Income Taxes (Details Textual) (USD $)	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Income Taxes (Textual) [Abstract]
Income tax provision	$ 22,495,000	$ 15,226,000
Effective rate of pre-tax income	29.00%	30.00%
Income tax assessment including interest under Canada Revenue Agency Audit		8,000,000
Expected recovery of U.S. federal and state income taxes		7,000,000
Net deferred tax assets (liabilities)	$ 17,400,000		$ 24,600,000

For entities that net deferred tax assets and tax liabilities, represents the unclassified net amount of deferred tax assets and liabilities as of the balance sheet date, which result from applying the applicable enacted tax rate to net temporary differences and carryforwards pertaining to assets or liabilities. A temporary difference is a difference between the tax basis of an asset or liability and its carrying amount in the financial statements prepared in accordance with generally accepted accounting principles that will reverse in ensuing periods.

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A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

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- Definition

The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

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- Definition

Reflects the effects of adjustments of previously recorded tax expense, significant settlements of income tax disputes, and unusual tax positions or infrequent actions taken by the entity, including tax assessment reversal, IRS tax settlement and unusual repatriation of foreign earnings.

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