Investments in Marketable Debt Securities (Tables)

3 Months Ended

Mar. 31, 2021

Available For Sale Securities [Abstract]

Marketable Debt Securities

Marketable debt securities at March 31, 2021 and December 31, 2020 consisted of the following:

	AMORTIZED		UNREALIZED		UNREALIZED		FAIR
At March 31, 2021	COST		GAINS		LOSSES		VALUE
U.S. tax-exempt securities	$	395.0	$	3.5	$	.2	$	398.3
U.S. corporate securities		226.2		2.0		.3		227.9
U.S. government and agency securities		91.9		1.8				93.7
Non-U.S. corporate securities		401.3		3.9		.6		404.6
Non-U.S. government securities		74.3		.2		.1		74.4
Other debt securities		219.7		2.7		.2		222.2
	$	1,408.4	$	14.1	$	1.4	$	1,421.1

	AMORTIZED		UNREALIZED		UNREALIZED		FAIR
At December 31, 2020	COST		GAINS		LOSSES		VALUE
U.S. tax-exempt securities	$	388.1	$	4.4	$	.1	$	392.4
U.S. corporate securities		229.6		3.3				232.9
U.S. government and agency securities		92.1		2.3				94.4
Non-U.S. corporate securities		406.0		5.5				411.5
Non-U.S. government securities		77.0		.5				77.5
Other debt securities		216.9		3.4				220.3
	$	1,409.7	$	19.4	$	.1	$	1,429.0

Marketable Debt Securities Continuous Unrealized Losses

Marketable debt securities with continuous unrealized losses and their related fair values were as follows:

	March 31, 2021				December 31, 2020
	LESS THAN		TWELVE MONTHS		LESS THAN		TWELVE MONTHS
	TWELVE MONTHS		OR GREATER		TWELVE MONTHS		OR GREATER
Fair value	$	339.8	$	1.2	$	81.1	$	1.3
Unrealized losses		1.4				.1

Contractual Maturities of Debt Securities

Contractual maturities of marketable debt securities at March 31, 2021 were as follows:

	AMORTIZED		FAIR
Maturities:	COST		VALUE
Within one year	$	342.2	$	343.9
One to five years		1,056.6		1,067.6
Six to ten years		5.6		5.6
More than ten years		4.0		4.0
	$	1,408.4	$	1,421.1