Guarantor Subsidiaries (Schedule Of Guarantor Subsidiaries - Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	$ 39,479	$ 84,418	$ 72,956	$ 69,531
Accounts receivable, including intercompany	116,152	91,770
Inventories	6,676	6,703
Current deferred income taxes	13,769	20,257
Prepaid income taxes	3,406	3,690
Prepaid expenses	18,930	17,818
Total current assets	198,412	224,656
Investments of deferred compensation plans	45,732	42,465
Properties and equipment, at cost, less accumulated depreciation	93,575	92,955
Identifiable intangible assets less accumulated amortization	56,276	56,556
Goodwill	466,961	466,871
Other assets	7,664	10,198
Total assets	868,620	893,701
Accounts payable, including intercompany	38,599	41,758
Current portion of long-term debt	185,825	183,564
Income taxes	3,967	111
Accrued insurance	39,391	41,859
Accrued compensation	38,233	48,323
Accrued legal	7,154	23,210
Other current liabilities	24,682	25,161
Total current liabilities	337,851	363,986
Deferred income taxes	28,232	27,301
Deferred compensation liabilities	45,498	42,348
Other liabilities	11,106	11,176
Stockholders' equity	445,933	448,890
Total liabilities and stockholders' equity	868,620	893,701
Parent [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	41,808	84,005	62,174	56,342
Accounts receivable, including intercompany	1,231	925
Prepaid income taxes	9,155	3,710
Prepaid expenses	6,612	6,925
Total current assets	58,806	95,565
Properties and equipment, at cost, less accumulated depreciation	9,963	10,184
Other assets	12,745	17,782
Investments in subsidiaries	964,753	945,450
Total assets	1,046,267	1,068,981
Accounts payable, including intercompany	398,529	417,593
Current portion of long-term debt	185,825	183,564
Income taxes		1,106
Accrued insurance	1,433	784
Accrued compensation	1,086	5,047
Accrued legal	6,043	6,031
Other current liabilities	4,288	2,739
Total current liabilities	597,204	616,864
Other liabilities	3,130	3,227
Stockholders' equity	445,933	448,890
Total liabilities and stockholders' equity	1,046,267	1,068,981
Guarantor Subsidiaries [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	(11,336)	(8,777)	2,588	4,674
Accounts receivable, including intercompany	517,646	509,580
Inventories	6,148	6,246
Current deferred income taxes	14,720	21,307
Prepaid income taxes		1,176
Prepaid expenses	11,958	10,682
Total current assets	539,136	540,214
Properties and equipment, at cost, less accumulated depreciation	81,033	80,144
Identifiable intangible assets less accumulated amortization	56,276	56,556
Goodwill	462,687	462,489
Other assets	1,877	1,775
Investments in subsidiaries	28,007	27,564
Total assets	1,169,016	1,168,742
Accounts payable, including intercompany	39,213	39,424
Income taxes	7,663	210
Accrued insurance	37,958	41,075
Accrued compensation	36,807	42,905
Accrued legal	1,111	17,179
Other current liabilities	21,429	22,219
Total current liabilities	144,181	163,012
Deferred income taxes	52,331	52,548
Other liabilities	6,879	6,914
Stockholders' equity	965,625	946,268
Total liabilities and stockholders' equity	1,169,016	1,168,742
Non-Guarantor Subsidiaries [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	9,007	9,190	8,194	8,515
Accounts receivable, including intercompany	1,256	1,000
Inventories	528	457
Current deferred income taxes	264	126
Prepaid income taxes	7	349
Prepaid expenses	360	211
Total current assets	11,422	11,333
Investments of deferred compensation plans	45,732	42,465
Properties and equipment, at cost, less accumulated depreciation	2,579	2,627
Goodwill	4,274	4,382
Other assets	17,141	15,888
Total assets	81,148	76,695
Accounts payable, including intercompany	4,838	4,476
Income taxes	2,060	340
Accrued compensation	340	371
Other current liabilities	180	1,379
Total current liabilities	7,418	6,566
Deferred compensation liabilities	45,498	42,348
Other liabilities	1,097	1,035
Stockholders' equity	27,135	26,746
Total liabilities and stockholders' equity	81,148	76,695
Consolidating Adjustments [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Accounts receivable, including intercompany	(403,981)	(419,735)
Current deferred income taxes	(1,215)	(1,176)
Prepaid income taxes	(5,756)	(1,545)
Total current assets	(410,952)	(422,456)
Other assets	(24,099)	(25,247)
Investments in subsidiaries	(992,760)	(973,014)
Total assets	(1,427,811)	(1,420,717)
Accounts payable, including intercompany	(403,981)	(419,735)
Income taxes	(5,756)	(1,545)
Other current liabilities	(1,215)	(1,176)
Total current liabilities	(410,952)	(422,456)
Deferred income taxes	(24,099)	(25,247)
Stockholders' equity	(992,760)	(973,014)
Total liabilities and stockholders' equity	$ (1,427,811)	$ (1,420,717)