Condensed Consolidating Financial Statements Consolidating Statement Of Cash Flows (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net cash provided by (used in) operating activities	$ 161,020	$ 134,844	$ 144,935
Investment in property and equipment	(15,443)	(10,924)	(24,368)
Acquisitions, net of cash acquired	0	0	(466)
Equity method investments	(20,285)	(5,000)	0
Issuance of notes receivable	(34,925)	(12,766)	(11,786)
Collections of notes receivable	3,561	4,754	5,083
Purchases of investments, employee benefit plans	(1,697)	(1,602)	(1,948)
Proceeds from sale of investments, employee benefit plans	11,223	644	1,649
Other items, net	(433)	(564)	(319)
Net cash used in investing activities	(57,999)	(23,804)	(32,155)
Net borrowings (repayments) pursuant to revolving credit facilities	57,000	(200)	(277,500)
Proceeds from the issuance of long-term debt	543,500	75	247,733
Principal payments on long-term debt	(4,422)	(297)	(25)
Settlement of forward starting interest rate swap agreement	0	0	(8,663)
Purchase of treasury stock	(22,586)	(53,617)	(11,212)
Excess tax benefits from stock-based compensation	1,559	1,227	625
Debt issuance costs	(4,759)	(2,356)	(800)
Proceeds from exercise of stock options	7,090	3,845	2,457
Dividends paid	(654,092)	(43,747)	(43,808)
Net cash provided from (used in) financing activities	(76,710)	(95,070)	(91,193)
Net change in cash and cash equivalents	26,311	15,970	21,587
Effect of foreign exchange rate changes on cash and cash equivalents	809	(172)	1,802
Cash and cash equivalents at beginning of period	107,057	91,259	67,870
Cash and cash equivalents at end of period	134,177	107,057	91,259
Parent [Member]
Net cash provided by (used in) operating activities	90,690	120,964	99,871
Investment in property and equipment	(7,404)	(2,839)	(1,448)
Acquisitions, net of cash acquired			0
Equity method investments	0	0
Issuance of notes receivable	(23,737)	(9,341)	(10,583)
Collections of notes receivable	3,269	4,690	5,000
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
Payments to Acquire Interest in Subsidiaries and Affiliates	0
Other items, net	(433)	(570)	(474)
Net cash used in investing activities	(28,305)	(6,406)	(7,505)
Net borrowings (repayments) pursuant to revolving credit facilities	57,000	(200)	(277,500)
Proceeds from the issuance of long-term debt	543,500	0	247,733
Principal payments on long-term debt	(3,750)	0	0
Settlement of forward starting interest rate swap agreement			(8,663)
Purchase of treasury stock	(22,586)	(53,617)	(11,212)
Excess tax benefits from stock-based compensation	262	38
Debt issuance costs	(4,759)	(2,356)
Proceeds from exercise of stock options	7,090	3,845
Proceeds from Contributions from Affiliates	0
Dividends paid	(654,092)	(43,747)	(43,808)
Other items, net			1,652
Net cash provided from (used in) financing activities	(77,335)	(96,037)	(91,798)
Net change in cash and cash equivalents	(14,950)	18,521	568
Effect of foreign exchange rate changes on cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	23,370	4,849	4,281
Cash and cash equivalents at end of period	8,420	23,370	4,849
Guarantor Subsidiaries [Member]
Net cash provided by (used in) operating activities	29,087	(7,122)	41,607
Investment in property and equipment	(7,800)	(7,690)	(22,606)
Acquisitions, net of cash acquired			0
Equity method investments	0	0
Issuance of notes receivable	(11,188)	(3,425)	(1,203)
Collections of notes receivable	292	64	83
Proceeds from sale of assets		0
Purchases of investments, employee benefit plans	(1,697)	(1,602)	(1,948)
Proceeds from sale of investments, employee benefit plans	11,223	644	1,649
Payments to Acquire Interest in Subsidiaries and Affiliates	(20,586)
Other items, net	0	(10)	144
Net cash used in investing activities	(29,756)	(12,019)	(23,881)
Net borrowings (repayments) pursuant to revolving credit facilities	0	0	0
Proceeds from the issuance of long-term debt	0	0	0
Principal payments on long-term debt	(653)	(275)	0
Settlement of forward starting interest rate swap agreement			0
Purchase of treasury stock	0	0	0
Excess tax benefits from stock-based compensation	1,297	1,189
Debt issuance costs	0	0
Proceeds from exercise of stock options	0	0
Proceeds from Contributions from Affiliates	0
Dividends paid	0	0	0
Other items, net			630
Net cash provided from (used in) financing activities	644	914	630
Net change in cash and cash equivalents	(25)	(18,227)	18,356
Effect of foreign exchange rate changes on cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	432	18,659	303
Cash and cash equivalents at end of period	407	432	18,659
Non-Guarantor Subsidiaries [Member]
Net cash provided by (used in) operating activities	41,243	21,002	3,457
Investment in property and equipment	(239)	(395)	(314)
Acquisitions, net of cash acquired			(466)
Equity method investments	(20,285)	(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
Payments to Acquire Interest in Subsidiaries and Affiliates	0
Other items, net	0	16	11
Net cash used in investing activities	(20,524)	(5,379)	(769)
Net borrowings (repayments) pursuant to revolving credit facilities	0	0	0
Proceeds from the issuance of long-term debt	0	75	0
Principal payments on long-term debt	(19)	(22)	(25)
Settlement of forward starting interest rate swap agreement			0
Purchase of treasury stock	0	0	0
Excess tax benefits from stock-based compensation	0	0
Debt issuance costs	0	0
Proceeds from exercise of stock options	0	0
Proceeds from Contributions from Affiliates	20,586
Dividends paid	0	0	0
Other items, net			0
Net cash provided from (used in) financing activities	20,567	53	(25)
Net change in cash and cash equivalents	41,286	15,676	2,663
Effect of foreign exchange rate changes on cash and cash equivalents	809	(172)	1,802
Cash and cash equivalents at beginning of period	83,255	67,751	63,286
Cash and cash equivalents at end of period	125,350	83,255	67,751
Eliminations [Member]
Net cash provided by (used in) operating activities	0	0	0
Investment in property and equipment	0	0	0
Acquisitions, net of cash acquired			0
Equity method investments	0	0
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
Payments to Acquire Interest in Subsidiaries and Affiliates	20,586
Other items, net	0	0	0
Net cash used in investing activities	20,586	0	0
Net borrowings (repayments) pursuant to revolving credit facilities	0	0	0
Proceeds from the issuance of long-term debt	0	0	0
Principal payments on long-term debt	0	0	0
Settlement of forward starting interest rate swap agreement			0
Purchase of treasury stock	0	0	0
Excess tax benefits from stock-based compensation	0	0
Debt issuance costs	0	0
Proceeds from exercise of stock options	0	0
Proceeds from Contributions from Affiliates	(20,586)
Dividends paid	0	0	0
Other items, net			0
Net cash provided from (used in) financing activities	(20,586)	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
Consolidated [Member]
Net cash provided by (used in) operating activities	161,020	134,844	144,935
Investment in property and equipment	(15,443)	(10,924)	(24,368)
Acquisitions, net of cash acquired			(466)
Equity method investments	(20,285)	(5,000)
Issuance of notes receivable	(34,925)	(12,766)	(11,786)
Collections of notes receivable	3,561	4,754	5,083
Proceeds from sale of assets		1,654
Purchases of investments, employee benefit plans	(1,697)	(1,602)	(1,948)
Proceeds from sale of investments, employee benefit plans	11,223	644	1,649
Payments to Acquire Interest in Subsidiaries and Affiliates	0
Other items, net	(433)	(564)	(319)
Net cash used in investing activities	(57,999)	(23,804)	(32,155)
Net borrowings (repayments) pursuant to revolving credit facilities	57,000	(200)	(277,500)
Proceeds from the issuance of long-term debt	543,500	75	247,733
Principal payments on long-term debt	(4,422)	(297)	(25)
Settlement of forward starting interest rate swap agreement			(8,663)
Purchase of treasury stock	(22,586)	(53,617)	(11,212)
Excess tax benefits from stock-based compensation	1,559	1,227
Debt issuance costs	(4,759)	(2,356)
Proceeds from exercise of stock options	7,090	3,845
Proceeds from Contributions from Affiliates	0
Dividends paid	(654,092)	(43,747)	(43,808)
Other items, net			2,282
Net cash provided from (used in) financing activities	(76,710)	(95,070)	(91,193)
Net change in cash and cash equivalents	26,311	15,970	21,587
Effect of foreign exchange rate changes on cash and cash equivalents	809	(172)	1,802
Cash and cash equivalents at beginning of period	107,057	91,259	67,870
Cash and cash equivalents at end of period	$ 134,177	$ 107,057	$ 91,259