Operating Segments and Related Information (Details 4) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
BU assets (accounts receivable, inventory and demo assets, Net)	$ 784,260	$ 711,058
BU assets (accounts receivable, inventory, demo assets and goodwill, Net)	2,136,458	1,615,629
Cash and cash equivalents	268,885	512,144	$ 507,942	$ 519,090
Prepaid expenses and other current assets	77,577	69,445
Property and equipment, net	251,684	247,407
Deferred Income Tax Assets, Net	98,330	100,620
Goodwill	1,352,198	904,571
Intangible assets, net	273,225	146,845
Other assets	138,527	89,152
Assets	3,244,686	2,781,242
Government and Defense
Segment Reporting, Asset Reconciling Item [Line Items]
BU assets (accounts receivable, inventory and demo assets, Net)	361,580	307,041
Goodwill	725,436	284,188
Industrial
Segment Reporting, Asset Reconciling Item [Line Items]
BU assets (accounts receivable, inventory and demo assets, Net)	273,938	266,457
Goodwill	391,079	391,603
Commercial
Segment Reporting, Asset Reconciling Item [Line Items]
BU assets (accounts receivable, inventory and demo assets, Net)	148,742	137,560
Goodwill	$ 235,683	$ 228,780