Parent Company Financial Information - Condensed Statements Of Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Income Statements, Captions [Line Items]
Interest income	$ 459,808	$ 291,707	$ 1,077,483	$ 861,420
Interest expense	88,015	38,205	197,204	106,078
Net interest income	371,793	253,502	880,279	755,342
Noninterest income
Total noninterest income	94,258	112,064	307,480	330,529
Noninterest expense
Compensation and employee benefits	155,745	124,996	395,953	372,174
Occupancy and equipment	49,229	42,337	132,789	123,562
Other	87,776	55,685	194,781	201,308
Total noninterest expense	425,620	246,423	915,544	764,442
Income before income tax expense	13,243	116,873	221,336	293,555
Income tax benefit	11,735	(28,034)	(28,866)	(66,083)
Preferred stock dividends	2,494	2,494	7,481	9,094
Impact of preferred stock redemption	0	0	0	3,481
Net income available to common shareholders	19,654	83,702	175,588	206,131
TCF
Condensed Income Statements, Captions [Line Items]
Interest income	89	48	166	160
Interest expense	199	0	199	0
Net interest income	(110)	48	(33)	160
Noninterest income
Dividends from TCF Bank	0	32,001	150,001	331,000
Management fees	0	0	0	0
Other	1,979	5,383	8,742	14,352
Total noninterest income	1,979	37,384	158,743	345,352
Noninterest expense
Compensation and employee benefits	4,838	4,739	12,255	15,320
Occupancy and equipment	141	82	296	220
Other	1,675	1,420	3,689	4,186
Total noninterest expense	6,654	6,241	16,240	19,726
Income before income tax expense	(58,744)	31,191	77,970	325,786
Income tax benefit	11,409	116	14,572	1,633
Income before equity in undistributed earnings (loss) of TCF Bank	(47,335)	31,307	92,542	327,419
Equity in undistributed earnings (loss) of TCF Bank	69,483	54,892	90,527	(108,713)
Net income	22,148	86,199	183,069	218,706
Preferred stock dividends	2,494	2,493	7,482	12,574
Impact of preferred stock redemption	0	0	0	0
Net income available to common shareholders	$ 19,654	$ 83,706	$ 175,587	$ 206,132