Share-Based Payments (Tables)

3 Months Ended

Mar. 31, 2013

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Share-based compensation expense included in consolidated statements of income

	For the Three Months Ended March 31,
(In millions)	2013			2012
Research and development	$	25.2		$	19.7
Selling, general and administrative	34.3			28.8
Subtotal	59.5			48.5
Capitalized share-based compensation costs	(2.3		)	(1.2		)
Share-based compensation expense included in total cost and expenses	57.2			47.3
Income tax effect	(16.6		)	(14.4		)
Share-based compensation expense included in net income attributable to Biogen Idec Inc.	$	40.6		$	32.9

Summary of share-based compensation expense associated with each of our share-based compensating programs

	For the Three Months Ended March 31,
(In millions)	2013			2012
Stock options	$	0.3		$	0.1
Market stock units	8.5			6.0
Time-vested restricted stock units	27.1			25.8
Performance-vested restricted stock units settled in shares	—			0.1
Cash settled performance shares	20.4			14.8
Employee stock purchase plan	3.2			1.7
Subtotal	59.5			48.5
Capitalized share-based compensation costs	(2.3		)	(1.2		)
Share-based compensation expense included in total cost and expenses	$	57.2		$	47.3

Summary of equity grants to employees, officers and directors under our current stock plans

	For the Three Months Ended March 31,
	2013	2012
Market stock units	253,000	286,000
Cash settled performance shares	270,000	310,000
Time-vested restricted stock units	638,000	771,000