Investments (Tables)

9 Months Ended

Sep. 30, 2012

Investments in Short and Long-Term Classified as Available-for-Sale Securities

Information regarding our investments is as follows (in millions):

	Amortized Cost		Gross Unrealized
			Gains		Losses			Fair value
As of September 30, 2012
Corporate debt securities	$	338.2	$	0.4	$	(0.1	)	$	338.5
U.S. government and agency debt securities		215.3		—		—			215.3
Foreign government debt securities		2.8		—		—			2.8
Commercial paper		139.6		0.1		—			139.7
Certificates of deposit		105.3		0.1		—			105.4
Total short and long-term investments	$	801.2	$	0.6	$	(0.1	)	$	801.7
As of December 31, 2011
Corporate debt securities	$	324.8	$	0.2	$	(0.3	)	$	324.7
U.S. government and agency debt securities		177.1		0.1		—			177.2
Municipal bonds		1.0		—		—			1.0
Foreign government debt securities		6.8		—		—			6.8
Commercial paper		74.5		—		—			74.5
Certificates of deposit		88.5		—		—			88.5
Total short and long-term investments	$	672.7	$	0.3	$	(0.3	)	$	672.7

Fair Values and Gross Unrealized Losses for All Available-for-Sale Securities in an Unrealized Loss Position Deemed to be Temporary

The following table shows the fair value and gross unrealized losses for all available-for-sale securities in an unrealized loss position deemed to be temporary (in millions):

	September 30, 2012					December 31, 2011
	Fair Value		Unrealized Losses			Fair value		Unrealized Losses
Corporate debt securities	$	85.9	$	(0.1	)	$	164.5	$	(0.3	)

The Cost and Fair Value of Available-for-Sale Fixed-Maturity Securities by Contractual Maturity

The amortized cost and fair value of our available-for-sale fixed-maturity securities by contractual maturity are as follows (in millions):

	September 30, 2012
	Amortized Cost		Fair Value
Due in one year or less	$	687.0	$	687.4
Due after one year through two years		114.2		114.3
Total	$	801.2	$	801.7