Stock-Based Compensation Plans Market Stock Units (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
MSU Expense	$ 900,000	$ 500,000	$ 500,000
Number of Market Stock Units
Outstanding on December 31, 2016	149,532
Granted	98,243
Cancelled	(25,839)
Outstanding on December 31, 2017	221,936	149,532
Maximum Shares Potentially Issuable
Outstanding on December 31, 2016	224,298
Granted	147,365
Cancelled	(38,759)
Outstanding on December 31, 2017	332,904	224,298
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential Shares From MSU Vest	$ 0
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential Shares From MSU Vest	$ 1.50
Trading days	60 days