Goodwill and Other Intangible Assets - Summary of Goodwill and Other Intangible Assets (Parenthetical) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Core Deposit
Goodwill And Other Intangible Assets [Line Items]
Accumulated amortization of intangible assets	$ 44,989	$ 39,385
Customer Lists
Goodwill And Other Intangible Assets [Line Items]
Accumulated amortization of intangible assets	20,311	19,709
Trademarks
Goodwill And Other Intangible Assets [Line Items]
Accumulated amortization of intangible assets	$ 16	$ 0