Investments In and Advances to Unconsolidated Joint Ventures Unconsolidated Joint Ventures - Inventory Impairments (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) project	Dec. 31, 2017 USD ($) project	Dec. 31, 2016 USD ($) project	Dec. 31, 2018 investment
Other than Temporary Impairment Losses, Investments	$ 1,100,000	$ 0	$ 0
Equity Method Investment, Impairment Of Joint Ventures	$ 28,776,000	$ 0	$ 0
Number Of Joint Venture Projects Impaired During Period | project	1	0	0
Equity Method Investments, Number	10	10	13	10
Homebuilding Joint Ventures [Member]
Equity Method Investment, Impairment Of Joint Ventures		$ 0
Land Development Joint Ventures [Member]
Equity Method Investment, Impairment Of Joint Ventures	$ 28,776,000	$ 0	$ 0