Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Summary of computation of basic and diluted earnings per share [Abstract]
Common shares outstanding at the beginning of the period					4,708,576	4,711,995	4,714,694	4,712,328
Weighted average number of net shares (redeemed) issued	(6,471)	(1,842)	(5,696)	1,523
Weighted average shares outstanding (basic)	4,702,105	4,712,852	4,706,299	4,713,851
Weighted average of potential dilutive shares attributable to stock options granted, computed under the treasury stock method	2,060	3,327	2,425	3,981
Weighted average number of shares (diluted)	4,704,165	4,716,179	4,708,724	4,717,832
Net income (In thousands)	$ 7,181	$ 6,914	$ 13,925	$ 13,724
Earnings per share [Abstract]
Basic (in dollars per share)	$ 1.53	$ 1.47	$ 2.96	$ 2.91
Diluted (in dollars per share)	$ 1.53	$ 1.47	$ 2.96	$ 2.91