Changes in Accumulated Other Comprehensive Loss by Component, Net of Tax (Detail) - USD ($) $ in Thousands	12 Months Ended
Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	$ 1,300,903	$ 1,313,084	$ 1,137,227
Other comprehensive income (loss) before reclassifications	(16,430)	23,453
Amounts reclassified from accumulated other comprehensive income (loss)	(22)	(35)
Total other comprehensive (loss) income	(16,452)	23,418	(10,618)
Ending Balance	1,489,098	1,300,903	1,313,084
Foreign Currency Translation
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(10,340)	(34,012)
Other comprehensive income (loss) before reclassifications	(16,585)	23,672
Total other comprehensive (loss) income	(16,585)	23,672
Ending Balance	(26,925)	(10,340)	(34,012)
Unrealized Gains and (Losses) on available- for-Sale Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(311)	(57)
Other comprehensive income (loss) before reclassifications	155	(219)
Amounts reclassified from accumulated other comprehensive income (loss)	(22)	(35)
Total other comprehensive (loss) income	133	(254)
Ending Balance	(178)	(311)	(57)
Accumulated Other Comprehensive Loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(10,651)	(34,069)	(23,451)
Ending Balance	$ (27,103)	$ (10,651)	$ (34,069)

Amount after tax, before reclassification adjustments, of other comprehensive income (loss), attributable to parent.

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