Unaudited Quarterly Results (Details) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares	Sep. 30, 2016 USD ($) $ / shares	Jun. 30, 2016 USD ($) $ / shares	Mar. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($) $ / shares	Sep. 30, 2015 USD ($) $ / shares	Jun. 30, 2015 USD ($) $ / shares	Mar. 31, 2015 USD ($) $ / shares	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($) $ / shares	Dec. 31, 2014 USD ($) $ / shares	Dec. 31, 2013
Quarterly Financial Information Disclosure [Line Items]
Excess tax benefit from stock-based compensation									$ 0	$ 405,317	$ 439,278
Revenues	$ 1,226,827	$ 1,220,122	$ 1,212,629	$ 1,200,849	$ 1,098,077	$ 1,137,422	$ 998,617	$ 869,612	4,860,427	4,103,728	2,819,557
Net income	$ 253,115	$ 264,804	$ 196,218	$ 181,385	$ 154,994	$ 210,398	$ 194,643	$ 76,021	$ 895,522	$ 636,056	$ 338,126
Net income per share - basic (in USD per shares) | $ / shares	$ 2.41	$ 2.53	$ 1.88	$ 1.74	$ 1.49	$ 2.04	$ 1.89	$ 0.74	$ 8.55	$ 6.17	$ 3.36
Net income per share - diluted (in USD per shares) | $ / shares	$ 2.19	$ 2.27	$ 1.69	$ 1.59	$ 1.34	$ 1.82	$ 1.69	$ 0.66	$ 7.70	$ 5.52	$ 2.98
Antibody Collaboration
Quarterly Financial Information Disclosure [Line Items]
Number of families of novel antibodies												2
Accounting Standards Update 2016-09 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member]
Quarterly Financial Information Disclosure [Line Items]
Excess tax benefit from stock-based compensation									$ 144,800
Accounting Standards Update 2016-09 [Member] | Additional Paid-in Capital | New Accounting Pronouncement, Early Adoption, Effect [Member]
Quarterly Financial Information Disclosure [Line Items]
Excess tax benefit from stock-based compensation				$ 15,600