Segment Information - Revenue from External Customers by Products and Services (Details) - Sales	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Breathing Apparatus
Revenue from External Customer [Line Items]
Concentration risk (percentage)	25.00%	26.00%	27.00%
Fixed Gas and Flame Detection
Revenue from External Customer [Line Items]
Concentration risk (percentage)	21.00%	21.00%	21.00%
Portable Gas Detection
Revenue from External Customer [Line Items]
Concentration risk (percentage)	12.00%	12.00%	13.00%
Head Protection
Revenue from External Customer [Line Items]
Concentration risk (percentage)	11.00%	10.00%	11.00%
Fire Helmets & Protective Apparel
Revenue from External Customer [Line Items]
Concentration risk (percentage)	9.00%	5.00%	5.00%
Fall Protection
Revenue from External Customer [Line Items]
Concentration risk (percentage)	8.00%	8.00%	5.00%
Other
Revenue from External Customer [Line Items]
Concentration risk (percentage)	14.00%	18.00%	18.00%