Fair value of financial instruments (Tables)
 12 Months Ended
Dec. 31, 2020
Fair Value Disclosures [Abstract]  
Schedule of Estimated Fair Values and Carrying Values of Financial Instruments
The following table contains the estimated fair values and the related carrying values of the Company's financial instruments. Items which are not financial instruments are not included.
 
 Fair Value
December 31, 2020Carrying amount Level 1Level 2Level 3Total
Financial assets:     
Cash and cash equivalents$1,317,898 $1,317,898 $— $— $1,317,898 
Investment securities1,176,991 — 1,176,991 — 1,176,991 
Loans, net6,912,570 — — 7,058,693 7,058,693 
Loans held for sale899,173 — 683,770 215,403 899,173 
Interest receivable43,603 33 5,254 38,316 43,603 
Mortgage servicing rights79,997 — — 79,997 79,997 
Derivatives68,938 — 68,938 — 68,938 
Financial liabilities: 
Deposits: 
Without stated maturities$8,020,783 $8,020,783 $— $— $8,020,783 
With stated maturities1,437,254 — 1,446,605 — 1,446,605 
Securities sold under agreement to
repurchase and federal funds sold
32,199 32,199 — — 32,199 
Subordinated debt189,527 — — 192,149 192,149 
Other borrowings16,598 — 16,598 — 16,598 
Interest payable6,772 327 4,210 2,235 6,772 
Derivatives48,242 — 48,242 — 48,242 

 
 Fair Value
December 31, 2019Carrying amount Level 1Level 2Level 3Total
Financial assets:     
Cash and cash equivalents$232,681 $232,681 $— $— $232,681 
Investment securities691,676 — 691,676 — 691,676 
Loans, net4,378,503 — — 4,363,903 4,363,903 
Loans held for sale262,518 — 262,518 — 262,518 
Interest receivable17,083 — 3,282 13,801 17,083 
Mortgage servicing rights75,521 — — 75,521 75,521 
Derivatives21,981 — 21,981 — 21,981 
Financial liabilities: 
Deposits: 
Without stated maturities$3,743,085 $3,743,085 $— $— $3,743,085 
With stated maturities1,191,853 — 1,200,145 — 1,200,145 
Securities sold under agreement to
repurchase and federal funds sold
23,745 23,745 — — 23,745 
Federal Home Loan Bank advances250,000 — 250,213 — 250,213 
Subordinated debt30,930 — 29,706 — 29,706 
Interest payable6,465 376 6,089 — 6,465 
Derivatives17,933 — 17,933 — 17,933 
Schedule of Balances and Levels of Assets Measured at Fair Value on Recurring Basis
The balances and levels of the assets measured at fair value on a recurring basis at December 31, 2020 are presented in the following table:
December 31, 2020Quoted prices
in active
markets for
identical assets
(liabilities)
(level 1)		Significant
other
observable
inputs
(level 2) 		Significant unobservable
inputs
(level 3) 		Total
Recurring valuations:    
Financial assets:     
Available-for-sale securities:    
U.S. government agency securities$— $2,003 $— $2,003 
Mortgage-backed securities - residential— 773,336 — 773,336 
Mortgage-backed securities - commercial— 21,588 — 21,588 
Municipals, tax-exempt— 356,329 — 356,329 
Treasury securities— 16,628 — 16,628 
Corporate securities— 2,516 — 2,516 
Equity securities— 4,591 — 4,591 
Total$— $1,176,991 $— $1,176,991 
Loans held for sale$— $683,770 $215,403 $899,173 
Mortgage servicing rights— — 79,997 79,997 
Derivatives— 68,938 — 68,938 
Financial Liabilities:
Derivatives— 48,242 — 48,242 
The balances and levels of the assets measured at fair value on a recurring basis at December 31, 2019 are presented in the following table: 
At December 31, 2019Quoted prices
in active
markets for
identical assets
(liabilities)
(level 1)		Significant
other
observable
inputs
(level 2) 		Significant unobservable
inputs
(level 3) 		Total
Recurring valuations:    
Financial assets:     
Available-for-sale securities:    
Mortgage-backed securities - residential$— $477,312 $— $477,312 
Mortgage-backed securities - commercial— 13,364 — 13,364 
Municipals, tax-exempt— 189,235 — 189,235 
Treasury securities— 7,448 — 7,448 
Corporate securities— 1,022 — 1,022 
Equity securities— 3,295 — 3,295 
Total$— $691,676 $— $691,676 
Loans held for sale$— $262,518 $— $262,518 
Mortgage servicing rights— — 75,521 75,521 
Derivatives— 21,981 — 21,981 
Financial Liabilities:
Derivatives— 17,933 — 17,933 
Schedule of Balances and Levels of Assets Measured at Fair Value on Non-recurring Basis
The balances and levels of the assets measured at fair value on a non-recurring basis at December 31, 2020 are presented in the following table: 
At December 31, 2020Quoted prices
in active
markets for
identical assets
(liabilities
(level 1)		Significant
other
observable
inputs
(level 2) 		Significant unobservable
inputs
(level 3) 		Total
Non-recurring valuations:    
Financial assets:    
Other real estate owned$— $— $6,662 $6,662 
Collateral dependent loans:
Commercial and industrial$— $— $1,728 $1,728 
Construction— — 3,877 3,877 
Residential real estate:
1-4 family mortgage— — 226 226 
Residential line of credit— — 1,174 1,174 
Commercial real estate:
Non-owner occupied— — 3,391 3,391 
Consumer and other— — 8,164 8,164 
Total collateral dependent loans$— $— $18,560 $18,560 
The balances and levels of the assets measured at fair value on a non-recurring basis at December 31, 2019 are presented in the following table: 
At December 31, 2019Quoted prices
in active
markets for
identical assets
(liabilities)
(level 1)		Significant
other observable inputs
(level 2)		Significant unobservable
inputs
(level 3)		Total
Non-recurring valuations:    
Financial assets:    
Other real estate owned$— $— $9,774 $9,774 
Impaired Loans (1):
Commercial and industrial$— $— $6,481 $6,481 
Residential real estate:
1-4 family mortgage— — 378 378 
Residential line of credit— — 321 321 
Commercial real estate: 
Owner occupied— — 951 951 
Non-owner occupied— — 2,560 2,560 
Total$— $— $10,691 $10,691 
(1) Includes both impaired non-purchased loans and collateral-dependent PCI loans.
Schedule of Information About Significant Unobservable Inputs (Level 3) Used in Valuation of Assets Measured at Fair Value on Nonrecurring Basis
The following table presents information as of December 31, 2020 about significant unobservable inputs (Level 3) used in the valuation of assets measured at fair value on a nonrecurring basis:
Financial instrumentFair ValueValuation techniqueSignificant 
Unobservable inputs		Range of
inputs
Collateral dependent loans$18,560 Valuation of collateralDiscount for comparable sales
0%-30%
Other real estate owned$6,662 Appraised value of property less costs to sellDiscount for costs to sell
0%-15%
The following table presents information as of December 31, 2019 about significant unobservable inputs (Level 3) used in the valuation of assets measured at fair value on a nonrecurring basis:
Financial instrumentFair ValueValuation techniqueSignificant 
Unobservable inputs		Range of
inputs
Impaired loans (1)
$10,691 Valuation of collateralDiscount for comparable sales
0%-30%
Other real estate owned$9,774 Appraised value of property less costs to sellDiscount for costs to sell
0%-15%
(1) Includes both impaired non-purchased loans and collateral-dependent PCI loans.
Schedule of Differences between Fair Value and Principal Balance for Loans Held for Sale Measured at Fair Value
The following table summarizes the differences between the fair value and the principal balance for loans held for sale and nonaccrual loans measured at fair value as of December 31, 2020 and 2019: 
December 31, 2020Aggregate
fair value 		Aggregate
Unpaid
Principal
Balance 		Difference
Mortgage loans held for sale measured at fair value$683,770 $651,887 $31,883 
Commercial loans held for sale measured at fair value208,914 226,867 (17,953)
Past due loans of 90 days or more83 163 (80)
Nonaccrual loans6,406 12,033 (5,627)
December 31, 2019 
Mortgage loans held for sale measured at fair value$262,518 $254,868 $7,650 
Past due loans of 90 days or more— — — 
Nonaccrual loans— — —