SHARE-BASED COMPENSATION: Other (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018
Share-based compensation
Payments related to tax withholding for share-based compensation	$ 14,600
Shares paid for tax withholding for share based compensation	496,055
Percentage of Increment	0.0333%
Share-based Activity - Other disclosures
Holdback expenses	$ 28,100
Non-cash stock compensation expense	35,465	$ 25,666
Other accrued expenses	$ 44,434		$ 39,624
Other performance based
Share-based compensation activity
Outstanding at the beginning of the period (in shares)	111,111
Vested (in shares)	(45,364)
Forfeited or cancelled (in shares)	(65,747)
Outstanding at the end of the period (in shares)	0		111,111
Share-based compensation, Weighted average fair value per share at grant date
Outstanding at the beginning of the period (in dollars per share)	$ 5.33
Vested (in dollars per share)	5.33
Forfeited or cancelled (in dollars per share)	5.33
Outstanding at the end of the period (in dollars per share)	$ 0		$ 5.33
Weighted-average remaining contractual term
Weighted average remaining contractual term (in years)	0 years		0 years
Arbor Holdback Agreement
Share-based Activity - Other disclosures
Period for recognition of unrecognized stock-based compensation expense	2 years
Holdback expenses	$ 7,700	7,700
Future expense expected	10,200
Arbor
Share-based Activity - Other disclosures
Holdback consideration transferred	38,300
Pacific Data Partners LLC
Share-based compensation
Business Combination, Separately Recognized Transactions, Expenses and Losses Recognized	9,800
Share-based Activity - Other disclosures
Non-cash stock compensation expense	7,900
Other accrued expenses			$ 8,900
Employee Service Share-based Compensation, Aggregate Disclosures [Abstract]
2019	7,900
2020	15,800
2021	15,800
2022	$ 15,700
Shares Vesting Based On Relevant Performance Period At March 31 2018 | Other performance based
Share-based compensation
Share-based compensation arrangement by share-based payment award, non-option equity instruments, percentage reduction in vested shares	59.00%
Share-based compensation activity
Outstanding at the end of the period (in shares)	111,111
Discontinued Operations
Share-based Activity - Other disclosures
Share-based compensation expense	$ 5,700	$ 5,200