Income Taxes - Additional Information (Details) - USD ($) $ in Thousands			3 Months Ended			12 Months Ended
	Sep. 30, 2021	Jan. 01, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2018	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Jan. 31, 2021
Operating Loss Carryforwards [Line Items]
Deferred tax expense	$ 127,600		$ 127,600			$ 127,600
CARES Act, tax benefit							$ 720,600
Net current income tax receivable	221,875		221,875	$ 488,428		221,875	488,428
Deferred tax asset	488,235		488,235	582,406		488,235	582,406
Valuation allowance for deferred tax assets	538,531		538,531	411,648		538,531	411,648
Deferred tax benefit						(334,866)	1,544,971	$ (28,537)
Recognized income tax benefit					$ (37,000)
Transition tax, net of overpayments and tax credits									$ 175,600
Valuation allowance - increase (decrease)						126,900	212,000
Excess tax benefit from the exercise of stock options and lapses of restricted stock units						8,200	3,900	7,900
Income tax payments, net of refunds						93,500	139,400	117,700
Undistributed earnings of international subsidiaries	3,200,000		3,200,000			3,200,000
Permanently reinvested cumulative undistributed earnings	2,000,000		2,000,000			2,000,000
Unrecognized tax benefits, including interest and penalties	522,800		522,800	498,300		522,800	498,300
Unrecognized tax benefits, including interest and penalties, net of federal benefit	467,900		467,900	455,500		467,900	455,500
Unrecognized tax benefits that would impact effective tax rate	449,700		449,700	437,200		449,700	437,200
Unrecognized tax benefits, interest and penalties	22,400		22,400	19,900		22,400	19,900
Unrecognized tax benefits						20,515	385,797	$ 18,819
Reduction of unrecognized tax benefits reasonably possible	12,400		12,400			12,400
Federal
Operating Loss Carryforwards [Line Items]
Potential tax benefits from net operating loss carryforwards	$ 5,000		5,000			5,000
Federal | Minimum
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, term (in years)	1 year
Federal | Maximum
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards, term (in years)	16 years
State
Operating Loss Carryforwards [Line Items]
Potential tax benefits from net operating loss carryforwards	$ 184,000		184,000			184,000
Tax credit carryforwards	4,900		4,900			4,900
Foreign
Operating Loss Carryforwards [Line Items]
Potential tax benefits from net operating loss carryforwards	217,000		217,000			217,000
Foreign | Alternative minimum tax credit carryforwards
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	2,100		2,100			2,100
Opioid Lawsuits and Investigations
Operating Loss Carryforwards [Line Items]
Legal accrual			147,700	6,700,000			6,600,000
Deferred tax benefit				$ 1,100,000
Unrecognized tax benefits							371,500
Swiss
Operating Loss Carryforwards [Line Items]
Reduced tax rate for a period (in years)		10 years
Deferred tax asset	488,200		488,200			488,200
Swiss | Swiss federal tax reforms
Operating Loss Carryforwards [Line Items]
Valuation allowance for deferred tax assets	204,600		204,600			204,600
PharMEDium Healthcare Holdings, Inc
Operating Loss Carryforwards [Line Items]
Worthless stock ordinary income tax deduction							2,400,000
Tax benefit							$ 655,000
Net current income tax receivable	$ 221,900		$ 221,900			$ 221,900