Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
ASSETS
Debt securities, available-for-sale, excluding accrued interest	$ 839,279	$ 770,393
Marketable equity securities	1,096	3,300
U.S. Treasury securities
ASSETS
Debt securities, available-for-sale, excluding accrued interest	74,804	10,282
Obligations of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	81,624	82,904
Collateralized mortgage obligations of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	201,350	209,296
Residential mortgage-backed securities of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	63,859	67,778
Commercial mortgage-backed securities of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	325,303	273,681
Obligations of states and political subdivisions
ASSETS
Debt securities, available-for-sale, excluding accrued interest	91,840	124,427
Fair Value Measurements, Recurring
ASSETS
Debt securities, available-for-sale, excluding accrued interest	839,279	770,393
Marketable equity securities	1,096	3,300
Total Securities	840,375	773,693
Securities held in a deferred compensation plan	7,808	6,794
Total Assets	898,398	861,706
LIABILITIES
Total Liabilities	49,568	79,418
Fair Value Measurements, Recurring | U.S. Treasury securities
ASSETS
Debt securities, available-for-sale, excluding accrued interest	74,804	10,282
Fair Value Measurements, Recurring | Obligations of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	81,624	82,904
Fair Value Measurements, Recurring | Collateralized mortgage obligations of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	201,350	209,296
Fair Value Measurements, Recurring | Residential mortgage-backed securities of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	63,859	67,778
Fair Value Measurements, Recurring | Commercial mortgage-backed securities of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	325,303	273,681
Fair Value Measurements, Recurring | Corporate obligations
ASSETS
Debt securities, available-for-sale, excluding accrued interest	499	2,025
Fair Value Measurements, Recurring | Obligations of states and political subdivisions
ASSETS
Debt securities, available-for-sale, excluding accrued interest	91,840	124,427
Fair Value Measurements, Recurring | Interest rate swaps
ASSETS
Derivative financial assets	49,078	78,319
LIABILITIES
Derivative financial liabilities	49,477	79,033
Fair Value Measurements, Recurring | Interest rate lock commitments
ASSETS
Derivative financial assets	1,137	2,900
Fair Value Measurements, Recurring | Forward sale contracts
LIABILITIES
Derivative financial liabilities	91	385
Fair Value Measurements, Recurring | Level 1
ASSETS
Debt securities, available-for-sale, excluding accrued interest	74,804	10,282
Marketable equity securities	1,015	3,228
Total Securities	75,819	13,510
Securities held in a deferred compensation plan	7,808	6,794
Total Assets	83,627	20,304
LIABILITIES
Total Liabilities	0	0
Fair Value Measurements, Recurring | Level 1 | U.S. Treasury securities
ASSETS
Debt securities, available-for-sale, excluding accrued interest	74,804	10,282
Fair Value Measurements, Recurring | Level 1 | Obligations of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	0	0
Fair Value Measurements, Recurring | Level 1 | Collateralized mortgage obligations of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	0	0
Fair Value Measurements, Recurring | Level 1 | Residential mortgage-backed securities of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	0	0
Fair Value Measurements, Recurring | Level 1 | Commercial mortgage-backed securities of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	0	0
Fair Value Measurements, Recurring | Level 1 | Corporate obligations
ASSETS
Debt securities, available-for-sale, excluding accrued interest	0	0
Fair Value Measurements, Recurring | Level 1 | Obligations of states and political subdivisions
ASSETS
Debt securities, available-for-sale, excluding accrued interest	0	0
Fair Value Measurements, Recurring | Level 1 | Interest rate swaps
ASSETS
Derivative financial assets	0	0
LIABILITIES
Derivative financial liabilities	0	0
Fair Value Measurements, Recurring | Level 1 | Interest rate lock commitments
ASSETS
Derivative financial assets	0	0
Fair Value Measurements, Recurring | Level 1 | Forward sale contracts
LIABILITIES
Derivative financial liabilities	0	0
Fair Value Measurements, Recurring | Level 2
ASSETS
Debt securities, available-for-sale, excluding accrued interest	764,475	760,111
Marketable equity securities	81	72
Total Securities	764,556	760,183
Securities held in a deferred compensation plan	0	0
Total Assets	813,634	838,502
LIABILITIES
Total Liabilities	49,568	79,418
Fair Value Measurements, Recurring | Level 2 | U.S. Treasury securities
ASSETS
Debt securities, available-for-sale, excluding accrued interest	0	0
Fair Value Measurements, Recurring | Level 2 | Obligations of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	81,624	82,904
Fair Value Measurements, Recurring | Level 2 | Collateralized mortgage obligations of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	201,350	209,296
Fair Value Measurements, Recurring | Level 2 | Residential mortgage-backed securities of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	63,859	67,778
Fair Value Measurements, Recurring | Level 2 | Commercial mortgage-backed securities of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	325,303	273,681
Fair Value Measurements, Recurring | Level 2 | Corporate obligations
ASSETS
Debt securities, available-for-sale, excluding accrued interest	499	2,025
Fair Value Measurements, Recurring | Level 2 | Obligations of states and political subdivisions
ASSETS
Debt securities, available-for-sale, excluding accrued interest	91,840	124,427
Fair Value Measurements, Recurring | Level 2 | Interest rate swaps
ASSETS
Derivative financial assets	49,078	78,319
LIABILITIES
Derivative financial liabilities	49,477	79,033
Fair Value Measurements, Recurring | Level 2 | Interest rate lock commitments
ASSETS
Derivative financial assets	0	0
Fair Value Measurements, Recurring | Level 2 | Forward sale contracts
LIABILITIES
Derivative financial liabilities	91	385
Fair Value Measurements, Recurring | Level 3
ASSETS
Debt securities, available-for-sale, excluding accrued interest	0	0
Marketable equity securities	0	0
Total Securities	0	0
Securities held in a deferred compensation plan	0	0
Total Assets	1,137	2,900
LIABILITIES
Total Liabilities	0	0
Fair Value Measurements, Recurring | Level 3 | U.S. Treasury securities
ASSETS
Debt securities, available-for-sale, excluding accrued interest	0	0
Fair Value Measurements, Recurring | Level 3 | Obligations of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	0	0
Fair Value Measurements, Recurring | Level 3 | Collateralized mortgage obligations of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	0	0
Fair Value Measurements, Recurring | Level 3 | Residential mortgage-backed securities of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	0	0
Fair Value Measurements, Recurring | Level 3 | Commercial mortgage-backed securities of U.S. government corporations and agencies
ASSETS
Debt securities, available-for-sale, excluding accrued interest	0	0
Fair Value Measurements, Recurring | Level 3 | Corporate obligations
ASSETS
Debt securities, available-for-sale, excluding accrued interest	0	0
Fair Value Measurements, Recurring | Level 3 | Obligations of states and political subdivisions
ASSETS
Debt securities, available-for-sale, excluding accrued interest	0	0
Fair Value Measurements, Recurring | Level 3 | Interest rate swaps
ASSETS
Derivative financial assets	0	0
LIABILITIES
Derivative financial liabilities	0	0
Fair Value Measurements, Recurring | Level 3 | Interest rate lock commitments
ASSETS
Derivative financial assets	1,137	2,900
Fair Value Measurements, Recurring | Level 3 | Forward sale contracts
LIABILITIES
Derivative financial liabilities	$ 0	$ 0