Note 12. Stockholders' Equity (Detail) (USD $)	1 Months Ended	3 Months Ended
	Dec. 31, 2011	Nov. 30, 2012		Nov. 30, 2011	Aug. 31, 2012
Preferred Stock, Shares Authorized		10,000,000			10,000,000
Preferred Stock, Par or Stated Value Per Share (in Dollars per share)		$ 0.01			$ 0.01
Common Stock, Par or Stated Value Per Share (in Dollars per share)		$ 0.01			$ 0.01
Common Stock, Shares Authorized	100,000,000	150,000,000			150,000,000
Treasury Stock, Shares, Retired	16,658,741
Treasury Stock, Value (in Dollars)	$ 850,900,000	$ 150,990,000			$ 122,749,000
Stock Repurchased During Period, Shares		270,000		150,000
Stock Repurchased During Period, Value (in Dollars)		25,400,000		14,600,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount (in Dollars)		164,300,000		128,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		92,715	[1]
Common Stock [Member]
Treasury Stock, Retired, Cost Method, Amount (in Dollars)	200,000
Additional Paid-in Capital [Member]
Treasury Stock, Retired, Cost Method, Amount (in Dollars)	361,400,000
Retained Earnings [Member]
Treasury Stock, Retired, Cost Method, Amount (in Dollars)	$ 489,300,000
Shares Repurchased to Cover Cost of Taxes [Member]
Stock Repurchased During Period, Shares		29,604

[1] Of the total 92,715 restricted stock awards that vested during the first quarter of fiscal 2013, 87,758 related to awards granted on October 23, 2009 at the grant date price of $66.46. These restricted stock awards cliff vest 60% after three years (on October 23, 2012) and the remaining 40% after five years (October 23, 2014). The awards are amortized to expense over the vesting period using the straight-line attribution method. As of November 30, 2012, unamortized stock-based compensation expense of $3.2 million is to be amortized to compensation expense over the remaining vesting period of 1.9 years. The remaining 4,957 restricted stock awards that vested during the first quarter of fiscal 2013 were previously granted between June 2010 and July 2011. These restricted stock units were performance-based and cliff vest 25% when certain ASV targets are met. Of the total units originally granted, 14,258 units vested during the fourth quarter of fiscal 2012 and the remaining 4,957 vested during the first quarter of fiscal 2013 because FactSet achieved all four ASV growth targets. As of November 30, 2012, there is no remaining unamortized stock-based compensation expense as all units vested.