March 31, 2017 and December 31, 2016, the Company held certain assets that are required to be measured at fair value on a recurring basis. Assets measured at fair value on a recurring basis are summarized below (in thousands):

	Fair Value Measurements as of March 31, 2017
	Total		Level 1		Level 2		Level 3
Marketable Securities
Bonds and bond funds	$	420,812	$	—	$	420,812	$	—
Commercial paper		61,952		—		61,952		—
Asset backed securities	$	482,764	$	—	$	482,764	$	—
Cash, Cash Equivalents and Restricted Cash		103,691		103,691		—		—
Total Assets Measured at Fair Value	$	586,455	$	103,691	$	482,764	$	—

	Fair Value Measurements as of December 31, 2016
	Total		Level 1		Level 2		Level 3
Marketable Securities
Bonds and bond funds	$	409,885	$	—	$	409,885	$	—
Commercial paper		13		—		13		—
Asset backed securities	$	409,898	$	—	$	409,898	$	—
Cash, Cash Equivalents and Restricted Cash		155,009		155,009		—		—
Total Assets Measured at Fair Value	$	564,907	$	155,009	$	409,898	$	—