SEGMENT INFORMATION (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net sales	$ 611,881	$ 567,901	$ 567,653	$ 523,591	$ 565,566	$ 507,092	$ 532,766	$ 503,507	$ 2,271,026	$ 2,108,931	$ 2,205,683
Operating income									339,743	308,098	310,617
Depreciation and amortization									99,995	96,008	100,810
Total assets	3,236,321				3,037,781				3,236,321	3,037,781	2,989,611
Capital expenditures related to discontinued operations											200
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Operating income									(23,200)	(23,215)	(34,790)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales									2,271,026	2,108,931	2,205,683
Operating income									339,743	308,098	310,617
Depreciation and amortization									99,995	96,008	99,475
Total assets	3,236,321				3,037,781				3,236,321	3,037,781	2,989,611
PropertyPlantAndEquipmentAdditions									52,705	46,776	35,512
Operating Segments [Member] | Commercial/Industrial
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment									1,163,510	1,120,326	1,189,120
Operating income									168,328	156,550	171,525
Depreciation and amortization									53,180	53,970	55,799
Total assets	1,444,097				1,391,040				1,444,097	1,391,040	1,480,052
PropertyPlantAndEquipmentAdditions									29,028	30,145	21,990
Operating Segments [Member] | Defense
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment									557,954	469,796	479,528
Operating income									109,355	98,291	98,895
Depreciation and amortization									20,702	14,488	15,965
Total assets	1,044,776				751,859				1,044,776	751,859	800,613
PropertyPlantAndEquipmentAdditions									9,276	5,870	3,834
Operating Segments [Member] | Power
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment									554,048	524,967	545,013
Operating income									85,260	76,472	74,987
Depreciation and amortization									22,019	23,032	23,419
Total assets	482,753				516,321				482,753	516,321	629,612
PropertyPlantAndEquipmentAdditions									10,039	6,653	6,163
Operating Segments [Member] | Corporate And Other [Member]
Segment Reporting Information [Line Items]
Operating income									(23,200)	(23,215)	(34,790)
Depreciation and amortization									4,094	4,518	4,292
Total assets	$ 264,695				$ 378,561				264,695	378,561	79,334
PropertyPlantAndEquipmentAdditions									4,362	4,108	3,525
Operating Segments [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment									$ (4,486)	$ (6,158)	$ (7,978)