Fair Value Measurements Assets and Liabilities Measured on a Non-Recurring Basis (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Valuation adjustments to investments in unconsolidated joint ventures	$ 0	$ 0	$ 1,047
Fair Value, Significant Unobservable Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Adjusted basis of inventory	12,921	11,885	3,730
Total losses	3,992	3,638	3,457
Initial basis of inventory	$ 16,913	$ 15,523	$ 7,187