SEGMENT INFORMATION (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total net sales									$ 2,411,835	$ 2,271,026	$ 2,108,931
Net Sales	$ 648,622	$ 595,393	$ 620,298	$ 547,522	$ 611,881	$ 567,901	$ 567,653	$ 523,591	2,411,835	2,271,026	2,108,931
Operating income									373,626	325,120	296,519
Depreciation and amortization									102,949	99,995	96,008
Total assets	3,255,385				3,236,321				3,255,385	3,236,321	3,037,781
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Operating income									(36,347)	(33,483)	(32,107)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales									2,411,835	2,271,026	2,108,931
Operating income									373,626	325,120	296,519
Depreciation and amortization									102,949	99,995	96,008
Total assets	3,255,385				3,236,321				3,255,385	3,236,321	3,037,781
PropertyPlantAndEquipmentAdditions									53,417	52,705	46,776
Operating Segments [Member] | Commercial/Industrial
Segment Reporting Information [Line Items]
Total net sales									1,209,943	1,163,510	1,120,326
Operating income									182,669	168,146	156,084
Depreciation and amortization									50,690	53,180	53,970
Total assets	1,398,601				1,444,097				1,398,601	1,444,097	1,391,040
PropertyPlantAndEquipmentAdditions									30,411	29,028	30,145
Operating Segments [Member] | Defense
Segment Reporting Information [Line Items]
Total net sales									559,058	557,954	469,796
Operating income									128,446	109,338	98,182
Depreciation and amortization									20,578	20,702	14,488
Total assets	961,298				1,044,776				961,298	1,044,776	751,859
PropertyPlantAndEquipmentAdditions									5,793	9,276	5,870
Operating Segments [Member] | Power
Segment Reporting Information [Line Items]
Total net sales									649,754	554,048	524,967
Operating income									98,858	81,119	74,360
Depreciation and amortization									27,737	22,019	23,032
Total assets	720,073				482,753				720,073	482,753	516,321
PropertyPlantAndEquipmentAdditions									11,350	10,039	6,653
Operating Segments [Member] | Corporate And Other [Member]
Segment Reporting Information [Line Items]
Operating income									(36,347)	(33,483)	(32,107)
Depreciation and amortization									3,944	4,094	4,518
Total assets	$ 175,413				$ 264,695				175,413	264,695	378,561
PropertyPlantAndEquipmentAdditions									5,863	4,362	4,108
Operating Segments [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total net sales									$ (6,920)	$ (4,486)	$ (6,158)