Restructuring (Rollforward of Restructuring Liability) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended	9 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Mar. 31, 2021
Restructuring Cost and Reserve [Line Items]
Total charges	$ 30.0	$ 0.0
Restructuring Reserve [Roll Forward]
Balance as of beginning of period	44.5		$ 0.0	$ 0.0
Accrued charges	23.9		94.1
Payments	(41.3)		(49.6)
Balance as of end of period	27.1		44.5	27.1
Non-cash charges	6.1		24.9	31.0
Cumulative charges incurred through March 31, 2021	149.0			149.0
Minimum
Restructuring Cost and Reserve [Line Items]
Estimated restructuring expenses remaining	100.0			100.0
Maximum
Restructuring Cost and Reserve [Line Items]
Estimated restructuring expenses remaining	$ 125.0			$ 125.0
Employee Compensation
Restructuring Cost and Reserve [Line Items]
Estimated restructuring expenses remaining (percent)	50.00%			50.00%
Restructuring Reserve [Roll Forward]
Balance as of beginning of period	$ 44.5		0.0	$ 0.0
Accrued charges	19.8		85.0
Payments	(40.2)		(40.5)
Balance as of end of period	24.1		44.5	24.1
Non-cash charges	4.8		19.5	24.3
Cumulative charges incurred through March 31, 2021	129.1			129.1
Other Expenses
Restructuring Reserve [Roll Forward]
Balance as of beginning of period	0.0		0.0	0.0
Accrued charges	4.1		9.1
Payments	(1.1)		(9.1)
Balance as of end of period	3.0		0.0	3.0
Non-cash charges	1.3		$ 5.4	6.7
Cumulative charges incurred through March 31, 2021	$ 19.9			$ 19.9