Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net sales	$ 189,349	$ 196,934	$ 565,801	$ 609,099
Cost of goods sold	156,685	161,706	460,333	495,259
Gross profit	32,664	35,228	105,468	113,840
Operating expenses:
Selling, general and administrative	17,803	19,525	57,505	64,548
Research & development expenses	1,179	1,240	3,751	3,989
Total operating expenses	18,982	20,765	61,256	68,537
Operating income	13,682	14,463	44,212	45,303
Interest expense, net	3,990	3,428	11,580	9,530
Foreign exchange loss (gain)	373	(531)	(478)	409
Other (income), net	(5)	(14)	(16)	(42)
Income before income taxes	9,324	11,580	33,126	35,406
Provision (benefit) for income taxes	2,873	(2,510)	16,580	4,155
Net income	6,451	14,090	16,546	31,251
Net income attributable to participating common shareholders	$ 6,417	$ 14,033	$ 16,474	$ 31,139
Income per participating share:
Basic (in dollars per share)	$ 0.33	$ 0.72	$ 0.84	$ 1.60
Diluted (in dollars per share)	$ 0.32	$ 0.71	$ 0.83	$ 1.57
Weighted average participating shares outstanding:
Basic (in shares)	19,583,316	19,525,284	19,575,764	19,511,097
Diluted (in shares)	19,785,045	19,838,962	19,740,262	19,790,570
Other comprehensive income (loss), net of tax:
Change in interest rate swaps, (net of tax of $41, $0, $732, and $0)	$ (122)	$ 0	$ (2,195)	$ 0
Change in pension and post-retirement plans, (net of tax of ($19), $16, $13, and $228)	288	(47)	(426)	436
Other comprehensive income (loss), net of tax	166	(47)	(2,621)	436	[1]
Comprehensive (loss) income	$ 6,617	$ 14,043	$ 13,925	$ 31,687

[1] Includes the impact of ASU 2018-02, which transferred those amounts from accumulated other comprehensive income (loss) to retained earnings. See Note 16 to the Condensed Consolidated Financial Statements.