Changes in Accumulated Other Comprehensive Loss by Component, Net of Tax (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	$ 1,361,404	$ 1,443,672	$ 1,489,098	$ 1,300,903
Other comprehensive income (loss) before reclassifications	7,590	(5,489)	(2,620)	(21,426)
Amounts reclassified from accumulated other comprehensive income (loss)	6	(3)	32	(16)
Total other comprehensive income (loss)	7,596	(5,492)	(2,588)	(21,442)
Ending Balance	1,429,853	1,460,609	1,429,853	1,460,609
Foreign Currency Translation
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(37,496)	(26,190)	(26,925)	(10,340)
Other comprehensive income (loss) before reclassifications	7,420	(5,358)	(3,151)	(21,208)
Total other comprehensive income (loss)	7,420	(5,358)	(3,151)	(21,208)
Ending Balance	(30,076)	(31,548)	(30,076)	(31,548)
Unrealized Gains and (Losses) on available- for-Sale Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	209	(411)	(178)	(311)
Other comprehensive income (loss) before reclassifications	170	(131)	531	(218)
Amounts reclassified from accumulated other comprehensive income (loss)	6	(3)	32	(16)
Total other comprehensive income (loss)	176	(134)	563	(234)
Ending Balance	385	(545)	385	(545)
Accumulated Other Comprehensive Loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning Balance	(37,287)	(26,601)	(27,103)	(10,651)
Ending Balance	$ (29,691)	$ (32,093)	$ (29,691)	$ (32,093)

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

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