Commitments and contingencies (Tables)
 12 Months Ended
Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]  
Schedule of Financial Instruments with Off-Balance Sheet Credit Risk
December 31,
 2020 2019 
Commitments to extend credit, excluding interest rate lock commitments$2,719,996 $1,086,173 
Letters of credit67,598 19,569 
Balance at end of period$2,787,594 $1,105,742 
Schedule of Allowance of Credit Losses on Unfunded Commitments
The table below presents activity within the allowance for credit losses on unfunded commitments:
For the Year Ended December 31,
2020 
Balance at beginning of period$— 
Impact of CECL adoption on provision for credit losses on unfunded commitments2,947 
Increase in provision for credit losses from unfunded commitments acquired in business combination10,499 
Provision for credit losses on unfunded commitments2,932 
Balance at end of period$16,378 
Schedule of Activity in the Repurchase Reserve
The following table summarizes the activity in the repurchase reserve:
For the Year Ended December 31,
 2020 2019 2018 
Balance at beginning of period$3,529 $3,273 $3,386 
Provision for loan repurchases or indemnifications2,607 362 174 
Recoveries on previous losses(208)(106)3 
Losses on loans repurchased or indemnified— — (290)
Balance at end of period$5,928 $3,529 $3,273