Segment Information - Goodwill and Total Assets (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jul. 01, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Goodwill	$ 129,122	$ 131,320	$ 79,743	$ 58,053
Total Assets	1,281,817	1,234,223
Industry [Member]
Segment Reporting Information [Line Items]
Goodwill	51,949	53,572
Total Assets	296,056	293,115
Science [Member]
Segment Reporting Information [Line Items]
Goodwill	77,173	77,748
Total Assets	369,298	401,795
Corporate Eliminations [Member]
Segment Reporting Information [Line Items]
Total Assets	$ 616,463	$ 539,313