Revenue Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Net sales	$ 224,910	$ 213,370	$ 442,010	$ 413,200
Consumer [Member]
Disaggregation of Revenue [Line Items]
Net sales	71,990	66,780	136,720	125,660
Aerospace [Member]
Disaggregation of Revenue [Line Items]
Net sales	45,620	47,580	91,430	93,000
Industrial [Member]
Disaggregation of Revenue [Line Items]
Net sales	55,970	50,000	110,320	99,290
Oil and gas [Member]
Disaggregation of Revenue [Line Items]
Net sales	$ 51,330	$ 49,010	$ 103,540	$ 95,250