Revenue Recognition (Contract Balances Included in Balance Sheet) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017		Mar. 31, 2017	Dec. 31, 2016
Revenue from Contract with Customer [Abstract]
Customer and builder deposits	$ 22,698	$ 21,447	[1]	$ 17,067	$ 14,088

[1] The Condensed Consolidated Balance Sheet at December 31, 2017 has been derived from the audited financial statements at that date, but does not include all of the footnotes required by U.S. generally accepted accounting principles for complete financial statements.