Income Taxes (Deferred Tax Liabilities (Assets)) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Abstract]
Depreciation	$ 22,782	$ 19,705
Goodwill	21,686	15,070
Intangible assets	24,111	13,921
Other	2,046	420
Gross deferred tax liabilities	70,625	49,116
Equity compensation	(8,526)	(8,456)
Other	(16,315)	(12,578)
Gross deferred tax assets	(24,841)	(21,034)
Valuation allowances	2,613	2,829
Deferred tax assets, net of valuation allowances	(22,228)	(18,205)
Net deferred tax liabilities	$ 48,397	$ 30,911