Acquisitions and Investments (Details) $ in Thousands, € in Millions	3 Months Ended					6 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($) business	Mar. 31, 2017 EUR (€)	Dec. 31, 2017 USD ($) customer_list	Dec. 31, 2018 USD ($) customer_list	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Investment acquired, non-controlling interest share	$ 5,000
Goodwill	214,489					$ 199,873	$ 214,489	$ 199,873	$ 178,228	$ 178,934
Acquisition of a business, net of cash acquired							22,500	14,579	1,964
Business Combinations, goodwill							20,282	$ 13,541	1,720
Software company
Business Acquisition [Line Items]
Purchase price of acquired assets		$ 25,000
Holdback payment		1,000
Contingent payment		$ 1,500
Contingent payment period		36 months
Goodwill		$ 20,300
Net tangible liabilities		300
Two software companies
Business Acquisition [Line Items]
Purchase price of acquired assets				$ 15,000
Contingent payment				$ 3,000
Contingent payment period				36 months
Number of businesses acquired | business				2
Acquisition of a business, net of cash acquired				$ 12,000
Business Combinations, goodwill			$ 13,300
Reference laboratory in Austria
Business Acquisition [Line Items]
Purchase price of acquired assets | €					€ 1.3
Reference laboratory diagnostic and consulting businesses
Business Acquisition [Line Items]
Acquisition of a business, net of cash acquired									$ 3,500
Customer relationships | Software company
Business Acquisition [Line Items]
Intangible assets		2,400
Customer relationships | Two software companies
Business Acquisition [Line Items]
Intangible assets			1,000
Technology-based intangible assets | Software company
Business Acquisition [Line Items]
Intangible assets		$ 2,600
Technology-based intangible assets | Two software companies
Business Acquisition [Line Items]
Intangible assets			$ 600
Customer lists | Reference laboratory in United States
Business Acquisition [Line Items]
Purchase price of acquired assets						$ 2,300	2,200
Contingent payment	$ 300						$ 300
Number of businesses acquired | customer_list						4	4