Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
State net operating loss carryforwards	$ 15,709	$ 17,237
Impairment losses	38,844	41,837
Prepaid income from land sales	2,597	3,734
Capitalized costs	2,107
Other	3,508	322
Total gross deferred tax assets	62,765	63,130
Valuation allowance		(4,993)
Total net deferred tax assets	62,765	58,137
Deferred tax liabilities:
Investment in real estate and property and equipment basis differences	2,358	525
Deferred gain on land sales and involuntary conversions	19,109	19,671
Installment sales	83,268	85,769
Pension Plan assets transferred to the 401(k) Plan	872	1,155
Other	1,473
Total gross deferred tax liabilities	107,080	107,120
Net deferred tax liabilities	$ (44,315)	$ (48,983)