Income Taxes - Components of Net Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred income tax assets:
Accrued expenses	$ 561	$ 578
Deferred revenues	654	652
Capitalization of costs	3,224	3,023
Pension adjustment	4,690	4,396
Stock grant expense	2,309	3,593
State deferred taxes	37	221
Book deferred gains	1,912	1,711
Joint venture allocations	932	860
Provision for additional capitalized costs	1,003	1,003
Interest rate swap	799	1,244
Other	41	3
Total deferred income tax assets	16,162	17,284
Deferred income tax liabilities:
Deferred gains	51	1,390
Depreciation	5,279	5,040
Cost of sales allocations	1,252	1,252
Joint venture allocations	5,389	3,121
Straight line rent	926	929
Prepaid expenses	323	149
State deferred taxes	470	617
Other	190	127
Total deferred income tax liabilities	13,880	12,625
Net deferred income tax asset	2,282	4,659
Allowance for deferred tax assets	0	0
Net deferred taxes	$ 2,282	$ 4,659