Selected Quarterly Financial Data (Unaudited) - Summary of Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Net interest income	$ 408,753	$ 371,793	$ 254,057	$ 254,429	$ 253,153	$ 253,502	$ 254,751	$ 247,089	$ 1,289,032	$ 1,008,495	$ 937,474
Provision for credit losses	14,403	27,188	13,569	10,122	18,894	2,270	14,236	11,368	65,282	46,768	68,443
Net interest income after provision for credit losses	394,350	344,605	240,488	244,307	234,259	251,232	240,515	235,721	1,223,750	961,727	869,031
Total noninterest income	158,052	94,258	109,718	103,504	123,868	112,064	110,151	108,314	465,532	454,397	436,063
Noninterest expense	416,571	425,620	236,849	253,075	249,958	246,423	272,039	245,980	1,332,115	1,014,400	1,059,934
Income before income tax expense	135,831	13,243	113,357	94,736	108,169	116,873	78,627	98,055	357,167	401,724	245,160
Income tax expense (benefit)	21,375	(11,735)	19,314	21,287	20,013	28,034	16,418	21,631	50,241	86,096	(33,624)
Income after income tax expense (benefit)	114,456	24,978	94,043	73,449	88,156	88,839	62,209	76,424	306,926	315,628	278,784
Income attributable to non-controlling interest	2,057	2,830	3,616	2,955	2,504	2,643	3,460	2,663	11,458	11,270	10,147
Net income attributable to TCF Financial Corporation	112,399	22,148	90,427	70,494	85,652	86,196	58,749	73,761	295,468	304,358	268,637
Preferred stock dividends	2,494	2,494	2,494	2,493	2,494	2,494	2,494	4,106	9,975	11,588	19,904
Impact of preferred stock redemption	0	0	0	0	0	0	0	3,481	0	3,481	5,779
Net income available to common shareholders	$ 109,905	$ 19,654	$ 87,933	$ 68,001	$ 83,158	$ 83,702	$ 56,255	$ 66,174	$ 285,493	$ 289,289	$ 242,954
Basic (in usd per share)	$ 0.72	$ 0.15	$ 1.07	$ 0.83	$ 1.00	$ 1.00	$ 0.67	$ 0.77	$ 2.56	$ 3.44	$ 2.83
Diluted (in usd per share)	$ 0.72	$ 0.15	$ 1.07	$ 0.83	$ 1.00	$ 1.00	$ 0.67	$ 0.77	$ 2.55	$ 3.43	$ 2.83