Guarantor Subsidiaries (Schedule Of Guarantor Subsidiaries - Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Cash and cash equivalents	$ 59,966	$ 38,081	$ 50,941	$ 49,917
Accounts receivable, less allowances	81,811	77,924
Inventories - net	8,146	8,668
Current deferred income taxes	13,226	12,540
Prepaid income taxes	4,187	2,131
Prepaid expenses	10,737	11,409
Total current assets	178,073	150,753
Investments of deferred compensation plans	33,215	31,629
Properties and equipment, at cost, less accumulated depreciation	88,571	82,951
Identifiable intangible assets less accumulated amortization	57,635	58,262
Goodwill	461,965	460,633
Other assets	11,669	11,677
Total Assets	831,128	795,905
Accounts payable	51,002	48,225
Income taxes	167	90
Accrued insurance	36,786	37,147
Accrued compensation	39,729	41,087
Other current liabilities	14,906	18,851
Total current liabilities	142,590	145,400
Deferred income taxes	25,257	29,463
Long-term debt	170,769	166,784
Deferred compensation liabilities	33,149	30,693
Other liabilities	11,918	9,881
Stockholders' equity	447,445	413,684
Total Liabilities and Stockholders' Equity	831,128	795,905
Parent [Member]
Cash and cash equivalents	53,280	32,470	53,191	45,324
Accounts receivable, less allowances	1,082	606
Current deferred income taxes	(1,311)	(650)
Prepaid income taxes	4,701	(114)
Prepaid expenses	980	503
Total current assets	58,732	32,815
Properties and equipment, at cost, less accumulated depreciation	11,203	11,641
Other assets	7,010	7,616
Investments in subsidiaries	833,241	793,277
Total Assets	910,186	845,349
Accounts payable	(748)	(683)
Intercompany payables	298,601	269,042
Accrued insurance	402	489
Accrued compensation	2,020	3,828
Other current liabilities	1,992	1,719
Total current liabilities	302,267	274,395
Deferred income taxes	(13,314)	(12,330)
Long-term debt	170,769	166,784
Other liabilities	3,019	2,816
Stockholders' equity	447,445	413,684
Total Liabilities and Stockholders' Equity	910,186	845,349
Guarantor Subsidiaries [Member]
Cash and cash equivalents	(803)	(1,422)	(8,582)	(1,571)
Accounts receivable, less allowances	80,120	76,816
Intercompany receivables	303,347	273,413
Inventories - net	7,414	8,032
Current deferred income taxes	14,329	13,059
Prepaid income taxes	(890)	1,689
Prepaid expenses	9,554	10,757
Total current assets	413,071	382,344
Properties and equipment, at cost, less accumulated depreciation	74,761	68,755
Identifiable intangible assets less accumulated amortization	57,635	58,262
Goodwill	457,487	456,183
Other assets	1,733	1,552
Investments in subsidiaries	23,043	21,148
Total Assets	1,027,730	988,244
Accounts payable	51,304	48,490
Accrued insurance	36,384	36,658
Accrued compensation	37,166	36,655
Other current liabilities	12,618	15,728
Total current liabilities	137,472	137,531
Deferred income taxes	49,264	51,601
Deferred compensation liabilities	30
Other liabilities	6,394	4,630
Stockholders' equity	834,570	794,482
Total Liabilities and Stockholders' Equity	1,027,730	988,244
Non-Guarantor Subsidiaries [Member]
Cash and cash equivalents	7,489	7,033	6,332	6,164
Accounts receivable, less allowances	609	502
Inventories - net	732	636
Current deferred income taxes	208	131
Prepaid income taxes	376	556
Prepaid expenses	203	149
Total current assets	9,617	9,007
Investments of deferred compensation plans	33,215	31,629
Properties and equipment, at cost, less accumulated depreciation	2,607	2,555
Goodwill	4,478	4,450
Other assets	2,926	2,509
Total Assets	52,843	50,150
Accounts payable	446	418
Intercompany payables	4,746	4,371
Income taxes	167	90
Accrued compensation	543	604
Other current liabilities	296	1,404
Total current liabilities	6,198	6,887
Deferred income taxes	(10,693)	(9,808)
Deferred compensation liabilities	33,119	30,693
Other liabilities	2,505	2,435
Stockholders' equity	21,714	19,943
Total Liabilities and Stockholders' Equity	52,843	50,150
Consolidating Adjustments [Member]
Intercompany receivables	(303,347)	(273,413)
Total current assets	(303,347)	(273,413)
Investments in subsidiaries	(856,284)	(814,425)
Total Assets	(1,159,631)	(1,087,838)
Intercompany payables	(303,347)	(273,413)
Total current liabilities	(303,347)	(273,413)
Stockholders' equity	(856,284)	(814,425)
Total Liabilities and Stockholders' Equity	$ (1,159,631)	$ (1,087,838)