Quarterly financial data (unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Quarterly financial data (unaudited)
Net sales	$ 151,525	$ 144,747	$ 143,551	$ 139,165	$ 143,796	$ 138,906	$ 142,845	$ 138,823	$ 578,988	$ 564,370	$ 545,635
Gross profit	116,422	108,718	108,858	105,804	111,127	106,640	108,758	106,129	439,802	432,654	407,185
Net income (loss)	12,392	12,378	9,958	(35,801)	7,964	8,520	10,232	17,492	(1,073)
Net income (loss) per common share:
Basic (in dollars per share)	$ 0.67	$ 0.67	$ 0.55	$ (2.00)	$ 0.45	$ 0.48	$ 0.58	$ 1.00	$ (0.06)	$ 2.51	$ 1.43
Diluted (in dollars per share)	$ 0.65	$ 0.66	$ 0.54	$ (2.00)	$ 0.44	$ 0.48	$ 0.57	$ 0.99	$ (0.06)	$ 2.47	$ 1.42
Net gain on sale of divested vascular operations								12,019		12,019
Charges related to U.S. Government resolutions				$ 46,000					$ 9,520