Loans And Allowance For Loan Losses (Southwest's Loan Classifications) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 1,877,132	$ 1,779,429
Less: Allowance for loan losses	(27,546)	(26,106)
Total loans, net	1,849,586	1,753,323
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	556,248	507,173
Installment And Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	19,631	21,429
Commercial Real Estate [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	882,071	938,462
Commercial Real Estate [Member] | Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	199,113	129,070
One-To-Four Family Residential [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	199,123	161,958
One-To-Four Family Residential [Member] | Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable	$ 20,946	$ 21,337