Short-Term Borrowings - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Oct. 31, 2012
Short-term Debt [Line Items]
Termination date for senior, unsecured revolving credit facility	Apr. 27, 2015
Minimum
Short-term Debt [Line Items]
Commitment fee on unused revolving credit facility	0.40%
Maximum
Short-term Debt [Line Items]
Commitment fee on unused revolving credit facility	0.50%
Covenant Requirement
Short-term Debt [Line Items]
Credit facility limits, aggregate amount available for dividend and repurchase of stock	50,000
Credit facility limits, aggregate amount available for dividend and repurchase of stock, percentage of cumulative net income	70.00%
Line of Credit Facility, Dividend Restrictions	The revolving credit facility limits the aggregate amount we can pay for dividends and repurchases of our stock over the four year term of the facility to $50,000 plus 70% of our cumulative net income.
Line of Credit
Short-term Debt [Line Items]
Term of Revolving Credit Facility	4 years
Revolving credit facility, maximum borrowing capacity	125,000
Percentage of net current account receivable included in cash and account receivable ratio	42.00%
Line of Credit Facility, Interest Rate Description	We have the option to pay interest based on: (i) London Interbank Offered Rate (LIBOR) with varying maturities commensurate with the borrowing period we select, plus a spread of between 2.25% and 3.25% based on a pricing grid tied to a financial covenant, or (ii) A base rate plus a spread of between 1.25% and 2.25%, based on a pricing grid tied to a financial covenant.
Line of Credit Facility, Covenant Terms	This revolving credit facility contains certain financial and other covenants, including the following: • Our adjusted quick ratio (ratio of the sum of cash and cash equivalents, short-term investments, and net current receivables to total current liabilities) shall not be less than1.00; • Our tangible net worth (stockholders’ equity less goodwill and other intangible assets) must exceed the calculated required tangible net worth as defined in the credit agreement; • Our leverage ratio (ratio of total liabilities less subordinated debt to the sum of subordinated debt and tangible net worth) shall be less than 2.00; • Our senior leverage ratio (ratio of total debt less subordinated debt to the sum of subordinated debt and tangible net worth) shall not be greater than 0.90; and • Our minimum cash and accounts receivable ratio (ratio of the sum of cash and cash equivalents, short-term investments, and 42.0% of net current accounts receivable, to outstanding credit agreement borrowings) shall not be less than 1.25.
Line of Credit | Federal Funds Rate
Short-term Debt [Line Items]
Debt instrument, basis spread on variable rate	0.50%
Line of Credit | One Month LIBOR
Short-term Debt [Line Items]
Debt instrument, basis spread on variable rate	1.00%
Line of Credit | Minimum
Short-term Debt [Line Items]
Adjusted quick ratio, lower limit	1.00
Cash and accounts receivable ratio, lower limit	1.25
Line of Credit | Minimum | LIBOR
Short-term Debt [Line Items]
Debt instrument, basis spread on variable rate	2.25%
Line of Credit | Minimum | Base Rate
Short-term Debt [Line Items]
Debt instrument, basis spread on variable rate	1.25%
Line of Credit | Maximum
Short-term Debt [Line Items]
Leverage ratio, upper limit	2.00
Senior leverage ratio, upper limit	0.90
Line of Credit | Maximum | LIBOR
Short-term Debt [Line Items]
Debt instrument, basis spread on variable rate	3.25%
Line of Credit | Maximum | Base Rate
Short-term Debt [Line Items]
Debt instrument, basis spread on variable rate	2.25%