Consolidated Investment Products - Schedule of Balances of Assets and Liabilities of CIPs Measured at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2025	Sep. 30, 2025
Assets [Abstract]
Investments, at fair value	$ 1,063.0	$ 1,179.5
CIPs [Member]
Assets [Abstract]
Investments, at fair value	12,472.5	12,278.8
Fair Value, Recurring [Member]
Assets [Abstract]
Total Assets Measured at Fair Value	1,075.4	1,150.5
Fair Value, Recurring [Member] \| Level 1 [Member]
Assets [Abstract]
Total Assets Measured at Fair Value	689.4	729.7
Fair Value, Recurring [Member] \| Level 2 [Member]
Assets [Abstract]
Total Assets Measured at Fair Value	283.4	317.9
Fair Value, Recurring [Member] \| Level 3 [Member]
Assets [Abstract]
Total Assets Measured at Fair Value	4.5	4.0
Fair Value, Recurring [Member] \| NAV as a Practical Expedient [Member]
Assets [Abstract]
Total Assets Measured at Fair Value	98.1	98.9
Fair Value, Recurring [Member] \| CIPs [Member]
Assets [Abstract]
Total Assets Measured at Fair Value	13,367.7	12,863.9
Fair Value, Recurring [Member] \| CIPs [Member] \| Level 1 [Member]
Assets [Abstract]
Total Assets Measured at Fair Value	1,256.7	865.3
Fair Value, Recurring [Member] \| CIPs [Member] \| Level 2 [Member]
Assets [Abstract]
Total Assets Measured at Fair Value	11,322.3	11,198.6
Fair Value, Recurring [Member] \| CIPs [Member] \| Level 3 [Member]
Assets [Abstract]
Total Assets Measured at Fair Value	595.1	610.9
Fair Value, Recurring [Member] \| CIPs [Member] \| NAV as a Practical Expedient [Member]
Assets [Abstract]
Total Assets Measured at Fair Value	193.6	189.1
Equity and debt securities [Member] \| Fair Value, Recurring [Member] \| CIPs [Member]
Assets [Abstract]
Investments, at fair value	1,886.8	1,914.8
Equity and debt securities [Member] \| Fair Value, Recurring [Member] \| CIPs [Member] \| Level 1 [Member]
Assets [Abstract]
Investments, at fair value	498.2	393.2
Equity and debt securities [Member] \| Fair Value, Recurring [Member] \| CIPs [Member] \| Level 2 [Member]
Assets [Abstract]
Investments, at fair value	599.9	731.5
Equity and debt securities [Member] \| Fair Value, Recurring [Member] \| CIPs [Member] \| Level 3 [Member]
Assets [Abstract]
Investments, at fair value	595.1	601.0
Equity and debt securities [Member] \| Fair Value, Recurring [Member] \| CIPs [Member] \| NAV as a Practical Expedient [Member]
Assets [Abstract]
Investments, at fair value	193.6	189.1
Loans [Member] \| Fair Value, Recurring [Member] \| CIPs [Member]
Assets [Abstract]
Investments, at fair value	10,585.7	10,364.0
Loans [Member] \| Fair Value, Recurring [Member] \| CIPs [Member] \| Level 1 [Member]
Assets [Abstract]
Investments, at fair value	0.0	0.0
Loans [Member] \| Fair Value, Recurring [Member] \| CIPs [Member] \| Level 2 [Member]
Assets [Abstract]
Investments, at fair value	10,585.7	10,354.1
Loans [Member] \| Fair Value, Recurring [Member] \| CIPs [Member] \| Level 3 [Member]
Assets [Abstract]
Investments, at fair value	0.0	9.9
Loans [Member] \| Fair Value, Recurring [Member] \| CIPs [Member] \| NAV as a Practical Expedient [Member]
Assets [Abstract]
Investments, at fair value	0.0	0.0
Collateralized loan obligations [Member]
Assets [Abstract]
Investments, at fair value	10,824.7	10,597.7
Collateralized loan obligations [Member] \| Fair Value, Recurring [Member]
Assets [Abstract]
Cash and cash equivalents of CLOs	758.5	472.1
Receivables of CLOs	136.7	113.0
Collateralized loan obligations [Member] \| Fair Value, Recurring [Member] \| Level 1 [Member]
Assets [Abstract]
Cash and cash equivalents of CLOs	758.5	472.1
Receivables of CLOs	0.0	0.0
Collateralized loan obligations [Member] \| Fair Value, Recurring [Member] \| Level 2 [Member]
Assets [Abstract]
Cash and cash equivalents of CLOs	0.0	0.0
Receivables of CLOs	136.7	113.0
Collateralized loan obligations [Member] \| Fair Value, Recurring [Member] \| Level 3 [Member]
Assets [Abstract]
Cash and cash equivalents of CLOs	0.0	0.0
Receivables of CLOs	0.0	0.0
Collateralized loan obligations [Member] \| Fair Value, Recurring [Member] \| NAV as a Practical Expedient [Member]
Assets [Abstract]
Cash and cash equivalents of CLOs	0.0	0.0
Receivables of CLOs	$ 0.0	$ 0.0

FRANKLIN RESOURCES INC 10-Q