Goodwill and Other Intangible Assets - Summary of Goodwill and Other Intangible Assets (Parenthetical) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Core Deposit
Goodwill And Other Intangible Assets [Line Items]
Accumulated amortization of intangible assets	$ 39,385	$ 38,091
Customer Lists
Goodwill And Other Intangible Assets [Line Items]
Accumulated amortization of intangible assets	$ 19,709	$ 18,097

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

Name:	us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant