Income Taxes (Details Textual) (USD $)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Income Taxes (Additional Textual) [Abstract]
Deferred tax assets related to acquisitions of noncontrolling interests	$ 800,000	$ 7,700,000
Tax receivable included in other current assets	4,200,000	3,600,000
Reduction in its current state income tax provision	814,000
Adjustment to state tax provision		162,000
Accrued interest and penalties associated with any unrecognized tax benefits	0	0
Interest expense recognized	$ 0	$ 0
Federal [Member]
Income Taxes (Textual) [Abstract]
Periods open for examination	2009 through 2011
State [Member]
Income Taxes (Textual) [Abstract]
Periods open for examination	2008 through 2011

This element represents the total of accruals as of the date of the statement of financial position for interest recognized for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity and the amount of statutory penalties for a tax position claimed or expected to be claimed by the entity, in its tax return, that does not meet the minimum statutory threshold to avoid payment of penalties.

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This element represents interest expense recognized for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity.

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