Short-term Investments - Summary of Investments in Continuous Unrealized Loss Position for Less Than 12 Months (Detail) $ in Thousands	Jun. 30, 2015 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair value	$ 26,489
Less Than 12 Months, Gross unrealized losses	(27)
12 Months or Greater, Fair value	4,395
12 Months or Greater, Gross unrealized losses	(2)
Total, Fair value	30,884
Total, Gross unrealized losses	(29)
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair value	26,489
Less Than 12 Months, Gross unrealized losses	(27)
12 Months or Greater, Fair value	3,002
12 Months or Greater, Gross unrealized losses	(2)
Total, Fair value	29,491
Total, Gross unrealized losses	$ (29)