Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended	6 Months Ended
		Jul. 31, 2015	Jul. 31, 2015		Jul. 31, 2014
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			$ 98,854		$ 103,702
Other comprehensive (loss) / income before reclassifications			(13,351)		(546)
Amounts reclassified from accumulated other comprehensive (loss) / income		$ 100	41	[1]	(81)
Net current-period other comprehensive (loss) / income			(13,310)		(627)
Ending Balance		85,544	85,544		103,075
Currency Translation Adjustments
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			98,642		103,438
Other comprehensive (loss) / income before reclassifications			(13,321)		(615)
Net current-period other comprehensive (loss) / income			(13,321)		(615)
Ending Balance		85,321	85,321		102,823
Available-for-sale securities
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			211		263
Other comprehensive (loss) / income before reclassifications			15		69
Amounts reclassified from accumulated other comprehensive (loss) / income					(81)
Net current-period other comprehensive (loss) / income			15		(12)
Ending Balance		226	226		251
Net Unrealized Income (Loss) On Hedging Contracts
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance			1		1
Other comprehensive (loss) / income before reclassifications			(45)
Amounts reclassified from accumulated other comprehensive (loss) / income	[1]		41
Net current-period other comprehensive (loss) / income			(4)
Ending Balance		$ (3)	$ (3)		$ 1

[1] Amounts reclassified to earnings in the Consolidated Statements of Operations.