Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Product revenues	$ 917,600	$ 856,445	$ 811,300
Cost of sales	622,563	580,066	569,618
Gross margin	295,037	276,379	241,682
Operating costs and expenses:
Research and development expenses	79,583	69,211	66,411
Reimbursed research and development expenses	(6,660)	(9,607)	(8,885)
Net research and development expenses	72,923	59,604	57,526
Acquisition transaction expenses	743		1,075
Selling, general and administrative expenses	115,252	95,456	84,647
Total operating costs and expenses	188,918	155,060	143,248
Operating income	106,119	121,319	98,434
Interest expense	(3,257)	(2,610)	(3,262)
Debt retirement expense			(1,370)
Revaluation of derivatives loss		(1,102)	(518)
Gain on settlement of lawsuit		9,949
Foreign currency gain (loss)	7,810	1,121	(218)
Gain from equity investment			785
Other (loss) income	(109)	261	370
Earnings before income tax	110,563	128,938	94,221
Income tax expense	33,965	33,545	24,102
Net income	$ 76,598	$ 95,393	$ 70,119
Basic earnings per share	$ 2.10	$ 2.65	$ 1.98
Diluted earnings per share	$ 2.09	$ 2.62	$ 1.95
Weighted average number of shares—basic	36,448,138	36,031,792	35,411,608
Weighted average number of shares—diluted	36,600,803	36,475,102	36,049,331