Marketable Securities Held in Trusts (Tables)

3 Months Ended

Mar. 31, 2021

Investments, Debt and Equity Securities [Abstract]

The estimated fair value of the investments in the RCRA Trusts as of March 31, 2021 and December 31, 2020 are as follows:


	March 31, 2021
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Level 1
Cash and cash equivalents	$	4.0	$	—	$	—	$	4.0
Level 2
Corporate debt securities	199.4		8.3		(1.0)		206.7
Municipal bonds	197.2		7.4		(0.6)		204.0
U.S. government bonds	300.8		1.2		(6.2)		295.8
Total	$	701.4	$	16.9	$	(7.8)	$	710.5

	December 31, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Level 1
Cash and cash equivalents	$	11.8	$	—	$	—	$	11.8
Level 2
Corporate debt securities	193.3		14.0		—		207.3
Municipal bonds	190.5		8.8		(0.3)		199.0
U.S. government bonds	300.7		4.7		(0.1)		305.3
Total	$	696.3	$	27.5	$	(0.4)	$	723.4

Fair value of available-for-sale debt securities in an unrealized loss position

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 deemed to be temporary as of March 31, 2021 and December 31, 2020:


	March 31, 2021				December 31, 2020
(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	$	44.9	$	(1.0)	$	1.5	$	—
Municipal bonds	35.9		(0.5)		16.0		(0.2)
U.S. government bonds	221.8		(6.2)		120.3		(0.1)
	$	302.6	$	(7.7)	$	137.8	$	(0.3)
Securities that have been in a continuous loss position for more than 12 months:


Corporate debt securities	$	—	$	—	$	—	$	—
Municipal bonds	7.0		(0.1)		4.6		(0.1)
U.S. government bonds	—		—		—		—
	$	7.0	$	(0.1)	$	4.6	$	(0.1)

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, 2021. 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, 2021
Due in one year or less	$	34.2
Due after one year through five years	219.2
Due after five years through ten years	412.6
Due after ten years	40.5
Total debt securities	$	706.5