Cash and Cash Equivalents and Investments - Additional Information (Detail)	6 Months Ended
Jun. 30, 2012
Cash And Cash Equivalents And Investments
Short-term available-for-sale investments, average remaining maturity period	5 months
Long-term available-for-sale investments, average remaining maturity period	23 months

Short-Term Available-For-Sale Investments, Average Remaining Maturity Period

No definition available.

Name:	qsft_ShortTermAvailableForSaleInvestmentsAverageRemainingMaturityPeriod
Namespace Prefix:	qsft_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration