CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenue	$ 189,893,926,000	$ 179,589,121,000	$ 167,939,635,000
Cost of goods sold	184,702,042,000	174,450,809,000	163,327,318,000
Gross profit	5,191,884,000	5,138,312,000	4,612,317,000
Operating expenses:
Distribution, selling, and administrative	2,767,217,000	2,663,508,000	2,460,301,000
Depreciation	280,187,000	294,965,000	283,971,000
Amortization	110,875,000	167,442,000	181,156,000
Employee severance, litigation, and other (Note 13)	6,807,307,000	330,474,000	183,520,000
Goodwill impairment	0	0	59,684,000
Impairment of PharMEDium assets (Note 1)	361,652,000	570,000,000	0
Operating (loss) income	(5,135,354,000)	1,111,923,000	1,443,685,000
Other (income) loss	(1,581,000)	(12,952,000)	25,469,000
Interest expense, net	137,883,000	157,769,000	174,699,000
Loss on consolidation of equity investments	0	0	42,328,000
Loss on early retirement of debt	22,175,000	0	23,766,000
(Loss) income before income taxes	(5,293,831,000)	967,106,000	1,177,423,000
Income tax (benefit) expense	(1,894,273,000)	112,971,000	(438,469,000)
Net (loss) income	(3,399,558,000)	854,135,000	1,615,892,000
Net (income) loss attributable to noncontrolling interest	(9,158,000)	1,230,000	42,513,000
Net (loss) income attributable to AmerisourceBergen Corporation	$ (3,408,716,000)	$ 855,365,000	$ 1,658,405,000
Earnings per share:
Basic (usd per share)	$ (16.65)	$ 4.07	$ 7.61
Diluted (usd per share)	$ (16.65)	$ 4.04	$ 7.53
Weighted average common shares outstanding:
Basic (shares)	204,783	210,165	217,872
Diluted (shares)	204,783	211,840	220,336