Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions		12 Months Ended
	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Loss Contingencies [Line Items]
Rent expense		$ 13.2	$ 12.9	$ 13.2
Incentive awarded to the company by the State of Connecticut, total	$ 9.0				$ 11.5
Incentive awarded to the company by the State of Connecticut, non-interest bearing loans	7.0				8.0
Incentive awarded to the company by the State of Connecticut, grants	2.0				$ 3.5
Non-interest bearing incentive loan term		10 years
Forgiveness awarded to the company by the state of Connecticut	6.0
Incentive awarded to the company by the State of Connecticut, revenue recognized		$ 1.4	1.4	$ 1.1
Incentive awarded to the company by the State of Connecticut, deferred revenue	$ 4.8	$ 4.8	$ 6.3
Maximum
Loss Contingencies [Line Items]
Non-cancellable operating leases expiration year		2030