Fair Value of Financial Instruments and Fair Value Measurements - Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale	$ 881,859	$ 785,977
Derivative assets	12,500	1,848
U.S. Government agencies and corporations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale	431	441
State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale	286,377	257,205
Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale	42,601	43,530
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale	245,590	191,855
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative assets	12,500	1,848
Derivative liabilities	16,305	3,242
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative assets	0	0
Derivative liabilities	0	0
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative assets	12,500	1,848
Derivative liabilities	16,305	3,242
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative assets	0	0
Derivative liabilities	0	0
Recurring | U.S. Government agencies and corporations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale	431	441
Recurring | U.S. Government agencies and corporations | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale		0
Recurring | U.S. Government agencies and corporations | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale	431	441
Recurring | U.S. Government agencies and corporations | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale		0
Recurring | State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale	286,377	257,205
Recurring | State and political subdivisions | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale		0
Recurring | State and political subdivisions | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale	286,377	257,205
Recurring | State and political subdivisions | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale		0
Recurring | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale	42,601	43,530
Recurring | Mortgage-backed securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale		0
Recurring | Mortgage-backed securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale	42,601	43,530
Recurring | Mortgage-backed securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale		0
Recurring | Collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale	306,860	292,946
Recurring | Collateralized mortgage obligations | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale		0
Recurring | Collateralized mortgage obligations | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale	306,860	292,946
Recurring | Collateralized mortgage obligations | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale		0
Recurring | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale	245,590	191,855
Recurring | Corporate debt securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale		0
Recurring | Corporate debt securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale	$ 245,590	191,855
Recurring | Corporate debt securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Debt securities available for sale		$ 0