Office Closing and Termination Costs - Summary of Termination Costs (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement Of Financial Position [Abstract]
Termination costs		$ 5,372		$ 1,414
Building lease		0		3,156
Stock-based compensation expense		2,999		1,720
Total termination costs	$ (77)	$ 8,371	$ 0	$ 6,290	$ 0