Office Closing and Termination Costs - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2015
Restructuring Cost And Reserve [Line Items]
Termination costs	$ 162	$ 5,950	$ 8,400
Stock-based compensation expense (gain)	0	1,287
Building lease	$ 162	$ 3,232		$ 3,200
Oklahoma City Restructuring
Restructuring Cost And Reserve [Line Items]
Additional accruals for severance costs				275
Stock-based compensation expense (gain)				$ 608