Revenues (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2020
Revenues [Abstract]
Reduction of net income due to recording of revenue on cash basis and write off outstanding straight-line receivable	$ 0.3	$ 1.5
Unpaid billed charges of rent and tenant reimbursements	1.8	6.6
Unrecorded revenue from tenants	$ 1.8	$ 6.6

Reduction of net income due to recording of revenue on cash basis and write off outstanding straight-line receivable .

No definition available.

Name:	cdr_ReductionOfNetIncomeDueToRecordingOfRevenueOnCashBasisAndWriteOffOutstandingStraightLineReceivable
Namespace Prefix:	cdr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration