Investment Securities - Additional Information (Details)	3 Months Ended
	Mar. 31, 2020 USD ($) security	Dec. 31, 2019 USD ($) security
Investment Securities [Line Items]
Equity securities	$ 49,701,000	$ 41,410,000
Number of security positions in the debt securities available for sale portfolio in an unrealized loss position (in security) | security	86	182
Fair value of debt securities available for sale pledged as collateral	$ 970,000,000.0
Weighted-average remaining expected life of residential mortgage-backed securities available for sale, years	4 years 9 months 18 days
Amortized cost	$ 1,705,781,000	$ 1,558,787,000
Fair Value	1,749,842,000	1,566,801,000
Gross unrealized losses	3,065,000	$ 5,582,000
Impairment loss	0
Allowance for credit losses	$ 0
Number of security positions in the securities held to maturity portfolio in an unrealized loss position (in security) | security	24	82
Fair value of investments held to maturity pledged as collateral	$ 1,500,000,000
Weighted-average remaining expected life of residential mortgage-backed securities held to maturity, years	6 years 6 months
Forecast period	2 years
Historical loss experience period	1 year
US States and Political Subdivisions Debt Securities, Special Revenue Bonds
Investment Securities [Line Items]
Amortized cost	$ 91,800,000
Fair Value	92,400,000
Gross unrealized losses	$ 234,000
Investment percentage	50.00%
Non-investment grade rated
Investment Securities [Line Items]
Number of debt securities held to maturity | security	0	0
Money market mutual fund
Investment Securities [Line Items]
Equity securities	$ 41,700,000	$ 41,400,000