Summary of Employee Stock Options Activity (Detail) (Employee Stock Option, USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2012
Employee Stock Option
Number Of Shares
Outstanding at December 31, 2011	15,779,000
Granted	133,000
Exercised	(1,418,000)
Canceled/forfeited/expired	(578,000)
Outstanding at June 30, 2012	13,916,000
Vested or expected to vest at June 30, 2012	12,939,000	[1]
Exercisable at June 30, 2012	5,680,000
Weighted-Average Exercise Price (per share)
Outstanding at December 31, 2011	$ 17.26
Granted	$ 19.36
Exercised	$ 16.79
Canceled/forfeited/expired	$ 18.39
Outstanding at June 30, 2012	$ 17.27
Vested or expected to vest at June 30, 2012	$ 17.23	[1]
Exercisable at June 30, 2012	$ 15.41
Weighted-Average Remaining Contractual Term (in years)
Outstanding at June 30, 2012	7 years 15 days
Vested or expected to vest at June 30, 2012	6 years 10 months 28 days	[1]
Exercisable at June 30, 2012	4 years 10 months 21 days
Aggregate Intrinsic Value
Outstanding at June 30, 2012	$ 146,675	[2]
Vested or expected to vest at June 30, 2012	136,847	[1],[2]
Exercisable at June 30, 2012	$ 70,426	[2]

[1] Contractual vesting may be altered by the ultimate terms and conditions associated with the completion of the pending merger transaction with Dell. (See Note 1).

[2] These amounts represent the difference between the exercise price and $27.81, the closing price of Quest Software, Inc. stock on June 30, 2012 as reported on the NASDAQ National Market, for all options outstanding that have an exercise price currently below the closing price.