Mortgage Loans Payable and Credit Facility (Schedule of Debt Related to Continuing Operations) (Parenthetical) (Details)		9 Months Ended
Sep. 08, 2017	Sep. 30, 2018
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility extension allowed period	1 year	1 year
Term Loan Four [Member] \| Interest Rate Swap [Member]
Debt Instrument [Line Items]
Expiration period		2019-02
Effective interest rate		3.20%
Term Loan Six [Member] \| Interest Rate Swap [Member]
Debt Instrument [Line Items]
Expiration period		2020-02
Effective interest rate		3.70%

Line of credit facility extension allowed period.

No definition available.

Name:	cdr_LineOfCreditFacilityExtensionAllowedPeriod
Namespace Prefix:	cdr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The expiration, mandatory redemption, or due date, month and year (YYYY-MM), of the financial instrument issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586

+ Details

Name:	us-gaap_DebtConversionConvertedInstrumentExpirationOrDueDateMonthAndYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Dividend or interest rate associated with the financial instrument issued in exchange for the original debt being converted in a noncash or part noncash transaction. Noncash are transactions that affect recognized assets or liabilities but that do not result in cash receipts or cash payments. Part noncash refers to that portion of the transaction not resulting in cash receipts or cash payments.

+ References

+ Details

Name:	us-gaap_DebtConversionConvertedInstrumentRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=cdr_TermLoanFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=cdr_TermLoanSixMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: