Segment Information - Revenue from External Customers by Products and Services (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue from External Customer [Line Items]
Revenues	$ 1,400,182	$ 1,348,223	$ 1,401,981
Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	100.00%	100.00%	100.00%
Breathing Apparatus
Revenue from External Customer [Line Items]
Revenues	$ 322,412	$ 329,179	$ 317,678
Breathing Apparatus | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	23.00%	24.00%	23.00%
Fixed Gas & Flame Detection
Revenue from External Customer [Line Items]
Revenues	$ 299,018	$ 287,414	$ 292,988
Fixed Gas & Flame Detection | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	21.00%	21.00%	21.00%
Firefighter Helmets & Protective Apparel
Revenue from External Customer [Line Items]
Revenues	$ 203,914	$ 162,207	$ 178,012
Firefighter Helmets & Protective Apparel | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	15.00%	12.00%	13.00%
Portable Gas Detection
Revenue from External Customer [Line Items]
Revenues	$ 162,761	$ 142,581	$ 169,479
Portable Gas Detection | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	12.00%	11.00%	12.00%
Industrial Head Protection
Revenue from External Customer [Line Items]
Revenues	$ 143,601	$ 125,921	$ 145,403
Industrial Head Protection | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	10.00%	9.00%	10.00%
Fall Protection
Revenue from External Customer [Line Items]
Revenues	$ 117,731	$ 103,075	$ 125,869
Fall Protection | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	8.00%	8.00%	9.00%
Other
Revenue from External Customer [Line Items]
Revenues	$ 150,745	$ 197,846	$ 172,552
Other | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	11.00%	15.00%	12.00%
Americas
Revenue from External Customer [Line Items]
Revenues	$ 908,068	$ 874,305	$ 915,118
Americas | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	100.00%	100.00%	100.00%
Americas | Breathing Apparatus
Revenue from External Customer [Line Items]
Revenues	$ 217,340	$ 220,650	$ 212,463
Americas | Breathing Apparatus | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	24.00%	25.00%	23.00%
Americas | Fixed Gas & Flame Detection
Revenue from External Customer [Line Items]
Revenues	$ 182,515	$ 158,924	$ 159,892
Americas | Fixed Gas & Flame Detection | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	20.00%	18.00%	17.00%
Americas | Firefighter Helmets & Protective Apparel
Revenue from External Customer [Line Items]
Revenues	$ 137,086	$ 133,653	$ 142,043
Americas | Firefighter Helmets & Protective Apparel | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	15.00%	15.00%	16.00%
Americas | Portable Gas Detection
Revenue from External Customer [Line Items]
Revenues	$ 109,543	$ 90,545	$ 113,914
Americas | Portable Gas Detection | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	12.00%	10.00%	12.00%
Americas | Industrial Head Protection
Revenue from External Customer [Line Items]
Revenues	$ 108,869	$ 92,075	$ 112,673
Americas | Industrial Head Protection | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	12.00%	11.00%	12.00%
Americas | Fall Protection
Revenue from External Customer [Line Items]
Revenues	$ 69,108	$ 58,060	$ 78,054
Americas | Fall Protection | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	8.00%	7.00%	9.00%
Americas | Other
Revenue from External Customer [Line Items]
Revenues	$ 83,607	$ 120,398	$ 96,079
Americas | Other | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	9.00%	14.00%	11.00%
International
Revenue from External Customer [Line Items]
Revenues	$ 492,114	$ 473,918	$ 486,863
International | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	100.00%	100.00%	100.00%
International | Breathing Apparatus
Revenue from External Customer [Line Items]
Revenues	$ 105,072	$ 108,529	$ 105,215
International | Breathing Apparatus | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	21.00%	23.00%	22.00%
International | Fixed Gas & Flame Detection
Revenue from External Customer [Line Items]
Revenues	$ 116,503	$ 128,490	$ 133,096
International | Fixed Gas & Flame Detection | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	24.00%	27.00%	27.00%
International | Firefighter Helmets & Protective Apparel
Revenue from External Customer [Line Items]
Revenues	$ 66,828	$ 28,554	$ 35,969
International | Firefighter Helmets & Protective Apparel | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	14.00%	6.00%	7.00%
International | Portable Gas Detection
Revenue from External Customer [Line Items]
Revenues	$ 53,218	$ 52,036	$ 55,565
International | Portable Gas Detection | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	11.00%	11.00%	11.00%
International | Industrial Head Protection
Revenue from External Customer [Line Items]
Revenues	$ 34,732	$ 33,846	$ 32,730
International | Industrial Head Protection | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	7.00%	7.00%	7.00%
International | Fall Protection
Revenue from External Customer [Line Items]
Revenues	$ 48,623	$ 45,015	$ 47,815
International | Fall Protection | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	10.00%	10.00%	10.00%
International | Other
Revenue from External Customer [Line Items]
Revenues	$ 67,138	$ 77,448	$ 76,473
International | Other | Sales | Product concentration risk
Revenue from External Customer [Line Items]
Concentration risk (percentage)	13.00%	16.00%	16.00%