Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2014	Jan. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 0	$ 3,990
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments		3,990
Contingent consideration	3,177	4,571
Assets And Liabilities Net Fair Value Disclosure		(581)
Level 1 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments		0
Contingent consideration	0	0
Assets And Liabilities Net Fair Value Disclosure		0
Level 2 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments		3,990
Contingent consideration	0	0
Assets And Liabilities Net Fair Value Disclosure		3,990
Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments		0
Contingent consideration	3,177	4,571
Assets And Liabilities Net Fair Value Disclosure		$ (4,571)