Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Summary of assets and liabilities recorded at fair value

(In millions)	As of December 31, 2015		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	$	909.5	$	—	$	909.5	$	—
Marketable debt securities:
Corporate debt securities	1,510.9		—		1,510.9		—
Government securities	2,875.9		—		2,875.9		—
Mortgage and other asset backed securities	494.1		—		494.1		—
Marketable equity securities	37.5		37.5		—		—
Derivative contracts	27.2		—		27.2		—
Plan assets for deferred compensation	40.1		—		40.1		—
Total	$	5,895.2	$	37.5	$	5,857.7	$	—
Liabilities:
Derivative contracts	$	14.7	$	—	$	14.7	$	—
Contingent consideration obligations	506.0		—		—		506.0
Total	$	520.7	$	—	$	14.7	$	506.0

(In millions)	As of December 31, 2014		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Cash equivalents	$	716.3	$	—	$	716.3	$	—
Marketable debt securities:
Corporate debt securities	1,063.0		—		1,063.0		—
Government securities	849.8		—		849.8		—
Mortgage and other asset backed securities	198.3		—		198.3		—
Marketable equity securities	6.9		6.9		—		—
Derivative contracts	72.7		—		72.7		—
Plan assets for deferred compensation	36.9		—		36.9		—
Total	$	2,943.9	$	6.9	$	2,937.0	$	—
Liabilities:
Derivative contracts	$	5.4	$	—	$	5.4	$	—
Contingent consideration obligations	215.5		—		—		215.5
Total	$	220.9	$	—	$	5.4	$	215.5

Summary of fair and carrying value of debt instruments

	As of December 31,
(In millions)	2015		2014
Notes payable to Fumedica	$	9.4	$	12.6
6.875% Senior Notes due March 1, 2018	602.6		634.6
2.900% Senior Notes due September 15, 2020	1,497.5		—
3.625% Senior Notes due September 15, 2022	1,014.2		—
4.050% Senior Notes due September 15, 2025	1,764.6		—
5.200% Senior Notes due September 15, 2045	1,757.6		—
Total	$	6,645.9	$	647.2

Fair value of contingent consideration obligations

	As of December 31,
(In millions)	2015			2014
Fair value, beginning of year	$	215.5		$	280.9
Additions	274.5			—
Changes in fair value	30.5			(38.9		)
Payments	(14.5		)	(26.5		)
Fair value, end of year	$	506.0		$	215.5