Guarantor Subsidiaries (Schedule Of Guarantor Subsidiaries - Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Cash and cash equivalents	$ 34,214	$ 38,081	$ 59,745	$ 49,917
Accounts receivable, less allowances	110,656	77,924
Inventories	8,468	8,668
Current deferred income taxes	13,725	12,540
Prepaid income taxes	637	2,131
Prepaid expenses	9,576	11,409
Total current assets	177,276	150,753
Investments of deferred compensation plans	35,055	31,629
Properties and equipment, at cost, less accumulated depreciation	88,579	82,951
Identifiable intangible assets less accumulated amortization	57,941	58,262
Goodwill	461,064	460,633
Other assets	11,568	11,677
Total Assets	831,483	795,905
Accounts payable	52,999	48,225
Income taxes	13,334	90
Accrued insurance	37,305	37,147
Accrued compensation	35,834	41,087
Other current liabilities	15,724	18,851
Total current liabilities	155,196	145,400
Deferred income taxes	27,256	29,463
Long-term debt	168,759	166,784
Deferred compensation liabilities	34,186	30,693
Other liabilities	11,629	9,881
Stockholders' equity	434,457	413,684
Total Liabilities and Stockholders' Equity	831,483	795,905
Parent [Member]
Cash and cash equivalents	26,204	32,470	61,443	45,324
Accounts receivable, less allowances	1,126	606
Current deferred income taxes	(568)	(650)
Prepaid income taxes	2,669	(114)
Prepaid expenses	363	503
Total current assets	29,794	32,815
Properties and equipment, at cost, less accumulated depreciation	11,422	11,641
Other assets	7,329	7,616
Investments in subsidiaries	813,062	793,277
Total Assets	861,607	845,349
Accounts payable	(823)	(683)
Intercompany payables	266,329	269,042
Income taxes	(2,016)
Accrued insurance	805	489
Accrued compensation	981	3,828
Other current liabilities	2,993	1,719
Total current liabilities	268,269	274,395
Deferred income taxes	(12,755)	(12,330)
Long-term debt	168,759	166,784
Other liabilities	2,877	2,816
Stockholders' equity	434,457	413,684
Total Liabilities and Stockholders' Equity	861,607	845,349
Guarantor Subsidiaries [Member]
Cash and cash equivalents	668	(1,422)	(7,872)	(1,571)
Accounts receivable, less allowances	109,059	76,816
Intercompany receivables	270,012	273,413
Inventories	7,732	8,032
Current deferred income taxes	14,099	13,059
Prepaid income taxes	(1,686)	1,689
Prepaid expenses	9,091	10,757
Total current assets	408,975	382,344
Properties and equipment, at cost, less accumulated depreciation	74,458	68,755
Identifiable intangible assets less accumulated amortization	57,941	58,262
Goodwill	456,523	456,183
Other assets	1,721	1,552
Investments in subsidiaries	22,366	21,148
Total Assets	1,021,984	988,244
Accounts payable	53,481	48,490
Income taxes	14,094
Accrued insurance	36,500	36,658
Accrued compensation	34,326	36,655
Other current liabilities	12,413	15,728
Total current liabilities	150,814	137,531
Deferred income taxes	50,599	51,601
Other liabilities	6,282	4,630
Stockholders' equity	814,289	794,482
Total Liabilities and Stockholders' Equity	1,021,984	988,244
Non-Guarantor Subsidiaries [Member]
Cash and cash equivalents	7,342	7,033	6,174	6,164
Accounts receivable, less allowances	471	502
Inventories	736	636
Current deferred income taxes	194	131
Prepaid income taxes	(346)	556
Prepaid expenses	122	149
Total current assets	8,519	9,007
Investments of deferred compensation plans	35,055	31,629
Properties and equipment, at cost, less accumulated depreciation	2,699	2,555
Goodwill	4,541	4,450
Other assets	2,518	2,509
Total Assets	53,332	50,150
Accounts payable	341	418
Intercompany payables	3,683	4,371
Income taxes	1,256	90
Accrued compensation	527	604
Other current liabilities	318	1,404
Total current liabilities	6,125	6,887
Deferred income taxes	(10,588)	(9,808)
Deferred compensation liabilities	34,186	30,693
Other liabilities	2,470	2,435
Stockholders' equity	21,139	19,943
Total Liabilities and Stockholders' Equity	53,332	50,150
Consolidating Adjustments [Member]
Intercompany receivables	(270,012)	(273,413)
Total current assets	(270,012)	(273,413)
Investments in subsidiaries	(835,428)	(814,425)
Total Assets	(1,105,440)	(1,087,838)
Intercompany payables	(270,012)	(273,413)
Total current liabilities	(270,012)	(273,413)
Stockholders' equity	(835,428)	(814,425)
Total Liabilities and Stockholders' Equity	$ (1,105,440)	$ (1,087,838)