Marketable Securities

6 Months Ended

Mar. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]

3.    MARKETABLE SECURITIES

The Company’s portfolio of available-for-sale marketable securities consists of the following (in millions):    

	Current				Noncurrent
	March 31, 2023		September 30, 2022		March 31, 2023		September 30, 2022
U.S. Treasury and government securities	$	164.5	$	13.1	$	—	$	0.5
Corporate bonds and notes	63.7		0.2		—		—
Municipal bonds	0.6		7.0		—		—
Total marketable securities	$	228.8	$	20.3	$	—	$	0.5

Neither gross unrealized gains and losses nor realized gains and losses were material as of March 31, 2023, or September 30, 2022.