Variable Interest Entities (Narrative) (Details) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020 USD ($) item property	Dec. 31, 2019 item property
Variable Interest Entity [Line Items]
Additional support contributions | $	$ 2.7
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Number of VIE real estate joint ventures	8	8
Number of real estate properties | property	21	21
Number of VIE real estate joint ventures guaranteed by company	1	1
Unconsolidated Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Number of VIE real estate joint ventures	2	2
Additional support contributions | $	$ 0.8
Number of joint venture arrangements	1
Number of loan renewal options	2
Period for debt renewal option (in years)	1 year