Loans and Allowance for Loan Losses - Loans Restructured as TDRs, Excluding Loans Acquired, Segregated by Class of Loans (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 loan	Jun. 30, 2017 USD ($) loan	Jun. 30, 2018 USD ($) loan	Jun. 30, 2017 USD ($) loan
Financing Receivable, Modifications [Line Items]
Number of Loans | loan	0	4	2	12
Balance Prior to TDR		$ 41	$ 152	$ 8,629
Balance		39	153	8,617
Financial Impact on Date of Restructure		0	0	33
Change in Maturity Date
Financing Receivable, Modifications [Line Items]
Balance		0	153	8,578
Change in Rate
Financing Receivable, Modifications [Line Items]
Balance		$ 39	$ 0	$ 39
Consumer
Financing Receivable, Modifications [Line Items]
Number of Loans | loan			1
Balance Prior to TDR			$ 91
Balance			91
Financial Impact on Date of Restructure			0
Consumer | Change in Maturity Date
Financing Receivable, Modifications [Line Items]
Balance			91
Consumer | Change in Rate
Financing Receivable, Modifications [Line Items]
Balance			$ 0
Consumer | Other consumer
Financing Receivable, Modifications [Line Items]
Number of Loans | loan			1
Balance Prior to TDR			$ 91
Balance			91
Financial Impact on Date of Restructure			0
Consumer | Other consumer | Change in Maturity Date
Financing Receivable, Modifications [Line Items]
Balance			91
Consumer | Other consumer | Change in Rate
Financing Receivable, Modifications [Line Items]
Balance			$ 0
Real estate
Financing Receivable, Modifications [Line Items]
Number of Loans | loan			1	3
Balance Prior to TDR			$ 61	$ 7,818
Balance			62	7,818
Financial Impact on Date of Restructure			0	33
Real estate | Change in Maturity Date
Financing Receivable, Modifications [Line Items]
Balance			62	7,818
Real estate | Change in Rate
Financing Receivable, Modifications [Line Items]
Balance			$ 0	$ 0
Real estate | Single family residential
Financing Receivable, Modifications [Line Items]
Number of Loans | loan			1
Balance Prior to TDR			$ 61
Balance			62
Financial Impact on Date of Restructure			0
Real estate | Single family residential | Change in Maturity Date
Financing Receivable, Modifications [Line Items]
Balance			62
Real estate | Single family residential | Change in Rate
Financing Receivable, Modifications [Line Items]
Balance			$ 0
Real estate | Construction
Financing Receivable, Modifications [Line Items]
Number of Loans | loan				1
Balance Prior to TDR				$ 456
Balance				456
Financial Impact on Date of Restructure				0
Real estate | Construction | Change in Maturity Date
Financing Receivable, Modifications [Line Items]
Balance				456
Real estate | Construction | Change in Rate
Financing Receivable, Modifications [Line Items]
Balance				$ 0
Real estate | Other commercial
Financing Receivable, Modifications [Line Items]
Number of Loans | loan				2
Balance Prior to TDR				$ 7,362
Balance				7,362
Financial Impact on Date of Restructure				33
Real estate | Other commercial | Change in Maturity Date
Financing Receivable, Modifications [Line Items]
Balance				7,362
Real estate | Other commercial | Change in Rate
Financing Receivable, Modifications [Line Items]
Balance				$ 0
Commercial
Financing Receivable, Modifications [Line Items]
Number of Loans | loan		4		9
Balance Prior to TDR		$ 41		$ 811
Balance		39		799
Financial Impact on Date of Restructure		0		0
Commercial | Change in Maturity Date
Financing Receivable, Modifications [Line Items]
Balance		0		760
Commercial | Change in Rate
Financing Receivable, Modifications [Line Items]
Balance		$ 39		$ 39
Commercial | Commercial
Financing Receivable, Modifications [Line Items]
Number of Loans | loan		4		9
Balance Prior to TDR		$ 41		$ 811
Balance		39		799
Financial Impact on Date of Restructure		0		0
Commercial | Commercial | Change in Maturity Date
Financing Receivable, Modifications [Line Items]
Balance		0		760
Commercial | Commercial | Change in Rate
Financing Receivable, Modifications [Line Items]
Balance		$ 39		$ 39