Non-Recourse Property Debt and Credit Agreement (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Summarizes property tax-exempt bond financings related to properties classified as held for use
Non-recourse property debt	$ 4,337,785	$ 4,413,083
Property Tax Exempt Bonds Payable
Summarizes property tax-exempt bond financings related to properties classified as held for use
Non-recourse property debt	217,545	217,819
Property Tax Exempt Bonds Payable | Fixed Rate
Summarizes property tax-exempt bond financings related to properties classified as held for use
Weighted Average Interest Rate	4.87%
Non-recourse property debt	85,634	87,220
Property Tax Exempt Bonds Payable | Variable Rate
Summarizes property tax-exempt bond financings related to properties classified as held for use
Weighted Average Interest Rate	1.09%
Non-recourse property debt	$ 131,911	$ 130,599