Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions |
3 Months Ended | |
|---|---|---|
Mar. 31, 2021 |
Mar. 31, 2020 |
|
| Significant Accounting Policies [Abstract] | ||
| Capitalized development and construction salaries and other related costs | $ 0.6 | $ 0.5 |
| Maximum period after cessation of major construction activity that projects are considered complete | 1 year | |