Operating Segments and Related Information (Details 2) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 494,784	$ 464,712	$ 434,124	$ 406,814	$ 474,738	$ 405,228	$ 402,729	$ 379,472	$ 1,800,434	$ 1,662,167	$ 1,557,067
Intersegment revenue									0	0	0
Earnings (loss) from operations									289,961	295,718	305,764
Surveillance
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									545,755	532,476	503,045
Intersegment revenue									14,074	18,835	10,761
Earnings (loss) from operations									151,983	151,516	149,560
Instruments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									357,834	336,141	347,476
Intersegment revenue									4,686	4,343	9,951
Earnings (loss) from operations									106,887	98,775	115,115
OEM & Emerging Markets
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									347,160	243,678	186,722
Intersegment revenue									42,985	33,442	33,059
Earnings (loss) from operations									103,334	66,141	43,660
Maritime
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									189,694	185,726	177,948
Intersegment revenue									2,440	3,450	2,108
Earnings (loss) from operations									23,019	18,564	17,383
Security
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									231,456	240,010	226,575
Intersegment revenue									15,845	13,838	12,033
Earnings (loss) from operations									13,760	15,885	29,366
Detection
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									128,535	124,136	115,301
Intersegment revenue									145	31	0
Earnings (loss) from operations									36,146	35,276	30,262
Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Intersegment revenue									80,175	73,939	67,912
Total Segments [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Earnings (loss) from operations									$ 435,129	$ 386,157	$ 385,346