Office Closing and Termination Costs - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Restructuring Cost And Reserve [Line Items]
Termination costs	$ 417	$ 0	$ 6,367	$ 0	$ 8,371
Additional accruals for severance costs			275
Stock-based compensation			1,721		2,999
Building lease costs			3,232		$ 0
Additional accruals for severance	$ 1,100		1,100
Oklahoma City Restructuring
Restructuring Cost And Reserve [Line Items]
Stock-based compensation			948
Other Restructuring
Restructuring Cost And Reserve [Line Items]
Stock-based compensation			$ 772