Consolidated Statement of Cash Flows - USD ($)	6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating activities:
Net income (loss)	$ 426,300,000	$ (9,000,000.0)
Adjustments to arrive at cash provided by operating activities:
Depreciation	62,100,000	68,500,000
Amortization of intangible assets	13,200,000	14,300,000
Change in fair value of investments	114,500,000	0
Share-based compensation expense	21,800,000	18,800,000
Retirement benefit expense	34,400,000	56,700,000
Pension contributions	(15,100,000)	(23,500,000)
Net loss on disposition of property	1,700,000	0
Settlement of treasury locks	(35,700,000)	0
Changes in assets and liabilities, excluding effects of acquisitions and foreign currency adjustments:
Receivables	(41,500,000)	(9,800,000)
Inventories	(86,000,000.0)	(7,900,000)
Accounts payable	(12,100,000)	7,200,000
Contract liabilities	41,200,000	42,800,000
Compensation and benefits	(90,500,000)	(67,700,000)
Income taxes	(66,700,000)	508,600,000
Other assets and liabilities	(11,800,000)	(4,900,000)
Cash provided by operating activities	355,800,000	594,100,000
Investing activities:
Capital expenditures	(80,900,000)	(56,200,000)
Acquisition of businesses, net of cash acquired	(20,700,000)	(9,900,000)
Purchases of investments	(2,800,000)	(276,600,000)
Proceeds from maturities of investments	219,200,000	690,300,000
Proceeds from sale of investments	0	155,300,000
Proceeds from sale of property	3,300,000	400,000
Cash provided by investing activities	118,100,000	503,300,000
Financing activities:
Net repayment of short-term debt	(549,700,000)	(41,900,000)
Issuance of long-term debt, net of discount and issuance costs	987,600,000	0
Repayment of long-term debt	0	(250,000,000.0)
Cash dividends	(232,500,000)	(213,500,000)
Purchases of treasury stock	(535,200,000)	(661,700,000)
Proceeds from the exercise of stock options	23,800,000	61,900,000
Other financing activities	0	1,800,000
Cash used for financing activities	(306,000,000.0)	(1,103,400,000)
Effect of exchange rate changes on cash	(6,700,000)	29,000,000.0
Increase in cash and cash equivalents	161,200,000	23,000,000.0
Cash and cash equivalents at beginning of period	618,800,000	1,410,900,000
Cash and cash equivalents at end of period	$ 780,000,000.0	$ 1,433,900,000