Common Shares (Activity Under At-The-Market Share Offering Program) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common shares sold	3,599	0	4,778
2017 ATM program [Member]
Total net consideration	$ 24,839,100		$ 2,513,600
Common shares sold	224,300		28,100
Average Price Per Common Share Sold	$ 111.88		$ 90.44