Parent Company Financial Information - Condensed Statements of Financial Condition (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets:
Cash and due from banks	$ 1,228,371	$ 587,057	$ 621,782	$ 609,603
Premises and equipment, net	533,138	427,534
Other assets	1,479,401	792,936
Total assets	46,651,553	23,699,612	23,002,159
Liabilities and Equity:
Long term borrowings	2,354,448
Accrued expenses and other liabilities	1,432,256	790,194
Total liabilities	40,924,312	21,143,352
Equity	5,707,015	2,537,801
Total liabilities and equity	46,651,553	23,699,612
TCF Financial Corporation
Assets:
Cash and due from banks	157,103	91,132	$ 80,471	$ 69,711
Premises and equipment, net	3,813	78
Deferred tax asset	8,536	2,974
Investment in TCF Bank	5,526,078	2,426,329
Accounts receivable from TCF Bank	25,887	23,780
Other assets	40,961	1,201
Total assets	5,762,378	2,545,494
Liabilities and Equity:
Long term borrowings	19,021	0
Accrued expenses and other liabilities	36,342	7,693
Total liabilities	55,363	7,693
Equity	5,707,015	2,537,801
Total liabilities and equity	$ 5,762,378	$ 2,545,494