Financial Instruments - Carrying Value and Estimated Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Cash and cash equivalents, Carrying amount	$ 51,300	$ 52,347	$ 43,005	$ 45,570
Accounts receivable, net, Carrying amount	12,386	8,760
Accounts payable, Carrying amount	3,207	2,671
Cash and cash equivalents, Fair value	51,300	52,347
Accounts receivable, net, Fair value	12,386	8,760
Accounts payable, Fair value	$ 3,207	$ 2,671