Per Share Data (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Convertible securities which would affect denominator in calculating basic and dilutive earnings per share (in shares)			0
Shares outstanding (in shares)	31,000		31,000
Strike price (in dollars per share)	$ 42.03		$ 42.03
Weighted average common shares issued (in shares)	5,006,252	5,003,979	5,005,707	5,003,396
Average treasury stock shares (in shares)	(272,452)	(242,403)	(269,863)	(222,620)
Weighted average common shares and common stock equivalents used to calculate basic and diluted earnings per share (in shares)	4,733,800	4,761,576	4,735,844	4,780,776