Recently Issued Accounting Pronouncements - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase (decrease) in cash, cash equivalents and restricted cash	$ 542	$ (4,507)
Increase in cash	85,351		$ 82,822
Accounting Standards Update 2016-18 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase (decrease) in cash, cash equivalents and restricted cash	18,000	18,000
Increase in cash	16,000	$ 18,000
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Additional royalty expenses	$ 2,200
Per share effect of increase in royalty expenses	$ 0.05