Stock Compensation Plans (Stock Purchase Plan) (Details) - Stock Purchase Plan - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Stock purchase plan
Purchase price of shares in terms compared to market price per share (as a percent)	90.00%
Annual purchase limitation per employee	$ 22,500
Compensation expense	$ 0
Common stock, shares authorized (in shares)	2,000,000
Shares sold to employees (in shares)	81,221	51,541
Value of shares sold to employees under purchase plan	$ 3,400,000	$ 2,800,000
Shares available (in shares)	393,925