Stock Repurchase Program (Details Textual) - USD ($)				12 Months Ended
	Jan. 23, 2018	Jan. 24, 2017	Jan. 26, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity Class Of Treasury Stock [Line Items]
Common stock, shares outstanding				4,420,136	4,420,255
Stock repurchase program, shares repurchased				12,863
Stock Repurchase Program on January 26, 2016
Equity Class Of Treasury Stock [Line Items]
Percentage of shares authorized to be repurchased to common stock outstanding			2.30%
Common stock, shares outstanding			4,404,783
Stock repurchase program expiration date				Dec. 31, 2016
Stock repurchase program, shares repurchased					0
Stock Repurchase Program on January 26, 2016 | Maximum
Equity Class Of Treasury Stock [Line Items]
Shares authorized to be repurchased			100,000
Stock Repurchase Program on January 24, 2017
Equity Class Of Treasury Stock [Line Items]
Percentage of shares authorized to be repurchased to common stock outstanding		2.30%
Common stock, shares outstanding		4,420,055
Stock repurchase program, authorized amount				$ 2,100,000
Stock repurchase program expiration date				Dec. 31, 2017
Stock repurchase program, shares repurchased				12,863
Stock Repurchase Program on January 24, 2017 | Maximum
Equity Class Of Treasury Stock [Line Items]
Shares authorized to be repurchased		100,000
Stock Repurchase Program on January 23, 2018
Equity Class Of Treasury Stock [Line Items]
Stock repurchase program expiration date				Dec. 31, 2018
Stock Repurchase Program on January 23, 2018 | Subsequent Event
Equity Class Of Treasury Stock [Line Items]
Percentage of shares authorized to be repurchased to common stock outstanding	2.30%
Common stock, shares outstanding	4,420,136
Stock Repurchase Program on January 23, 2018 | Subsequent Event | Maximum
Equity Class Of Treasury Stock [Line Items]
Shares authorized to be repurchased	100,000