Loans Receivable - Past Due Loans (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 14,409,000
Current	4,581,460,000
Total	4,595,869,000	$ 4,468,647,000
90 days or more and still accruing	0	0
Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	5,614,000
90 Days or Greater
Financing Receivable, Past Due [Line Items]
Total Past Due	8,795,000
Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	13,053,000	16,479,000
Current	3,876,368,000	3,698,727,000
Total	3,889,421,000	3,715,206,000
Commercial Portfolio Segment [Member] \| Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	4,875,000	6,024,000
Commercial Portfolio Segment [Member] \| 90 Days or Greater
Financing Receivable, Past Due [Line Items]
Total Past Due	8,178,000	10,455,000
Commercial Portfolio Segment [Member] \| Commercial and Industrial [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	12,571,000	12,703,000
Current	680,968,000	720,395,000
Total	693,539,000	733,098,000
Commercial Portfolio Segment [Member] \| Commercial and Industrial [Member] \| Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	4,393,000	4,621,000
Commercial Portfolio Segment [Member] \| Commercial and Industrial [Member] \| 90 Days or Greater
Financing Receivable, Past Due [Line Items]
Total Past Due	8,178,000	8,082,000
Commercial Portfolio Segment [Member] \| SBA PPP Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Current	886,761,000	715,121,000
Total	886,761,000	715,121,000
Commercial Portfolio Segment [Member] \| SBA PPP Loans [Member] \| Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Commercial Portfolio Segment [Member] \| SBA PPP Loans [Member] \| 90 Days or Greater
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Commercial Portfolio Segment [Member] \| Owner Occupied Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	0	1,394,000
Current	881,168,000	855,290,000
Total	881,168,000	856,684,000
Commercial Portfolio Segment [Member] \| Owner Occupied Commercial Real Estate [Member] \| Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	0	991,000
Commercial Portfolio Segment [Member] \| Owner Occupied Commercial Real Estate [Member] \| 90 Days or Greater
Financing Receivable, Past Due [Line Items]
Total Past Due	0	403,000
Commercial Portfolio Segment [Member] \| Non Owner Occupied Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	482,000	2,382,000
Current	1,427,471,000	1,407,921,000
Total	1,427,953,000	1,410,303,000
Commercial Portfolio Segment [Member] \| Non Owner Occupied Commercial Real Estate [Member] \| Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	482,000	412,000
Commercial Portfolio Segment [Member] \| Non Owner Occupied Commercial Real Estate [Member] \| 90 Days or Greater
Financing Receivable, Past Due [Line Items]
Total Past Due	0	1,970,000
Residential Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	46,000	781,000
Current	114,810,000	121,975,000
Total	114,856,000	122,756,000
Residential Portfolio Segment [Member] \| Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	0	765,000
Residential Portfolio Segment [Member] \| 90 Days or Greater
Financing Receivable, Past Due [Line Items]
Total Past Due	46,000	16,000
Real Estate Construction and Land Development
Financing Receivable, Past Due [Line Items]
Total Past Due	571,000	2,225,000
Current	297,122,000	303,488,000
Total	297,693,000	305,713,000
Real Estate Construction and Land Development \| Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	0	2,225,000
Real Estate Construction and Land Development \| 90 Days or Greater
Financing Receivable, Past Due [Line Items]
Total Past Due	571,000	0
Real Estate Construction and Land Development \| One-to-four Family Real Estate Construction
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Current	79,878,000	78,259,000
Total	79,878,000	78,259,000
Real Estate Construction and Land Development \| One-to-four Family Real Estate Construction \| Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Real Estate Construction and Land Development \| One-to-four Family Real Estate Construction \| 90 Days or Greater
Financing Receivable, Past Due [Line Items]
Total Past Due	0	0
Real Estate Construction and Land Development \| Five or More Family Residential and Commercial Properties [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	571,000	2,225,000
Current	217,244,000	225,229,000
Total	217,815,000	227,454,000
Real Estate Construction and Land Development \| Five or More Family Residential and Commercial Properties [Member] \| Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	0	2,225,000
Real Estate Construction and Land Development \| Five or More Family Residential and Commercial Properties [Member] \| 90 Days or Greater
Financing Receivable, Past Due [Line Items]
Total Past Due	571,000	0
Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	739,000	1,437,000
Current	293,160,000	323,535,000
Total	293,899,000	324,972,000
Consumer Portfolio Segment [Member] \| Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due	739,000	1,407,000
Consumer Portfolio Segment [Member] \| 90 Days or Greater
Financing Receivable, Past Due [Line Items]
Total Past Due	$ 0	30,000
Loans Receivable Excluding PCI Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due		20,922,000
Current		4,447,725,000
Loans Receivable Excluding PCI Loans [Member] \| Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due		10,421,000
Loans Receivable Excluding PCI Loans [Member] \| 90 Days or Greater
Financing Receivable, Past Due [Line Items]
Total Past Due		$ 10,501,000