Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue out of scope of ASC 606									$ 306,647	$ 243,956	$ 249,305
Total noninterest income	$ 127,236	$ 118,810	$ 133,054	$ 136,963	$ 158,052	$ 94,258	$ 109,718	$ 103,504	516,063	465,532	454,397
Fees and service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Revenue out of scope of ASC 606									619	98	135
Total noninterest income									112,681	127,860	113,242
Wealth management revenue
Disaggregation of Revenue [Line Items]
Revenue out of scope of ASC 606									19,862	8,209
Total noninterest income									25,701	10,413
Card and ATM revenue
Disaggregation of Revenue [Line Items]
Revenue out of scope of ASC 606									8,409	5,743	283
Total noninterest income									88,699	87,221	78,406
Other noninterest income
Disaggregation of Revenue [Line Items]
Revenue out of scope of ASC 606									277,757	229,906	248,887
Total noninterest income									288,982	240,038	262,749
Consumer Banking
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606									191,263	204,946	188,365
Total noninterest income									318,029	273,915	262,797
Consumer Banking \| Fees and service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606									101,897	121,080	108,883
Consumer Banking \| Wealth management revenue
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606									5,839	2,204
Consumer Banking \| Card and ATM revenue
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606									80,195	81,472	78,119
Consumer Banking \| Other noninterest income
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606									3,332	190	1,363
Commercial Banking
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606									17,304	16,072	15,720
Total noninterest income									186,304	198,898	190,442
Commercial Banking \| Fees and service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606									10,165	6,682	4,224
Commercial Banking \| Wealth management revenue
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606									0	0
Commercial Banking \| Card and ATM revenue
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606									95	6	4
Commercial Banking \| Other noninterest income
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606									7,044	9,384	11,492
Enterprise Services
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606									849	558	1,007
Total noninterest income									11,730	(7,281)	1,158
Enterprise Services \| Fees and service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606									0	0	0
Enterprise Services \| Wealth management revenue
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606									0	0
Enterprise Services \| Card and ATM revenue
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606									0	0	0
Enterprise Services \| Other noninterest income
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606									$ 849	$ 558	$ 1,007

TCF FINANCIAL CORP 10-K