Goodwill and Intangible Assets - Summary of Carrying Amount of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Cost	$ 21,388	$ 389
Accumulated Amortization	(2,776)	(57)
Net Book Value	18,612	332
Core deposit intangible
Finite-Lived Intangible Assets [Line Items]
Cost	16,057
Accumulated Amortization	(2,408)
Net Book Value	13,649
Customer lists
Finite-Lived Intangible Assets [Line Items]
Cost	5,214	364
Accumulated Amortization	(308)	(43)
Net Book Value	4,906	321
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Cost	117	25
Accumulated Amortization	(60)	(14)
Net Book Value	$ 57	$ 11