Shareholders' Equity | Components of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss) balance	$ 3,052	$ 200,040	$ 43,786	$ 288,292
Other comprehensive income (loss), before reclassification	(31,102)	(96,982)	(72,200)	(185,234)
Reclassification of (gain) loss form AOCI into income	(451)	(5,073)	(87)	(5,073)
Accumulated other comprehensive income (loss) balance	(28,501)	97,985	(28,501)	97,985
Foreign currency translation adjustment, net of taxes
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss) balance	3,263	200,040	43,786	288,292
Other comprehensive income (loss), before reclassification	(31,822)	(96,982)	(72,345)	(185,234)
Reclassification of (gain) loss form AOCI into income	0	(5,073)	0	(5,073)
Accumulated other comprehensive income (loss) balance	(28,559)	97,985	(28,559)	97,985
Unrealized gains (losses) on cash flow hedges, net of taxes
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss) balance	(211)	0	0	0
Other comprehensive income (loss), before reclassification	720	0	145	0
Reclassification of (gain) loss form AOCI into income	(451)	0	(87)	0
Accumulated other comprehensive income (loss) balance	$ 58	$ 0	$ 58	$ 0