Segment and Geographic Information - Segment Information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Sales to external customers	$ 891,738	$ 826,426	$ 634,222
Gross profit	415,630	367,366	269,264
Number of customers representing more than 10% of revenue	0	0	0
Industry [Member]
Segment Reporting Information [Line Items]
Sales to external customers	433,424	376,533	314,574
Gross profit	220,267	185,156	147,442
Science [Member]
Segment Reporting Information [Line Items]
Sales to external customers	458,314	449,893	319,648
Gross profit	$ 195,363	$ 182,210	$ 121,822

Concentration Risk Number of Customers Accounting For More Than 10% of Revenue.

No definition available.

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- Definition

Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1,2)

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

+ Details

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- Definition

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 5

-Section 03

-Paragraph 1

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

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- Details

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