Investments in Marketable Debt Securities (Tables)

3 Months Ended

Mar. 31, 2012

Marketable Debt Securities

Marketable debt securities at March 31, 2012 and December 31, 2011 consisted of the following:

At March 31, 2012	AMORTIZED COST		UNREALIZED GAINS		UNREALIZED LOSSES		FAIR VALUE
U.S. tax-exempt securities	$	294.2	$	2.6	$	.1	$	296.7
U.S. corporate securities		28.9		.3				29.2
U.S. government and agency securities		1.5						1.5
Non-U.S. government securities		384.5		5.9		.2		390.2
Non-U.S. corporate securities		149.2		.9				150.1
Other debt securities		79.6		.5				80.1
	$	937.9	$	10.2	$	.3	$	947.8

At December 31, 2011	AMORTIZED COST		UNREALIZED GAINS		UNREALIZED LOSSES		FAIR VALUE
U.S. tax-exempt securities	$	291.9	$	2.6	$	.1	$	294.4
U.S. corporate securities		27.4		.3		.2		27.5
U.S. government and agency securities		1.9						1.9
Non-U.S. government securities		361.2		6.0		.1		367.1
Non-U.S. corporate securities		148.0		.5		.2		148.3
Other debt securities		70.3		.6				70.9
	$	900.7	$	10.0	$	.6	$	910.1

Contractual Maturities of Marketable Debt Securities

Contractual maturities on marketable debt securities at March 31, 2012 were as follows:

Maturities:	AMORTIZED COST		FAIR VALUE
Within one year	$	310.9	$	311.8
One to five years		624.6		633.6
Six to ten years		.2		.2
More than ten years		2.2		2.2
	$	937.9	$	947.8