Borrowings (Details) (Revolving credit facilities, USD $)	12 Months Ended
Dec. 31, 2014
Borrowings
Maximum borrowing capacity	60,000,000
Available borrowing base	48,600,000
debt outstanding	11,400,000
Weighted average interest rate	4.05%us-gaap_DebtWeightedAverageInterestRate
Unamortized debt fees	1,300,000us-gaap_UnamortizedDebtIssuanceExpense
Minimum
Borrowings
Unused line fee	0.375%
Maximum
Borrowings
Unused line fee	0.50%
U.S. \| LIBOR
Borrowings
Percentage points added to the reference rate	1.00%
Variable interest rate base	LIBOR
U.S. \| LIBOR \| Minimum
Borrowings
Percentage points added to the reference rate	2.25%
U.S. \| LIBOR \| Maximum
Borrowings
Percentage points added to the reference rate	2.75%
U.S. \| Federal Funds Rate
Borrowings
Percentage points added to the reference rate	0.50%
Variable interest rate base	Federal Funds Rate
U.S. \| Wells Fargo Prime rate
Borrowings
Variable interest rate base	prime rate
U.S. \| Wells Fargo Prime rate \| Minimum
Borrowings
Percentage points added to the reference rate	1.25%
U.S. \| Wells Fargo Prime rate \| Maximum
Borrowings
Percentage points added to the reference rate	1.75%
U.S. \| Wells Fargo Default Covenant \| Maximum
Borrowings
Percentage of facility available for borrowing	25.00%
Available borrowing capacity under credit facility	15,000,000
U.S. \| Wells Fargo Default Covenant \| Consecutive Days
Borrowings
Number of consecutive days during which the entity has to maintain certain covenants	5 days
U.S. \| Wells Fargo Default Covenant \| Consecutive Days \| Maximum
Borrowings
Percentage of facility available for borrowing	30.00%
Available borrowing capacity under credit facility	18,000,000
U.S. \| Wells Fargo Default Covenant Cure
Borrowings
Number of consecutive days during which the entity has to maintain certain covenants	30 days
U.S. \| Wells Fargo Default Covenant Cure \| Minimum
Borrowings
Percentage of facility available for borrowing	30.00%
Available borrowing capacity under credit facility	18,000,000
Foreign \| LIBOR
Borrowings
Variable interest rate base	LIBOR
Foreign \| LIBOR \| Minimum
Borrowings
Percentage points added to the reference rate	2.25%
Foreign \| LIBOR \| Maximum
Borrowings
Percentage points added to the reference rate	2.75%

Represents the number of consecutive days during which the entity has to maintain certain covenant requirements.

No definition available.

Name:	cbr_DebtInstrumentCovenantComplianceMaintenanceConsecutiveDaysNumber
Namespace Prefix:	cbr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Required amount of available borrowing capacity under the credit facility to be in compliance with debt covenants.

+ References

No definition available.

+ Details

Name:	cbr_DebtInstrumentRestrictiveCovenantLineOfCreditFacilityAvailableBorrowingCapacity
Namespace Prefix:	cbr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the required percentage of credit facility available for borrowing to be in compliance with debt covenants.

+ References

No definition available.

+ Details

Name:	cbr_DebtInstrumentRestrictiveCovenantLineOfCreditFacilityAvailableBorrowingCapacityPercentage
Namespace Prefix:	cbr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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

- Details

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

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value of the amount outstanding under the credit facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13476-108611

+ Details

Name:	us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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

- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ References

+ Details

Name:	us-gaap_UnamortizedDebtIssuanceExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant