Business Segment Information - Summary of Net Sales of Company Recognized at a Point in Time Versus Over Time (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Total net sales	$ 716,294	$ 577,278	$ 599,162	$ 513,862	$ 715,019	$ 578,021	$ 596,219	$ 530,670	$ 2,406,596	$ 2,419,929	$ 2,309,078
Chemistry Consumables [Member]
Disaggregation of Revenue [Line Items]
Total net sales									412,018	400,287	372,157
Service [Member]
Disaggregation of Revenue [Line Items]
Total net sales									839,407	814,936	756,729
Net Sales Recognized at a Point in Time: [Member]
Disaggregation of Revenue [Line Items]
Total net sales									1,890,436	1,922,542	1,851,734
Net Sales Recognized at a Point in Time: [Member] \| Instrument Systems [Member]
Disaggregation of Revenue [Line Items]
Total net sales									1,155,171	1,204,706	1,180,192
Net Sales Recognized at a Point in Time: [Member] \| Chemistry Consumables [Member]
Disaggregation of Revenue [Line Items]
Total net sales									412,018	400,287	372,157
Net Sales Recognized at a Point in Time: [Member] \| Service [Member]
Disaggregation of Revenue [Line Items]
Total net sales									323,247	317,549	299,385
Net Sales Recognized Over Time: [Member] \| Service [Member]
Disaggregation of Revenue [Line Items]
Total net sales									$ 516,160	$ 497,387	$ 457,344