Earnings Per Share - Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Net income (loss)	$ 1,317	$ 449
Weighted shares outstanding for basic EPS
Weighted average shares outstanding	4,807,158,000	4,876,677,000
Less: Weighted average unallocated ESOP shares	164,987,000	172,895,000
Weighted average shares outstanding for basic EPS	4,642,171	4,703,782
Additional dilutive shares	43,037,000
Weighted average shares outstanding for basic and dilutive EPS	4,685,208,000	4,703,782,000
Basic and diluted income (loss) per share	$ 0.28	$ 0.10
Diluted income per share	$ 0.28	$ 0.10