Income Taxes (Summary Of Deferred Tax Assets And Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Abstract]
Accounts receivable, principally due to the allowance for doubtful accounts	$ 3,251	$ 3,201
Accrued expenses not currently deductible for tax	1,652	1,284
Stock based compensation	8,289	6,070
Foreign tax credit	177	177
Net operating loss carryforwards	3,168	2,865
Other	363	217
Deferred tax assets before valuation allowance	16,900	13,814
Valuation allowance	(1,709)	(1,784)
Deferred tax assets, net	15,191	12,030
Property and equipment, principally due to differences between book and tax depreciation	(4,020)	(2,297)
Intangibles-including goodwill	(119,254)	(88,504)
Deferred tax liabilities	(123,274)	(90,801)
Net deferred tax liabilities	$ (108,083)	$ (78,771)