Significant Accounting Policies Update - Effects of Changes (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Jan. 01, 2018	Jun. 29, 2018	Jun. 30, 2017	Jun. 29, 2018	Jun. 30, 2017	Dec. 31, 2017
Assets
Accounts receivable, net	$ 284,209	$ 250,293		$ 250,293		$ 313,451
Contract assets	82,699	125,204		125,204		0
Contract costs, current portion	3,022	3,487		3,487		0
Inventories	293,763	291,058		291,058		367,437
Income tax refunds receivable		3,692		3,692		2,889
Other current assets	27,221	32,173		32,173		27,188
Deferred income taxes	31,773	22,998		22,998		27,603
Contract costs, noncurrent portion	7,852	12,847		12,847		0
Liabilities
Accounts payable – trade	128,659	136,140		136,140		127,591
Contract liabilities, current portion	10,705	9,928		9,928		0
Advances on contracts, current portion	0	0		0		8,527
Other current liabilities	51,796	54,462		54,462		52,812
Deferred income taxes		7,738		7,738		8,024
Income taxes payable	3,042	0		0		1,517
Contract liabilities, noncurrent portion	689	76,330		76,330		0
Advances on contracts, noncurrent portion		0		0
Equity
Retained earnings	578,293	596,270		596,270		587,877
Net sales		468,129	$ 449,006	931,456	$ 884,947
Cost of sales		332,486	314,513	661,706	626,108
Gross profit		135,643	134,493	269,750	258,839
Selling, general and administrative expenses		114,339	107,952	226,092	218,829
Restructuring costs		1,954	0	3,647	0
Net (gain) loss on sale of assets		(1,525)	15	(1,588)	(5)
Operating income		20,875	26,526	41,599	40,015
Interest expense, net		5,002	6,122	10,354	10,282
Other expense (income), net		361	(69)	19	(228)
Non-service pension and post retirement benefit cost (income)		(3,039)	(866)	(6,068)	(1,585)
Earnings before income taxes		18,551	21,339	37,294	31,546
Income tax expense		3,457	7,881	8,134	11,797
Net earnings		15,094	13,458	29,160	19,749
Corporate
Equity
Operating income		(16,937)	(14,828)	(30,772)	(28,805)
Distribution
Equity
Net sales		289,523	278,706	573,455	550,324
Distribution | Operating segments
Equity
Net sales		289,523	278,706	573,455	550,324
Operating income		13,546	15,657	25,380	27,073
Aerospace
Equity
Net sales		178,606	170,300	358,001	334,623
Aerospace | Operating segments
Equity
Net sales		178,606	170,300	358,001	334,623
Operating income		22,741	25,712	45,403	41,742
Scenario, Previously Reported [Member]
Equity
Cost of sales			314,043		625,168
Gross profit			134,963		259,779
Selling, general and administrative expenses			107,556		218,184
Operating income			27,392		41,600
Non-service pension and post retirement benefit cost (income)			0		0
Scenario, Previously Reported [Member] | Corporate
Equity
Operating income			(14,797)		(28,892)
Scenario, Previously Reported [Member] | Distribution | Operating segments
Equity
Operating income			15,934		27,628
Scenario, Previously Reported [Member] | Aerospace | Operating segments
Equity
Operating income			26,270		42,859
Accounting Standard Update 2017-07 | Restatement Adjustment [Member]
Equity
Cost of sales			470		940
Gross profit			(470)		(940)
Selling, general and administrative expenses			396		645
Operating income			(866)		(1,585)
Non-service pension and post retirement benefit cost (income)			(866)		(1,585)
Accounting Standard Update 2017-07 | Restatement Adjustment [Member] | Corporate
Equity
Operating income			(31)		87
Accounting Standard Update 2017-07 | Restatement Adjustment [Member] | Distribution | Operating segments
Equity
Operating income			(277)		(555)
Accounting Standard Update 2017-07 | Restatement Adjustment [Member] | Aerospace | Operating segments
Equity
Operating income			$ (558)		$ (1,117)
Calculated under Revenue Guidance in Effect before Topic 606
Assets
Accounts receivable, net		269,648		269,648		313,451
Contract assets		0		0		0
Contract costs, current portion		0		0		0
Inventories		412,409		412,409		367,437
Income tax refunds receivable		8,414		8,414
Other current assets		31,990		31,990		27,188
Deferred income taxes		18,744		18,744		27,603
Contract costs, noncurrent portion		0		0		0
Liabilities
Accounts payable – trade		135,160		135,160		127,591
Contract liabilities, current portion		0		0		0
Advances on contracts, current portion		9,919		9,919		8,527
Other current liabilities		55,034		55,034		52,812
Deferred income taxes		7,735		7,735
Income taxes payable						1,517
Contract liabilities, noncurrent portion		0		0		0
Advances on contracts, noncurrent portion		76,330		76,330
Equity
Retained earnings		596,143		596,143		$ 587,877
Net sales		449,656		869,482
Cost of sales		319,116		615,078
Gross profit		130,540		254,404
Selling, general and administrative expenses		112,395		223,571
Restructuring costs		1,954		3,647
Net (gain) loss on sale of assets		(1,525)		(1,588)
Operating income		17,716		28,774
Interest expense, net		5,002		10,354
Other expense (income), net		361		19
Non-service pension and post retirement benefit cost (income)		(3,039)		(6,068)
Earnings before income taxes		15,392		24,469
Income tax expense		2,644		5,020
Net earnings		12,748		19,449
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Assets
Accounts receivable, net	(29,242)	19,355		19,355
Contract assets	82,699	(125,204)		(125,204)
Contract costs, current portion	3,022	(3,487)		(3,487)
Inventories	(73,674)	121,351		121,351
Income tax refunds receivable		4,722		4,722
Other current assets	33	(183)		(183)
Deferred income taxes	4,170	(4,254)		(4,254)
Contract costs, noncurrent portion	7,852	(12,847)		(12,847)
Liabilities
Accounts payable – trade	1,068	(980)		(980)
Contract liabilities, current portion	10,705	(9,928)		(9,928)
Advances on contracts, current portion	(8,527)	9,919		9,919
Other current liabilities	(1,016)	572		572
Deferred income taxes		(3)		(3)
Income taxes payable	1,525
Contract liabilities, noncurrent portion	689	(76,330)		(76,330)
Advances on contracts, noncurrent portion		76,330		76,330
Equity
Retained earnings	(9,584)	(127)		(127)
Net sales		(18,473)		(61,974)
Cost of sales		(13,370)		(46,628)
Gross profit		(5,103)		(15,346)
Selling, general and administrative expenses		(1,944)		(2,521)
Restructuring costs		0		0
Net (gain) loss on sale of assets		0		0
Operating income		(3,159)		(12,825)
Interest expense, net		0		0
Other expense (income), net		0		0
Non-service pension and post retirement benefit cost (income)		0		0
Earnings before income taxes		(3,159)		(12,825)
Income tax expense		(813)		(3,114)
Net earnings		$ (2,346)		$ (9,711)
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Aerospace
Equity
Retained earnings	(32,500)
Net sales	62,300
Gross profit	$ 20,200