Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Commitments [Line Items]
Liability for deferred rent	$ 1.1	$ 0.8
Operating lease rent expense	$ 5.6	$ 4.4	$ 3.4
Minimum [Member]
Other Commitments [Line Items]
Operating lease expiration year	2017
Maximum [Member]
Other Commitments [Line Items]
Operating lease expiration year	2023