Share-Based Compensation - Option Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based Compensation Expense	$ 10,996	$ 4,861	$ 3,724
2020 Stock option awards [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based Compensation Expense	385	0	0
Unrecognized Compensation Expense, Options	1,200
2019 Stock option awards [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based Compensation Expense	698	665	0
Unrecognized Compensation Expense, Options	300
2018 Stock option awards [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based Compensation Expense	357	364	310
Unrecognized Compensation Expense, Options	100
2017 Stock option awards [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based Compensation Expense	$ 51	$ 369	$ 367