Financial Instruments and Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2017

Financial Instruments and Fair Value Measurements

Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table identifies our assets and liabilities that were measured at fair value on a recurring basis (in thousands):

	Balance		Level 1		Level 2		Level 3
September 30, 2017
Assets:
Money market	$	590,037	$	590,037	$	—	$	—
U.S. treasury securities		16,499		—		16,499		—
Total assets at fair value	$	606,536	$	590,037	$	16,499	$	—
December 31, 2016
Assets:
Money market	$	202,361	$	202,361	$	—	$	—
U.S. treasury securities		49,997		—		49,997		—
Total assets at fair value	$	252,358	$	202,361	$	49,997	$	—