Income Taxes - Reconciliation of Statutory Federal Income Tax to Effective Tax (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Income Tax Disclosure [Abstract]
Federal tax statutory tax rate									$ 13,475	$ 10,182	$ 2,263
State taxes									904	880	218
Nondeductible expenses									55	80	96
Research and development credit									(880)	(351)	(121)
Domestic manufacturing deduction									(1,124)	(699)	(131)
Stock-based compensation									1,802	231
Foreign rate differential									(164)	(50)	118
Valuation allowance									512	(52)
Others									305	89	(20)
Provision for income taxes	$ 4,696	$ 3,585	$ 3,775	$ 2,829	$ 3,075	$ 3,109	$ 2,454	$ 1,672	$ 14,885	$ 10,310	$ 2,423