Acquisitions, Consideration Paid (Details) £ in Millions, $ in Millions			9 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2014 GBP (£)	May. 31, 2015 USD ($)
Consideration paid [Abstract]
Cash	$ 4,900	£ 3,133
Total consideration transferred	15,900		$ 13,300
Fair value of the investment in Alliance Boots held before the Second Step Transaction	$ 11,000
Alliance Boots [Member]
Consideration paid [Abstract]
Cash			4,874
Common stock			10,977
Total consideration transferred			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			8,293
Total consideration			$ 21,575