Loans and Allowance for Loan Losses - Schedule of Loans Classified by Aging Analysis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivables Greater Than 90 Days Past Due and Still Accruing | Commercial construction
Financing Receivables, By Class	$ 0
Financing Receivables Greater Than 90 Days Past Due and Still Accruing | Commercial Real Estate
Financing Receivables, By Class	0
Financing Receivables Greater Than 90 Days Past Due and Still Accruing | Industrial revenue bonds
Financing Receivables, By Class	0
Financing Receivables Greater Than 90 Days Past Due and Still Accruing | Consumer auto
Financing Receivables, By Class	0
Financing Receivables Greater Than 90 Days Past Due and Still Accruing | Home Equity Line of Credit
Financing Receivables, By Class	0
Financing Receivables Greater Than 90 Days Past Due and Still Accruing | Land development
Financing Receivables, By Class	0
Financing Receivables Greater Than 90 Days Past Due and Still Accruing | One- to four-family residential construction
Financing Receivables, By Class	0
Financing Receivables Greater Than 90 Days Past Due and Still Accruing | Subdivision construction
Financing Receivables, By Class	0
Financing Receivables Greater Than 90 Days Past Due and Still Accruing | Owner occupied one- to four-family residential
Financing Receivables, By Class	0
Financing Receivables Greater Than 90 Days Past Due and Still Accruing | Non-owner occupied one- to four-family residential
Financing Receivables, By Class	0
Financing Receivables Greater Than 90 Days Past Due and Still Accruing | Other residential
Financing Receivables, By Class	0
Financing Receivables Greater Than 90 Days Past Due and Still Accruing | Commercial business
Financing Receivables, By Class	0
Financing Receivables Greater Than 90 Days Past Due and Still Accruing | Consumer other
Financing Receivables, By Class	0
Financing Receivables Greater Than 90 Days Past Due and Still Accruing | Acquired Loans Net of Discount
Financing Receivables, By Class	0
Financing Receivables Greater Than 90 Days Past Due and Still Accruing | Less Acquired Loans Net of Discount
Financing Receivables, By Class	0
Loans Receivable, Gross
Financing Receivables, By Class	0
Loans Receivable
Financing Receivables, By Class	0
Financial Asset, 30 to 59 Days Past Due | Commercial construction
Financing Receivables, By Class	0	$ 15,085
Financial Asset, 30 to 59 Days Past Due | Commercial Real Estate
Financing Receivables, By Class	0	549
Financial Asset, 30 to 59 Days Past Due | Industrial revenue bonds
Financing Receivables, By Class	0
Financial Asset, 30 to 59 Days Past Due | Consumer auto
Financing Receivables, By Class	364	1,101
Financial Asset, 30 to 59 Days Past Due | Home Equity Line of Credit
Financing Receivables, By Class	153	296
Financial Asset, 30 to 59 Days Past Due | Land development
Financing Receivables, By Class	20
Financial Asset, 30 to 59 Days Past Due | One- to four-family residential construction
Financing Receivables, By Class	1,365
Financial Asset, 30 to 59 Days Past Due | Subdivision construction
Financing Receivables, By Class	0
Financial Asset, 30 to 59 Days Past Due | Owner occupied one- to four-family residential
Financing Receivables, By Class	1,379	1,453
Financial Asset, 30 to 59 Days Past Due | Non-owner occupied one- to four-family residential
Financing Receivables, By Class	0	152
Financial Asset, 30 to 59 Days Past Due | Other residential
Financing Receivables, By Class	0	376
Financial Asset, 30 to 59 Days Past Due | Commercial business
Financing Receivables, By Class	0	60
Financial Asset, 30 to 59 Days Past Due | Consumer other
Financing Receivables, By Class	443	278
Financial Asset, 30 to 59 Days Past Due | Acquired Loans Net of Discount
Financing Receivables, By Class	1,662	2,177
Financial Asset, 30 to 59 Days Past Due | Less Acquired Loans Net of Discount
Financing Receivables, By Class	1,662	2,177
Financial Asset, 30 to 59 Days Past Due | Loans Receivable, Gross
Financing Receivables, By Class	5,386	21,527
Financial Asset, 30 to 59 Days Past Due | Loans Receivable
Financing Receivables, By Class	3,724	19,350
Financial Asset, 60 to 89 Days Past Due | Commercial construction
Financing Receivables, By Class	0
Financial Asset, 60 to 89 Days Past Due | Commercial Real Estate
Financing Receivables, By Class	79	119
Financial Asset, 60 to 89 Days Past Due | Industrial revenue bonds
Financing Receivables, By Class	0
Financial Asset, 60 to 89 Days Past Due | Consumer auto
Financing Receivables, By Class	119	259
Financial Asset, 60 to 89 Days Past Due | Home Equity Line of Credit
Financing Receivables, By Class	111
Financial Asset, 60 to 89 Days Past Due | Land development
Financing Receivables, By Class	0	27
Financial Asset, 60 to 89 Days Past Due | One- to four-family residential construction
Financing Receivables, By Class	0
Financial Asset, 60 to 89 Days Past Due | Subdivision construction
Financing Receivables, By Class	0
Financial Asset, 60 to 89 Days Past Due | Owner occupied one- to four-family residential
Financing Receivables, By Class	113	1,631
Financial Asset, 60 to 89 Days Past Due | Non-owner occupied one- to four-family residential
Financing Receivables, By Class	0
Financial Asset, 60 to 89 Days Past Due | Other residential
Financing Receivables, By Class	0
Financial Asset, 60 to 89 Days Past Due | Commercial business
Financing Receivables, By Class	0
Financial Asset, 60 to 89 Days Past Due | Consumer other
Financing Receivables, By Class	7	233
Financial Asset, 60 to 89 Days Past Due | Acquired Loans Net of Discount
Financing Receivables, By Class	641	709
Financial Asset, 60 to 89 Days Past Due | Less Acquired Loans Net of Discount
Financing Receivables, By Class	641	709
Financial Asset, 60 to 89 Days Past Due | Loans Receivable, Gross
Financing Receivables, By Class	1,070	2,978
Financial Asset, 60 to 89 Days Past Due | Loans Receivable
Financing Receivables, By Class	429	2,269
Financial Asset, Equal to or Greater than 90 Days Past Due | Commercial construction
Financing Receivables, By Class	0
Financial Asset, Equal to or Greater than 90 Days Past Due | Commercial Real Estate
Financing Receivables, By Class	587	632
Financial Asset, Equal to or Greater than 90 Days Past Due | Industrial revenue bonds
Financing Receivables, By Class	0
Financial Asset, Equal to or Greater than 90 Days Past Due | Consumer auto
Financing Receivables, By Class	169	558
Financial Asset, Equal to or Greater than 90 Days Past Due | Home Equity Line of Credit
Financing Receivables, By Class	508	517
Financial Asset, Equal to or Greater than 90 Days Past Due | Land development
Financing Receivables, By Class	0
Financial Asset, Equal to or Greater than 90 Days Past Due | One- to four-family residential construction
Financing Receivables, By Class	0
Financial Asset, Equal to or Greater than 90 Days Past Due | Subdivision construction
Financing Receivables, By Class	0
Financial Asset, Equal to or Greater than 90 Days Past Due | Owner occupied one- to four-family residential
Financing Receivables, By Class	1,502	1,198
Financial Asset, Equal to or Greater than 90 Days Past Due | Non-owner occupied one- to four-family residential
Financing Receivables, By Class	69	181
Financial Asset, Equal to or Greater than 90 Days Past Due | Other residential
Financing Receivables, By Class	0
Financial Asset, Equal to or Greater than 90 Days Past Due | Commercial business
Financing Receivables, By Class	114	1,235
Financial Asset, Equal to or Greater than 90 Days Past Due | Consumer other
Financing Receivables, By Class	94	198
Financial Asset, Equal to or Greater than 90 Days Past Due | Acquired Loans Net of Discount
Financing Receivables, By Class	3,843	6,191
Financial Asset, Equal to or Greater than 90 Days Past Due | Less Acquired Loans Net of Discount
Financing Receivables, By Class	3,843	6,191
Financial Asset, Equal to or Greater than 90 Days Past Due | Loans Receivable, Gross
Financing Receivables, By Class	6,886	10,710
Financial Asset, Equal to or Greater than 90 Days Past Due | Loans Receivable
Financing Receivables, By Class	3,043	4,519
Financing Receivables Past Due | Commercial construction
Financing Receivables, By Class	0	15,085
Financing Receivables Past Due | Commercial Real Estate
Financing Receivables, By Class	666	1,300
Financing Receivables Past Due | Industrial revenue bonds
Financing Receivables, By Class	0
Financing Receivables Past Due | Consumer auto
Financing Receivables, By Class	652	1,918
Financing Receivables Past Due | Home Equity Line of Credit
Financing Receivables, By Class	772	813
Financing Receivables Past Due | Land development
Financing Receivables, By Class	20	27
Financing Receivables Past Due | One- to four-family residential construction
Financing Receivables, By Class	1,365
Financing Receivables Past Due | Subdivision construction
Financing Receivables, By Class	0
Financing Receivables Past Due | Owner occupied one- to four-family residential
Financing Receivables, By Class	2,994	4,282
Financing Receivables Past Due | Non-owner occupied one- to four-family residential
Financing Receivables, By Class	69	333
Financing Receivables Past Due | Other residential
Financing Receivables, By Class	0	376
Financing Receivables Past Due | Commercial business
Financing Receivables, By Class	114	1,295
Financing Receivables Past Due | Consumer other
Financing Receivables, By Class	544	709
Financing Receivables Past Due | Acquired Loans Net of Discount
Financing Receivables, By Class	6,146	9,077
Financing Receivables Past Due | Less Acquired Loans Net of Discount
Financing Receivables, By Class	6,146	9,077
Financing Receivables Past Due | Loans Receivable, Gross
Financing Receivables, By Class	13,342	35,215
Financing Receivables Past Due | Loans Receivable
Financing Receivables, By Class	7,196	26,138
Financing Receivables Current | Commercial construction
Financing Receivables, By Class	1,212,837	1,307,776
Financing Receivables Current | Commercial Real Estate
Financing Receivables, By Class	1,553,011	1,492,872
Financing Receivables Current | Industrial revenue bonds
Financing Receivables, By Class	14,003	13,189
Financing Receivables Current | Consumer auto
Financing Receivables, By Class	85,521	149,936
Financing Receivables Current | Home Equity Line of Credit
Financing Receivables, By Class	113,917	118,175
Financing Receivables Current | Land development
Financing Receivables, By Class	53,990	40,404
Financing Receivables Current | One- to four-family residential construction
Financing Receivables, By Class	41,428	33,963
Financing Receivables Current | Subdivision construction
Financing Receivables, By Class	30,894	16,088
Financing Receivables Current | Owner occupied one- to four-family residential
Financing Receivables, By Class	467,442	382,734
Financing Receivables Current | Non-owner occupied one- to four-family residential
Financing Receivables, By Class	114,500	120,010
Financing Receivables Current | Other residential
Financing Receivables, By Class	1,021,145	865,630
Financing Receivables Current | Commercial business
Financing Receivables, By Class	370,784	311,914
Financing Receivables Current | Consumer other
Financing Receivables, By Class	40,218	46,011
Financing Receivables Current | Acquired Loans Net of Discount
Financing Receivables, By Class	92,497	118,129
Financing Receivables Current | Less Acquired Loans Net of Discount
Financing Receivables, By Class	92,497	118,129
Financing Receivables Current | Loans Receivable, Gross
Financing Receivables, By Class	5,212,187	5,016,831
Financing Receivables Current | Loans Receivable
Financing Receivables, By Class	5,119,690	4,898,702
Financing Receivables Total | Commercial construction
Financing Receivables, By Class	1,212,837	1,322,861
Financing Receivables Total | Commercial Real Estate
Financing Receivables, By Class	1,553,677	1,494,172
Financing Receivables Total | Industrial revenue bonds
Financing Receivables, By Class	14,003	13,189
Financing Receivables Total | Consumer auto
Financing Receivables, By Class	86,173	151,854
Financing Receivables Total | Home Equity Line of Credit
Financing Receivables, By Class	114,689	118,988
Financing Receivables Total | Land development
Financing Receivables, By Class	54,010	40,431
Financing Receivables Total | One- to four-family residential construction
Financing Receivables, By Class	42,793	33,963
Financing Receivables Total | Subdivision construction
Financing Receivables, By Class	30,894	16,088
Financing Receivables Total | Owner occupied one- to four-family residential
Financing Receivables, By Class	470,436	387,016
Financing Receivables Total | Non-owner occupied one- to four-family residential
Financing Receivables, By Class	114,569	120,343
Financing Receivables Total | Other residential
Financing Receivables, By Class	1,021,145	866,006
Financing Receivables Total | Commercial business
Financing Receivables, By Class	370,898	313,209
Financing Receivables Total | Consumer other
Financing Receivables, By Class	40,762	46,720
Financing Receivables Total | Acquired Loans Net of Discount
Financing Receivables, By Class	98,643	127,206
Financing Receivables Total | Less Acquired Loans Net of Discount
Financing Receivables, By Class	98,643	127,206
Financing Receivables Total | Loans Receivable, Gross
Financing Receivables, By Class	5,225,529	5,052,046
Financing Receivables Total | Loans Receivable
Financing Receivables, By Class	$ 5,126,886	$ 4,924,840