Earnings Per Common Share - Calculation of EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Basic Earnings Per Common Share:
Net income attributable to TCF Financial Corporation	$ 51,899	$ 70,494
Preferred stock dividends	2,493	2,493
Net income available to common stockholders	49,406	68,001
Less: Earnings allocated to participating securities	0	13
Earnings allocated to common stock	$ 49,406	$ 67,988
Weighted-average common shares outstanding used in basic earnings per common share calculation (in shares)	151,902,357	82,245,577
Basic earnings per common share (in usd per share)	$ 0.33	$ 0.83
Diluted Earnings Per Common Share:
Earnings allocated to common stock	$ 49,406	$ 67,988
Weighted-average common shares outstanding used in basic earnings per common share calculation (in shares)	151,902,357	82,245,577
Net dilutive effect of:
Non-participating restricted stock (in shares)	83,580	0
Stock options (in shares)	128,080	0
Weighted-average common shares outstanding used in diluted earnings per common share calculation (in shares)	152,114,017	82,245,577
Diluted earnings per common share (in usd per share)	$ 0.32	$ 0.83
Non-participating restricted stock
Anti-dilutive shares outstanding not included in the computation of diluted earnings per share:
Non-participating restricted stock (in shares)	1,173,331	956,589
Stock options
Anti-dilutive shares outstanding not included in the computation of diluted earnings per share:
Non-participating restricted stock (in shares)	90,144	0