INCOME TAXES, Tax credits (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Tax credits
Operating loss	$ 29,677	$ 28,028	$ 65,672	$ 49,164	$ 93,001	$ 13,256	$ (41,621)	$ (38,670)	$ 172,541	$ 25,966	$ (671,963)
Income tax receivable	78,726				$ 37,971				78,726	$ 37,971
Federal
Tax credits
Operating loss									125,100
Income tax receivable	39,800								39,800
Federal | MOTIVE Merger
Tax credits
Tax credit carryforwards		$ 300
Foreign
Tax credits
Tax credit carryforwards	34,900								34,900
Amount of foreign tax credit carryforwards	30,200								30,200
Minimum tax credit carryforwards	$ 600								$ 600