Segment Reporting (Narrative) (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting Information [Line Items]
Number of business segments | segment									3
Revenue	$ 442,996	$ 448,308	$ 466,569	$ 417,550	$ 399,685	$ 406,387	$ 413,343	$ 382,477	$ 1,775,423	$ 1,601,892	$ 1,485,807
CAG Diagnostics [Member]
Segment Reporting Information [Line Items]
Revenue									$ 1,400	$ 500
CAG/LPD Segment Transition [Member]
Segment Reporting Information [Line Items]
Revenue											$ 13,800