Subordinated Debentures (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 shares	Nov. 01, 2016 USD ($)
Subordinated Borrowing [Line Items]
Number of Unconsolidated Statutory Business Trusts	13
Investments trust preferred securities	$ 2,900
Subordinated debentures and notes	$ 203,637	$ 141,258
Conversion of subordinated debt into common stock (in shares) | shares	0	0	0
5.75%
Subordinated Borrowing [Line Items]
Fixed interest rate	5.75%
Senior Subordinated Notes [Member]
Subordinated Borrowing [Line Items]
Senior Subordinated Notes				$ 50,000
Subordinated Notes, Redemption Price	100.00%
Trust preferred securities [Member]
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 92,290	$ 92,132
Trust preferred securities [Member] | EFSC Clayco Statutory Trust I
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 3,196	3,196
Maturity Date	Dec. 17, 2033
Initial Call Date (1)	Dec. 17, 2008
Description of variable rate	3 Month LIBOR
Floating interest rate	0.0285
Trust preferred securities [Member] | EFSC Capital Trust II
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 5,155	5,155
Maturity Date	Jun. 17, 2034
Initial Call Date (1)	Jun. 17, 2009
Description of variable rate	3 Month LIBOR
Floating interest rate	0.0265
Trust preferred securities [Member] | EFSC Statutory Trust III
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 11,341	11,341
Maturity Date	Dec. 15, 2034
Initial Call Date (1)	Dec. 15, 2009
Description of variable rate	3 Month LIBOR
Floating interest rate	0.0197
Trust preferred securities [Member] | EFSC Clayco Statutory Trust II
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 4,124	4,124
Maturity Date	Sep. 15, 2035
Initial Call Date (1)	Sep. 15, 2010
Description of variable rate	3 Month LIBOR
Floating interest rate	0.0183
Trust preferred securities [Member] | EFSC Statutory Trust IV
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 10,310	10,310
Maturity Date	Dec. 15, 2035
Initial Call Date (1)	Dec. 15, 2010
Description of variable rate	3 Month LIBOR
Floating interest rate	0.0144
Trust preferred securities [Member] | EFSC Statutory Trust V
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 4,124	4,124
Maturity Date	Sep. 15, 2036
Initial Call Date (1)	Sep. 15, 2011
Description of variable rate	3 Month LIBOR
Floating interest rate	0.0160
Trust preferred securities [Member] | EFSC Capital Trust VI
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 14,433	14,433
Maturity Date	Mar. 30, 2037
Initial Call Date (1)	Mar. 30, 2012
Description of variable rate	3 Month LIBOR
Floating interest rate	0.0160
Trust preferred securities [Member] | EFSC Capital Trust VII
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 4,124	4,124
Maturity Date	Dec. 15, 2037
Initial Call Date (1)	Dec. 15, 2012
Description of variable rate	3 Month LIBOR
Floating interest rate	0.0225
Trust preferred securities [Member] | JEFFCO Stat Trust I [Member]
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 7,752	7,886
Maturity Date	Feb. 22, 2031
Initial Call Date (1)	Feb. 22, 2011
Fixed interest rate	10.20%
Trust preferred securities [Member] | EFSC Capital Trust VIII
Subordinated Borrowing [Line Items]
Fixed interest rate	9.00%
Trust preferred securities [Member] | JEFFCO Stat Trust II [Member]
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 4,443	4,388
Maturity Date	Mar. 17, 2034
Initial Call Date (1)	Mar. 17, 2009
Description of variable rate	3 Month LIBOR
Fixed interest rate	2.75%
Trust preferred securities [Member] | Trinity Capital Trust III [Member]
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 5,272	5,206
Maturity Date	Sep. 08, 2034
Initial Call Date (1)	Sep. 08, 2009
Description of variable rate	3 Month LIBOR
Fixed interest rate	2.70%
Trust preferred securities [Member] | Trinity Capital Trust IV [Member]
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 10,310	10,302
Maturity Date	Nov. 23, 2035
Initial Call Date (1)	Aug. 23, 2010
Fixed interest rate	6.88%
Trust preferred securities [Member] | Trinity Capital Trust V [Member]
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 7,706	7,543
Maturity Date	Dec. 15, 2036
Initial Call Date (1)	Sep. 15, 2011
Description of variable rate	3 Month LIBOR
Fixed interest rate	1.65%
Senior Subordinated Notes [Member]
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 50,000	50,000
Debt issuance costs	(1,903)	(874)
Subordinated notes, net of issuance costs	$ 111,347	49,126
Maturity Date	Nov. 01, 2026
Initial Call Date (1)	Nov. 01, 2021
Floating interest rate	0.03387
Fixed interest rate	4.75%
Senior Subordinated Notes [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Subordinated Borrowing [Line Items]
Floating interest rate	0.0566
Senior Subordinated Notes [Member] | 5.75%
Subordinated Borrowing [Line Items]
Subordinated debentures and notes	$ 63,250	$ 0
Maturity Date	Jun. 01, 2030
Initial Call Date (1)	Jun. 01, 2025