Acquisitions - Schedule of Business Acquisitions (Details) - USD ($) $ in Thousands						12 Months Ended
	Apr. 19, 2019	Apr. 18, 2019	Jan. 29, 2019	Jul. 31, 2018	Feb. 01, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Consideration transferred
Net purchase price			$ 36,500			$ 127,083	$ 185,396	$ 77,757
Fair value of tangible assets acquired and liabilities assumed
Goodwill						$ 562,146	$ 497,442
GECO Avionics, LLC
Business Acquisition [Line Items]
Acquired intangible assets, estimated useful lives			15 years
Consideration transferred
Cash paid at closing			$ 36,500
Net purchase price			36,500
Fair value of tangible assets acquired and liabilities assumed
Accounts receivable			1,320
Inventory			1,454
Fixed assets			459
Accounts payable			(217)
Accrued expenses			(239)
Fair value of net tangible assets acquired			2,777
Fair value of identifiable intangible assets			12,500
Goodwill			21,223
Fair value of assets acquired			$ 36,500
The Athena Group, Inc
Consideration transferred
Cash paid at closing		$ 34,049
Working capital and net debt adjustment		(446)
Less cash acquired	$ (49)	(49)
Net purchase price	$ 33,554	33,554
Fair value of tangible assets acquired and liabilities assumed
Cash		49
Accounts receivable		726
Fixed assets		74
Other current and non-current assets		260
Accounts payable		(48)
Accrued expenses		(143)
Other current and non-current liabilities		(600)
Deferred tax liability		(6,414)
Fair value of net tangible assets acquired		(6,096)
Fair value of identifiable intangible assets		23,700
Goodwill		15,999
Fair value of assets acquired		$ 33,603
Syntonic Microwave LLC
Business Acquisition [Line Items]
Acquired intangible assets, estimated useful lives		15 years
Consideration transferred
Cash paid at closing		$ 13,118
Less cash acquired		(1,118)
Net purchase price		12,000
Fair value of tangible assets acquired and liabilities assumed
Cash		1,118
Accounts receivable		281
Inventory		482
Fixed assets		31
Other current and non-current assets		6
Accounts payable		(71)
Accrued expenses		(61)
Fair value of net tangible assets acquired		1,786
Fair value of identifiable intangible assets		7,100
Goodwill		4,232
Fair value of assets acquired		$ 13,118
Germane Systems, LC
Business Acquisition [Line Items]
Acquired intangible assets, estimated useful lives				15 years
Consideration transferred
Cash paid at closing				$ 47,166
Working capital and net debt adjustment				(1,244)
Less cash acquired				(193)
Net purchase price				45,729
Fair value of tangible assets acquired and liabilities assumed
Cash				193
Accounts receivable				4,277
Inventory				8,575
Fixed assets				867
Other current and non-current assets				596
Accounts payable				(3,146)
Accrued expenses				(1,229)
Other current and non-current liabilities				(232)
Fair value of net tangible assets acquired				9,901
Fair value of identifiable intangible assets				12,910
Goodwill				23,111
Fair value of assets acquired				$ 45,922
Themis Computer Acquisition
Consideration transferred
Cash paid at closing					$ 187,089
Working capital and net debt adjustment					(1,274)
Less cash acquired					(6,810)
Net purchase price					179,005
Fair value of tangible assets acquired and liabilities assumed
Cash					6,810
Accounts receivable					7,713
Inventory					7,333
Fixed assets					479
Other current and non-current assets					2,896
Accounts payable					(3,287)
Accrued expenses					(5,319)
Other current and non-current liabilities					(1,210)
Deferred tax liability					(14,307)
Fair value of net tangible assets acquired					1,108
Fair value of identifiable intangible assets					71,720
Goodwill					112,987
Fair value of assets acquired					$ 185,815