Stock-Based Compensation - Option Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based Compensation Expense	$ 6,349	$ 5,919	$ 5,309
Current Year Stock Option Awards [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based Compensation Expense	282	0	0
Unrecognized Compensation Expense, Options	700
Prior Year Stock Option Awards [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based Compensation Expense	276	232	0
Unrecognized Compensation Expense, Options	300
Second Prior Year Stock Option Awards [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based Compensation Expense	254	257	227
Unrecognized Compensation Expense, Options	100
Third Prior Year Stock Option Awards [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based Compensation Expense	$ 36	$ 200	$ 213