Stock Options and Incentive Plans (Schedules of Stock Option Activity) (Details) - Stock Options [Member] - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Shares
Shares under option	88,773	187,233	228,533
Options canceled
Options exercised	26,383	98,460	41,300
Shares under option at December 31	62,390	88,773	187,233
Options exercisable at December 31	62,390	88,773	187,233
Weighted Average Exercise Price
Shares under option January 1	$ 18.67	$ 18.99	$ 18.94
Options canceled
Options exercised	19.60	19.27	18.71
Shares under option December 31	18.28	18.67	18.99
Options exercisable December 31	$ 18.28	$ 18.67	$ 18.99