Information on Business Segments (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment	2
Revenues	$ 1,495,889	$ 1,436,499	$ 1,230,754
Operating profit	231,764	206,451	194,296
Assets	2,808,970	2,365,716	2,137,500
Depreciation and amortization	94,238	90,150	80,154
Capital expenditures	57,273	58,712	47,577
Interest expense	16,841	14,571	11,883
Other expense (income), net	7,428	(3,819)	(208)
Income before income taxes	$ 207,495	$ 195,699	$ 182,621
General Electric [Member]
Segment Reporting Information [Line Items]
Revenue by major customer	18.00%	18.00%	17.00%
Aerospace [Member]
Segment Reporting Information [Line Items]
Revenues	$ 501,162	$ 462,600	$ 406,500
Operating profit	101,400	83,600	62,500
Assets	692,600	667,100	647,800
Depreciation and amortization	35,900	33,600	30,000
Capital expenditures	23,600	27,500	21,100
Industrial [Member]
Segment Reporting Information [Line Items]
Revenues	994,727	973,900	824,200
Operating profit	130,400	122,800	131,800
Assets	1,962,400	1,505,400	1,356,100
Depreciation and amortization	57,600	54,800	49,500
Capital expenditures	33,400	31,000	25,900
Other [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0
Operating profit	0	0	0
Assets	154,000	193,300	133,700
Depreciation and amortization	800	1,700	700
Capital expenditures	$ 300	$ 200	$ 500