Share-Based Compensation Arrangements (Share Options Activity) (Details) - Stock Options [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Share Options:
Beginning of period	248,815
Granted	81,530	61,800	47,950
Exercised	(4,100)
Forfeited or expired	0
End of period	326,245	248,815
Options exercisable	134,965
Options expected to vest in future periods	191,280
Weighted Average Exercise Price (in dollars per share):
Beginning of period	$ 45.38
Granted	32.23
Exercised	17.52
Forfeited or expired	0
End of period	42.44	$ 45.38
Options exercisable	41.40
Options expected to vest in future periods	$ 43.18
Outstanding Weighted Average Remaining Contractual Term	7 years 2 months 23 days
Exercisable Weighted Average Remaining Contractual Term	4 years 9 months 7 days
Expected to Vest Weighted Average Remaining Contractual Term	8 years 11 months 19 days
Outstanding Aggregate Intrinsic Value	$ 2,011
Exercisable Aggregate Intrinsic Value	986
Expected to Vest Aggregate Intrinsic Value	$ 1,025