Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2014

Investments, All Other Investments [Abstract]

Marketable debt and equity securities

The following tables summarize our marketable debt and equity securities:

As of June 30, 2014 (In millions)	Fair Value		Gross Unrealized Gains		Gross Unrealized Losses			Amortized Cost
Available-for-sale:
Corporate debt securities
Current	$	125.0	$	0.1	$	—		$	124.9
Non-current	492.2		0.6		(0.2		)	491.8
Government securities
Current	584.9		0.1		(0.1		)	584.9
Non-current	363.1		0.2		—			362.9
Mortgage and other asset backed securities
Current	—		—		—			—
Non-current	155.4		0.1		(0.1		)	155.4
Total marketable debt securities	$	1,720.6	$	1.1	$	(0.4	)	$	1,719.9
Marketable equity securities, non-current	$	0.4	$	—	$	(0.1	)	$	0.5

As of December 31, 2013 (In millions)	Fair Value		Gross Unrealized Gains		Gross Unrealized Losses			Amortized Cost
Available-for-sale:
Corporate debt securities
Current	$	100.7	$	—	$	—		$	100.7
Non-current	339.1		0.4		(0.1		)	338.8
Government securities
Current	519.5		—		—			519.5
Non-current	155.2		—		(0.1		)	155.3
Mortgage and other asset backed securities
Current	—		—		—			—
Non-current	131.4		—		(0.1		)	131.5
Total marketable debt securities	$	1,245.9	$	0.4	$	(0.3	)	$	1,245.8
Marketable equity securities, non-current	$	11.2	$	8.7	$	—		$	2.5

Summary of financial assets with original maturities of less than 90 days included within cash and cash equivalents

The following table summarizes our financial assets with maturities of less than 90 days from the date of purchase included within cash and cash equivalents on the accompanying condensed consolidated balance sheet:

(In millions)	As of June 30, 2014		As of December 31, 2013
Commercial paper	$	5.9	$	1.2
Overnight reverse repurchase agreements	294.8		22.4
Short-term debt securities	174.5		401.1
Total	$	475.2	$	424.7

Summary of contractual maturities: available-for-sale securities

The estimated fair value and amortized cost of our marketable debt securities available-for-sale by contractual maturity are summarized as follows:

	As of June 30, 2014				As of December 31, 2013
(In millions)	Estimated Fair Value		Amortized Cost		Estimated Fair Value		Amortized Cost
Due in one year or less	$	709.8	$	709.8	$	620.2	$	620.2
Due after one year through five years	931.0		930.3		573.1		572.9
Due after five years	79.8		79.8		52.6		52.7
Total available-for-sale securities	$	1,720.6	$	1,719.9	$	1,245.9	$	1,245.8

Proceeds from marketable debt securities

The proceeds from maturities and sales of marketable debt securities and resulting realized gains and losses are summarized as follows:

	For the Three Months Ended June 30,					For the Six Months Ended June 30,
(In millions)	2014			2013		2014			2013
Proceeds from maturities and sales	$	560.1		$	78.3	$	1,317.5		$	4,404.7
Realized gains	$	0.2		$	—	$	0.4		$	6.3
Realized losses	$	(0.1	)	$	—	$	(0.2	)	$	(2.0	)