Business - Additional Information (Detail) $ in Millions	Sep. 30, 2018 Location Subsidiary	Aug. 10, 2018 USD ($)
Schedule Of Description Of Company [Line Items]
Number of inactive subsidiaries | Subsidiary	1
Bank operated banking centers	68
Bank operated trust office locations, number	3
Community Bank [Member]
Schedule Of Description Of Company [Line Items]
Bank operated banking centers		16
Total assets | $		$ 4,090