Changes in Carrying Amount of Goodwill by Reportable Segments (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2014
Goodwill [Line Items]
Beginning Balance	$ 3,733
Acquisitions	6
Dispositions	(40)
Ending Balance	3,699
Retail
Goodwill [Line Items]
Beginning Balance	1,007
Acquisitions	0
Dispositions	0
Ending Balance	1,007
Employer Group
Goodwill [Line Items]
Beginning Balance	363
Acquisitions	0
Dispositions	0
Ending Balance	363
Health And Well-Being Services
Goodwill [Line Items]
Beginning Balance	2,271
Acquisitions	6
Dispositions	(40)
Ending Balance	2,237
Other Businesses
Goodwill [Line Items]
Beginning Balance	92
Acquisitions	0
Dispositions	0
Ending Balance	$ 92

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

-URI http://asc.fasb.org/extlink&oid=14024403&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

+ Details

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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

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=14024403&loc=d3e13816-109267

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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Balance Type:	na
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- 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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267

+ Details

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