Securities - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Financing Receivable, Nonaccrual [Line Items]
Available-for-sale securities pledged	$ 1,900,000,000		$ 1,900,000,000		$ 1,600,000,000
Held-to-maturity securities pledged as collateral	0		0		0
Realized gains (losses) on securities available-for-sale	0	$ 0	0	$ 1,005,000
Securities Receivable
Financing Receivable, Nonaccrual [Line Items]
Accrued interest receivable	$ 11,100,000		$ 11,100,000		$ 11,900,000