Reconciliation of Denominator of Net Income Per Share Attributable to Quest Software Incorporation Stockholders - Additional Information (Detail) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Earnings Per Share
Shares used in computing basic net income per share	84,368		88,320		83,896		90,301
Dilutive effect of stock options and restricted stock units	2,401	[1]	2,043	[1]	2,091	[1]	2,441	[1]
Shares used in computing diluted net income per share	86,769		90,363		85,987		92,742

[1] Options to purchase 2.7 million and 4.8 million shares of common stock were outstanding during the three months ended June 30, 2012 and 2011, respectively, and 2.7 million and 2.8 million shares of common stock were outstanding for the six months ended June 30, 2012 and 2011, respectively, but were not included in the computation of diluted net income per share as inclusion would have been anti-dilutive.