Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2015

Fair Value Measurements.

Schedule of financial assets subject to fair value measurements

	As of March 31, 2015		Level 1		Level 2		Level 3
	(In thousands)
Money market funds and cash equivalents	$	109,288	$	—	$	109,288	$	—
Marketable securities	237,603		—		237,603		—
	$	346,891	$	—	$	346,891	$	—

	As of December 31, 2014		Level 1		Level 2		Level 3
	(In thousands)
Money market funds and cash equivalents	$	18,677	$	—	$	18,677	$	—
Marketable securities	173,023		—		173,023		—
	$	191,700	$	—	$	191,700	$	—