Operating Segments and Related Information (Details 2) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 406,814	$ 379,472
Intersegment revenue	0	0
Earnings from operations	59,086	57,377
Surveillance
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	118,729	124,151
Intersegment revenue	4,756	4,224
Earnings from operations	26,365	35,865
Instruments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	77,855	79,418
Intersegment revenue	5,790	1,575
Earnings from operations	21,146	19,981
Security
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	45,078	47,061
Intersegment revenue	3,126	2,473
Earnings from operations	315	(2,169)
OEM & Emerging Markets
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	84,765	47,845
Intersegment revenue	9,170	8,176
Earnings from operations	24,357	10,686
Maritime
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	48,550	51,720
Intersegment revenue	677	615
Earnings from operations	5,205	5,806
Detection
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	31,837	29,277
Intersegment revenue	0	0
Earnings from operations	8,737	8,237
Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Intersegment revenue	23,519	17,063
Total Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Earnings from operations	$ 86,125	$ 78,406