Changes in Carrying Amount of Goodwill by Reportable Segments (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended					6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014 Retail	Dec. 31, 2013 Retail	Jun. 30, 2014 Employer Group	Dec. 31, 2013 Employer Group	Jun. 30, 2014 Healthcare Services	Jun. 30, 2014 Other Businesses	Dec. 31, 2013 Other Businesses
Goodwill [Line Items]
Beginning Balance	$ 3,733	$ 1,007	$ 1,007	$ 363	$ 363	$ 2,271	$ 92	$ 92
Acquisitions	3					3
Dispositions	(40)					(40)
Ending Balance	$ 3,696	$ 1,007	$ 1,007	$ 363	$ 363	$ 2,234	$ 92	$ 92