Segment Reporting Information - Operations and Assets (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2019 USD ($)	Sep. 28, 2018 USD ($)	Sep. 27, 2019 USD ($) segment	Sep. 28, 2018 USD ($)	Dec. 28, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			3
Revenues	$ 400,555	$ 415,936	$ 1,233,753	$ 1,246,854
Operating Earnings	103,399	114,779	320,287	339,853
Total Assets	1,637,424		1,637,424		$ 1,472,741
Operating Segments | Industrial
Segment Reporting Information [Line Items]
Revenues	175,016	195,855	552,623	581,510
Operating Earnings	57,023	70,572	186,654	206,727
Total Assets	611,075		611,075		640,683
Operating Segments | Process
Segment Reporting Information [Line Items]
Revenues	84,090	84,556	256,048	249,650
Operating Earnings	18,194	17,862	56,586	52,629
Total Assets	375,933		375,933		350,306
Operating Segments | Contractor
Segment Reporting Information [Line Items]
Revenues	141,449	135,525	425,082	415,694
Operating Earnings	34,005	32,739	100,598	102,532
Total Assets	370,707		370,707		283,727
Unallocated corporate
Segment Reporting Information [Line Items]
Operating Earnings	(5,823)	$ (6,394)	(23,551)	$ (22,035)
Total Assets	$ 279,709		$ 279,709		$ 198,025