For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Aggregate revenue during the period from the sale of goods in the normal course of business, after deducting returns, allowances and discounts.

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Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs.

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Total of the deductions in a given period to allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs, representing receivables written off as uncollectible and portions of the reserves utilized, respectively.

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Net Product Sales (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Revenue Disclosure [Line Items]
Net product sales	$ 418,022	$ 333,893	$ 780,400	$ 652,633
Activity of Sales Related Deductions [Roll Forward]
Balance	25,082		25,082		24,601
Provision related to current period sales			51,841
Credits/payments			(51,360)
Rebates and Chargebacks
Activity of Sales Related Deductions [Roll Forward]
Balance	4,140		4,140		4,400
Provision related to current period sales			14,817
Credits/payments			(15,077)
Distribution Related Fees
Activity of Sales Related Deductions [Roll Forward]
Balance	20,420		20,420		19,663
Provision related to current period sales			36,206
Credits/payments			(35,449)
Other Sales Related Deductions
Activity of Sales Related Deductions [Roll Forward]
Balance	522		522		538
Provision related to current period sales			818
Credits/payments			(834)
Customer concentration risk \| Gross Sales Revenue
Risks and Uncertainties [Abstract]
Concentration risk, percentage	73.00%	76.00%	76.00%	77.00%
EYLEA
Revenue Disclosure [Line Items]
Net product sales	414,800	329,800	773,800	643,700
ARCALYST
Revenue Disclosure [Line Items]
Net product sales	$ 3,200	$ 4,100	$ 6,600	$ 8,900