Accrued Payroll and Benefit Costs (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Payroll and benefits	$ 245,272	$ 240,793
Employee deferred compensation plans	221,027	212,220
Workers’ compensation	26,408	25,834
Payroll taxes	14,233	25,935
Accrued payroll and benefit costs	506,940	504,782
Chief Executive Officer
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation plan and other benefits related to the Company’s Chief Executive Officer	$ 82,192	$ 81,874