Equity - Restricted Retained Earnings and Treasury Stock and Other (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restricted Retained Earnings
Undistributed earnings of TCF's bank subsidiary	$ 170,200,000
Amount of provision for federal income taxes related to undistributed earnings of TCF's bank subsidiary	0
Treasury Stock and Other
Treasury stock at cost and other (4,909,069 Treasury shares at December 31, 2018)	0	$ 222,816,000
Shares held in trust for deferred compensation plans, at cost	28,037,000	29,366,000
Total	28,037,000	252,182,000
Repurchases of common stock	86,309,000	$ 212,929,000	$ 9,163,000
Aggregate value remaining in the stock repurchase program	$ 122,500,000
Treasury stock reissued (in shares)	347,329	8,130	0
Treasury stock reissued	$ 12,900,000	$ 378,000