Mortage Servicing Rights - Summary of Activity in Mortgage Servicing Rights (Detail) $ in Thousands	2 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)
Servicing Asset at Amortized Cost [Line Items]
Addition from acquisition of subsidiary			$ 20,123
MSRs valuation allowance beginning balance		$ 0	0
MSRs impairment	$ (710)	(710)	(710)
MSRs valuation allowance ending balance	(710)	(710)	(710)
MSRs, net of valuation allowance	20,200	20,200	20,200
Mortgage Servicing Rights [Member]
Servicing Asset at Amortized Cost [Line Items]
MSRs beginning balance		0	0
Addition from acquisition of subsidiary		20,123	20,123
Amount capitalized		1,891	1,891
Purchased servicing		0	0
Amount amortized		(1,104)	(1,104)
MSRs ending balance	$ 20,910	$ 20,910	20,910
MSRs impairment			$ (710)