Fair Value Measurement of Assets and Liabilities

3 Months Ended

Mar. 31, 2013

Fair Value Disclosures [Abstract]

Fair Value Measurement of Assets and Liabilities

9. Fair Value Measurement of Assets and Liabilities

The following assets and liabilities are recorded at fair value on a recurring basis (in millions):

	As of March 31, 2013
			Fair Value Measurements at Reporting Date Using:
Description	Recorded Balance		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable  Inputs (Level 3)
Assets
Available-for-sale securities
Corporate debt securities	$	401.6	$	—	$	401.6	$	—
U.S. government and agency debt securities		263.9		—		263.9		—
Foreign government debt securities		5.0		—		5.0		—
Commercial paper		16.0		—		16.0		—
Certificates of deposit		89.3		—		89.3		—
Total available-for-sale securities		775.8		—		775.8		—
Derivatives, current and long-term
Foreign currency forward contracts and options		61.7		—		61.7		—
Interest rate swaps		30.6		—		30.6		—
	$	868.1	$	—	$	868.1	$	—
Liabilities
Derivatives, current and long-term
Foreign currency forward contracts and options	$	3.4	$	—	$	3.4	$	—

	As of December 31, 2012
			Fair Value Measurements at Reporting Date Using:
Description	Recorded Balance		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets
Available-for-sale securities
Corporate debt securities	$	383.8	$	—	$	383.8	$	—
U.S. government and agency debt securities		295.9		—		295.9		—
Foreign government debt securities		5.0		—		5.0		—
Commercial paper		138.7		—		138.7		—
Certificates of deposit		92.3		—		92.3		—
Total available-for-sale securities		915.7		—		915.7		—
Derivatives, current and long-term
Foreign currency forward contracts and options		28.4		—		28.4		—
Interest rate swaps		33.9		—		33.9		—
	$	978.0	$	—	$	978.0	$	—
Liabilities
Derivatives, current and long-term
Foreign currency forward contracts and options	$	10.8	$	—	$	10.8	$	—

We value our available-for-sale securities using a market approach based on broker prices for identical assets in over-the-counter markets and perform ongoing assessments of counterparty credit risk.

We value our foreign currency forward contracts and foreign currency options using a market approach based on foreign currency exchange rates obtained from active markets and we perform ongoing assessments of counterparty credit risk.

We value our interest rate swaps using a market approach based on publicly available market yield curves and the terms of our swaps and we perform ongoing assessments of counterparty credit risk.