Acquisitions - Schedule of Purchase Price of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Sep. 17, 2021	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Assets
Goodwill		$ 162,788	$ 151,238	$ 151,238
TCF National Bank
Assets
Cash	$ 4,012
Commercial	99,893
Residential mortgage	54,218
Consumer	52,224
Total loans	206,335
Premises and equipment, net	6,901
Goodwill	11,550
Core deposit intangible	887
Interest receivable	519
Other assets	260
Total assets purchased	230,204
Liabilities
Non-interest bearing	181,403
NOW accounts	303,050
Savings and money market	262,488
Certificates of deposit	99,468
Total deposits	846,409
Interest payable	16
Other liabilities	2,206
Total liabilities assumed	848,631
Net cash received	$ (618,167)