Significant Accounting Policies (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) segment board_seat individual	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) segment	Aug. 15, 2017 board_seat	Dec. 31, 2014 USD ($)
Accounting Policies [Line Items]
Direct finance lease, interest rate, minimum	0.00%
Direct finance lease, interest rate, maximum	12.00%
Allowance for doubtful accounts	$ 0	$ 0
Asset Impairment Charges	96,303	0	$ 0
Variable Interest Entity, Consolidated, Assets, Not Pledged	52,200,000	24,600,000
Earnest money deposits written-off during period	200,000	200,000	200,000
Land not owned under option agreements	0	9,293,000
Deferred tax assets	31,265,000	67,755,000
Deferred income tax assets, net	31,211,000	67,598,000
Valuation allowance for deferred tax assets	(1,346,000)	(1,147,000)	$ (1,161,000)
Deferred tax asset related to net operating loss carryforwards	14,078,000	40,800,000
Deferred tax asset related to basis in partnership	$ 13,377,000	22,922,000
Percentage of controlling interests in several builders by parent	50.00%
Equity Method Investment Board Seats Held | board_seat	2
Equity Method Investment Board Seats | board_seat	3
Number of individuals required for approval (at least) | individual	1
Percentage of noncontrolling interests in several builders by parent	50.00%
Income tax expense (benefit) related to the Tax Act	$ 19,017,000
Number of reportable segments | segment			2
Number of operating segments | segment	3		2
Overstatement of accrued expenses					$ 1,900,000
Salary expense	$ 21,823,000	21,871,000	$ 16,272,000
Selling, general and administrative expense	17,193,000	16,758,000	13,704,000
Cost of residential units	$ 342,065,000	283,454,000	201,768,000
Minimum
Accounting Policies [Line Items]
Community life cycle	2 years
Useful lives of assets	3 years
Maximum
Accounting Policies [Line Items]
Community life cycle	6 years
Useful lives of assets	10 years
Selling, General and Administrative Expenses
Accounting Policies [Line Items]
Advertising expense	$ 800,000	700,000	500,000
Cash
Accounting Policies [Line Items]
Variable Interest Entity, Consolidated, Assets, Not Pledged	900,000	900,000
Inventory
Accounting Policies [Line Items]
Variable Interest Entity, Consolidated, Assets, Not Pledged	47,800,000	22,100,000
Other Assets
Accounting Policies [Line Items]
Payments of Debt Issuance Costs	1,200,000	800,000
Federal
Accounting Policies [Line Items]
Net operating loss carryforward	$ 67,000,000
Operating loss carryforward, expiration date	Dec. 31, 2029
Mechanic Liens | Other Nonoperating Income/Expense
Accounting Policies [Line Items]
Other nonoperating income	$ 4,400,000	12,500,000	7,700,000
Other nonoperating expense	$ 3,800,000	$ 11,100,000	5,900,000
Change in Classification of Indirect Project Costs
Accounting Policies [Line Items]
Salary expense			(4,400,000)
Selling, general and administrative expense			$ (800,000)
Corporate and Other
Accounting Policies [Line Items]
Percentage of total revenue	95.90%	96.10%	87.30%
Challenger Subsidiary [Member]
Accounting Policies [Line Items]
Asset Impairment Charges	$ 0
Equity Method Investment Board Seats Held | board_seat				2
Equity Method Investment Board Seats | board_seat				5