REVENUE RECOGNITION - Financial Statement Impact of Adoption (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Apr. 01, 2018	Mar. 31, 2018
ASSETS:
Accounts receivable and unbilled costs	$ 165,331		$ 214,633	$ 213,438
Prepaid expenses and other current assets	32,407		38,128	33,502
Other assets	19,036		17,614	12,866
LIABILITIES:
Deferred revenue and customer deposits	248,165		271,698	301,925
Deferred tax liability	143,542		159,462	151,563
Long-term deferred revenue and customer deposits	80,491		90,157	91,409
STOCKHOLDERS' EQUITY:
Retained earnings	368,138		430,642	$ 396,493
Income Statement [Abstract]
Total revenue	205,111	$ 225,756
Total cost of revenue	62,027	66,562
Sales and marketing	78,132	85,361
Income tax provision	(19,242)	(12,468)
Net loss	$ (62,504)	$ (24,222)
Basic net loss per share (in USD per share)	$ (0.78)	$ (0.27)
Diluted net loss per share (in USD per share)	$ (0.78)	$ (0.27)
Balance without Adoption of Topic 606
ASSETS:
Accounts receivable and unbilled costs	$ 161,554
Prepaid expenses and other current assets	28,472
Other assets	12,353
LIABILITIES:
Deferred revenue and customer deposits	268,230
Deferred tax liability	135,914
Long-term deferred revenue and customer deposits	88,416
STOCKHOLDERS' EQUITY:
Retained earnings	334,867
Income Statement [Abstract]
Total revenue	203,354
Total cost of revenue	62,027
Sales and marketing	77,524
Income tax provision	(19,513)
Net loss	$ (63,382)
Basic net loss per share (in USD per share)	$ (0.79)
Diluted net loss per share (in USD per share)	$ (0.79)
Accounting Standards Update 2014-09 | Effect of Change Higher (Lower)
ASSETS:
Accounts receivable and unbilled costs	$ 3,777		1,195
Prepaid expenses and other current assets	3,935		4,626
Other assets	6,683		4,748
LIABILITIES:
Deferred revenue and customer deposits	(20,065)		(30,227)
Deferred tax liability	7,628		7,899
Long-term deferred revenue and customer deposits	(7,925)		(1,252)
STOCKHOLDERS' EQUITY:
Retained earnings	33,271		$ 34,149
Income Statement [Abstract]
Total revenue	1,757
Total cost of revenue	0
Sales and marketing	608
Income tax provision	271
Net loss	$ 878
Basic net loss per share (in USD per share)	$ 0.01
Diluted net loss per share (in USD per share)	$ 0.01