Income Taxes 4 (Details)	12 Months Ended
Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Income tax rate reconciliation
Statutory federal income tax rate	35.00%	35.00%	35.00%
Effect of state income taxes, net of federal benefit	2.10%	0.10%	(15.10%)
Effect of noncontrolling interests on income tax rate	(1.90%)	(1.40%)	(6.40%)
Effect of gains (losses) on investments, sales of assets and impairment of assets on income tax rate			1.80%
Other differences effect on income tax rate	(1.20%)	0.10%	(2.30%)
Total income tax rate	34.00%	33.80%	13.00%

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 109

-Paragraph 47

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph h

-Subparagraph 2

-Article 4

+ Details

Name:	us-gaap_EffectiveIncomeTaxRateContinuingOperations
Namespace Prefix:	us-gaap
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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 shall be the regular tax rate if there are alternative tax systems.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 109

-Paragraph 47

+ Details

Name:	us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
Namespace Prefix:	us-gaap
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to the disposition of assets.

+ Details

Name:	us-gaap_EffectiveIncomeTaxRateReconciliationDispositionOfAssets
Namespace Prefix:	us-gaap
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to noncontrolling interest income (expense) that is exempt from income taxes under enacted tax laws.

+ Details

Name:	us-gaap_EffectiveIncomeTaxRateReconciliationMinorityInterestIncomeExpense
Namespace Prefix:	us-gaap
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to all other items not otherwise listed in the existing taxonomy.

+ Details

Name:	us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments
Namespace Prefix:	us-gaap
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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 (benefit), net of the federal tax benefit (expense) thereon, recorded during the period.

+ Details

Name:	us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes
Namespace Prefix:	us-gaap
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration