Investments in Marketable Debt Securities (Tables)

3 Months Ended

Mar. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Marketable Debt Securities

Marketable debt securities at March 31, 2016 and December 31, 2015 consisted of the following:

At March 31, 2016	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
U.S. tax-exempt securities	$	490.0	$	1.7	$	.1	$	491.6
U.S. corporate securities		79.8		.3		.1		80.0
U.S. government and agency securities		16.3		.3				16.6
Non-U.S. corporate securities		600.1		2.4		.2		602.3
Non-U.S. government securities		171.3		1.4				172.7
Other debt securities		102.6		.4		.1		102.9
	$	1,460.1	$	6.5	$	.5	$	1,466.1
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

Marketable Debt Securities Continuous Unrealized Losses

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

	March 31, 2016			December 31, 2015
	Less than Twelve Months		Twelve Months or Greater	Less than Twelve Months		Twelve Months or Greater
Fair value	$	337.1		$	579.0
Unrealized losses		.5			1.1

Contractual Maturities of Debt Securities

Contractual maturities on marketable debt securities at March 31, 2016 were as follows:

Maturities:	Amortized Cost		Fair Value
Within one year	$	483.1	$	483.6
One to five years		976.8		982.3
Six to ten years		.2		.2
	$	1,460.1	$	1,466.1