Stock-Based Compensation Plans (Summary of Nonvested Stock Options) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Awards
Nonvested, beginning	9,450
Granted	0
Vested	(3,600)
Forfeited	(2,400)
Nonvested, ending	3,450	9,450
Weighted- Average Grant Date Fair Value
Nonvested, beginning	$ 6.59
Granted	0.00	$ 5.17	$ 5.87
Vested	7.80
Forfeited	5.48
Nonvested, ending	$ 6.11	$ 6.59