Goodwill and Identifiable Intangible Assets - Carrying Amount of Goodwill and Intangibles (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Intangible Assets And Goodwill [Line Items]
Goodwill, Beginning Balance	$ 2,714	$ 2,714	$ 2,714
Total, Beginning Balance	3,940	4,239
Additions	237
Amortization Expense	(261)	(299)
Total, Ending Balance	3,916	3,940
Mortgage Servicing Rights [Member]
Intangible Assets And Goodwill [Line Items]
Beginning Balance	1,226	1,525
Additions	237
Amortization Expense	(261)	(299)
Ending Balance	$ 1,202	$ 1,226