Acquisitions (Details) - USD ($) $ in Thousands					3 Months Ended					9 Months Ended		18 Months Ended
	Nov. 30, 2016	Feb. 02, 2016	Dec. 21, 2015	Nov. 04, 2015	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Sep. 30, 2016
Acquisitions
Sales					$ 361,869		$ 375,240			$ 1,040,255	$ 1,055,077
Operating income (Loss)					(1,697)		13,893			(7,870)	(3,270)
Net income (loss)					(21,957)		4,498			(24,364)	9,228
Compensation expense					469		2,828			3,826	6,916
Amortization of purchased intangibles					7,865		9,666			25,093	24,620
Contingent consideration paid										1,988	1,679
Change in fair value of contingent consideration					(2,519)		(1,050)			(4,713)	(2,756)
Purchase price allocation
Goodwill					410,902					410,902		$ 410,902	$ 406,946
Selling, general and administrative
Acquisitions
Compensation expense					340		2,516			3,414	6,060
Vocality
Acquisitions
Sales					400					1,200
Operating income (Loss)					(700)					(2,300)
Net income (loss)					(600)					(2,100)
Amortization					200					400
Acquisition-related expenses					300					1,500
Fair value of consideration transferred	$ 9,600
Cash consideration paid	8,900
Contingent consideration	1,100
Cash paid related to compensation expenses										400
Purchase price allocation
Inventory	1,700
Accounts payable and accrued expenses	(400)
Other net liabilities assumed	(200)
Net identifiable assets acquired	6,000
Goodwill	3,600
Net assets acquired	$ 9,600
Weighted average useful life of intangible assets	9 years
Estimated amortization expense related to the intangible assets
2017													600
2018													800
2019													700
2020													600
2021													500
Thereafter													1,700
Vocality | Selling, general and administrative
Acquisitions
Compensation expense						$ 400
Vocality | Customer relationships
Purchase price allocation
Amortizable intangible assets	$ 2,100
Vocality | Technology
Purchase price allocation
Amortizable intangible assets	2,400
Vocality | Corporate trade names
Purchase price allocation
Amortizable intangible assets	$ 400
GATR
Acquisitions
Sales					24,000		9,300			51,400	18,600
Operating income (Loss)					2,700		(3,800)			(2,600)	(24,500)
Net income (loss)					1,600		(2,300)			(1,600)	(20,600)
Amortization					3,100		3,600			9,700	6,000
Gains (losses) for changes in fair value of contingent consideration					1,500		(600)			3,200	(700)
Acquisition-related expenses					500		800			1,300	20,200
Fair value of consideration transferred		$ 220,500
Cash consideration paid		236,100
Contingent consideration		2,500
Cash paid related to compensation expenses		$ 18,100						$ 15,400
Period for contingent consideration contracts		12 months
Purchase price allocation
Accounts receivable		$ 10,600
Inventory		3,400
Income tax receivable		5,100
Accounts payable and accrued expenses		(2,400)
Tax liabilities		(23,800)
Net identifiable assets acquired		64,600
Goodwill		155,900
Net assets acquired		$ 220,500
Weighted average useful life of intangible assets		9 years
Estimated amortization expense related to the intangible assets
2017													12,700
2018													11,100
2019													9,800
2020													8,300
2021													6,900
Thereafter													13,200
GATR | Maximum
Acquisitions
Contingent consideration		$ 7,500
GATR | Selling, general and administrative
Acquisitions
Compensation expense								$ 18,500
GATR | Customer relationships
Purchase price allocation
Amortizable intangible assets		51,700
GATR | Backlog
Purchase price allocation
Amortizable intangible assets		3,400
GATR | Technology
Purchase price allocation
Amortizable intangible assets		10,700
GATR | Non-compete agreements
Purchase price allocation
Amortizable intangible assets		1,200
GATR | Corporate trade names
Purchase price allocation
Amortizable intangible assets		$ 4,700
TeraLogics
Acquisitions
Sales					3,000		4,200			14,000	8,000
Operating income (Loss)					(900)		(400)			(1,100)	(2,400)
Net income (loss)					(600)		(200)			(700)	(1,400)
Amortization					900		1,000			2,700	2,000
Gains (losses) for changes in fair value of contingent consideration							(200)			(200)	(100)
Acquisition-related expenses					100		100			200	2,300
Compensation expense									$ 1,300
Fair value of consideration transferred			$ 33,900
Cash consideration paid			28,900
Contingent consideration			5,000
Contingent consideration paid												$ 32,400
Change in fair value of contingent consideration										3,200
Purchase price allocation
Accounts receivable			1,400
Accounts payable and accrued expenses			(500)
Other net liabilities assumed			(100)
Net identifiable assets acquired			15,700
Goodwill			18,200
Net assets acquired			$ 33,900
Weighted average useful life of intangible assets			7 years
Estimated amortization expense related to the intangible assets
2017													3,500
2018													2,800
2019													2,100
2020													1,400
2021													800
Thereafter													$ 1,400
TeraLogics | Maximum
Acquisitions
Contingent consideration			$ 9,000
TeraLogics | Maximum | Revenue thresholds
Acquisitions
Contingent consideration			6,000
TeraLogics | Maximum | Contract extensions
Acquisitions
Contingent consideration			3,000
TeraLogics | Customer relationships
Purchase price allocation
Amortizable intangible assets			6,700
TeraLogics | Backlog
Purchase price allocation
Amortizable intangible assets			5,600
TeraLogics | Software.
Purchase price allocation
Amortizable intangible assets			2,500
TeraLogics | Non-compete agreements
Purchase price allocation
Amortizable intangible assets			$ 100
H4 Global
Acquisitions
Sales					1,000		800			2,600	1,400
Operating income (Loss)					(200)		100			(500)	100
Net income (loss)					(200)		$ 100			(400)	100
Amortization										$ 100
Gains (losses) for changes in fair value of contingent consideration					$ (100)						200
Acquisition-related expenses											$ 100
Fair value of consideration transferred				$ 1,900
Cash consideration paid				900
Contingent consideration				$ 1,000
Period for contingent consideration contracts				5 years
Purchase price allocation
Goodwill				$ 1,900
H4 Global | Maximum
Acquisitions
Contingent consideration				$ 4,100