Commitments and Contingencies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Commitments And Contingencies Disclosure [Abstract]
Lease cancellation notice period	30 days
Commitment maturing in the next fiscal year	$ 52,900,000
Other commitment, due in second year	18,400,000
Other commitment, due in third year	$ 447,000
Lease term expiration date	Mar. 31, 2020
Tenant improvement allowance	$ 6,300,000
Early termination right effective date	Mar. 31, 2018
Early termination fees	$ 1,000,000
Rent expense	$ 1,800,000	$ 1,700,000	$ 1,200,000