Goodwill and Other Intangible Assets - Summary of Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount	$ 84,962	$ 84,962
Accumulated Amortization	(59,440)	(54,823)
Net Carrying Amount	25,522	30,139
Core deposit intangibles
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount	82,492	82,492
Accumulated Amortization	(58,020)	(53,539)
Net Carrying Amount	24,472	28,953
Customer relationship intangible
Finite-Lived Intangible Assets, Net [Abstract]
Gross Carrying Amount	2,470	2,470
Accumulated Amortization	(1,420)	(1,284)
Net Carrying Amount	$ 1,050	$ 1,186