Geographical Information - Revenues Based on Geographical Information (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues, net
Revenues, net	$ 165,858	$ 163,503	$ 155,621	$ 143,510	$ 135,286	$ 122,457	$ 119,738	$ 121,797	$ 628,492	$ 499,278	$ 478,452
United States
Revenues, net
Revenues, net									496,418	368,870	353,274
United Kingdom
Revenues, net
Revenues, net									108,868	101,789	92,601
Rest of World
Revenues, net
Revenues, net									$ 23,206	$ 28,619	$ 32,577