Subordinated Debentures (Details) (USD $)	0 Months Ended		12 Months Ended
	Mar. 14, 2014	Aug. 15, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Subordinated Borrowing [Line Items]
Subordinated debentures			$ 56,807,000	$ 62,581,000
Subordinated debentures held by trusts			1,700,000
Conversion of subordinated debt into common stock (in shares)	287,852	1,200,000	287,852	1,176,470	0
Additional stock issued as an inducement (in shares)		25,060
Expense related to inducement				400,000
EFSC Capital Trust VIII
Subordinated Borrowing [Line Items]
Trust preferred subordinated debentures	5,000,000	20,000,000
Conversion price (usd per share)	17.37
Trust preferred securities [Member] | EFSC Clayco Statutory Trust I
Subordinated Borrowing [Line Items]
Subordinated debentures			3,196,000	3,196,000
Maturity Date			Dec. 17, 2033
Call Date			Dec. 17, 2008
Description of variable rate			3 Month LIBOR
Floating interest rate			2.85%
Trust preferred securities [Member] | EFSC Capital Trust II
Subordinated Borrowing [Line Items]
Subordinated debentures			5,155,000	5,155,000
Maturity Date			Jun. 17, 2034
Call Date			Jun. 17, 2009
Description of variable rate			3 Month LIBOR
Floating interest rate			2.65%
Trust preferred securities [Member] | EFSC Statutory Trust III
Subordinated Borrowing [Line Items]
Subordinated debentures			11,341,000	11,341,000
Maturity Date			Dec. 15, 2034
Call Date			Dec. 15, 2009
Description of variable rate			3 Month LIBOR
Floating interest rate			1.97%
Trust preferred securities [Member] | EFSC Clayco Statutory Trust II
Subordinated Borrowing [Line Items]
Subordinated debentures			4,124,000	4,124,000
Maturity Date			Sep. 15, 2035
Call Date			Sep. 15, 2010
Description of variable rate			3 Month LIBOR
Floating interest rate			1.83%
Trust preferred securities [Member] | EFSC Statutory Trust IV
Subordinated Borrowing [Line Items]
Subordinated debentures			10,310,000	10,310,000
Maturity Date			Dec. 15, 2035
Call Date			Dec. 15, 2010
Description of variable rate			3 Month LIBOR
Floating interest rate			1.44%
Trust preferred securities [Member] | EFSC Statutory Trust V
Subordinated Borrowing [Line Items]
Subordinated debentures			4,124,000	4,124,000
Maturity Date			Sep. 15, 2036
Call Date			Sep. 15, 2011
Description of variable rate			3 Month LIBOR
Floating interest rate			1.60%
Trust preferred securities [Member] | EFSC Capital Trust VI
Subordinated Borrowing [Line Items]
Subordinated debentures			14,433,000	14,433,000
Maturity Date			Mar. 30, 2037
Call Date			Mar. 30, 2012
Description of variable rate			3 Month LIBOR
Floating interest rate			1.60%
Trust preferred securities [Member] | EFSC Capital Trust VII
Subordinated Borrowing [Line Items]
Subordinated debentures			4,124,000	4,124,000
Maturity Date			Dec. 15, 2037
Call Date			Dec. 15, 2012
Description of variable rate			3 Month LIBOR
Floating interest rate			2.25%
Trust preferred securities [Member] | EFSC Capital Trust VIII
Subordinated Borrowing [Line Items]
Subordinated debentures			$ 0	$ 5,774,000
Maturity Date			Dec. 15, 2038
Call Date			Dec. 15, 2013
Fixed interest rate			9.00%