Marketable Securities Held in Trusts (Tables)

3 Months Ended

Mar. 31, 2026

Investments, Debt and Equity Securities [Abstract]

The estimated fair value of the investments in the RCRA Trusts as of March 31, 2026 and December 31, 2025 are as follows:


	March 31, 2026
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Level 1
Cash and cash equivalents	$	4.5	$	—	$	—	$	4.5
Level 2
Corporate debt securities	216.1		1.6		(3.4)		214.3
Municipal bonds	210.5		2.5		(1.7)		211.3
U.S. government bonds	317.5		—		(2.3)		315.2

Total	$	748.6	$	4.1	$	(7.4)	$	745.3

	December 31, 2025
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Level 1
Cash and cash equivalents	$	4.8	$	—	$	—	$	4.8
Level 2
Corporate debt securities	218.8		3.4		(2.8)		219.4
Municipal bonds	208.3		3.9		(1.3)		210.9
U.S. government bonds	308.7		—		(0.5)		308.2

Total	$	740.6	$	7.3	$	(4.6)	$	743.3

Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value

The following tables show gross unrealized losses and fair values of the RCRA Trusts’ available-for-sale securities that have been in a continuous unrealized loss position for which an allowance for credit losses has not been recorded as of March 31, 2026 and December 31, 2025:


	March 31, 2026				December 31, 2025
(in millions)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Securities that have been in a continuous loss position for less than 12 months:
Corporate debt securities	$	74.1	$	(0.9)	$	17.0	$	(0.2)
Municipal bonds	49.5		(0.8)		14.0		—
U.S. government bonds	313.0		(2.3)		306.2		(0.5)
	$	436.6	$	(4.0)	$	337.2	$	(0.7)
Securities that have been in a continuous loss position for more than 12 months:


Corporate debt securities	$	35.8	$	(2.5)	$	48.3	$	(2.7)
Municipal bonds	25.4		(0.9)		40.2		(1.2)

	$	61.2	$	(3.4)	$	88.5	$	(3.9)

Schedule of maturity dates for debt securities

The following table summarizes the balance by contractual maturity of the available-for-sale debt securities invested by the RCRA Trusts as of March 31, 2026. Actual maturities may differ from contractual maturities because the issuers of the securities may have the right to prepay obligations before the underlying contracts mature.


	March 31, 2026
Due in one year or less	$	13.6
Due after one year through five years	187.2
Due after five years through ten years	496.0
Due after ten years	44.0
Total debt securities	$	740.8