Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Basic earnings per share:
Net income	$ 3,420	$ 518	$ 4,463	$ 865
Weighted average number of shares outstanding, basic (in shares)	738,439	757,323	759,012	760,297
Per share amount, basic (in dollars per share)	$ 4.63	$ 0.68	$ 5.88	$ 1.14
Effect of dilutive securities:
Stock options (in shares)	432	1,218	432	1,218
Diluted earnings per share:
Net income plus assumed conversions	$ 3,420	$ 518	$ 4,463	$ 865
Weighted average number of shares outstanding, diluted (in shares)	738,871	758,541	759,444	761,515
Per share amount, diluted (in dollars per share)	$ 4.63	$ 0.68	$ 5.88	$ 1.14