Goodwill and Other Intangible Assets - Summary of Goodwill and Other Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Goodwill And Other Intangible Assets [Line Items]
Goodwill	$ 307,083	$ 317,817
Other intangible assets, net	7,317	10,223
Total goodwill and intangible assets	314,400	328,040
Core Deposit
Goodwill And Other Intangible Assets [Line Items]
Other intangible assets, net	301	1,595
Customer Lists
Goodwill And Other Intangible Assets [Line Items]
Other intangible assets, net	6,992	8,604
Trademarks
Goodwill And Other Intangible Assets [Line Items]
Other intangible assets, net	$ 24	$ 24