Parent Company Financial Information - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Share-based compensation expense	$ 28,351	$ 17,824	$ 14,743
Depreciation and amortization	308,638	204,778	191,824
Provision (benefit) for deferred income taxes	30,410	58,986	(53,729)
Net change in other assets	(263,351)	(35,154)	(108,700)
Net change in other liabilities	162,533	39,898	17,826
Other, net	(65,921)	(41,949)	(36,196)
Cash flows from investing activities
Purchases of premises and equipment and lease equipment	(154,540)	(155,664)	(168,272)
Cash flows from financing activities
Redemption of preferred stock	0	(100,000)	0
Net proceeds from public offering of Series C preferred stock	0	0	169,302
Repurchases of common stock	(86,309)	(212,929)	(9,163)
Common shares sold to TCF employee benefit plans	0	715	23,254
Dividends paid on preferred stock	(9,975)	(11,588)	(19,904)
Dividends paid on common stock	(156,060)	(99,490)	(50,617)
Payments related to tax-withholding upon conversion of share-based awards	(6,198)	(6,865)	(5,506)
Exercise of stock options	29	(997)	(57)
Net change in cash and due from banks	641,314	(34,725)	12,179
Cash and cash equivalents at beginning of period	587,057	621,782	609,603
Cash and cash equivalents at end of period	1,228,371	587,057	621,782
TCF Financial Corporation
Condensed Statements of Cash Flows
Net income	295,468	304,358	268,637
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Equity in undistributed (earnings) loss of TCF Bank	(134,726)	122,487	(206,067)
Share-based compensation expense	28,351	17,824	14,743
Depreciation and amortization	(640)	4,986	9,110
Provision (benefit) for deferred income taxes	4,893	(583)	4,690
Net gains (losses) on sales of assets	6	(402)	0
Net change in other assets	(1,072)	753	0
Net change in other liabilities	(1,154)	(374)	(2,494)
Other, net	(21,719)	(7,958)	(12,645)
Net cash provided by operating activities	169,407	441,091	75,974
Cash flows from investing activities
Purchases of premises and equipment and lease equipment	(95)	(3)	(23)
Proceeds from sales of premises and equipment	17	727	0
Net cash acquired in business combination	155,155	0	0
Net cash provided by (used in) investing activities	155,077	724	(23)
Cash flows from financing activities
Net proceeds from public offering of Series C preferred stock	0	0	169,302
Repurchases of common stock	(86,309)	(212,929)	(9,163)
Common shares sold to TCF employee benefit plans	0	715	23,254
Dividends paid on preferred stock	(9,975)	(11,588)	(19,904)
Dividends paid on common stock	(156,060)	(99,490)	(50,617)
Payments related to tax-withholding upon conversion of share-based awards	(6,198)	(6,865)	(5,506)
Exercise of stock options	29	(997)	(57)
Net cash used in financing activities	(258,513)	(431,154)	(65,191)
Net change in cash and due from banks	65,971	10,661	10,760
Cash and cash equivalents at beginning of period	91,132	80,471	69,711
Cash and cash equivalents at end of period	157,103	91,132	80,471
TCF Financial Corporation | Series B Preferred Stock
Cash flows from financing activities
Redemption of preferred stock	0	(100,000)	0
TCF Financial Corporation | Series A Preferred Stock
Cash flows from financing activities
Redemption of preferred stock	$ 0	$ 0	$ (172,500)