Operating Segments and Related Information (Details 2) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Business Unit Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 444,736	$ 439,618
Intersegment revenue	0	0
Earnings from operations	81,082	55,492
Government and Defense
Business Unit Reporting, Revenue Reconciling Item [Line Items]
Revenue	173,350	159,331
Intersegment revenue	(1,512)	(1,528)
Earnings from operations	48,267	46,182
Industrial
Business Unit Reporting, Revenue Reconciling Item [Line Items]
Revenue	179,370	170,658
Intersegment revenue	(6,198)	(6,332)
Earnings from operations	56,897	45,455
Commercial
Business Unit Reporting, Revenue Reconciling Item [Line Items]
Revenue	92,016	109,629
Intersegment revenue	(4,433)	(4,481)
Earnings from operations	12,948	14,472
Eliminations
Business Unit Reporting, Revenue Reconciling Item [Line Items]
Intersegment revenue	(12,143)	(12,341)
Total Segments [Member]
Business Unit Reporting, Revenue Reconciling Item [Line Items]
Revenue	444,736	439,618
Earnings from operations	$ 118,112	$ 106,109