Goodwill and Other Intangible Assets - Summary of Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount	$ 56,928	$ 49,962
Accumulated Amortization	(30,710)	(25,888)
Net Carrying Amount	26,218	24,074
Core Deposit Intangibles
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount	54,958	47,992
Accumulated Amortization	(29,911)	(25,188)
Net Carrying Amount	25,047	22,804
Customer Relationship Intangible
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount	1,970	1,970
Accumulated Amortization	(799)	(700)
Net Carrying Amount	$ 1,171	$ 1,270