Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Income tax benefits due to deferred tax assets and state tax rate	$ 3,600
State	(2,873)	$ 12,823	$ 11,820
Decrease in the state effective tax rate	1,000
Acquired thrift's tax bad debt reserve	5,800	5,800	5,800
Deferred tax assets, net	57,378	43,382
Operating Loss Carryforwards, Valuation Allowance	2,100	2,000
Unrecognized tax benefit that would affect effective tax rate	12,300	13,000	13,100
Park Bank
Income Taxes [Line Items]
Deferred tax assets, net	5,000
Bridgeview Bancorp, Inc.
Income Taxes [Line Items]
Deferred tax assets, net		$ 32,100
State
Income Taxes [Line Items]
State	$ 2,600
Federal
Income Taxes [Line Items]
Revaluation of deferred tax assets			$ 8,700