Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Significant Accounting Policies [Abstract]
Capitalized development and construction salaries and other related costs	$ 0.7	$ 0.4	$ 1.9	$ 1.3
Maximum period after cessation of major construction activity that projects are considered complete			1 year