Mortgage Loans Payable And Credit Facility (Summary Of The Derivative Financial Instruments Held) (Details) - Interest Rate Swap [Member]	6 Months Ended	12 Months Ended
Jun. 30, 2017 USD ($) contract	Dec. 31, 2016 USD ($) contract
Derivatives Fair Value [Line Items]
Count \| contract	2	2
Notional value	$ 150,000,000	$ 150,000,000
Fair value	$ 1,708,000	$ 2,321,000
Minimum [Member]
Derivatives Fair Value [Line Items]
Maturity dates	2019	2019
Maximum [Member]
Derivatives Fair Value [Line Items]
Maturity dates	2021	2021
Cash Flow Hedging, Count 3 [Member]
Derivatives Fair Value [Line Items]
Count \| contract	3	3
Notional value	$ 200,000,000	$ 200,000,000
Fair value	$ 2,689,000	$ 3,074,000
Cash Flow Hedging, Count 3 [Member] \| Minimum [Member]
Derivatives Fair Value [Line Items]
Maturity dates	2020	2020
Cash Flow Hedging, Count 3 [Member] \| Maximum [Member]
Derivatives Fair Value [Line Items]
Maturity dates	2023	2023

Derivative maturity year.

No definition available.

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Namespace Prefix:	cdr_
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Balance Type:	na
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- Definition

Nominal or face amount used to calculate payments on the derivative liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Notional Amount
-URI http://asc.fasb.org/extlink&oid=6519104

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5579245-113959

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Fair value as of the balance sheet date of all interest rate derivative liabilities designated as cash flow hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624163-113959

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of interest rate derivative instruments held by the entity at the reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5579245-113959

+ Details

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Balance Type:	na
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- Details

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- Details

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- Details

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- Details

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