Cash and Cash Equivalents and Short Term Investments - Summary of Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash And Cash Equivalents [Line Items]
Total cash and cash equivalents	$ 99,780	$ 119,423	$ 57,613	$ 175,894
Cash
Cash And Cash Equivalents [Line Items]
Total cash and cash equivalents	29,915	75,421
Money market funds
Cash And Cash Equivalents [Line Items]
Total cash and cash equivalents	$ 69,865	$ 44,002