Business Segment Information - Reconciliation of Segment Operating Income to Income (Loss) from Operations before Income Taxes (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment operating income	$ 389,195,000	$ 170,376,000	$ 1,289,588,000	$ 1,195,344,000
Gain from antitrust litigation settlements	35,600,000	0	35,900,000	1,400,000
LIFO credit			16,142,000	82,919,000
Employee severance, litigation, and other	75,553,000	284,517,000	143,023,000	317,517,000
Other (income) loss	(3,158,000)	1,398,000	26,289,000	(3,958,000)
Interest expense, net	47,151,000	35,603,000	131,652,000	109,874,000
Loss on consolidation of equity investments	0	0	42,328,000	0
Loss on early retirement of debt	0	0	23,766,000	0
Income before income taxes	345,202,000	133,375,000	1,065,553,000	1,089,428,000
Operating segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment operating income	474,423,000	471,116,000	1,548,805,000	1,545,781,000
Segment reconciling items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Gain from antitrust litigation settlements	35,600,000	0	35,938,000	1,395,000
LIFO credit	16,142,000	24,723,000	16,142,000	82,919,000
PharMEDium remediation costs	(15,501,000)	0	(38,007,000)	0
Acquisition-related intangibles amortization	(45,916,000)	(40,946,000)	(130,267,000)	(117,234,000)
Employee severance, litigation, and other	(75,553,000)	(284,517,000)	(143,023,000)	(317,517,000)
Loss on consolidation of equity investments	$ 0	$ 0	$ 42,328,000	$ 0