Income Taxes - Components of Net Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred income tax assets:
Accrued expenses	$ 318	$ 393
Deferred revenues	697	209
Capitalization of costs	1,937	2,138
Pension adjustment	2,937	2,996
Stock grant expense	2,674	2,130
State deferred taxes	25	0
Book deferred gains	941	941
Joint venture allocations	1,091	1,025
Provision for additional capitalized costs	699	699
Interest rate swap	0	267
Other	155	423
Total deferred income tax assets	11,474	11,221
Deferred income tax liabilities:
Deferred gains	32	32
Depreciation	3,100	3,563
Cost of sales allocations	872	872
Joint venture allocations	4,914	3,972
Straight line rent	611	631
Prepaid expenses	298	132
State deferred taxes	256	322
Interest rate swap	28	0
Other	134	135
Total deferred income tax liabilities	10,245	9,659
Net deferred income tax asset	1,229	1,562
Allowance for deferred tax assets	0	0
Net deferred taxes	$ 1,229	$ 1,562