Summary Of Significant Accounting Policies And Recent Accounting Pronouncements (Narrative) (Details) - USD ($)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Significant Accounting Policies [Line Items]
Percentage of general reserve on receivables one to thirty days overdue	1.00%
Percentage of reserve on receivables one year overdue	100.00%
Maximum period for general reserve with specific maximum percentage	1 year
Unamortized debt issuance cost	$ 12,600,000	$ 14,800,000
Minimum [Member]
Significant Accounting Policies [Line Items]
Period for general reserve with specific minimum percentage	1 day
Minimum [Member] \| Other Specialized Equipment [Member]
Significant Accounting Policies [Line Items]
Estimated useful life	12 years 6 months
Residual value	$ 1,000
Maximum [Member]
Significant Accounting Policies [Line Items]
Period for general reserve with specific minimum percentage	30 days
Maximum [Member] \| Other Specialized Equipment [Member]
Significant Accounting Policies [Line Items]
Estimated useful life	15 years
Residual value	$ 3,500
Logistics [Member]
Significant Accounting Policies [Line Items]
Proceeds from Divestiture of Businesses	6,200,000
Railcar Assets [Member]
Significant Accounting Policies [Line Items]
Proceeds from Divestiture of Businesses	$ 228,100,000

Maximum period for general reserve with specific maximum percentage

No definition available.

Name:	cai_MaximumPeriodAccountsOverdueForGeneralReserveWithSpecificMaximumPercentage
Namespace Prefix:	cai_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of reserve on receivables overdue one to thirty days (in hundredths)

+ References

No definition available.

+ Details

Name:	cai_PercentageOfReserveOnReceivablesOverdueOneToThirtyDays
Namespace Prefix:	cai_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of reserve on receivables overdue one year (in hundredths)

+ References

No definition available.

+ Details

Name:	cai_PercentageOfReserveOnReceivablesOverdueOneYear
Namespace Prefix:	cai_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Period for general reserve with specific minimum percentage.

+ References

No definition available.

+ Details

Name:	cai_PeriodAccountsOverdueForGeneralReserveWithSpecificMinimumPercentage
Namespace Prefix:	cai_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Significant Accounting Policies [Line Items]

+ References

No definition available.

+ Details

Name:	cai_SignificantAccountingPoliciesLineItems
Namespace Prefix:	cai_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3179-108585

+ Details

Name:	us-gaap_ProceedsFromDivestitureOfBusinesses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The estimated or actual value of the asset at the end of its useful life or when it is no longer serviceable (cannot be used for its original purpose).

+ References

No definition available.

+ Details

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

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_OtherTransportationEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=cai_LogisticsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=cai_RailcarAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: