Investments in Marketable Debt Securities (Tables)

3 Months Ended

Mar. 31, 2020

Available For Sale Securities [Abstract]

Marketable Debt Securities

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

	AMORTIZED		UNREALIZED		UNREALIZED		FAIR
At March 31, 2020	COST		GAINS		LOSSES		VALUE
U.S. tax-exempt securities	$	306.1	$	1.6	$	.8	$	306.9
U.S. corporate securities		157.9		1.3		.6		158.6
U.S. government and agency securities		119.4		4.0				123.4
Non-U.S. corporate securities		299.8		1.0		2.6		298.2
Non-U.S. government securities		70.8		.4				71.2
Other debt securities		137.0		1.8		.1		138.7
	$	1,091.0	$	10.1	$	4.1	$	1,097.0

	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:

	March 31, 2020			December 31, 2019
	LESS THAN		TWELVE MONTHS	LESS THAN		TWELVE MONTHS
	TWELVE MONTHS		OR GREATER	TWELVE MONTHS		OR GREATER
Fair value	$	366.0		$	177.0	$	31.4
Unrealized losses		4.1			.4		.1

Contractual Maturities of Debt Securities

Contractual maturities of marketable debt securities at March 31, 2020 were as follows:

	AMORTIZED		FAIR
Maturities:	COST		VALUE
Within one year	$	217.5	$	218.0
One to five years		834.5		840.0
Six to ten years		23.0		23.0
More than ten years		16.0		16.0
	$	1,091.0	$	1,097.0