SEGMENT INFORMATION (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total net sales									$ 2,487,961,000	$ 2,411,835,000	$ 2,271,026,000
Net Sales	$ 655,771,000	$ 614,880,000	$ 638,996,000	$ 578,314,000	$ 648,622,000	$ 595,393,000	$ 620,298,000	$ 547,522,000	2,487,961,000	2,411,835,000	2,271,026,000
Operating income									403,953,000	373,626,000	325,120,000
Depreciation and amortization									102,412,000	102,949,000	99,995,000
Total assets	3,764,261,000				3,255,385,000				3,764,261,000	3,255,385,000	3,236,321,000
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Operating income									(35,109,000)	(36,347,000)	(33,483,000)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Sales									2,487,961,000	2,411,835,000	2,271,026,000
Operating income									403,953,000	373,626,000	325,120,000
Depreciation and amortization									102,412,000	102,949,000	99,995,000
Total assets	3,764,261,000				3,255,385,000				3,764,261,000	3,255,385,000	3,236,321,000
PropertyPlantAndEquipmentAdditions									69,752,000	53,417,000	52,705,000
Operating Segments [Member] | Commercial/Industrial
Segment Reporting Information [Line Items]
Total net sales									1,240,697,000	1,209,943,000	1,163,510,000
Operating income									196,455,000	182,669,000	168,146,000
Depreciation and amortization									48,227,000	50,690,000	53,180,000
Total assets	1,470,477,000				1,398,601,000				1,470,477,000	1,398,601,000	1,444,097,000
PropertyPlantAndEquipmentAdditions									34,077,000	30,411,000	29,028,000
Operating Segments [Member] | Defense
Segment Reporting Information [Line Items]
Total net sales									580,845,000	559,058,000	557,954,000
Operating income									129,653,000	128,446,000	109,338,000
Depreciation and amortization									21,495,000	20,578,000	20,702,000
Total assets	1,184,116,000				961,298,000				1,184,116,000	961,298,000	1,044,776,000
PropertyPlantAndEquipmentAdditions									4,034,000	5,793,000	9,276,000
Operating Segments [Member] | Power
Segment Reporting Information [Line Items]
Total net sales									670,950,000	649,754,000	554,048,000
Operating income									112,954,000	98,858,000	81,119,000
Depreciation and amortization									28,589,000	27,737,000	22,019,000
Total assets	804,432,000				720,073,000				804,432,000	720,073,000	482,753,000
PropertyPlantAndEquipmentAdditions									28,051,000	11,350,000	10,039,000
Operating Segments [Member] | Corporate And Other [Member]
Segment Reporting Information [Line Items]
Operating income									(35,109,000)	(36,347,000)	(33,483,000)
Depreciation and amortization									4,101,000	3,944,000	4,094,000
Total assets	$ 305,236,000				$ 175,413,000				305,236,000	175,413,000	264,695,000
PropertyPlantAndEquipmentAdditions									3,590,000	5,863,000	4,362,000
Operating Segments [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total net sales									$ (4,531,000)	$ (6,920,000)	$ (4,486,000)