Income Taxes (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income tax expense from continuing operations by applying the statutory U.S. federal income tax rate to income before income taxes
Tax expense at statutory rate	$ 108,446	$ 153,010	$ 70,496
Percentage of tax expense at statutory rate	35.00%	35.00%	35.00%
Increase in income taxes resulting from:
State and local income taxes, net of federal income tax effect	4,239	9,418	2,549
Percentage of state and local income taxes, net of federal income tax effect	1.40%	2.20%	1.30%
Effect of nondeductible expenses and other, net	1,540	1,372	1,544
Effect of nondeductible expenses and other, net in percentage	0.50%	0.30%	0.70%
Decrease in income taxes resulting from:
IRS pre-filing agreement on qui tam settlement			(22,449)
Percentage of IRS pre-filing agreement on qui tam settlement			(11.10%)
Tax benefit recorded by the company	$ 114,225	$ 163,800	$ 52,140
Percentage of total income tax expense	36.90%	37.50%	25.90%

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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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The domestic federal statutory tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period. The "statutory" tax rate is the regular tax rate if there are alternative tax systems.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate that can be explained by the state and local income tax expense or benefit, net of the federal tax benefit (expense) thereon, recorded during the period.

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The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to pretax Income or Loss from continuing operations; income tax expense or benefit may include interest and penalties on tax uncertainties based on the entity's accounting policy.

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