Unaudited Quarterly Results (Details) (USD $)	3 Months Ended																12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Line Items]
Revenues	$ 802,329,000	[1]	$ 725,788,000	[1]	$ 665,700,000	[1]	$ 625,740,000	[1]	$ 610,412,000	[2]	$ 597,027,000	[2]	$ 457,642,000	[2]	$ 439,664,000	[2]	$ 2,819,557,000	$ 2,104,745,000	$ 1,378,477,000
Net income	110,176,000	[3]	79,720,000	[3]	92,735,000	[3]	65,443,000	[3]	96,806,000		141,306,000		87,376,000		98,874,000		348,074,000	424,362,000	750,269,000
Net income per share - basic	$ 1.09		$ 0.79		$ 0.92		$ 0.66		$ 0.98		$ 1.44		$ 0.89		$ 1.02		$ 3.46	$ 4.33	$ 7.92
Net income per share - diluted	$ 0.96		$ 0.70		$ 0.82		$ 0.58		$ 0.86		$ 1.25		$ 0.79		$ 0.90		$ 3.07	$ 3.81	$ 6.75
Substantive milestone payment	30,000,000		30,000,000		15,000,000		30,000,000		25,000,000		45,000,000
Branded Prescription Drug Fee																	40,600,000
Antibody Collaboration
Quarterly Financial Information Disclosure [Line Items]
Number of families of novel antibodies													2					2
Up-front payments made to acquire full rights to antibodies																	0	20,000,000	0
Ang2
Quarterly Financial Information Disclosure [Line Items]
Up-front payments made to acquire full rights to antibodies													10,000,000
PDGFR-beta
Quarterly Financial Information Disclosure [Line Items]
Up-front payments made to acquire full rights to antibodies													$ 10,000,000

[1] Revenues in the first, second, third, and fourth quarters of 2014 included recognition of sales milestones of $30.0 million, $15.0 million, $30.0 million, and $30.0 million, respectively.

[2] Revenues in the second quarter of 2013 were reduced by two $10 million up-front payments made to Sanofi to acquire full rights to antibodies to PDGF and antibodies to Ang2 in ophthalmology, as described in Note 4 above. Revenues in the third and fourth quarter of 2013 included recognition of sales and substantive development milestones of $45.0 million and $25.0 million, respectively.

[3] Net income in the third quarter of 2014 included a $40.6 million incremental charge related to the Branded Prescription Drug Fee based on final regulations issued by the IRS in July 2014 as described in Note 3 above.