Fair Value Measurements (Details) (Recurring [Member], USD $) In Millions, unless otherwise specified	Feb. 28, 2015		Aug. 31, 2014
Restricted Cash [Member]
Assets [Abstract]
Fair value of assets	$ 206	[1]
Money Market Funds [Member]
Assets [Abstract]
Fair value of assets	1,881	[2]	1,879	[2]
Available-for-sale Investments [Member]
Assets [Abstract]
Fair value of assets	1,255	[3]	887	[3]
Interest Rate Swaps [Member]
Assets [Abstract]
Fair value of assets	22	[4]	16	[4]
Basis Swap [Member]
Assets [Abstract]
Fair value of assets	6
Foreign Currency Forwards [Member]
Assets [Abstract]
Fair value of assets	60	[5]
Liabilities [Abstract]
Fair value of liabilities	7	[5]
Warrants [Member]
Assets [Abstract]
Fair value of assets	2,231	[6]	553	[5]
Forward Interest Rate Swaps [Member]
Liabilities [Abstract]
Fair value of liabilities			44	[7]
Level 1 [Member] | Restricted Cash [Member]
Assets [Abstract]
Fair value of assets	206	[1]
Level 1 [Member] | Money Market Funds [Member]
Assets [Abstract]
Fair value of assets	1,881	[2]	1,879	[2]
Level 1 [Member] | Available-for-sale Investments [Member]
Assets [Abstract]
Fair value of assets	1,255	[3]	887	[3]
Level 1 [Member] | Interest Rate Swaps [Member]
Assets [Abstract]
Fair value of assets	0	[4]	0	[4]
Level 1 [Member] | Basis Swap [Member]
Assets [Abstract]
Fair value of assets	0
Level 1 [Member] | Foreign Currency Forwards [Member]
Assets [Abstract]
Fair value of assets	0	[5]
Liabilities [Abstract]
Fair value of liabilities	0	[5]
Level 1 [Member] | Warrants [Member]
Assets [Abstract]
Fair value of assets	0	[6]	0	[5]
Level 1 [Member] | Forward Interest Rate Swaps [Member]
Liabilities [Abstract]
Fair value of liabilities			0	[7]
Level 2 [Member] | Restricted Cash [Member]
Assets [Abstract]
Fair value of assets	0	[1]
Level 2 [Member] | Money Market Funds [Member]
Assets [Abstract]
Fair value of assets	0	[2]	0	[2]
Level 2 [Member] | Available-for-sale Investments [Member]
Assets [Abstract]
Fair value of assets	0	[3]	0	[3]
Level 2 [Member] | Interest Rate Swaps [Member]
Assets [Abstract]
Fair value of assets	22	[4]	16	[4]
Level 2 [Member] | Basis Swap [Member]
Assets [Abstract]
Fair value of assets	6
Level 2 [Member] | Foreign Currency Forwards [Member]
Assets [Abstract]
Fair value of assets	60	[5]
Liabilities [Abstract]
Fair value of liabilities	7	[5]
Level 2 [Member] | Warrants [Member]
Assets [Abstract]
Fair value of assets	2,231	[6]	553	[5]
Level 2 [Member] | Forward Interest Rate Swaps [Member]
Liabilities [Abstract]
Fair value of liabilities			44	[7]
Level 3 [Member] | Restricted Cash [Member]
Assets [Abstract]
Fair value of assets	0	[1]
Level 3 [Member] | Money Market Funds [Member]
Assets [Abstract]
Fair value of assets	0	[2]	0	[2]
Level 3 [Member] | Available-for-sale Investments [Member]
Assets [Abstract]
Fair value of assets	0	[3]	0	[3]
Level 3 [Member] | Interest Rate Swaps [Member]
Assets [Abstract]
Fair value of assets	0	[4]	0	[4]
Level 3 [Member] | Basis Swap [Member]
Assets [Abstract]
Fair value of assets	0
Level 3 [Member] | Foreign Currency Forwards [Member]
Assets [Abstract]
Fair value of assets	0	[5]
Liabilities [Abstract]
Fair value of liabilities	0	[5]
Level 3 [Member] | Warrants [Member]
Assets [Abstract]
Fair value of assets	0	[6]	0	[5]
Level 3 [Member] | Forward Interest Rate Swaps [Member]
Liabilities [Abstract]
Fair value of liabilities			$ 0	[7]

[1] Restricted cash consists of deposits restricted under agency agreements and cash restricted by law and other obligations.

[2] Money market funds are valued at the closing price reported by the fund sponsor.

[3] Fair values of quoted investments are based on current bid prices as of the balance sheet dates. See Note 6, Available-for-Sale Investments for additional disclosures.

[4] The fair value of interest rate swaps is calculated by discounting the estimated cash flows received and paid based on the applicable observable yield curves. See Note 10, Financial Instruments for additional disclosures.

[5] The fair value of forward currency contracts is estimated by discounting the difference between the contractual forward price and the current available forward price for the residual maturity of the contract using observable market rates.

[6] Warrants were valued using a Monte Carlo simulation. Key assumptions used in the valuation include risk-free interest rates using constant maturity treasury rates; the dividend yield for AmerisourceBergen's common stock; AmerisourceBergen's common stock price at the valuation date; AmerisourceBergen's equity volatility; the number of shares of AmerisourceBergen's common stock outstanding; the number of AmerisourceBergen employee stock options and the exercise price; and the details specific to the warrants.

[7] Forward interest rate swaps were valued using three-month LIBOR rates. See Note 10, Financial Instruments for additional disclosures.