Investments

9 Months Ended

Sep. 30, 2011

Investments [Abstract]

Investments

6. 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 September 30, 2011
Corporate debt securities	$	308.8	$	0.1	$	(0.3	)	$	308.6
U.S. government and agency debt securities		83.9		—		—			83.9
Municipal bonds		1.0		—		—			1.0
Foreign government debt securities		7.5		—		—			7.5
Commercial paper		49.5		—		—			49.5
Certificates of deposit		135.5		0.1		—			135.6
Total short and long-term investments	$	586.2	$	0.2	$	(0.3	)	$	586.1
As of December 31, 2010
Corporate debt securities	$	203.9	$	0.1	$	(0.2	)	$	203.8
U.S. government and agency debt securities		47.9		—		—			47.9
Municipal bonds		1.1		—		—			1.1
Foreign government debt securities		10.3		—		—			10.3
Commercial paper		16.1		—		—			16.1
Certificates of deposit		131.5		—		(0.1	)		131.4
Total short and long-term investments	$	410.8	$	0.1	$	(0.3	)	$	410.6

Unrealized gains and losses on these investments are recorded in accumulated other comprehensive income in our 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):

	As of September 30, 2011					As of December 31, 2010
	Fair Value		Unrealized Losses			Fair value		Unrealized Losses
Corporate debt securities	$	169.4	$	(0.3	)	$	126.1	$	(0.2	)
Certificates of deposit		—		—			50.6		(0.1	)
Total	$	169.4	$	(0.3	)	$	176.7	$	(0.3	)

All securities in the table above have been in an unrealized loss position for less than twelve months. A total of 86 securities were in an unrealized loss position as of September 30, 2011.

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 September 30, 2011 are temporary because we do not intend to sell these investments before maturity, 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):

	As of September 30, 2011
	Amortized Cost		Fair Value
Due in one year or less	$	424.8	$	424.9
Due after one year through two years		161.4		161.2
Total	$	586.2	$	586.1