Income Taxes - Valuation Allowance (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Valuation allowances
Net deferred tax assets	$ 78,105				$ 122,309				$ 78,105	$ 122,309
Income (loss) before income taxes	$ 15,044	$ (2,349)	$ 1,469	$ 4,168	$ 17,496	$ 11,935	$ 7,296	$ 859	18,332	37,586	$ 12,386
Homebuilding revenues									$ 821,616	$ 764,041	$ 498,915