Office Closing and Termination Costs - Summary of Termination Costs (Detail) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Termination costs	$ 0	$ 1,431
Building lease	162	3,232		$ 3,200
Stock-based compensation expense (gain)	0	1,287
Total termination costs	$ 162	$ 5,950	$ 8,400