Long-Lived Assets 5 (Details) - USD ($) $ in Millions	12 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Goodwill activity by segment
Balance at beginning of year	$ 6,086	$ 5,806
Acquisitions	771	316
Divestitures		(36)
Balance at end of year	6,857	6,086
Mainframe Solutions
Goodwill activity by segment
Balance at beginning of year	4,178	4,178
Acquisitions	0	0
Divestitures		0
Balance at end of year	4,178	4,178
Enterprise Solutions
Goodwill activity by segment
Balance at beginning of year	1,827	1,547
Acquisitions	771	316
Divestitures		(36)
Balance at end of year	2,598	1,827
Services
Goodwill activity by segment
Balance at beginning of year	81	81
Acquisitions	0	0
Divestitures		0
Balance at end of year	$ 81	$ 81

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=64834752&loc=SL49117168-202975

+ Details

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

- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

+ Details

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

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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

- Definition

Amount of divestiture of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

+ Details

Name:	us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=ca_MainframeSolutionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=ca_EnterpriseSolutionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=ca_ServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: