Redeemable Noncontrolling Interests (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Noncontrolling Interest [Line Items]
Balance at beginning of period	$ 933.0
Net income (loss)	7.5	$ 18.7
Net subscriptions (distributions) and other	(27.8)	93.3
Balance at End of Period	983.4
Minority Interests
Noncontrolling Interest [Line Items]
Balance at beginning of period	310.5	144.6
Net income (loss)	12.3	5.7
Net subscriptions (distributions) and other	(1.9)	0.0
Net consolidations (deconsolidations)	0.0	0.0
Balance at End of Period	320.9	150.3
Redeemable Noncontrolling Interests [Member]
Noncontrolling Interest [Line Items]
Balance at beginning of period	933.0	541.9
Net income (loss)	7.5	18.7
Net subscriptions (distributions) and other	164.4	(29.9)
Net consolidations (deconsolidations)	(121.5)	84.9
Balance at End of Period	983.4	615.6
CIPs [Member]
Noncontrolling Interest [Line Items]
Balance at beginning of period	622.5	397.3
Net income (loss)	(4.8)	13.0
Net subscriptions (distributions) and other	166.3	(29.9)
Net consolidations (deconsolidations)	(121.5)	84.9
Balance at End of Period	$ 662.5	$ 465.3