Accrued Payroll and Benefit Costs (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Payables and Accruals [Abstract]
Payroll and benefits	$ 261,779	$ 213,962
Employee deferred compensation plans	194,364	181,709
Workers’ compensation	28,521	26,127
Payroll taxes	24,251	26,317
Total accrued payroll costs and retirement obligations	508,915	448,115
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	$ 80,809	$ 79,060