Document and Entity Information Document (USD $)	12 Months Ended
	Dec. 31, 2012	Mar. 01, 2013	Jun. 30, 2012
Entity Information [Line Items]
Entity Registrant Name	ENTERPRISE FINANCIAL SERVICES CORP
Entity Central Index Key	0001025835
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q4
Amendment Flag	false
Entity Common Stock, Shares Outstanding		18,038,212
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 182,393,876