Short-term Investments - Summary of Investments in a Continuous Loss Position (Details) $ in Thousands	Jun. 30, 2018 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair value	$ 17,938
Less Than 12 Months, Gross unrealized losses	(67)
12 Months or Greater, Fair value	0
12 Months or Greater, Gross unrealized losses	0
Total, Fair value	17,938
Total, Gross unrealized losses	67
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair value	9,008
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	9,008
Total, Gross unrealized losses	24
U.S. government-related debt securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair value	8,930
Less Than 12 Months, Gross unrealized losses	(43)
12 Months or Greater, Fair value	0
12 Months or Greater, Gross unrealized losses	0
Total, Fair value	8,930
Total, Gross unrealized losses	$ 43