Fair Value Measurements - Narrative (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale:	$ 1,339,408,000	$ 1,243,693,000
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale:	1,339,408,000	1,243,693,000
Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale:	0	0
Assets value	$ 0	$ 0