Summary Of Significant Accounting Policies (Goodwill And Other Intangible Assets) (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Summary Of Significant Accounting Policies [Abstract]
Goodwill balance	$ 174.6		$ 174.6		$ 174.6
Shurgard trade name, book value	18.8		18.8		18.8
In-place and leasehold interests in land, net book value	13.5		13.5		12.5
In-place and leasehold interests in land, accumulated amortization	31.3		31.3		$ 27.5
In-place and leasehold interests in land, amortization expense	4.3	$ 4.5	9.0	$ 8.4
Estimated future amortization expense, remainder of 2020	4.6		4.6
Estimated future amortization expense, 2021	2.8		2.8
Estimated future amortization expense, thereafter	$ 6.1		6.1
Increase in in-place and leasehold interests in land			$ 10.0