Summary Of Significant Accounting Policies (Goodwill And Other Intangible Assets) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary Of Significant Accounting Policies [Abstract]
Goodwill balance	$ 174.6	$ 174.6
Shurgard trade name, book value	18.8	18.8
In-place and leasehold interests in land, net book value	12.5	16.5
In-place and leasehold interests in land, accumulated amortization	27.5	29.6
In-place and leasehold interests in land, amortization expense	16.8	16.6	$ 15.0
Estimated future amortization expense, 2020	10.8
Estimated future amortization expense, 2021	1.3
Estimated future amortization expense, thereafter	0.4
Increase in in-place and leasehold interests in land	$ 18.5	$ 11.6	$ 17.2