Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Series A Preferred Stock	Series B Preferred Stock	Series C Preferred Stock	Preferred Stock	Preferred Stock Series A Preferred Stock	Preferred Stock Series B Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Series A Preferred Stock	Retained Earnings Series B Preferred Stock	Retained Earnings Series C Preferred Stock	Accumulated Other Comprehensive Income (Loss)	Treasury Stock and Other	Total	Total Series A Preferred Stock	Total Series B Preferred Stock	Total Series C Preferred Stock	Non-controlling Interest
Increase (Decrease) in Equity
Change in accounting principle									$ 1,319	$ (1,319)
Adjusted balance after cumulative adjustment related to change in accounting principle	$ 2,444,645				$ 263,240			$ 86,903	778,902	1,381,582				$ (33,725)	$ (49,419)	$ 2,427,483				$ 17,162
Balance (in shares) at Dec. 31, 2016					4,006,900			86,902,632
Balance at Dec. 31, 2016	2,444,645				$ 263,240			$ 86,903	777,583	1,382,901				(33,725)	(49,419)	2,427,483				17,162
Increase (Decrease) in Equity
Reclassification of stranded tax effects from AOCI to retained earnings										3,392				(3,392)
Net income	278,784									268,637						268,637				10,147
Other comprehensive income (loss), net of tax	18,600													18,600		18,600
Net investment by (distribution to) non-controlling interest	$ (9,482)																			(9,482)
Treasury Stock, Shares, Acquired	226,848
Public offering of Series C Preferred Stock (in shares)					7,000
Public offering of Series C Preferred Stock	$ 169,302				$ 169,302											169,302
Redemption of Series B Preferred Stock (in shares)						(6,900)
Redemption of Series B Preferred Stock		$ (172,500)				$ (166,721)					$ (5,779)						$ (172,500)
Repurchases of shares of common stock	(9,163)														(9,163)	(9,163)
Dividends on Preferred Stock		$ (11,320)	$ (6,450)	$ (2,134)							$ (11,320)	$ (6,450)	$ (2,134)				$ (11,320)	$ (6,450)	$ (2,134)
Dividends on common stock	(50,617)									(50,617)						(50,617)
Common shares purchased by TCF employee benefit plans (in shares)								701,914
Common shares purchased by TCF employee benefit plans	23,254							$ 702	22,552							23,254
Stock compensation plans, net of tax (in shares)								(130,838)
Stock compensation plans, net of tax	7,665							$ (131)	7,796							7,665
Change in shares held in trust for deferred compensation plans, at cost									(17,785)						17,785
Balance (in shares) at Dec. 31, 2017					4,007,000			87,473,708
Balance at Dec. 31, 2017	2,680,584				$ 265,821			$ 87,474	791,465	1,577,311				(18,517)	(40,797)	2,662,757				17,827
Increase (Decrease) in Equity
Change in accounting principle	(116)									(116)						(116)
Adjusted balance after cumulative adjustment related to change in accounting principle	2,680,468				$ 265,821			$ 87,474	791,465	1,577,195				(18,517)	(40,797)	2,662,641				17,827
Net income	315,628									304,358						304,358				11,270
Other comprehensive income (loss), net of tax	(14,621)													(14,621)		(14,621)
Net investment by (distribution to) non-controlling interest	$ (10,638)																			(10,638)
Treasury Stock, Shares, Acquired	4,668,722
Redemption of Series B Preferred Stock (in shares)							(4,000,000)
Redemption of Series B Preferred Stock			(100,000)				$ (96,519)					(3,481)						(100,000)
Repurchases of shares of common stock	$ (212,929)														(212,929)	(212,929)
Dividends on Preferred Stock			$ (1,613)	(9,975)								$ (1,613)	(9,975)					$ (1,613)	(9,975)
Dividends on common stock	(99,490)									(99,490)						(99,490)
Common stock warrants exercised (in shares)								553,279
Common stock warrants exercised								$ 553	(553)
Common shares purchased by TCF employee benefit plans (in shares)								17,594
Common shares purchased by TCF employee benefit plans	715							$ 18	697							715
Stock compensation plans, net of tax (in shares)								153,879
Stock compensation plans, net of tax	8,715							$ 153	8,184						378	8,715
Change in shares held in trust for deferred compensation plans, at cost									(1,166)						1,166
Balance (in shares) at Dec. 31, 2018					7,000			88,198,460
Balance at Dec. 31, 2018	2,556,260				$ 169,302			$ 88,198	798,627	1,766,994				(33,138)	(252,182)	2,537,801				18,459
Increase (Decrease) in Equity
Net income	306,926									295,468						295,468				11,458
Other comprehensive income (loss), net of tax	87,415													87,415		87,415
Reverse merger with Chemical Financial Corporation (in shares)								65,539,678
Reverse merger with Chemical Financial Corporation	3,018,556							$ 65,540	2,687,153						265,863	3,018,556
Net investment by (distribution to) non-controlling interest	$ (9,691)																			(9,691)
Treasury Stock, Shares, Acquired	2,111,725							657,817
Repurchases of shares of common stock	$ (86,309)							$ (658)	(26,846)						(58,805)	(86,309)
Dividends on Preferred Stock				$ (9,975)									$ (9,975)						$ (9,975)
Dividends on common stock	(156,060)									(156,060)						(156,060)
Stock compensation plans, net of tax (in shares)								(114,750)
Stock compensation plans, net of tax	20,119							$ (114)	4,474						15,759	20,119
Change in shares held in trust for deferred compensation plans, at cost									(1,328)						1,328
Balance (in shares) at Dec. 31, 2019					7,000			152,965,571
Balance at Dec. 31, 2019	$ 5,727,241				$ 169,302			$ 152,966	$ 3,462,080	$ 1,896,427				$ 54,277	$ (28,037)	$ 5,707,015				$ 20,226