Debt - Non-Recourse Mortgages and Notes Payable (Details) - Non-recourse mortgages and notes payable - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Long-Term Debt
Outstanding principal balances per real estate development, low end of range	$ 1.8	$ 1.7
Outstanding principal balances per real estate development, high end of range	41.1	32.6
Real estate	$ 79.5	$ 155.6

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