Loans - Financing Receivable Credit Quality Indicators, Prior to Adoption of ASU 2016-13 (Details) $ in Thousands	Jun. 30, 2020 USD ($)
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	$ 2,756,138
Pass
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	2,694,017
Special Mention
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	33,803
Substandard
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	28,095
Doubtful
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	207
Loss
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	16
Commercial Loans | Paycheck Protection Program
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	80,697
Commercial Loans | Commercial real estate
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	1,047,084
Commercial Loans | Construction and development
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	215,344
Commercial Loans | Commercial and industrial
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	153,263
Commercial Loans | Equipment finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	229,239
Commercial Loans | Municipal finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	127,987
Commercial Loans | Pass | Paycheck Protection Program
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	80,697
Commercial Loans | Pass | Commercial real estate
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	1,028,709
Commercial Loans | Pass | Construction and development
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	212,370
Commercial Loans | Pass | Commercial and industrial
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	130,202
Commercial Loans | Pass | Equipment finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	228,288
Commercial Loans | Pass | Municipal finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	127,706
Commercial Loans | Special Mention | Paycheck Protection Program
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Commercial Loans | Special Mention | Commercial real estate
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	7,580
Commercial Loans | Special Mention | Construction and development
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	2,723
Commercial Loans | Special Mention | Commercial and industrial
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	20,439
Commercial Loans | Special Mention | Equipment finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	150
Commercial Loans | Special Mention | Municipal finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	281
Commercial Loans | Substandard | Paycheck Protection Program
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Commercial Loans | Substandard | Commercial real estate
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	10,779
Commercial Loans | Substandard | Construction and development
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	250
Commercial Loans | Substandard | Commercial and industrial
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	2,622
Commercial Loans | Substandard | Equipment finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	801
Commercial Loans | Substandard | Municipal finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Commercial Loans | Doubtful | Paycheck Protection Program
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Commercial Loans | Doubtful | Commercial real estate
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Commercial Loans | Doubtful | Construction and development
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	1
Commercial Loans | Doubtful | Commercial and industrial
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Commercial Loans | Doubtful | Equipment finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Commercial Loans | Doubtful | Municipal finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Commercial Loans | Loss | Paycheck Protection Program
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Commercial Loans | Loss | Commercial real estate
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	16
Commercial Loans | Loss | Construction and development
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Commercial Loans | Loss | Commercial and industrial
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Commercial Loans | Loss | Equipment finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Commercial Loans | Loss | Municipal finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Retail Consumer Loans | One-to-four family
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	469,220
Retail Consumer Loans | HELOCs - originated
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	137,447
Retail Consumer Loans | HELOCs - purchased
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	71,781
Retail Consumer Loans | Construction and land/lots
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	81,514
Retail Consumer Loans | Indirect auto finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	132,303
Retail Consumer Loans | Consumer
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	10,259
Retail Consumer Loans | Pass | One-to-four family
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	458,248
Retail Consumer Loans | Pass | HELOCs - originated
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	134,697
Retail Consumer Loans | Pass | HELOCs - purchased
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	71,119
Retail Consumer Loans | Pass | Construction and land/lots
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	81,112
Retail Consumer Loans | Pass | Indirect auto finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	130,975
Retail Consumer Loans | Pass | Consumer
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	9,894
Retail Consumer Loans | Special Mention | One-to-four family
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	1,724
Retail Consumer Loans | Special Mention | HELOCs - originated
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	902
Retail Consumer Loans | Special Mention | HELOCs - purchased
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Retail Consumer Loans | Special Mention | Construction and land/lots
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Retail Consumer Loans | Special Mention | Indirect auto finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Retail Consumer Loans | Special Mention | Consumer
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	4
Retail Consumer Loans | Substandard | One-to-four family
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	9,042
Retail Consumer Loans | Substandard | HELOCs - originated
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	1,848
Retail Consumer Loans | Substandard | HELOCs - purchased
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	662
Retail Consumer Loans | Substandard | Construction and land/lots
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	402
Retail Consumer Loans | Substandard | Indirect auto finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	1,328
Retail Consumer Loans | Substandard | Consumer
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	361
Retail Consumer Loans | Doubtful | One-to-four family
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	206
Retail Consumer Loans | Doubtful | HELOCs - originated
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Retail Consumer Loans | Doubtful | HELOCs - purchased
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Retail Consumer Loans | Doubtful | Construction and land/lots
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Retail Consumer Loans | Doubtful | Indirect auto finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Retail Consumer Loans | Doubtful | Consumer
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Retail Consumer Loans | Loss | One-to-four family
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Retail Consumer Loans | Loss | HELOCs - originated
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Retail Consumer Loans | Loss | HELOCs - purchased
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Retail Consumer Loans | Loss | Construction and land/lots
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Retail Consumer Loans | Loss | Indirect auto finance
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	0
Retail Consumer Loans | Loss | Consumer
Financing Receivable, Recorded Investment
Non-purchased and purchased performing loans	$ 0