Shareholders' Equity - Narrative (Details) - USD ($)	1 Months Ended	6 Months Ended
	Sep. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Feb. 25, 2016
Equity, Class of Treasury Stock [Line Items]
Common equity issued	$ 5,000,000
Common stock, shares issued (in shares)		8,520,328		8,520,328
Common stock, shares outstanding (in shares)		8,520,328		8,520,328
Common stocks
Equity, Class of Treasury Stock [Line Items]
Stock repurchased and retired during period, shares		0	0
Common stock, shares issued (in shares)		8,520,328		8,520,328
Common stock, shares outstanding (in shares)		8,520,328		8,520,328
Stock Repurchase Program, February 2016
Equity, Class of Treasury Stock [Line Items]
Authorized amount of stock repurchase program					$ 2,100,000.0
Private placement
Equity, Class of Treasury Stock [Line Items]
Common equity issued (in shares)	800,000
Offering price per share (in dollars per share)	$ 6.25