Income Taxes - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Income Taxes [Line Items]
Expected decrease in unrecognized tax benefits	$ 0
Bad debt reserves, created for tax purposes	52,800,000
Unrecognized deferred income tax liability	13,000,000.0
Valuation allowance recorded	0	$ 0
Federal
Income Taxes [Line Items]
Operating loss carryforwards	52,400,000	78,500,000
State
Income Taxes [Line Items]
Operating loss carryforwards	136,300,000	$ 148,400,000
AnchorBank WI
Income Taxes [Line Items]
Bad debt reserves, created for tax purposes	50,900,000
Lafayette Savings Bank
Income Taxes [Line Items]
Bad debt reserves, created for tax purposes	$ 1,900,000