Fair Value of Financial Instruments - Financial instruments Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	$ 1,453,132	$ 821,945
Foreclosed properties	2,424	3,873
Government-sponsored enterprise securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	70,206	20,009
Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,337,706	767,285
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring | Government-sponsored enterprise securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Presold mortgages in process of settlement	42,271	19,712
Impaired loans	0	0
Foreclosed properties	0	0
Significant Other Observable Inputs (Level 2) | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,453,132	821,945
Significant Other Observable Inputs (Level 2) | Recurring | Government-sponsored enterprise securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	70,206	20,009
Significant Other Observable Inputs (Level 2) | Recurring | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,337,706	767,285
Significant Other Observable Inputs (Level 2) | Recurring | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	45,220	34,651
Significant Other Observable Inputs (Level 2) | Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Presold mortgages in process of settlement	0	0
Impaired loans	0	0
Foreclosed properties	0	0
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	16,000	10,718
Foreclosed properties	1,484	1,830
Significant Unobservable Inputs (Level 3) | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Significant Unobservable Inputs (Level 3) | Recurring | Government-sponsored enterprise securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Significant Unobservable Inputs (Level 3) | Recurring | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Significant Unobservable Inputs (Level 3) | Recurring | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	0	0
Significant Unobservable Inputs (Level 3) | Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Presold mortgages in process of settlement	0	0
Impaired loans	22,142	16,215
Foreclosed properties	1,484	1,830
Estimated Fair Value | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,453,132	821,945
Estimated Fair Value | Recurring | Government-sponsored enterprise securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	70,206	20,009
Estimated Fair Value | Recurring | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,337,706	767,285
Estimated Fair Value | Recurring | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	45,220	34,651
Estimated Fair Value | Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Presold mortgages in process of settlement	42,271	19,712
Impaired loans	22,142	16,215
Foreclosed properties	$ 1,484	$ 1,830