Business combinations and disposals (Schedule of Assets and Liabilities Recorded in the Company's Financial Statements) (Details) - USD ($) $ in Thousands			9 Months Ended		12 Months Ended
	Feb. 29, 2016	Apr. 01, 2015	Jun. 30, 2016	Jun. 30, 2015	Sep. 30, 2015	Dec. 15, 2015
Business Acquisition [Line Items]
Estimated purchase consideration, net of cash acquired			$ 46,736	$ 289,612
Goodwill			398,929		$ 376,302
Ascend Management Innovations LLC
Business Acquisition [Line Items]
Fair value of consideration			44,000
Billed and unbilled receivables			4,069
Other assets			407
Property and equipment			707
Intangible assets — customer relationships	$ 22,300		22,300
Total identifiable assets acquired			27,483
Accounts payable and other liabilities			1,414
Deferred revenue			554
Total liabilities assumed			1,968
Net identifiable assets acquired			25,515
Goodwill	$ 18,500		18,495
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net			44,010
Amortization period of intangible assets (in years)	18 years
Acentia LLC
Business Acquisition [Line Items]
Estimated purchase consideration, net of cash acquired		$ 293,500	293,504
Billed and unbilled receivables			35,333
Other assets			3,091
Property and equipment			2,140
Intangible assets — customer relationships			69,900
Total identifiable assets acquired			110,464
Accounts payable and other liabilities			31,350
Deferred revenue			251
Capital lease obligations			567
Deferred tax liabilities			6,741
Total liabilities assumed			38,909
Net identifiable assets acquired			71,555
Goodwill			221,949
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net			293,504
Percentage of goodwill anticipated to be deductible for tax purpose		$ 175,000
Acentia LLC | Customer relationships
Business Acquisition [Line Items]
Amortization period of intangible assets (in years)		14 years
Assessments Australia
Business Acquisition [Line Items]
Intangible assets — customer relationships						$ 400
Previously Reported | Acentia LLC
Business Acquisition [Line Items]
Estimated purchase consideration, net of cash acquired					293,504
Billed and unbilled receivables					35,333
Other assets					5,050
Property and equipment					2,140
Intangible assets — customer relationships					69,900
Total identifiable assets acquired					112,423
Accounts payable and other liabilities					32,426
Deferred revenue					251
Capital lease obligations					567
Deferred tax liabilities					0
Total liabilities assumed					33,244
Net identifiable assets acquired					79,179
Goodwill					214,325
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net					$ 293,504
Purchase Accounting Adjustment | Acentia LLC
Business Acquisition [Line Items]
Estimated purchase consideration, net of cash acquired			0
Other assets			(1,959)
Total identifiable assets acquired			(1,959)
Accounts payable and other liabilities			(1,076)
Deferred tax liabilities			6,741
Total liabilities assumed			5,665
Net identifiable assets acquired			(7,624)
Goodwill			7,624
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net			$ 0