Fair Value of Assets and Liabilities - Summary of Estimated Fair Values of Company Financial Instruments (Details) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Financial assets
Total available-for-sale securities	$ 1,222,198,000	$ 879,240,000
Held-to-maturity securities	7,105,000	5,119,000
Equity securities	301,000	218,000
Fair Value, Inputs, Level 1 [Member]
Financial assets
Cash and due from banks	339,407,000	415,973,000
Federal funds sold	1,334,000	1,308,000
Certificates of deposit investments	0	0
Total available-for-sale securities	0	0
Held-to-maturity securities	2,041,000	0
Equity securities	301,000	218,000
Loans held for sale	0	0
Loans net of allowance for credit losses	0	0
Interest receivable	0	0
Federal Reserve Bank stock	0	0
Federal Home Loan Bank stock	0	0
Financial liabilities
Deposits	0	0
Securities sold under agreements to repurchase	0	0
Interest payable	0	0
Federal Home Loan Bank borrowings	0	0
Fair Value, Inputs, Level 1 [Member] | Subordinated Debt
Financial liabilities
Subordinated debt, net	0	0
Fair Value, Inputs, Level 1 [Member] | Junior Subordinated Debentures
Financial liabilities
Subordinated debt, net	0	0
Fair Value, Inputs, Level 2 [Member]
Financial assets
Cash and due from banks	0	0
Federal funds sold	0	0
Certificates of deposit investments	2,450,000	2,695,000
Total available-for-sale securities	1,221,583,000	878,446,000
Held-to-maturity securities	5,064,000	5,119,000
Equity securities	0	0
Loans held for sale	2,867,000	1,924,000
Loans net of allowance for credit losses	0	0
Interest receivable	19,124,000	19,287,000
Federal Reserve Bank stock	13,799,000	9,401,000
Federal Home Loan Bank stock	6,528,000	5,450,000
Financial liabilities
Deposits	4,016,729,000	3,215,715,000
Securities sold under agreements to repurchase	151,400,000	206,945,000
Interest payable	1,831,000	2,345,000
Federal Home Loan Bank borrowings	113,852,000	96,669,000
Fair Value, Inputs, Level 2 [Member] | Subordinated Debt
Financial liabilities
Subordinated debt, net	94,326,000	94,253,000
Fair Value, Inputs, Level 2 [Member] | Junior Subordinated Debentures
Financial liabilities
Subordinated debt, net	14,444,000	14,604,000
Level 3
Financial assets
Cash and due from banks	0	0
Federal funds sold	0	0
Certificates of deposit investments	0	0
Total available-for-sale securities	615,000	794,000
Held-to-maturity securities	0	0
Equity securities	0	0
Loans held for sale	0	0
Loans net of allowance for credit losses	3,690,274,000	3,056,344,000
Interest receivable	0	0
Federal Reserve Bank stock	0	0
Federal Home Loan Bank stock	0	0
Financial liabilities
Deposits	726,702,000	481,390,000
Securities sold under agreements to repurchase	0	0
Interest payable	0	0
Federal Home Loan Bank borrowings	0	0
Level 3 | Subordinated Debt
Financial liabilities
Subordinated debt, net	0	0
Level 3 | Junior Subordinated Debentures
Financial liabilities
Subordinated debt, net	0	0
Carrying Amount
Financial assets
Cash and due from banks	339,407,000	415,973,000
Federal funds sold	1,334,000	1,308,000
Certificates of deposit investments	2,450,000	2,695,000
Total available-for-sale securities	1,222,198,000	879,240,000
Held-to-maturity securities	7,049,000	5,016,000
Equity securities	301,000	218,000
Loans held for sale	2,867,000	1,924,000
Loans net of allowance for credit losses	3,738,840,000	3,094,585,000
Interest receivable	19,124,000	19,287,000
Federal Reserve Bank stock	13,799,000	9,401,000
Federal Home Loan Bank stock	6,528,000	5,450,000
Financial liabilities
Deposits	4,739,322,000	3,692,784,000
Securities sold under agreements to repurchase	151,394,000	206,937,000
Interest payable	1,831,000	2,345,000
Federal Home Loan Bank borrowings	112,753,000	93,969,000
Carrying Amount | Subordinated Debt
Financial liabilities
Subordinated debt, net	94,326,000	94,253,000
Carrying Amount | Junior Subordinated Debentures
Financial liabilities
Subordinated debt, net	19,111,000	19,027,000
Fair Value
Financial assets
Cash and due from banks	339,407,000	415,973,000
Federal funds sold	1,334,000	1,308,000
Certificates of deposit investments	2,450,000	2,695,000
Total available-for-sale securities	1,222,198,000	879,240,000
Held-to-maturity securities	7,105,000	5,119,000
Equity securities	301,000	218,000
Loans held for sale	2,867,000	1,924,000
Loans net of allowance for credit losses	3,690,274,000	3,056,344,000
Interest receivable	19,124,000	19,287,000
Federal Reserve Bank stock	13,799,000	9,401,000
Federal Home Loan Bank stock	6,528,000	5,450,000
Financial liabilities
Deposits	4,743,431,000	3,697,105,000
Securities sold under agreements to repurchase	151,400,000	206,945,000
Interest payable	1,831,000	2,345,000
Federal Home Loan Bank borrowings	113,852,000	96,669,000
Fair Value | Subordinated Debt
Financial liabilities
Subordinated debt, net	94,326,000	94,253,000
Fair Value | Junior Subordinated Debentures
Financial liabilities
Subordinated debt, net	$ 14,444,000	$ 14,604,000