Income Taxes - Sources of Temporary Differences (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred Tax Liabilities, Gross [Abstract]
Fixed assets	$ (16,488)	$ (17,360)
Other	(201)	(221)
State deferred taxes	(1,242)	(1,523)
Total deferred tax liabilities	(17,931)	(19,104)
Deferred Tax Assets, Gross [Abstract]
Captive insurance subsidiary	413	429
Accrued liabilities	2,741	2,633
Stock compensation	1,713	1,346
Solar credit	0	2,167
Other	1,548	309
SmartStop TRS	365	1,085
State deferred taxes	6,078	6,016
Total deferred tax assets	12,858	13,985
Valuation allowance	(4,765)	(5,609)
Net deferred income tax liabilities	$ (9,838)	$ (10,728)