Regulatory Matters (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Enterprise Financial Services Corp [Member]
Total Capital (to Risk Weighted Assets) [Abstract]
Actual, Amount	$ 369,868	$ 339,433
Actual, Ratio	13.40%	13.78%
For Capital Adequacy Purposes, Amount	220,858	197,088
For Capital Adequacy Purposes, Ratio	8.00%	8.00%
To Be Well Capitalized Under Applicable Action Provisions, Amount	0	0
To Be Well Capitalized Under Applicable Action Provisions, Ratio	0.00%	0.00%
Tier 1 Capital (to Risk Weighted Assets) [Abstract]
Actual, Amount	335,221	308,490
Actual, Ratio	12.14%	12.52%
For Capital Adequacy Purposes, Amount	110,429	98,544
For Capital Adequacy Purposes, Ratio	4.00%	4.00%
To Be Well Capitalized Under Applicable Action Provisions, Amount	0	0
To Be Well Capitalized Under Applicable Action Provisions, Ratio	0.00%	0.00%
Tier 1 Capital (to Average Assets) [Abstract]
Actual, Amount	335,221	308,490
Actual, Ratio	10.48%	9.94%
For Capital Adequacy Purposes, Amount	96,000	93,121
For Capital Adequacy Purposes, Ratio	3.00%	3.00%
To Be Well Capitalized Under Applicable Action Provisions, Amount	0	0
To Be Well Capitalized Under Applicable Action Provisions, Ratio	0.00%	0.00%
Enterprise Bank and Trust [Member]
Total Capital (to Risk Weighted Assets) [Abstract]
Actual, Amount	343,334	318,149
Actual, Ratio	12.51%	13.00%
For Capital Adequacy Purposes, Amount	219,645	195,802
For Capital Adequacy Purposes, Ratio	8.00%	8.00%
To Be Well Capitalized Under Applicable Action Provisions, Amount	274,556	244,752
To Be Well Capitalized Under Applicable Action Provisions, Ratio	10.00%	10.00%
Tier 1 Capital (to Risk Weighted Assets) [Abstract]
Actual, Amount	308,874	287,405
Actual, Ratio	11.25%	11.74%
For Capital Adequacy Purposes, Amount	109,823	97,901
For Capital Adequacy Purposes, Ratio	4.00%	4.00%
To Be Well Capitalized Under Applicable Action Provisions, Amount	164,734	146,851
To Be Well Capitalized Under Applicable Action Provisions, Ratio	6.00%	6.00%
Tier 1 Capital (to Average Assets) [Abstract]
Actual, Amount	308,874	287,405
Actual, Ratio	9.71%	9.31%
For Capital Adequacy Purposes, Amount	95,411	92,587
For Capital Adequacy Purposes, Ratio	3.00%	3.00%
To Be Well Capitalized Under Applicable Action Provisions, Amount	$ 159,018	$ 154,312
To Be Well Capitalized Under Applicable Action Provisions, Ratio	5.00%	5.00%