Regulatory Matters (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Enterprise Financial Services Corp [Member]
Total Capital (to Risk Weighted Assets) [Abstract]
Actual, Amount	$ 418,367	$ 369,868
Actual, Ratio	11.85%	13.40%
For Capital Adequacy Purposes, Amount	$ 282,442	$ 220,858
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	$ 374,676	$ 335,221
Actual, Ratio	10.61%	12.14%
For Capital Adequacy Purposes, Amount	$ 211,831	$ 110,429
For Capital Adequacy Purposes, Ratio	6.00%	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 One Common Equity Capital	$ 319,553
Tier One Common Equity Capital to Risk Weighted Assets	9.05%
Tier One Common Equity Capital Required for Capital Adequacy	$ 158,873
Tier One Common Equity Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%
Tier One Common Equity Capital Required to be Well Capitalized	$ 0
Tier One Common Equity Capital Required to be Well Capitalized to Risk Weighted Assets	0.00%
Tier 1 Capital (to Average Assets) [Abstract]
Actual, Amount	$ 374,676	$ 335,221
Actual, Ratio	10.71%	10.48%
For Capital Adequacy Purposes, Amount	$ 139,893	$ 96,000
For Capital Adequacy Purposes, Ratio	4.00%	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	$ 386,531	$ 343,334
Actual, Ratio	10.98%	12.51%
For Capital Adequacy Purposes, Amount	$ 281,632	$ 219,645
For Capital Adequacy Purposes, Ratio	8.00%	8.00%
To Be Well Capitalized Under Applicable Action Provisions, Amount	$ 352,040	$ 274,556
To Be Well Capitalized Under Applicable Action Provisions, Ratio	10.00%	10.00%
Tier 1 Capital (to Risk Weighted Assets) [Abstract]
Actual, Amount	$ 342,840	$ 308,874
Actual, Ratio	9.74%	11.25%
For Capital Adequacy Purposes, Amount	$ 211,224	$ 109,823
For Capital Adequacy Purposes, Ratio	6.00%	4.00%
To Be Well Capitalized Under Applicable Action Provisions, Amount	$ 281,632	$ 164,734
To Be Well Capitalized Under Applicable Action Provisions, Ratio	8.00%	6.00%
Tier One Common Equity Capital	$ 342,816
Tier One Common Equity Capital to Risk Weighted Assets	9.74%
Tier One Common Equity Capital Required for Capital Adequacy	$ 158,418
Tier One Common Equity Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%
Tier One Common Equity Capital Required to be Well Capitalized	$ 228,826
Tier One Common Equity Capital Required to be Well Capitalized to Risk Weighted Assets	6.50%
Tier 1 Capital (to Average Assets) [Abstract]
Actual, Amount	$ 342,840	$ 308,874
Actual, Ratio	9.84%	9.71%
For Capital Adequacy Purposes, Amount	$ 139,311	$ 95,411
For Capital Adequacy Purposes, Ratio	4.00%	3.00%
To Be Well Capitalized Under Applicable Action Provisions, Amount	$ 174,138	$ 159,018
To Be Well Capitalized Under Applicable Action Provisions, Ratio	5.00%	5.00%