Investments

6 Months Ended

Jun. 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		Gross Unrealized
	Cost		Gains		Losses			Fair value
As of June 30, 2011
Corporate debt securities	$	240.4	$	0.3	$	(0.1	)	$	240.6
U.S. government and agency debt securities		37.9		—		—			37.9
Municipal bonds		1.0		—		—			1.0
Foreign government debt securities		7.5		—		—			7.5
Commercial paper		9.5		—		—			9.5
Certificates of deposit		129.1		0.1		—			129.2
Total short and long-term investments	$	425.4	$	0.4	$	(0.1	)	$	425.7
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 June 30, 2011					As of December 31, 2010
			Unrealized					Unrealized
	Fair Value		Losses			Fair value		Losses
Corporate debt securities	$	62.4	$	(0.1	)	$	126.1	$	(0.2	)
Certificates of deposit		—		—			50.6		(0.1	)
Total	$	62.4	$	(0.1	)	$	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 36 securities were in an unrealized loss position as of June 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 June 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 June 30, 2011
	Amortized
	Cost		Fair Value
Due in one year or less	$	321.2	$	321.4
Due after one year through two years		104.2		104.3
Total	$	425.4	$	425.7