Goodwill and Other Intangible Assets - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 1,382,442,000		$ 1,382,442,000
Goodwill impairment	0	$ 0
Net impairment (net recovery)	(791,000)	109,000
Amortization of other intangible assets	$ 6,006,000	5,470,000
Core Deposits
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period, years	8 years 10 months 24 days
Other
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period, years	7 years 7 months 6 days
Core Deposits and Other
Finite-Lived Intangible Assets [Line Items]
Impairment of core deposits and other intangibles	$ 0	$ 0