Short-Term Borrowings - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	1 Months Ended	9 Months Ended
	Apr. 30, 2011	Oct. 31, 2011
Short-term Debt [Line Items]
Termination date for senior, unsecured revolving credit facility	2015-04-27
Revolving credit facility, maximum borrowing capacity	125,000	125,000
Covenant Requirement
Short-term Debt [Line Items]
Revolving credit facility terms of covenants		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.
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%
Minimum
Short-term Debt [Line Items]
Commitment fee on unused revolving credit facility	0.40%	0.40%
Maximum
Short-term Debt [Line Items]
Commitment fee on unused revolving credit facility	0.50%	0.50%
Line of Credit
Short-term Debt [Line Items]
Description of interest payment option		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.
Revolving credit facility financial and other covenants		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 than 1.00; • 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, which establishes a fixed level of required tangible net worth. Each quarter the required level increases by 70% of any positive net income in the quarter (but in the aggregate no more than 70% of positive net income for any full fiscal year), 100% of the amortization of intangible assets in the quarter, and100% of certain stock issuance proceeds. The required level also decreases each quarter by 50% of amounts paid for dividends or repurchases of our stock and certain amounts of acquired intangible assets; • 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.
Percentage of tangible net worth increase of any positive net income required by credit agreement, for each quarter		70.00%
Percentage of amortization of intangible assets required by credit agreement, for each quarter		100.00%
Percentage of stock issuance proceeds required by credit agreement		100.00%
Percentage of payment decrease for dividends repurchases of stock and acquired intangible assets required by credit agreement		50.00%
Percentage of net current account receivable ratio included in cash and account receivable ratio		42.00%
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
Percentage of tangible net worth increase of any positive net income required by credit agreement, for any full fiscal year		70.00%
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%