Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Interest income
Interest and fees on loans and leases	$ 392,826	$ 283,282	$ 835,922	$ 566,520
Interest on investment securities:
Taxable	32,505	22,041	73,425	38,707
Tax-exempt	4,155	1,208	8,504	3,892
Interest on loans held-for-sale	3,322	599	4,883	1,424
Interest on other earning assets	5,562	3,651	11,028	7,132
Total interest income	438,370	310,781	933,762	617,675
Interest expense
Interest on deposits	46,785	40,646	114,204	78,254
Interest on borrowings	13,226	16,078	39,718	30,935
Total interest expense	60,011	56,724	153,922	109,189
Net interest income	378,359	254,057	779,840	508,486
Provision for credit losses	78,726	13,569	175,669	23,691
Net interest income after provision for credit losses	299,633	240,488	604,171	484,795
Noninterest income
Noninterest income	133,054	109,718	270,017	213,222
Net gains on sales of loans and leases	29,034	11,141	49,624	19,358
Net gains on investment securities	8	1,066	8	1,517
Other	14,125	5,373	27,708	11,997
Total noninterest income	133,054	109,718	270,017	213,222
Noninterest expense
Compensation and employee benefits	171,799	116,266	343,327	240,208
Occupancy and equipment	54,107	41,850	111,395	83,560
Lease financing equipment depreciation	18,212	19,133	36,662	38,389
Net foreclosed real estate and repossessed assets	998	2,448	2,857	7,078
Merger-related expenses	81,619	4,226	118,347	13,684
Other	73,506	52,926	162,252	107,005
Total noninterest expense	400,241	236,849	774,840	489,924
Income before income tax expense	32,446	113,357	99,348	208,093
Income tax expense	6,213	19,314	19,299	40,601
Income after income tax expense	26,233	94,043	80,049	167,492
Income attributable to non-controlling interest	2,469	3,616	4,386	6,571
Net income attributable to TCF Financial Corporation	23,764	90,427	75,663	160,921
Preferred stock dividends	2,494	2,494	4,987	4,987
Net income available to common shareholders	$ 21,270	$ 87,933	$ 70,676	$ 155,934
Earnings per common share:
Basic earnings per common share (in usd per share)	$ 0.14	$ 1.07	$ 0.47	$ 1.89
Diluted earnings per common share (in usd per share)	$ 0.14	$ 1.07	$ 0.47	$ 1.89
Weighted-average common shares outstanding
Basic (in shares)	151,613,126	82,298,920	151,757,742	82,272,396
Diluted (in shares)	151,660,139	82,298,920	151,837,226	82,272,396
Leasing revenue
Noninterest income
Noninterest income	$ 37,172	$ 39,277	$ 70,737	$ 77,442
Fees and service charges on deposit accounts
Noninterest income
Noninterest income	22,832	27,842	57,429	54,120
Card and ATM revenue
Noninterest income
Noninterest income	20,636	20,496	42,321	39,155
Wealth management revenue
Noninterest income
Noninterest income	6,206	0	12,357	0
Servicing fee revenue
Noninterest income
Noninterest income	$ 3,041	$ 4,523	$ 9,833	$ 9,633