Fair Value Measurement - Assets and Liabilities Measured at Fair Value on Nonrecurring Basis (Detail) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Foreclosed assets (Residential real estate)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	$ 123		$ 979
Individually evaluated loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	4,912		1,424
Fair Value Nonrecurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	5,035		2,403
Total Gains/(Losses)	(1,583)		(1,334)
Fair Value Nonrecurring Basis | Individually evaluated loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	4,912	$ 162	1,424
Total Gains/(Losses)	(1,604)	(16)	(1,489)
Fair Value Nonrecurring Basis | Foreclosed Assets | Foreclosed assets (Residential real estate)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	123		979
Total Gains/(Losses)	21		155
Fair Value Nonrecurring Basis | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	0		0
Fair Value Nonrecurring Basis | Level 1 | Individually evaluated loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	0	0	0
Fair Value Nonrecurring Basis | Level 1 | Foreclosed Assets | Foreclosed assets (Residential real estate)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	0		0
Fair Value Nonrecurring Basis | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	0		0
Fair Value Nonrecurring Basis | Level 2 | Individually evaluated loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	0	0	0
Fair Value Nonrecurring Basis | Level 2 | Foreclosed Assets | Foreclosed assets (Residential real estate)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	0		0
Fair Value Nonrecurring Basis | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	5,035		2,403
Fair Value Nonrecurring Basis | Level 3 | Individually evaluated loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	4,912	$ 162	1,424
Fair Value Nonrecurring Basis | Level 3 | Foreclosed Assets | Foreclosed assets (Residential real estate)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	$ 123		$ 979