Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Interest income
Interest and fees on loans and leases	$ 443,096	$ 283,238
Interest on investment securities:
Taxable	40,920	16,666
Tax-exempt	4,349	2,684
Interest on loans held-for-sale	1,561	825
Interest on other earning assets	5,466	3,481
Total interest income	495,392	306,894
Interest expense
Interest on deposits	67,419	37,608
Interest on borrowings	26,492	14,857
Total interest expense	93,911	52,465
Net interest income	401,481	254,429
Provision for credit losses	96,943	10,122
Net interest income after provision for credit losses	304,538	244,307
Noninterest income
Noninterest income	136,963	51,561
Net gains on sales of loans and leases	20,590	8,217
Net gains (losses) on investment securities	0	451
Other	13,583	6,624
Total noninterest income	136,963	103,504
Noninterest expense
Compensation and employee benefits	171,528	123,942
Occupancy and equipment	57,288	41,710
Lease financing equipment depreciation	18,450	19,256
Net foreclosed real estate and repossessed assets	1,859	4,630
Merger-related expenses	36,728	9,458
Other	88,746	54,079
Total noninterest expense	374,599	253,075
Income before income tax expense	66,902	94,736
Income tax expense	13,086	21,287
Income after income tax expense	53,816	73,449
Income attributable to non-controlling interest	1,917	2,955
Net income attributable to TCF Financial Corporation	51,899	70,494
Preferred stock dividends	2,493	2,493
Net income available to common shareholders	$ 49,406	$ 68,001
Earnings per common share:
Basic earnings per common share (in usd per share)	$ 0.33	$ 0.83
Diluted earnings per common share (in usd per share)	$ 0.32	$ 0.83
Weighted-average common shares outstanding
Basic (in shares)	151,902,357	82,245,577
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Assets	$ (17,200)
Diluted (in shares)	152,114,017	82,245,577
Leasing revenue
Noninterest income
Noninterest income	$ 33,565	$ 38,165
Fees and service charges on deposit accounts
Noninterest income
Noninterest income	34,597	26,278
Card and ATM revenue
Noninterest income
Noninterest income	21,685	18,659
Servicing fee revenue
Noninterest income
Noninterest income	6,792	5,110
Wealth management revenue
Noninterest income
Noninterest income	$ 6,151	$ 0