MARKETABLE INVESTMENT SECURITIES (Tables)

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Schedule of Fair Value for Available-for-Sale Securities by Major Security Type and Class of Security

The amortized cost, gross unrealized holding gains, gross unrealized holding losses, and fair value for debt securities classified as available-for-sale securities by major security type and class of security at December 31, 2023 and December 31, 2022 were as follows:


(in millions)	Amortized cost		Gross unrealized holding gains		Gross unrealized holding losses		Estimated fair value
December 31, 2023:
Cash and cash equivalents:
Cash	$	129.9	$	—	$	—	$	129.9
Cash equivalents	2.2		—		—		2.2
Total cash and cash equivalents	132.1		—		—		132.1
Available-for-sale:
Corporate bonds and notes	8.4		—		(0.1)		8.3
Municipal bonds	0.5		—		—		0.5


Total	$	141.0	$	—	$	(0.1)	$	140.9


(in millions)	Amortized cost		Gross unrealized holding gains		Gross unrealized holding losses		Estimated fair value
December 31, 2022:
Cash and cash equivalents:
Cash	$	53.6	$	—	$	—	$	53.6
Cash equivalents	3.3		—		—		3.3
Total cash and cash equivalents	56.9		—		—		56.9
Available-for-sale:
Corporate bonds and notes	66.7		—		(1.6)		65.1
Municipal bonds	16.3		—		(0.3)		16.0
Federal agency issues	20.7		—		(0.7)		20.0
U.S. government securities	11.8		—		(0.1)		11.7
Total	$	172.4	$	—	$	(2.7)	$	169.7

Schedule of Cash, Cash Equivalents, and Maturities of Debt Securities Classified as Available-For-Sale Securities

Cash, cash equivalents, and maturities of debt securities classified as available-for-sale were as follows at December 31, 2023:


(in millions)	Amortized cost		Estimated fair value
Cash	$	129.9	$	129.9
Cash equivalents	2.2		2.2
Available-for-sale:
Due within one year	8.9		8.8


Total	$	141.0	$	140.9