Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 260.0	$ (571.9)
Other Comprehensive Income (Loss)
Currency translation adjustments, net of tax	(14.6)	15.8
Net unrealized losses on defined benefit plans, net of tax	(0.4)	(1.1)
Net unrealized gains on investments, net of tax	0.0	3.5
Total other comprehensive income (loss)	(15.0)	18.2
Total comprehensive income (loss)	245.0	(553.7)
Less: comprehensive income (loss) attributable to
Nonredeemable noncontrolling interests	(0.5)	(0.1)
Redeemable noncontrolling interests	(15.4)	11.5
Comprehensive Income (Loss) Attributable to Franklin Resources, Inc.	$ 260.9	$ (565.1)