Goodwill and Other Intangible Assets - Summary of Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Goodwill And Other Intangible Assets [Line Items]
Goodwill	$ 43,061	$ 485,336
Other intangible assets, net	99,721	105,613
Total goodwill and intangible assets, net	142,782	590,949
Core Deposit
Goodwill And Other Intangible Assets [Line Items]
Other intangible assets, net	85,829	90,788
Customer Lists
Goodwill And Other Intangible Assets [Line Items]
Other intangible assets, net	11,369	11,993
Noncompete Agreements
Goodwill And Other Intangible Assets [Line Items]
Other intangible assets, net	1,184	1,473
Trademarks
Goodwill And Other Intangible Assets [Line Items]
Other intangible assets, net	$ 1,339	$ 1,359