Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 212,740	$ 202,044
Accumulated depreciation	(137,665)	(140,188)
Property and equipment, net	75,075	61,856
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	77,921	69,278
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	806	2,349
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	33,827	35,780
Computer equipment and software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 100,186	$ 94,637