Changes in Carrying Amount of Goodwill by Reportable Segments (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Goodwill [Roll Forward]
Beginning balance	$ 3,733	$ 3,640
Acquisitions	19	116
Dispositions	(40)	(17)
Subsequent payments/adjustments	(1)	(6)
Ending balance	3,711	3,733
Retail
Goodwill [Roll Forward]
Beginning balance	1,069	993
Acquisitions	0	76
Dispositions	0	0
Subsequent payments/adjustments	0	0
Ending balance	1,069	1,069
Group
Goodwill [Roll Forward]
Beginning balance	385	385
Acquisitions	0	0
Dispositions	0	0
Subsequent payments/adjustments	0	0
Ending balance	385	385
Healthcare Services
Goodwill [Roll Forward]
Beginning balance	2,279	2,262
Acquisitions	19	40
Dispositions	(40)	(17)
Subsequent payments/adjustments	(1)	(6)
Ending balance	2,257	2,279
Other Businesses
Goodwill [Roll Forward]
Beginning balance	0	0
Acquisitions	0	0
Dispositions	0	0
Subsequent payments/adjustments	0	0
Ending balance	$ 0	$ 0

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=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

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- 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=35741047&loc=d3e13816-109267

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

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

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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=35741047&loc=d3e13816-109267

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