Summary of Significant Accounting Policies (Other Expense (Income), Net) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other expense (income), net [Line Items]
Impairment Losses Related to Real Estate Partnerships	$ 8,000	$ 8,017	$ 0	$ 0
Write-off of deposits and pre-acquisition costs		11,367	17,157	5,021
Amortization of intangible assets		13,800	13,800	12,900
Equity in (earnings) loss of unconsolidated entities		1,985	(8,337)	(7,355)
Interest income		(2,537)	(3,236)	(3,107)
Interest expense		503	686	788
Miscellaneous, net		1,104	17,101	6,653
Other expense, net		27,951	48,814	17,363
Charges related to contractual dispute			15,000	20,000
Homebuilding [Member]
Other expense (income), net [Line Items]
Lease exit and related costs		1,729	11,643	2,463
Equity in (earnings) loss of unconsolidated entities		$ 2,610	$ (7,806)	$ (7,355)