Cash Equivalents and Investments (Tables)

3 Months Ended

Mar. 31, 2013

Cash Equivalents and Investments [Abstract]

Unrealized gains and losses, and fair value of available-for-sale and trading securities [Table Text Block]

The following tables summarize the Company's unrealized gains and losses and fair value of investments designated as available-for-sale and trading securities as of March 31, 2013 and December 31, 2012 (in millions):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
As of March 31, 2013
Cash equivalents:
Certificate of deposit	$	0.3	$	—	$	—		$	0.3
Money market funds	749.6		—		—			749.6
U.S. government securities	6.0		—		—			6.0
Total cash equivalents	755.9		—		—			755.9
Restricted investments:
Money market funds	89.5		—		—			89.5
Mutual funds	2.9		0.1		—			3.0
Total restricted investments	92.4		0.1		—			92.5
Fixed income securities:
Asset-backed securities	234.7		0.2		(0.1		)	234.8
Certificates of deposit	44.7		—		—			44.7
Corporate debt securities	614.0		2.0		(0.3		)	615.7
Foreign government debt securities	15.8		—		—			15.8
Government-sponsored enterprise obligations	270.4		0.2		—			270.6
U.S. government securities	430.1		0.2		—			430.3
Total fixed income securities	1,609.7		2.6		(0.4		)	1,611.9
Publicly-traded equity securities	2.9		—		(0.3		)	2.6
Total available-for-sale securities	2,460.9		2.7		(0.7		)	2,462.9
Trading securities in mutual funds(*)	13.8		—		—			13.8
Total	$	2,474.7	$	2.7	$	(0.7	)	$	2,476.7
Reported as:
Cash equivalents	$	755.9	$	—	$	—		$	755.9
Restricted investments	92.4		0.1		—			92.5
Short-term investments	613.0		0.4		(0.3		)	613.1
Long-term investments	1,013.4		2.2		(0.4		)	1,015.2
Total	$	2,474.7	$	2.7	$	(0.7	)	$	2,476.7

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^(*)  Balance includes the Company's non-qualified deferred compensation plan assets.

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
As of December 31, 2012
Cash equivalents:
Certificate of deposit	$	0.6	$	—	$	—		$	0.6
Commercial paper	10.8		—		—			10.8
Government-sponsored enterprise obligations	6.1		—		—			6.1
Money market funds	1,042.6		—		—			1,042.6
U.S. government securities	165.8		—		—			165.8
Total cash equivalents	1,225.9		—		—			1,225.9
Restricted investments:
Money market funds	102.6		—		—			102.6
Mutual funds	2.9		0.1		—			3.0
Total restricted investments	105.5		0.1		—			105.6
Fixed income securities:
Asset-backed securities	226.2		0.3		(0.1		)	226.4
Certificates of deposit	41.9		—		—			41.9
Commercial paper	11.6		—		—			11.6
Corporate debt securities	533.4		2.3		(0.1		)	535.6
Foreign government debt securities	5.0		—		—			5.0
Government-sponsored enterprise obligations	264.6		0.3		—			264.9
U.S. government securities	328.6		0.1		—			328.7
Total fixed income securities	1,411.3		3.0		(0.2		)	1,414.1
Publicly-traded equity securities	3.0		—		(0.1		)	2.9
Total available-for-sale securities	2,745.7		3.1		(0.3		)	2,748.5
Trading securities in mutual funds(*)	12.6		—		—			12.6
Total	$	2,758.3	$	3.1	$	(0.3	)	$	2,761.1
Reported as:
Cash equivalents	$	1,225.9	$	—	$	—		$	1,225.9
Restricted investments	105.5		0.1		—			105.6
Short-term investments	441.3		0.3		(0.1		)	441.5
Long-term investments	985.6		2.7		(0.2		)	988.1
Total	$	2,758.3	$	3.1	$	(0.3	)	$	2,761.1

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^(*)  Balance includes the Company's non-qualified deferred compensation plan assets.

Maturities of fixed income securities [Table Text Block]

The following table presents the maturities of the Company's total fixed income securities as of March 31, 2013 (in millions):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Due within one year	$	596.3	$	0.4	$	—		$	596.7
Due between one and five years	1,013.4		2.2		(0.4		)	1,015.2
Total	$	1,609.7	$	2.6	$	(0.4	)	$	1,611.9

Available For Sale Investments In Unrealized Loss Position [Table Text Block]

The following tables present the Company's available-for-sale investments that were in an unrealized loss position as of March 31, 2013 and December 31, 2012 (in millions):

	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
As of March 31, 2013
Fixed income securities:
Asset-backed securities	$	112.5	$	(0.1	)	$	—	$	—	$	112.5	$	(0.1	)
Corporate debt securities	180.8		(0.3		)	—		—		180.8		(0.3		)
Foreign government debt securities	15.1		—			—		—		15.1		—
Government-sponsored enterprise obligations	85.3		—			—		—		85.3		—
U.S. government securities	10.0		—			—		—		10.0		—
Total fixed income securities	403.7		(0.4		)	—		—		403.7		(0.4		)
Publicly-traded equity securities	2.6		(0.3		)	—		—		2.6		(0.3		)
Total available-for sale securities	$	406.3	$	(0.7	)	$	—	$	—	$	406.3	$	(0.7	)

	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
As of December 31, 2012
Fixed income securities:
Asset-backed securities(*)	$	55.1	$	(0.1	)	$	0.1	$	—	$	55.2	$	(0.1	)
Certificates of deposit	0.3		—			—		—		0.3		—
Commercial paper	10.0		—			—		—		10.0		—
Corporate debt securities	116.0		(0.1		)	—		—		116.0		(0.1		)
Government-sponsored enterprise obligations	30.0		—			—		—		30.0		—
U.S. government securities	68.2		—			—		—		68.2		—
Total fixed income securities	279.6		(0.2		)	0.1		—		279.7		(0.2		)
Publicly-traded equity securities	2.9		(0.1		)	—		—		2.9		(0.1		)
Total available-for sale securities	$	282.5	$	(0.3	)	$	0.1	$	—	$	282.6	$	(0.3	)

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^(*) Balance greater than 12 months includes investments that were in an immaterial unrealized loss position as of December 31, 2012.

Restricted cash and investments [Table Text Block]

The following table summarizes the Company's cash and investments that are classified as restricted cash and investments in the Condensed Consolidated Balance Sheets (in millions):

	As of
	March 31, 2013		December 31, 2012
Restricted cash	$	1.9	$	0.8
Restricted investments	92.5		105.6
Total restricted cash and investments	$	94.4	$	106.4