Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Shares	Common Shares Held In Treasury	Common Stock	Retained Earnings	Common Stock In Treasury	Accumulated Other Comprehensive Income (Loss)	Other Equity
Beginning balance (in shares) at Dec. 31, 2017		20,107
Beginning balances (in Treasury shares) at Dec. 31, 2017			(7,042)
Beginning balances at Dec. 31, 2017	$ 494,981			$ 223,484	$ 536,116	$ (166,128)	$ (102,937)	$ 4,446
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	21,708			0	21,708	0	0	0
Other comprehensive income (loss)	3,256			0	0	0	3,256	0
Pension curtailment	0
Tax Cuts and Jobs Act of 2017 Reclassification From Aoci to Retained Earnings	0			0	(575)	0	575	0
Cumulative effect of accounting change	425			0	425	0	0	0
Cash dividends declared	(4,137)			0	(4,137)	0	0	0
Stock-based compensation activity (in shares)		181	181
Stock-based compensation activity	2,164			7,220	(14)	(5,042)	0	0
Payments of withholding taxes for stock-based compensation awards (in shares)		(53)	(53)
Payments of withholding taxes for stock-based compensation awards	(2,765)			0	0	(2,765)	0	0
Directors' deferred compensation	109	$ 1	$ 2	59	0	110	0	(60)
Ending balance (in shares) at Jun. 29, 2018		20,236
Ending balances (in Treasury shares) at Jun. 29, 2018			(6,912)
Ending balances at Jun. 29, 2018	515,741			230,763	553,523	(173,825)	(99,106)	4,386
Beginning balance (in shares) at Mar. 30, 2018		20,191
Beginning balances (in Treasury shares) at Mar. 30, 2018			(6,958)
Beginning balances at Mar. 30, 2018	504,329			227,694	545,093	(171,574)	(101,221)	4,337
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	11,144			0	11,144	0	0	0
Other comprehensive income (loss)	1,540			0	0	0	1,540	0
Tax Cuts and Jobs Act of 2017 Reclassification From Aoci to Retained Earnings	0			0	(575)	0	575	0
Cumulative effect of accounting change	0			0	0	0	0	0
Cash dividends declared	(2,125)			0	(2,125)	0	0	0
Stock-based compensation activity (in shares)		55	55
Stock-based compensation activity	1,393			3,020	(14)	(1,613)	0	0
Payments of withholding taxes for stock-based compensation awards (in shares)		(11)	(11)
Payments of withholding taxes for stock-based compensation awards	(632)			0	0	(632)	0	0
Directors' deferred compensation	92	$ 1	$ 2	49	0	(6)	0	49
Ending balance (in shares) at Jun. 29, 2018		20,236
Ending balances (in Treasury shares) at Jun. 29, 2018			(6,912)
Ending balances at Jun. 29, 2018	515,741			230,763	553,523	(173,825)	(99,106)	4,386
Beginning balance (in shares) at Dec. 31, 2018		20,242
Beginning balances (in Treasury shares) at Dec. 31, 2018			(6,906)
Beginning balances at Dec. 31, 2018	553,906			234,704	548,374	(175,426)	(58,234)	4,488
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	32,446			0	32,446	0	0	0
Other comprehensive income (loss)	10,960			0	0	0	10,960	0
Pension curtailment	3,296			0	0	0	3,296	0
Cumulative effect of accounting change	(179)			0	(179)	0	0	0
Cash dividends declared	(4,368)			0	(4,368)	0	0	0
Stock-based compensation activity (in shares)		247	247
Stock-based compensation activity	3,541			11,046	(62)	(7,443)	0	0
Payments of withholding taxes for stock-based compensation awards (in shares)		(87)	(87)
Payments of withholding taxes for stock-based compensation awards	(4,763)			0	0	(4,763)	0	0
Repurchase of shares (in shares)		(5)	(5)
Repurchase of shares	(199)			0	0	(199)	0	0
Directors' deferred compensation	145	$ 2	$ 2	35	0	607	0	(497)
Ending balance (in shares) at Jun. 28, 2019		20,399
Ending balances (in Treasury shares) at Jun. 28, 2019			(6,749)
Ending balances at Jun. 28, 2019	594,785			245,785	576,211	(187,224)	(43,978)	3,991
Beginning balance (in shares) at Mar. 29, 2019		20,354
Beginning balances (in Treasury shares) at Mar. 29, 2019			(6,794)
Beginning balances at Mar. 29, 2019	566,877			241,480	562,941	(184,812)	(57,270)	4,538
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	15,540			0	15,540	0	0	0
Other comprehensive income (loss)	9,996			0	0	0	9,996	0
Pension curtailment	3,296			0	0	0	3,296	0
Cash dividends declared	(2,243)			0	(2,243)	0	0	0
Stock-based compensation activity (in shares)		55	55
Stock-based compensation activity	1,994			4,287	(27)	(2,266)	0	0
Payments of withholding taxes for stock-based compensation awards (in shares)		(12)	(12)
Payments of withholding taxes for stock-based compensation awards	(785)			0	0	(785)	0	0
Repurchase of shares (in shares)		0	0
Repurchase of shares	0			0	0	0	0	0
Directors' deferred compensation	110	$ 2	$ 2	18	0	639	0	(547)
Ending balance (in shares) at Jun. 28, 2019		20,399
Ending balances (in Treasury shares) at Jun. 28, 2019			(6,749)
Ending balances at Jun. 28, 2019	$ 594,785			$ 245,785	$ 576,211	$ (187,224)	$ (43,978)	$ 3,991