Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
State net operating loss carryforwards	$ 14,956,000	$ 11,400,000
Alternative minimum tax credit carryforward	13,477,000	0
Impairment losses	63,108,000	112,143,000
Prepaid income from land sales	5,461,000	5,490,000
Other	0	1,358,000
Total gross deferred tax assets	97,002,000	130,391,000
Valuation allowance	(5,135,000)	(6,012,000)
Total net deferred tax assets	91,867,000	124,379,000
Deferred tax liabilities:
Investment in real estate and property and equipment basis differences	647,000	3,071,000
Deferred gain on land sales and involuntary conversions	28,920,000	28,691,000
Installment sales	127,260,000	126,741,000
Pension Plan assets transferred to the 401(k) Plan	2,170,000	2,723,000
Other	1,716,000	0
Total gross deferred tax liabilities	160,713,000	161,226,000
Net deferred tax liability	$ (68,846,000)	$ (36,847,000)