SHORT-TERM INVESTMENTS: (Tables)

12 Months Ended

Dec. 31, 2024

SHORT-TERM INVESTMENTS:

Schedule of short-term investments

Short-term investments were as follows ($ in millions):

	At December 31,
	2024			2023
Trading securities	$	245.2		$	599.1
Weighted average interest rate		4.7	%		5.7	%
Available-for-sale	$	0.2		$	0.2
Weighted average interest rate		0.9	%		0.8	%
Total	$	245.3		$	599.3

Summary of activity investments

The following table summarizes the activity of these investments by category (in millions):

	Years ended
	December 31,
	2024		2023
Trading:
Interest earned	$	25.7	$	21.0
Unrealized gain (loss) at the end of the period	$	(*)	$	(*)
Available-for-sale:
Interest earned	$	(*)	$	(*)
Investment redeemed	$	—	$	0.1

(*)   Less than $0.1 million

Schedule of contractual maturities of the Company's available-for-sale debt securities

At December 31, 2024 and 2023, contractual maturities of the available-for-sale debt securities are as follows (in millions):

	2024		2023
One year or less	$	—	$	—
Maturing after one year through five years		—		—
Maturing after five years through ten years		—		—
Due after 10 years		0.2		0.2
Total debt securities	$	0.2	$	0.2