Operating Segments and Related Information (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Business Unit Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 452,707	$ 434,124	$ 892,325	$ 840,938
Intersegment revenue	0	0	0	0
Earnings from operations	88,666	66,630	144,158	125,716
Government and Defense
Business Unit Reporting, Revenue Reconciling Item [Line Items]
Revenue	161,027	145,715	320,358	283,896
Intersegment revenue	(4,573)	(3,896)	(6,101)	(7,163)
Earnings from operations	45,548	38,153	91,730	71,473
Industrial
Business Unit Reporting, Revenue Reconciling Item [Line Items]
Revenue	188,421	164,736	359,079	319,521
Intersegment revenue	(6,164)	(4,786)	(12,496)	(9,728)
Earnings from operations	58,096	47,047	103,550	89,865
Commercial
Business Unit Reporting, Revenue Reconciling Item [Line Items]
Revenue	103,259	123,673	212,888	237,521
Intersegment revenue	(3,601)	(4,265)	(8,081)	(8,065)
Earnings from operations	17,367	15,475	31,839	25,463
Eliminations
Business Unit Reporting, Revenue Reconciling Item [Line Items]
Intersegment revenue	(14,338)	(12,947)	(26,678)	(24,956)
Total Segments [Member]
Business Unit Reporting, Revenue Reconciling Item [Line Items]
Revenue	452,707	434,124	892,325	840,938
Earnings from operations	$ 121,011	$ 100,675	$ 227,119	$ 186,801