Investments in Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2021

Investments Debt And Equity Securities [Abstract]

Marketable Securities

Marketable securities at September 30, 2021 and December 31, 2020 consisted of the following:

			UNREALIZED		UNREALIZED		FAIR
At September 30, 2021	COST		GAINS		LOSSES		VALUE
Marketable debt securities
U.S. tax-exempt securities	$	494.1	$	2.4	$	.6	$	495.9
U.S. corporate securities		208.5		1.3		.3		209.5
U.S. government and agency securities		85.6		1.1				86.7
Non-U.S. corporate securities		435.1		2.4		.8		436.7
Non-U.S. government securities		64.0		.1		.1		64.0
Other debt securities		251.8		1.9		.3		253.4
Marketable equity securities		5.4				2.2		3.2
Total marketable securities	$	1,544.5	$	9.2	$	4.3	$	1,549.4

			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
Total marketable securities	$	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:

	September 30, 2021				December 31, 2020
	LESS THAN		TWELVE MONTHS		LESS THAN		TWELVE MONTHS
	TWELVE MONTHS		OR GREATER		TWELVE MONTHS		OR GREATER
Fair value	$	591.6	$	2.5	$	81.1	$	1.3
Unrealized losses		2.0		.1		.1

Contractual Maturities of Debt Securities

Contractual maturities of marketable debt securities at September 30, 2021 were as follows:

	AMORTIZED		FAIR
	COST		VALUE
Within one year	$	432.9	$	434.7
One to five years		1,083.7		1,089.1
Six to ten years		10.8		10.8
More than ten years		11.7		11.6
	$	1,539.1	$	1,546.2