Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 61,551	$ 55,863
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of intangible assets	333	433
Depreciation expense	12,200	11,747
Stock-based compensation expense-restricted stock and stock units	8,774	8,208
Excess tax benefits from stock-based compensation	(707)	(992)
Deferred income taxes	2,710	(4,117)
Provision for doubtful accounts	3,456	2,642
Changes in assets and liabilities:
Increase in accounts receivable	(38,909)	(42,598)
Decrease in accounts payable, accrued expenses, accrued payroll costs and retirement obligations	(14,230)	(25,011)
Increase in income taxes payable	31,320	31,092
Change in other assets, net of change in other liabilities	(7,273)	(9,382)
Net cash flows provided by operating activities	59,225	27,885
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(12,443)	(8,082)
Increase in trusts for employee benefits and retirement plans	(5,283)	(29,669)
Net cash flows used in investing activities	(17,726)	(37,751)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repurchases of common stock	(35,025)	(45,673)
Cash dividends paid	(24,394)	(22,021)
Decrease in notes payable and other indebtedness	(31)	(2,643)
Excess tax benefits from stock-based compensation	707	992
Proceeds from exercises of stock options	8,676	19,938
Net cash flows used in financing activities	(50,067)	(49,407)
Effect of exchange rate changes on cash and cash equivalents	541	(3,011)
Net decrease in cash and cash equivalents	(8,027)	(62,284)
Cash and cash equivalents at beginning of period	275,764	287,635
Cash and cash equivalents at end of period	267,737	225,351
Non-cash items:
Stock repurchases awaiting settlement	$ 8,266