Operating Segments and Related Information (Details 2) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 448,463	$ 434,898	$ 452,707	$ 439,618	$ 494,784	$ 464,712	$ 434,124	$ 406,814	$ 1,775,686	$ 1,800,434	$ 1,662,167
Intersegment revenue									0	0	0
Earnings (loss) from operations									318,606	289,961	295,718
Industrial
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									717,882	672,120	552,580
Intersegment revenue									19,482	21,747	19,874
Earnings (loss) from operations									216,880	199,903	156,749
Government and defense
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									663,436	629,147	616,777
Intersegment revenue									11,409	11,283	10,344
Earnings (loss) from operations									199,702	179,160	176,749
Commercial
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									394,368	499,167	492,810
Intersegment revenue									20,056	14,942	17,277
Earnings (loss) from operations									57,399	56,066	52,659
Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Intersegment revenue									50,947	47,972	47,495
Total Segments [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue										1,800,434
Earnings (loss) from operations									$ 473,981	$ 435,129	$ 386,157