Acquisitions, Consideration paid (Details) In Millions, unless otherwise specified	0 Months Ended		6 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2014 GBP (£)	Feb. 28, 2015 USD ($)	Feb. 28, 2015 Alliance Boots [Member] USD ($)
Consideration paid [Abstract]
Cash	$ 4,900	£ 3,133		$ 4,874
Common stock				10,977
Total consideration transferred	15,900		13,300	15,851
Less: consideration attributed to WBAD				(2,569)
Total consideration after attributed amount to WBAD				13,282
Fair value of the investment in Alliance Boots held before the Second Step Transaction	11,000			8,290
Total consideration				$ 21,572