Investments

3 Months Ended

Mar. 31, 2012

Investments [Abstract]

Investments

5. Investments

We invest in short and long-term investments classified as available-for-sale securities. Information regarding our investments is as follows (in millions):

	Amortized Cost		Gross Unrealized					Fair value
			Gains		Losses
As of March 31, 2012
Corporate debt securities	$	331.1	$	0.4	$	(0.1	)	$	331.4
U.S. government and agency debt securities		200.5		—		(0.1	)		200.4
Foreign government debt securities		2.8		—		—			2.8
Commercial paper		127.3		—		—			127.3
Certificates of deposit		90.1		—		—			90.1
Total short and long-term investments	$	751.8	$	0.4	$	(0.2	)	$	752.0
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

Unrealized gains and losses on these investments are recorded in accumulated other comprehensive income in our condensed consolidated balance sheet.

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):

	March 31, 2012					December 31, 2011
	Fair Value		Unrealized Losses			Fair value		Unrealized Losses
Corporate debt securities	$	131.1	$	(0.1	)	$	164.5	$	(0.3	)
U.S. government and agency debt securities		173.0		(0.1	)		—		—
Total	$	304.1	$	(0.2	)	$	164.5	$	(0.3	)

All securities in the table above have been in an unrealized loss position for less than twelve months. A total of 94 securities were in an unrealized loss position as of March 31, 2012.

The unrealized losses on our investments in corporate debt securities were caused by increases in interest yields resulting from adverse conditions in the global credit markets. We believe the unrealized losses associated with our available-for-sale securities as of March 31, 2012 are temporary because we do not intend to sell these investments, and we do not believe we will be required to sell them before recovery of their amortized cost basis.

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

	March 31, 2012
	Amortized Cost		Fair Value
Due in one year or less	$	555.0	$	555.1
Due after one year through two years		196.8		196.9
Total	$	751.8	$	752.0