Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Cash and cash equivalents
Cash	$ 22,839	$ 27,186
Restricted cash	525	525
Money market funds	62,234	62,244
Total cash and cash equivalents	85,598	89,955	$ 79,358	$ 90,697
Long-term investments
Long-term restricted cash	2,595	2,600
Total cash and cash equivalents and investments	88,193	$ 92,555
Fair Value, Inputs, Level 1
Long-term investments
Cash and Cash Equivalents, Fair Value Disclosure	85,600
Restricted Cash And Cash Equivalents Noncurrent Fair Value Disclosure	$ 2,600