CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 55,863	$ 48,334
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of intangible assets	433	35
Depreciation expense	11,747	12,246
Stock-based compensation expense-restricted stock and stock units	8,208	8,886
Excess tax benefits from stock-based compensation	(992)	(2,438)
Deferred income taxes	(4,117)	(1,554)
Provision for doubtful accounts receivable	2,642	2,321
Changes in assets and liabilities:
Increase in accounts receivable	(42,598)	(28,518)
Decrease in accounts payable, accrued expenses, accrued payroll costs and retirement obligations	(25,011)	(37,161)
Increase in income taxes payable	31,092	26,070
Change in other assets, net of change in other liabilities	(9,382)	(5,007)
Net cash flows provided by operating activities	27,885	23,214
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(8,082)	(10,372)
Increase in trusts for employee benefits and retirement plans	(29,669)	(1,478)
Net cash flows used in investing activities	(37,751)	(11,850)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repurchases of common stock	(45,673)	(56,394)
Cash dividends paid	(22,021)	(21,016)
Decrease in notes payable and other indebtedness	(2,643)	(32)
Excess tax benefits from stock-based compensation	992	2,438
Proceeds from exercises of stock options	19,938	26,081
Net cash flows used in financing activities	(49,407)	(48,923)
Effect of exchange rate changes on cash and cash equivalents	(3,011)	2,676
Net decrease in cash and cash equivalents	(62,284)	(34,883)
Cash and cash equivalents at beginning of period	287,635	279,336
Cash and cash equivalents at end of period	225,351	244,453
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Interest	98	107
Income taxes, net of refunds	$ 7,356	$ 7,028