Property and Equipment - Property and Equipment at Cost (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment	$ 1,088,205	$ 1,053,678
Land and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	5,531	5,445
Building [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	73,424	71,926
Telephone and Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	862,352	840,396
Office Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	37,043	37,094
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	57,057	59,384
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 52,798	$ 39,433