Investments in Marketable Debt Securities (Tables)

12 Months Ended

Dec. 31, 2015

Investments, Debt and Equity Securities [Abstract]

Marketable Debt Securities

Marketable debt securities consisted of the following at December 31:

2015	AMORTIZED COST		UNREALIZED GAINS		UNREALIZED LOSSES		FAIR VALUE
U.S. tax-exempt securities	$	505.0	$	.7	$	.3	$	505.4
U.S. corporate securities		76.7		.1		.1		76.7
U.S. government and agency securities		15.7		.1		.1		15.7
Non-U.S. corporate securities		585.6		1.8		.4		587.0
Non-U.S. government securities		192.7		1.1		.1		193.7
Other debt securities		69.6		.1		.1		69.6
	$	1,445.3	$	3.9	$	1.1	$	1,448.1
2014	AMORTIZED COST		UNREALIZED GAINS		UNREALIZED LOSSES		FAIR VALUE
U.S. tax-exempt securities	$	362.9	$	.8	$	.3	$	363.4
U.S. corporate securities		80.9		.6				81.5
U.S. government and agency securities		8.0						8.0
Non-U.S. corporate securities		528.1		3.9				532.0
Non-U.S. government securities		192.1		2.0				194.1
Other debt securities		92.8		.3		.1		93.0
	$	1,264.8	$	7.6	$	.4	$	1,272.0

Marketable Debt Securities Continuous Unrealized Losses

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

At December 31,	2015			2014
	LESS THAN TWELVE  MONTHS		TWELVE MONTHS OR GREATER	LESS THAN TWELVE MONTHS		TWELVE MONTHS OR GREATER
Fair value	$	579.0		$	249.6
Unrealized losses		1.1			.4

Contractual Maturities of Debt Securities

Contractual maturities at December 31, 2015 were as follows:

Maturities:	AMORTIZED COST		FAIR             VALUE
Within one year	$	437.1	$	437.4
One to five years		1,008.0		1,010.5
Six to ten years		.2		.2
	$	1,445.3	$	1,448.1