TOPIC 606 ADOPTION IMPACT AND REVENUE FROM CONTRACTS WITH CUSTOMERS: Impact of changes in accounting policies (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Apr. 01, 2018	Mar. 31, 2018
ASSETS
Deferred commissions, net	$ 8,490		$ 8,490			$ 0
Others	1,179,302		1,179,302
TOTAL ASSETS	1,187,792		1,187,792			1,209,497
Liabilities
Deferred income taxes	15,952		15,952			40,243
Other liabilities	411,162		411,162
Total liabilities	427,114		427,114
Equity
Retained earnings	658,666		658,666			628,331
Other equity	102,012		102,012
Total equity	760,678		760,678			749,095
TOTAL LIABILITIES AND EQUITY	1,187,792		1,187,792			$ 1,209,497
Income Statement [Abstract]
Revenues	64,812	$ 54,013	127,283	$ 100,770
Cost of revenue	24,466	24,009	48,120	48,070
Gross profit	40,346	30,004	79,163	52,700
Operating expenses:
Sales and marketing	35,940	25,981	69,263	50,072
Other operating expenses			77,701
Total operating expenses	78,545	68,137	146,964	130,652
Loss from operations	(38,199)	(38,133)	(67,801)	(77,952)
Total other income (expense)	(281)	263	75	(317)
Loss from continuing operations before income taxes	(38,480)	(37,870)	(67,726)	(78,269)
Income taxes (benefit)	2,700	(11,869)	1,272	(25,189)
Net loss from continuing operations	(41,180)	(26,001)	(68,998)	(53,080)
Statement of Comprehensive Income [Abstract]
Net loss	20,623	(3,336)	17,608	(4,636)
Other comprehensive income (loss):
Change in foreign currency translation adjustment	1,293	759	(575)	1,411
Comprehensive loss	21,916	(2,577)	17,033	(3,225)
Cash flows from operating activities:
Earnings (loss) from discontinued operations, net of tax	(61,803)	(22,665)	(86,606)	(48,444)
Adjustments to reconcile net loss to net cash provided by operating activities:
Deferred income taxes			12,444	(2,632)
Others			53,111
Changes in operating assets and liabilities:
Accounts receivable, net			(2,649)	(4,675)
Deferred costs and other assets, net			(2,047)	0
Other assets			(12,480)	(1,136)
Accounts payable and other liabilities			(7,276)	(3,804)
Deferred Revenue			(1,515)	(1,228)
Net cash provided by operating activities			(29,410)	(18,851)
Net cash from investing activities			(5,857)	100
Net cash from financing activities			(55,862)	(16,232)
Net cash provided by discontinued operations			39,642	34,046
Effect of exchange rate changes on cash			(1,484)	609
Net change in cash and cash equivalents			(52,971)	(328)
Cash and cash equivalents at beginning of period			140,018	168,680
Cash and cash equivalents at end of period	87,047	$ 168,352	87,047	$ 168,352
ASC 606 Adjustments | Accounting Standards Update 2014-09
ASSETS
Deferred commissions, net	(8,490)		(8,490)
Others	0		0
TOTAL ASSETS	(8,490)		(8,490)
Liabilities
Deferred income taxes	(2,281)		(2,281)
Other liabilities	0		0
Total liabilities	(2,281)		(2,281)
Equity
Retained earnings	(6,209)		(6,209)		$ 12,700
Other equity	0		0
Total equity	(6,209)		(6,209)
TOTAL LIABILITIES AND EQUITY	(8,490)		(8,490)
Income Statement [Abstract]
Revenues			0
Cost of revenue			0
Gross profit			0
Operating expenses:
Sales and marketing			2,047
Other operating expenses			0
Total operating expenses			2,047
Loss from operations			(2,047)
Total other income (expense)			0
Loss from continuing operations before income taxes			(2,047)
Income taxes (benefit)			(487)
Net loss from continuing operations			(1,560)
Statement of Comprehensive Income [Abstract]
Net loss			(1,560)
Other comprehensive income (loss):
Change in foreign currency translation adjustment			0
Comprehensive loss			(1,560)
Cash flows from operating activities:
Earnings (loss) from discontinued operations, net of tax			0
Adjustments to reconcile net loss to net cash provided by operating activities:
Deferred income taxes			(487)
Others			0
Changes in operating assets and liabilities:
Accounts receivable, net			0
Deferred costs and other assets, net			2,047
Other assets			0
Accounts payable and other liabilities			0
Deferred Revenue			0
Net cash provided by operating activities			0
Net cash from investing activities			0
Net cash from financing activities			0
Net cash provided by discontinued operations			0
Effect of exchange rate changes on cash			0
Net change in cash and cash equivalents			0
Cash and cash equivalents at beginning of period			0
Cash and cash equivalents at end of period	0		0
Before ASC topic 606
ASSETS
Deferred commissions, net	0		0
Others	1,179,302		1,179,302
TOTAL ASSETS	1,179,302		1,179,302
Liabilities
Deferred income taxes	13,671		13,671
Other liabilities	411,162		411,162
Total liabilities	424,833		424,833
Equity
Retained earnings	652,457		652,457
Other equity	102,012		102,012
Total equity	754,469		754,469
TOTAL LIABILITIES AND EQUITY	1,179,302		1,179,302
Income Statement [Abstract]
Revenues			127,283
Cost of revenue			48,120
Gross profit			79,163
Operating expenses:
Sales and marketing			71,310
Other operating expenses			77,701
Total operating expenses			149,011
Loss from operations			(69,848)
Total other income (expense)			75
Loss from continuing operations before income taxes			(69,773)
Income taxes (benefit)			785
Net loss from continuing operations			(70,558)
Statement of Comprehensive Income [Abstract]
Net loss			16,048
Other comprehensive income (loss):
Change in foreign currency translation adjustment			(575)
Comprehensive loss			15,473
Cash flows from operating activities:
Earnings (loss) from discontinued operations, net of tax			(86,606)
Adjustments to reconcile net loss to net cash provided by operating activities:
Deferred income taxes			11,957
Others			53,111
Changes in operating assets and liabilities:
Accounts receivable, net			(2,649)
Deferred costs and other assets, net			0
Other assets			(12,480)
Accounts payable and other liabilities			(7,276)
Deferred Revenue			(1,515)
Net cash provided by operating activities			(29,410)
Net cash from investing activities			(5,857)
Net cash from financing activities			(55,862)
Net cash provided by discontinued operations			39,642
Effect of exchange rate changes on cash			(1,484)
Net change in cash and cash equivalents			(52,971)
Cash and cash equivalents at beginning of period			140,018
Cash and cash equivalents at end of period	$ 87,047		$ 87,047