Summary of Significant Accounting Policies Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Revenue	$ 722,485	$ 567,842	$ 558,098	$ 437,857	$ 621,702	$ 476,423	$ 456,866	$ 406,980	$ 2,286,282	$ 1,961,971	$ 1,691,327
Gain (Loss) on Hedging Activity									3,600	700	(3,000)
Construction [Member]
Disaggregation of Revenue [Line Items]
Revenue									2,217,197	1,878,572	1,610,496
Land [Member]
Disaggregation of Revenue [Line Items]
Revenue									16,889	33,706	38,820
Financial Services [Member]
Disaggregation of Revenue [Line Items]
Revenue									52,196	49,693	42,011
Midwest Homebuilding [Member]
Disaggregation of Revenue [Line Items]
Revenue									933,119	742,577	637,894
Southern Homebuilding [Member]
Disaggregation of Revenue [Line Items]
Revenue									925,404	730,482	602,273
Mid-Atlantic Homebuilding [Member]
Disaggregation of Revenue [Line Items]
Revenue									375,563	439,219	409,149
Financial Services [Member]
Disaggregation of Revenue [Line Items]
Revenue									$ 52,196	$ 49,693	$ 42,011