Available-for-Sale Investments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015	Aug. 31, 2015
Summary of cost and fair value of available-for-sale securities [Abstract]
Amortized cost basis	$ 755		$ 755		$ 754
Gross unrealized gains	276		276		430
Gross unrealized losses	(4)		(4)		(1)
Fair value	$ 1,027		$ 1,027		1,183
AmerisourceBergen Common Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Maximum number of shares in minority equity position (in shares)	19,859,795		19,859,795
Percentage of outstanding common stock held	5.60%		5.60%
Sale of acquired available-for-sale securities	$ 1	$ 0	$ 3	$ 0
Number of shares held (in shares)	11,500,000		11,500,000
Summary of cost and fair value of available-for-sale securities [Abstract]
Amortized cost basis	$ 717		$ 717		717
Gross unrealized gains	276		276		430
Gross unrealized losses	0		0		0
Fair value	993		993		1,147
Other Investments [Member]
Summary of cost and fair value of available-for-sale securities [Abstract]
Amortized cost basis	38		38		37
Gross unrealized gains	0		0		0
Gross unrealized losses	(4)		(4)		(1)
Fair value	$ 34		$ 34		$ 36