Condensed Consolidating Financial Statements Consolidating Statement Of Cash Flows (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net cash provided by operating activities	$ 134,844	$ 144,935	$ 112,216
Investment in property and equipment	(10,924)	(24,368)	(11,135)
Payments to Acquire Businesses, Net of Cash Acquired	0	466	0
Payments to Acquire Equity Method Investments	(5,000)	0	0
Issuance of notes receivable	(12,766)	(11,786)	(1,995)
Collections of notes receivable	4,754	5,083	324
Proceeds from sale of assets	1,654	0	0
Purchases of investments, employee benefit plans	(1,602)	(1,948)	(3,854)
Proceeds from sale of investments, employee benefit plans	644	1,649	13,895
Other items, net	(564)	(319)	(584)
Net cash used in investing activities	(23,804)	(32,155)	(3,349)
Proceeds from issuance of long-term debt	75	247,733	0
Net repayments pursuant to revolving credit facilities	(200)	(277,500)	(6,700)
Principle payments of long-term debt	(297)	(25)	0
Settlement of forward starting interest rate swap agreement	(53,617)	(11,212)	(59,128)
Purchase of treasury stock	(53,617)	(11,212)	(59,128)
Payments of Debt Issuance Costs	(2,356)	(800)	0
Excess tax benefits from stock-based compensation	1,227	625	5,834
Dividends paid	(43,747)	(43,808)	(44,274)
Proceeds from Stock Options Exercised	3,845	2,457	9,158
Net cash used in financing activities	(95,070)	(91,193)	(95,110)
Net change in cash and cash equivalents	15,970	21,587	13,757
Effect of foreign exchange rate changes on cash and cash equivalents	(172)	1,802	1,433
Cash and cash equivalents at beginning of period	91,259	67,870	52,680
Cash and cash equivalents at end of period	107,057	91,259	67,870
Payments for (Proceeds from) Hedge, Financing Activities	0	8,663	0
Parent [Member]
Net cash provided by operating activities	120,964	99,871	67,568
Investment in property and equipment	(2,839)	(1,448)	(5,602)
Payments to Acquire Businesses, Net of Cash Acquired		0
Payments to Acquire Equity Method Investments	0
Issuance of notes receivable	(9,341)	(10,583)	(222)
Collections of notes receivable	4,690	5,000	0
Proceeds from sale of assets	(1,654)
Purchases of investments, employee benefit plans	0	0	0
Proceeds from sale of investments, employee benefit plans	0	0	0
Other items, net	(570)	(474)	(598)
Net cash used in investing activities	(6,406)	(7,505)	(6,422)
Proceeds from issuance of long-term debt	(200)	247,733
Net repayments pursuant to revolving credit facilities	0	(277,500)	(6,700)
Principle payments of long-term debt	0	0
Settlement of forward starting interest rate swap agreement	(53,617)	(11,212)	(59,128)
Purchase of treasury stock	(53,617)	(11,212)	(59,128)
Payments of Debt Issuance Costs	(2,356)
Excess tax benefits from stock-based compensation	(38)		1,345
Dividends paid	43,747	(43,808)	(44,274)
Proceeds from Stock Options Exercised	3,845		9,158
Other items, net		1,652
Net cash used in financing activities	(96,037)	(91,798)	(99,599)
Net change in cash and cash equivalents	18,521	568	(38,453)
Effect of foreign exchange rate changes on cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	4,849	4,281	42,734
Cash and cash equivalents at end of period	23,370	4,849	4,281
Payments for (Proceeds from) Hedge, Financing Activities		8,663
Guarantor Subsidiaries [Member]
Net cash provided by operating activities	(7,122)	41,607	(8,344)
Investment in property and equipment	(7,690)	(22,606)	(4,651)
Payments to Acquire Businesses, Net of Cash Acquired		0
Payments to Acquire Equity Method Investments	0
Issuance of notes receivable	(3,425)	(1,203)	(1,773)
Collections of notes receivable	64	83	324
Proceeds from sale of assets	0
Purchases of investments, employee benefit plans	1,602	(1,948)	(3,854)
Proceeds from sale of investments, employee benefit plans	644	1,649	13,895
Other items, net	(10)	144	(8)
Net cash used in investing activities	(12,019)	(23,881)	3,933
Proceeds from issuance of long-term debt	0	0
Net repayments pursuant to revolving credit facilities	(275)	0	0
Principle payments of long-term debt	0	0
Settlement of forward starting interest rate swap agreement	0	0	0
Purchase of treasury stock	0	0	0
Payments of Debt Issuance Costs	0
Excess tax benefits from stock-based compensation	(1,189)		4,489
Dividends paid	0	0	0
Proceeds from Stock Options Exercised	0		0
Other items, net		630
Net cash used in financing activities	914	630	4,489
Net change in cash and cash equivalents	(18,227)	18,356	78
Effect of foreign exchange rate changes on cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	18,659	303	225
Cash and cash equivalents at end of period	432	18,659	303
Payments for (Proceeds from) Hedge, Financing Activities		0
Non-Guarantor Subsidiaries [Member]
Net cash provided by operating activities	21,002	3,457	52,992
Investment in property and equipment	(395)	(314)	(882)
Payments to Acquire Businesses, Net of Cash Acquired		466
Payments to Acquire Equity Method Investments	(5,000)
Issuance of notes receivable	0	0	0
Collections of notes receivable	0	0	0
Proceeds from sale of assets	0
Purchases of investments, employee benefit plans	0	0	0
Proceeds from sale of investments, employee benefit plans	0	0	0
Other items, net	16	11	22
Net cash used in investing activities	(5,379)	(769)	(860)
Proceeds from issuance of long-term debt	0	0
Net repayments pursuant to revolving credit facilities	(22)	0	0
Principle payments of long-term debt	75	(25)
Settlement of forward starting interest rate swap agreement	0	0	0
Purchase of treasury stock	0	0	0
Payments of Debt Issuance Costs	0
Excess tax benefits from stock-based compensation	0		0
Dividends paid	0	0	0
Proceeds from Stock Options Exercised	0		0
Other items, net		0
Net cash used in financing activities	53	(25)	0
Net change in cash and cash equivalents	15,676	2,663	52,132
Effect of foreign exchange rate changes on cash and cash equivalents	(172)	1,802	1,433
Cash and cash equivalents at beginning of period	67,751	63,286	9,721
Cash and cash equivalents at end of period	83,255	67,751	63,286
Payments for (Proceeds from) Hedge, Financing Activities		0
Eliminations [Member]
Net cash provided by operating activities	0	0	0
Investment in property and equipment	0	0	0
Payments to Acquire Businesses, Net of Cash Acquired		0
Payments to Acquire Equity Method Investments	0
Issuance of notes receivable	0	0	0
Collections of notes receivable	0	0
Proceeds from sale of assets	0
Purchases of investments, employee benefit plans	0	0	0
Proceeds from sale of investments, employee benefit plans	0	0	0
Other items, net	0	0	0
Net cash used in investing activities	0	0	0
Proceeds from issuance of long-term debt	0	0
Net repayments pursuant to revolving credit facilities	0	0	0
Principle payments of long-term debt	0	0
Settlement of forward starting interest rate swap agreement	0	0	0
Purchase of treasury stock	0	0	0
Payments of Debt Issuance Costs	0
Excess tax benefits from stock-based compensation	0		0
Dividends paid	0	0	0
Proceeds from Stock Options Exercised	0		0
Other items, net		0
Net cash used in financing activities	0	0	0
Net change in cash and cash equivalents	0	0	0
Effect of foreign exchange rate changes on cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	0	0	0
Cash and cash equivalents at end of period	0	0	0
Payments for (Proceeds from) Hedge, Financing Activities		0
Consolidated [Member]
Net cash provided by operating activities	134,844	144,935	112,216
Investment in property and equipment	(10,924)	(24,368)	(11,135)
Payments to Acquire Businesses, Net of Cash Acquired		466
Payments to Acquire Equity Method Investments	(5,000)
Issuance of notes receivable	(12,766)	(11,786)	(1,995)
Collections of notes receivable	4,754	5,083	324
Proceeds from sale of assets	(1,654)
Purchases of investments, employee benefit plans	1,602	(1,948)	(3,854)
Proceeds from sale of investments, employee benefit plans	644	1,649	13,895
Other items, net	(564)	(319)	(584)
Net cash used in investing activities	(23,804)	(32,155)	(3,349)
Proceeds from issuance of long-term debt	(200)	247,733
Net repayments pursuant to revolving credit facilities	(297)	(277,500)	(6,700)
Principle payments of long-term debt	75	(25)
Settlement of forward starting interest rate swap agreement	(53,617)	(11,212)	(59,128)
Purchase of treasury stock	(53,617)	(11,212)	(59,128)
Payments of Debt Issuance Costs	(2,356)
Excess tax benefits from stock-based compensation	(1,227)		5,834
Dividends paid	43,747	(43,808)	(44,274)
Proceeds from Stock Options Exercised	3,845		9,158
Other items, net		2,282
Net cash used in financing activities	(95,070)	(91,193)	(95,110)
Net change in cash and cash equivalents	15,970	21,587	13,757
Effect of foreign exchange rate changes on cash and cash equivalents	(172)	1,802	1,433
Cash and cash equivalents at beginning of period	91,259	67,870	52,680
Cash and cash equivalents at end of period	107,057	91,259	67,870
Payments for (Proceeds from) Hedge, Financing Activities		$ 8,663