Business Combinations (Details) $ in Millions, CAD in Billions			1 Months Ended		3 Months Ended
	Apr. 01, 2016 USD ($) cancer_treatment_facility state	Feb. 29, 2016 USD ($)	Mar. 31, 2016 USD ($) pharmacy	Mar. 31, 2016 CAD	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)
Business Acquisition [Line Items]
Net purchase consideration					$ 1,819	$ 6
Goodwill			$ 9,786		$ 11,127
Biologics
Business Acquisition [Line Items]
Net purchase consideration	$ 692
Goodwill	613
Intangible assets	112
UDG
Business Acquisition [Line Items]
Net purchase consideration	447
Goodwill	165
Total assets acquired, excluding goodwill and intangibles	497
Total liabilities acquired, excluding goodwill and intangibles	$ 329
Sainsbury | U.K.
Business Acquisition [Line Items]
Gross purchase consideration paid		$ 174
Interest rate (percent)		0.033
Vantage
Business Acquisition [Line Items]
Number of cancer treatment facilities acquired | cancer_treatment_facility	51
Number of states | state	13
Net purchase consideration	$ 515
Goodwill	606
Fair value of noncontrolling interests	152
Intangible assets	24
Rexall Health | CANADA
Business Acquisition [Line Items]
Number of cancer treatment facilities acquired | pharmacy			470
Gross purchase consideration paid			$ 2,300	CAD 3
Currency exchange ratio (in CAD per USD)			0.77
Service agreements | Biologics
Business Acquisition [Line Items]
Intangible assets	$ 32
Estimated weighted average life of the acquired intangibles	3 years
Noncompete Agreements | Vantage
Business Acquisition [Line Items]
Intangible assets	$ 14
Estimated weighted average life of the acquired intangibles	4 years
Trademarks | Biologics
Business Acquisition [Line Items]
Intangible assets	$ 65
Estimated weighted average life of the acquired intangibles	14 years
Customer relationships | UDG
Business Acquisition [Line Items]
Intangible assets	$ 114
Estimated weighted average life of the acquired intangibles	10 years