Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Oct. 31, 2017	Jul. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016
Income Taxes Disclosure [Line Items]
Income tax provision (benefit)	$ 1,154		$ (420)	$ 1,458	$ 14,415
Tax expense attributable to shift in jurisdictions where income is earned				1,800
Irish Operations [Member]
Income Taxes Disclosure [Line Items]
Charge to deferred tax liability related to the foreign income		$ 14,700
Reversal of tax reserves for uncertain tax positions due to the expiration of statute of limitations				$ 600