Trust Preferred Securities and Subordinated Debentures (Schedule of Trust Preferred Securities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Oct. 14, 2003	Sep. 04, 2003	Jun. 26, 2003
Subordinated Borrowing [Line Items]
Subordinated debentures	$ 46,393	$ 51,548
Trust Preferred Securities of the Trusts	45,000	50,000
OKSB Statutory Trust I [Member]
Subordinated Borrowing [Line Items]
Subordinated debentures	20,619	20,619
Trust Preferred Securities of the Trusts	$ 20,000	$ 20,000			$ 20,000
Rates	4.10%	3.70%
Final Maturity Date	Jun. 26, 2033	Jun. 26, 2033
SBI Capital Trust II [Member]
Subordinated Borrowing [Line Items]
Subordinated debentures	$ 25,774	$ 25,774
Trust Preferred Securities of the Trusts	$ 25,000	$ 25,000	$ 25,000
Rates	3.73%	3.17%
Final Maturity Date	Oct. 07, 2033	Oct. 07, 2033
FCBI Statutory Trust I [Member]
Subordinated Borrowing [Line Items]
Subordinated debentures		$ 5,155
Trust Preferred Securities of the Trusts		$ 5,000		$ 5,000
Rates		3.33%
Final Maturity Date		Sep. 04, 2033