Rental Equipment (Schedule Of Rental Equipment) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Rental equipment, gross	$ 2,636,381	$ 2,510,507
Accumulated depreciation	(529,866)	(505,546)
Rental equipment, net of accumulated depreciation	2,106,515	2,004,961
Dry Containers [Member]
Property, Plant and Equipment [Line Items]
Rental equipment, gross	1,627,517	1,533,063
Refrigerated Containers [Member]
Property, Plant and Equipment [Line Items]
Rental equipment, gross	345,037	345,744
Other Specialized Equipment [Member]
Property, Plant and Equipment [Line Items]
Rental equipment, gross	180,176	160,529
Railcars [Member]
Property, Plant and Equipment [Line Items]
Rental equipment, gross	483,651	$ 471,171
Rental equipment, net of accumulated depreciation	$ 449,700

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.

No definition available.

+ Details

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

- Definition

Amount before accumulated depreciation, depletion and amortization of other physical assets used in the normal conduct of business to produce goods and services and not intended for resale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

+ Details

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

- Definition

Amount of accumulated depreciation of long-lived, physical assets used to produce goods and services and not intended for resale, classified as other.

+ References

No definition available.

+ Details

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

- Definition

Amount after depreciation of long-lived, physical assets used to produce goods and services and not intended for resale, classified as other.

+ References

No definition available.

+ Details

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

- Details

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

- Details

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