Earnings Per Common Share - Computations of basic and diluted earnings per common share (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Basic Earnings Per Common Share:
Net income attributable to TCF Financial Corporation		$ 304,358	$ 268,637	$ 212,124
Preferred stock dividends		11,588	19,904	19,388
Impact of preferred stock redemption	[1]	3,481	5,779	0
Net income available to common stockholders		289,289	242,954	192,736
Less: Earnings allocated to participating securities		42	42	49
Earnings allocated to common stock		$ 289,247	$ 242,912	$ 192,687
Weighted-average common shares outstanding used in basic earnings per common share calculation (in shares)		165,585,493	168,679,501	167,219,964
Basic earnings per common share (in dollars per share)		$ 1.75	$ 1.44	$ 1.15
Diluted Earnings Per Common Share:
Earnings allocated to common stock		$ 289,247	$ 242,912	$ 192,687
Weighted-average common shares outstanding used in basic earnings per common share calculation (in shares)		165,585,493	168,679,501	167,219,964
Net dilutive effect of:
Non-participating restricted stock (in shares)		600,884	353,610	505,162
Stock options (in shares)		2,332	28,625	82,325
Warrants (in shares)		372,996	27,508	0
Weighted-average common shares outstanding used in diluted earnings per common share calculation (in shares)		166,561,705	169,089,244	167,807,451
Diluted earnings per common share (in dollars per share)		$ 1.74	$ 1.44	$ 1.15

[1] Amounts represent the deferred stock issuance costs originally recorded in preferred stock that were reclassified to retained earnings.