Short-term Investments Short-term Investments - Summary of Investments in a Continuous Loss Position (Details) $ in Thousands	Mar. 31, 2017 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair value	$ 35,727
Less Than 12 Months, Gross unrealized losses	(52)
12 Months or Greater, Fair value	0
12 Months or Greater, Gross unrealized losses	0
Total, Fair value	35,727
Total, Gross unrealized losses	(52)
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair value	21,244
Less Than 12 Months, Gross unrealized losses	(28)
12 Months or Greater, Fair value	0
12 Months or Greater, Gross unrealized losses	0
Total, Fair value	21,244
Total, Gross unrealized losses	(28)
U.S. government-related debt securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair value	14,483
Less Than 12 Months, Gross unrealized losses	(24)
12 Months or Greater, Fair value	0
12 Months or Greater, Gross unrealized losses	0
Total, Fair value	14,483
Total, Gross unrealized losses	$ (24)