Income Taxes - Sources of Temporary Differences (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred Tax Liabilities, Gross [Abstract]
Fixed assets	$ (15,271)	$ (16,488)
Other	(108)	(201)
State deferred taxes	(2,822)	(1,242)
Total deferred tax liabilities	(18,201)	(17,931)
Deferred Tax Assets, Gross [Abstract]
Captive insurance subsidiary	252	413
Accrued liabilities	873	2,741
Stock compensation	1,287	1,713
Solar credit	43	0
Other	57	1,548
SmartStop TRS	219	365
State deferred taxes	7,802	6,078
Total deferred tax assets	10,533	12,858
Valuation allowance	(4,924)	(4,765)
Net deferred income tax liabilities	$ (12,592)	$ (9,838)