Property and Equipment, Net (Summary Of Depreciation And Amortization, Capitalized Computer Software For Internal Use And Unpaid Property Equipment Reflected In Account Payable And Accrued Expenses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 78,495	$ 74,208	$ 73,797
Unpaid property and equipment, reflected in accounts payable and accrued liabilities	24,688	17,894	11,744
Reagent rental programs
Property, Plant and Equipment [Line Items]
Rental and operating-type reagent rental program instruments transferred from inventory to property and equipment (Note 3)	14,498	20,360	16,313
Capitalized computer software developed for internal use
Property, Plant and Equipment [Line Items]
Capitalized computer software developed for internal use	$ 20,130	$ 17,115	$ 16,131