Goodwill and Intangibles - Summary of Other Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 116,515	$ 118,373
Accumulated Amortization	(31,957)	(22,456)
Net Intangible Assets	84,558	95,917
Core deposits
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	95,711	95,711
Accumulated Amortization	(22,727)	(13,326)
Net Intangible Assets	$ 72,984	$ 82,385
Amortization Period	10 years	10 years
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 15,281	$ 17,561
Accumulated Amortization	(6,600)	(7,416)
Net Intangible Assets	$ 8,681	$ 10,145
Customer relationships | Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization Period	7 years	7 years
Customer relationships | Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization Period	15 years	15 years
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 221	$ 221
Accumulated Amortization	(190)	(146)
Net Intangible Assets	$ 31	$ 75
Amortization Period	5 years	5 years
Loan servicing rights
Finite-Lived Intangible Assets [Line Items]
Gross Intangible Assets	$ 5,302	$ 4,880
Accumulated Amortization	(2,440)	(1,568)
Net Intangible Assets	$ 2,862	$ 3,312
Loan servicing rights | Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization Period	10 years	10 years
Loan servicing rights | Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization Period	25 years	25 years