Investments in Marketable Debt Securities (Tables)

9 Months Ended

Sep. 30, 2020

Available For Sale Securities [Abstract]

Marketable Debt Securities

Marketable debt securities at September 30, 2020 and December 31, 2019 consisted of the following:

	AMORTIZED		UNREALIZED		UNREALIZED		FAIR
At September 30, 2020	COST		GAINS		LOSSES		VALUE
U.S. tax-exempt securities	$	294.2	$	4.8			$	299.0
U.S. corporate securities		180.7		3.7				184.4
U.S. government and agency securities		102.9		2.8				105.7
Non-U.S. corporate securities		348.2		5.5		.1		353.6
Non-U.S. government securities		78.8		.5				79.3
Other debt securities		169.0		3.3				172.3
	$	1,173.8	$	20.6	$	.1	$	1,194.3

	AMORTIZED		UNREALIZED		UNREALIZED		FAIR
At December 31, 2019	COST		GAINS		LOSSES		VALUE
U.S. tax-exempt securities	$	318.1	$	2.2	$	.1	$	320.2
U.S. corporate securities		163.8		1.9				165.7
U.S. government and agency securities		128.4		.9				129.3
Non-U.S. corporate securities		347.7		2.3		.2		349.8
Non-U.S. government securities		72.3		.2		.1		72.4
Other debt securities		123.7		1.1		.1		124.7
	$	1,154.0	$	8.6	$	.5	$	1,162.1

Marketable Debt Securities Continuous Unrealized Losses

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

	September 30, 2020			December 31, 2019
	LESS THAN		TWELVE MONTHS	LESS THAN		TWELVE MONTHS
	TWELVE MONTHS		OR GREATER	TWELVE MONTHS		OR GREATER
Fair value	$	61.9		$	177.0	$	31.4
Unrealized losses		.1			.4		.1

Contractual Maturities of Debt Securities

Contractual maturities of marketable debt securities at September 30, 2020 were as follows:

	AMORTIZED		FAIR
Maturities:	COST		VALUE
Within one year	$	316.5	$	319.1
One to five years		851.9		869.8
Six to ten years		5.2		5.2
More than ten years		.2		.2
	$	1,173.8	$	1,194.3