Summary of Significant Accounting Policies - Deferred Revenue (Details) $ in Millions	3 Months Ended
Mar. 31, 2020 USD ($)
Accounting Policies [Abstract]
Cash received in advance and not recognized as revenue	$ 91.5
Net additions from acquisition	5.7
Increase from netting of contract assets and liabilities on contract by contract basis	2.1
Increase in revenue recognized from current year invoices	74.8
Revenue recognized that was included in the contract liability balance	$ 17.7

Contract With Customer, Liability, Increase From Cash Receipts

No definition available.

Name:	qtwo_ContractWithCustomerLiabilityIncreaseFromCashReceipts
Namespace Prefix:	qtwo_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Contract With Customer, Liability, Increase From Current Year Invoices

+ References

No definition available.

+ Details

Name:	qtwo_ContractWithCustomerLiabilityIncreaseFromCurrentYearInvoices
Namespace Prefix:	qtwo_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Increase (Decrease) in Contract with Customer, Liability, Net Contract Assets and Contract Liabilities

+ References

No definition available.

+ Details

Name:	qtwo_IncreaseDecreaseinContractwithCustomerLiabilityNetContractAssetsandContractLiabilities
Namespace Prefix:	qtwo_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_AccountingPoliciesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of increase (decrease) in obligation to transfer good or service to customer for which consideration from customer has been received or is due, from business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130551-203045

+ Details

Name:	us-gaap_ContractWithCustomerLiabilityIncreaseDecreaseForContractAcquiredInBusinessCombination
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130549-203045

+ Details

Name:	us-gaap_ContractWithCustomerLiabilityRevenueRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration