Subordinated Debentures (Schedule of Trust Preferred Securities) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Subordinated Borrowing [Line Items]
Subordinated debentures	$ 46,393	$ 81,963
Trust Preferred Securities of the Trusts	45,000	79,500
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
Rates	3.35%	3.41%
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
Rates	3.09%	3.19%
Final Maturity Date	Oct. 07, 2033	Oct. 07, 2033
Southwest Capital Trust II [Member]
Subordinated Borrowing [Line Items]
Subordinated debentures		35,570
Trust Preferred Securities of the Trusts	$ 34,500	$ 34,500
Rates		10.50%
Final Maturity Date		Sep. 15, 2038