REVENUE RECOGNITION REVENUE RECOGNITION - ASU NO. 2014-09 ADOPTION BALANCE SHEET (Details) - USD ($) $ in Thousands	Oct. 31, 2018	Feb. 01, 2018	Jan. 31, 2018	Oct. 31, 2017	Jan. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable, net	$ 311,492	$ 350,006	$ 296,324
Contract assets	70,076	69,217	0
Deferred cost of revenue	9,651	8,152	6,096
Prepaid expenses and other current assets	85,310	81,261	82,090
Long-term deferred cost of revenue	4,283	4,997	2,804
Deferred income taxes		28,630
Other assets	101,643	66,949	82,915
Accrued expenses and other current liabilities	181,452	174,203	224,765
Contract liabilities	306,240	335,624	196,107
Long-term contract liabilities	27,512	31,037	24,519
Deferred income taxes		36,268
Total stockholders' equity	1,213,499	1,170,383	1,132,336	$ 1,073,367	$ 1,015,040
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounts receivable, net	44,995	53,682
Contract assets	70,076	69,217
Deferred cost of revenue	(1,519)	2,056
Prepaid expenses and other current assets	(1,152)	(829)
Long-term deferred cost of revenue	3,069	2,193
Deferred income taxes		(2,248)
Other assets	22,313	14,912
Accrued expenses and other current liabilities	(35,185)	(46,062)
Contract liabilities	99,041	139,517
Long-term contract liabilities	812	6,518
Deferred income taxes		963
Total stockholders' equity	$ 72,192	$ 38,047
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred income taxes			30,878
Other assets			52,037
Accrued expenses and other current liabilities			220,265
Deferred income taxes			35,305
Total stockholders' equity			$ 1,132,336