Stock Based Employee Benefit Plans - Additional Information (Detail) (USD $)	12 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 21,229,000	$ 15,500,000	$ 17,305,000
Tax benefit related to share-based compensation expense	7,800,000	5,800,000	6,600,000
Unrecognized compensation cost related to non-vested share-based compensation arrangements	47,300,000
Unrecognized compensation cost, weighted average recognition period	3 years 4 days
Weighted average fair value of options granted	$ 12.32	$ 8.02	$ 7.58
Number of options that had exercise prices lower than the market price of common stock	3,800,000
Market price of common stock	$ 44.26
Total intrinsic value of options exercised	31,200,000	4,400,000	2,700,000
Weighted average fair value of restricted stock units and non-vested shares granted	$ 38.30
Cash received from stock option exercises and the issuance of stock under the Purchase Plan	70,800,000
Tax benefit realized for tax deductions from option exercises	12,400,000
Treasury stock, shares	54,018,000	51,773,000
Restricted stock units and non-vested shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of restricted stock units and non-vested shares granted	$ 37.80	$ 24.38	$ 22.05
Total intrinsic value of restricted stock units and non-vested shares vested	$ 15,500,000	$ 9,700,000	$ 7,700,000
2003 Employment Inducement Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares of common stock for grant under stock plan	2,250,000
2012 Long-Term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares of common stock for grant under stock plan	6,000,000
Shares available for grants under stock plan	4,242,714
Stock option awards maximum term	7 years
Stock option awards vesting period	4 years
2012 Long-Term Incentive Plan \| Awards Granted Prior to October 1, 2005
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option awards maximum term	10 years
Stock option awards vesting period	4 years
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares of common stock for grant under stock plan	5,062,500
Shares available for grants under stock plan	2,707,966
Employee stock purchase plans, percentage of salary withheld through payroll deductions to purchase FICO common stock	10.00%
Employee stock purchase plans, purchase price of the stock as a percentage of fair market value on the exercise date	85.00%
Employee stock purchase plans, offering period (in months)	6 months

Share Based Compensation Arrangement By Share Based Payment Award Employee Stock Purchase Plan Offering Term

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- Definition

Share Based Compensation Arrangement by Share Based Payment Award, Equity Instruments Other than Options, Grants in Period, Aggregate Intrinsic Value

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No definition available.

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- Definition

Share Based Compensation Arrangement by Share Based Payment Award, Options, Maximum Expiration Term

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- Definition

Share based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, with Exercise Prices Lower than Market Price

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No definition available.

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- Definition

As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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- Definition

The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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- Definition

The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The discount rate from market value on purchase date that participants pay for shares.

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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- Definition

The highest percentage of annual salary that an employee is permitted to utilize with respect to the plan.

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- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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- Definition

Price of a single share of a number of saleable stocks of a company.

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- Definition

Tax benefits realized from the exercise of stock options resulting in reductions in the entity's income taxes, which increases net cash provided by operating activities.

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Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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