Income Taxes (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Line Items]
Provision to return and deferred tax adjustments	$ 190,000	$ 3,548,000
Unrealized losses on interest rate swap, tax	11,219,000	1,383,000
Percentage of qualifying capital investment expensed	100.00%	100.00%
Mexico [Member]
Income Taxes [Line Items]
Operating loss carryforward	2,200,000
Operating loss carryforward first year of expiration	2016
U.K. [Member]
Income Taxes [Line Items]
Operating loss carryforward	6,700,000
Canada [Member]
Income Taxes [Line Items]
Operating loss carryforward	543,000
Operating loss carryforward first year of expiration	2028
United States Federal [Member]
Income Taxes [Line Items]
Operating loss carryforward	53,600,000
Operating loss carryforward first year of expiration	2025
Tax benefits from previous stock-based compensation activities	34,900,000
Alternative minimum tax credit	300,000
United States Federal [Member] | Minimum [Member]
Income Taxes [Line Items]
Operating loss carryforward first year of expiration	12
United States Federal [Member] | Maximum [Member]
Income Taxes [Line Items]
Operating loss carryforward first year of expiration	24
Company's 2011 Acquisitions [Member]
Income Taxes [Line Items]
Net deferred tax assets	21,600,000
Operating loss carryforward	$ 14,900,000