Segment Reporting Information - Operations and Assets (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2020 USD ($)	Sep. 27, 2019 USD ($)	Sep. 25, 2020 USD ($) segment	Sep. 27, 2019 USD ($)	Dec. 27, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			3
Revenues	$ 439,316	$ 400,555	$ 1,179,775	$ 1,233,753
Operating Earnings	125,005	103,399	259,590	320,287
Total Assets	1,993,995		1,993,995		$ 1,692,210
Operating Segments | Industrial
Segment Reporting Information [Line Items]
Revenues	172,805	175,016	464,776	552,623
Operating Earnings	60,776	57,023	148,010	186,654
Total Assets	622,294		622,294		615,486
Operating Segments | Process
Segment Reporting Information [Line Items]
Revenues	78,773	84,090	242,610	256,048
Operating Earnings	16,187	18,194	45,970	56,586
Total Assets	398,770		398,770		387,216
Operating Segments | Contractor
Segment Reporting Information [Line Items]
Revenues	187,738	141,449	472,389	425,082
Operating Earnings	54,841	34,005	124,580	100,598
Total Assets	433,627		433,627		368,832
Unallocated corporate
Segment Reporting Information [Line Items]
Operating Earnings	(6,532)	(5,823)	(23,741)	(23,551)
Impairment - Segment Information	(267)	$ 0	(35,229)	$ 0
Total Assets	$ 539,304		$ 539,304		$ 320,676