Stockholders' Equity - Accumulated Other Comprehensive Income (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) swap_agreement	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Number of interest rate swaps | swap_agreement	2
Increase to accumulated other comprehensive loss	$ (74)		$ (1,684)
Period of impact on net income	10 years
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income	$ 102	$ 168	$ 950
Forward Starting Swaps [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(1,401)
Other comprehensive loss before reclassifications	176
Amounts reclassified from accumulated other comprehensive income (loss)	(74)
Other comprehensive income	102
Balance, end of period	(1,299)	(1,401)
Interest Rate Swap [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Increase to accumulated other comprehensive loss	100
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	1,400
Balance, end of period	$ 1,300	$ 1,400