Accrued Payroll and Benefit Costs (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Payroll and benefits	$ 238,587	$ 243,301
Employee deferred compensation plans	257,545	252,349
Workers’ compensation	19,945	19,361
Payroll taxes	30,823	24,037
Accrued payroll and benefit costs	546,900	539,048
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	$ 83,628	$ 83,899