Fair Value Measurements - Carrying Values and Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
ASSETS
Securities, at fair value	$ 840,375	$ 773,693
Portfolio loans, net	6,897,715	7,108,248
LIABILITIES
Junior subordinated debt securities		64,083
Carrying Value
ASSETS
Cash and due from banks, including interest-bearing deposits	985,278	229,666
Securities, at fair value	840,375	773,693
Loans held for sale	7,648	18,528
Portfolio loans, net	6,897,715	7,108,248
Bank owned life insurance	83,087	82,303
Collateral receivable	45,703	77,936
Securities held in a deferred compensation plan	7,808	6,794
Mortgage servicing rights	6,658	4,976
LIABILITIES
Deposits	8,015,264	7,420,538
Securities sold under repurchase agreements	68,587	65,163
Short-term borrowings	0	75,000
Long-term borrowings	22,969	23,681
Junior subordinated debt securities	64,112	64,083
Carrying Value | Interest rate swaps
ASSETS
Derivative financial assets	49,078	78,319
LIABILITIES
Derivative financial liabilities	49,477	79,033
Carrying Value | Interest rate lock commitments
ASSETS
Derivative financial assets	1,137	2,900
Carrying Value | Forward sale contracts
LIABILITIES
Derivative financial liabilities	91	385
Fair Value Measurements
ASSETS
Cash and due from banks, including interest-bearing deposits	985,278	229,666
Securities, at fair value	840,375	773,693
Loans held for sale	7,648	18,528
Portfolio loans, net	6,808,655	7,028,446
Bank owned life insurance	0	82,303
Collateral receivable	45,703	77,936
Securities held in a deferred compensation plan	7,808	6,794
Mortgage servicing rights	6,658	4,976
LIABILITIES
Deposits	8,014,963	7,422,894
Securities sold under repurchase agreements	68,587	65,163
Short-term borrowings	0	75,000
Long-term borrowings	23,529	24,545
Junior subordinated debt securities	64,112	64,083
Fair Value Measurements | Interest rate swaps
ASSETS
Derivative financial assets	49,078	78,319
LIABILITIES
Derivative financial liabilities	49,477	79,033
Fair Value Measurements | Interest rate lock commitments
ASSETS
Derivative financial assets	1,137	2,900
Fair Value Measurements | Forward sale contracts
LIABILITIES
Derivative financial liabilities	91	385
Fair Value Measurements | Level 1
ASSETS
Cash and due from banks, including interest-bearing deposits	985,278	229,666
Securities, at fair value	75,819	13,510
Loans held for sale	0	0
Portfolio loans, net	0	0
Bank owned life insurance	0	0
Collateral receivable	45,703	77,936
Securities held in a deferred compensation plan	7,808	6,794
Mortgage servicing rights	0	0
LIABILITIES
Deposits	6,745,643	6,033,075
Securities sold under repurchase agreements	68,587	65,163
Short-term borrowings	0	75,000
Long-term borrowings	4,398	4,494
Junior subordinated debt securities	64,112	64,083
Fair Value Measurements | Level 1 | Interest rate swaps
ASSETS
Derivative financial assets	0	0
LIABILITIES
Derivative financial liabilities	0	0
Fair Value Measurements | Level 1 | Interest rate lock commitments
ASSETS
Derivative financial assets	0	0
Fair Value Measurements | Level 1 | Forward sale contracts
LIABILITIES
Derivative financial liabilities	0	0
Fair Value Measurements | Level 2
ASSETS
Cash and due from banks, including interest-bearing deposits	0	0
Securities, at fair value	764,556	760,183
Loans held for sale	7,648	0
Portfolio loans, net	0	0
Bank owned life insurance	0	82,303
Collateral receivable	0	0
Securities held in a deferred compensation plan	0	0
Mortgage servicing rights	0	0
LIABILITIES
Deposits	1,269,320	1,389,819
Securities sold under repurchase agreements	0	0
Short-term borrowings	0	0
Long-term borrowings	19,131	20,051
Junior subordinated debt securities	0	0
Fair Value Measurements | Level 2 | Interest rate swaps
ASSETS
Derivative financial assets	49,078	78,319
LIABILITIES
Derivative financial liabilities	49,477	79,033
Fair Value Measurements | Level 2 | Interest rate lock commitments
ASSETS
Derivative financial assets	0	0
Fair Value Measurements | Level 2 | Forward sale contracts
LIABILITIES
Derivative financial liabilities	91	385
Fair Value Measurements | Level 3
ASSETS
Cash and due from banks, including interest-bearing deposits	0	0
Securities, at fair value	0	0
Loans held for sale	0	18,528
Portfolio loans, net	6,808,655	7,028,446
Bank owned life insurance	0	0
Collateral receivable	0	0
Securities held in a deferred compensation plan	0	0
Mortgage servicing rights	6,658	4,976
LIABILITIES
Deposits	0	0
Securities sold under repurchase agreements	0	0
Short-term borrowings	0	0
Long-term borrowings	0	0
Junior subordinated debt securities	0	0
Fair Value Measurements | Level 3 | Interest rate swaps
ASSETS
Derivative financial assets	0	0
LIABILITIES
Derivative financial liabilities	0	0
Fair Value Measurements | Level 3 | Interest rate lock commitments
ASSETS
Derivative financial assets	1,137	2,900
Fair Value Measurements | Level 3 | Forward sale contracts
LIABILITIES
Derivative financial liabilities	$ 0	$ 0