Consolidated Statements of Equity (Unaudited) - USD ($) $ in Thousands	Total	Series C Preferred Stock	Total	Total Series C Preferred Stock	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Series C Preferred Stock	Accumulated Other Comprehensive Income (Loss)	Other	Non-controlling Interest	Cumulative Effect, Period of Adoption, Adjustment	[1]	Cumulative Effect, Period of Adoption, Adjustment Total	[1]	Cumulative Effect, Period of Adoption, Adjustment Retained Earnings	[1]	Cumulative Effect, Period of Adoption, Adjustment Non-controlling Interest	[1]	Cumulative Effect, Period of Adoption, Adjusted Balance	Cumulative Effect, Period of Adoption, Adjusted Balance Total	Cumulative Effect, Period of Adoption, Adjusted Balance Preferred Stock	Cumulative Effect, Period of Adoption, Adjusted Balance Common Stock	Cumulative Effect, Period of Adoption, Adjusted Balance Additional Paid-in Capital	Cumulative Effect, Period of Adoption, Adjusted Balance Retained Earnings	Cumulative Effect, Period of Adoption, Adjusted Balance Accumulated Other Comprehensive Income (Loss)	Cumulative Effect, Period of Adoption, Adjusted Balance Other	Cumulative Effect, Period of Adoption, Adjusted Balance Non-controlling Interest
Balance (in shares) at Dec. 31, 2018					7,000	88,198,460
Balance at Dec. 31, 2018	$ 2,556,260		$ 2,537,801		$ 169,302	$ 88,198	$ 798,627	$ 1,766,994		$ (33,138)	$ (252,182)	$ 18,459
Increase (Decrease) in Equity
Income after income tax (benefit) expense	192,470		183,069					183,069				9,401
Other comprehensive income (loss), net of tax	89,366		89,366							89,366
Reverse merger with Chemical Financial Corporation (in shares)						65,539,678
Reverse merger with Chemical Financial Corporation	3,018,556		3,018,556			$ 65,540	2,687,153				265,863
Net investment by (distribution to) non-controlling interest	$ (4,547)											(4,547)
Repurchases of shares of common stock (in shares)	(1,453,908)
Repurchases of shares of common stock	$ (58,805)		(58,805)								(58,805)
Dividends on 5.70% Series C Preferred Stock		$ (7,481)		$ (7,481)				(7,481)
Dividends on common stock	(102,368)		(102,368)					(102,368)
Stock compensation plans, net of tax (in shares)						(166,757)
Stock compensation plans, net of tax	9,966		9,966			$ (167)	(5,626)				15,759
Change in shares held in trust for deferred compensation plans, at cost							(1,995)				1,995
Balance (in shares) at Sep. 30, 2019					7,000	153,571,381
Balance at Sep. 30, 2019	5,693,417		5,670,104		$ 169,302	$ 153,571	3,478,159	1,840,214		56,228	(27,370)	23,313
Balance (in shares) at Jun. 30, 2019					7,000	87,943,860
Balance at Jun. 30, 2019	2,710,517		2,685,659		$ 169,302	$ 87,944	781,788	1,874,308		37,334	(265,017)	24,858
Increase (Decrease) in Equity
Income after income tax (benefit) expense	24,978		22,148					22,148				2,830
Other comprehensive income (loss), net of tax	18,894		18,894							18,894
Reverse merger with Chemical Financial Corporation (in shares)						65,539,678
Reverse merger with Chemical Financial Corporation	3,018,556		3,018,556			$ 65,540	2,687,153				265,863
Net investment by (distribution to) non-controlling interest	$ (4,375)											(4,375)
Repurchases of shares of common stock (in shares)	(780,716)
Repurchases of shares of common stock	$ (32,310)		(32,310)								(32,310)
Dividends on 5.70% Series C Preferred Stock		(2,494)		(2,494)					$ (2,494)
Dividends on common stock	(53,748)		(53,748)					(53,748)
Stock compensation plans, net of tax (in shares)						87,843
Stock compensation plans, net of tax	13,399		13,399			$ 87	13,070				242
Change in shares held in trust for deferred compensation plans, at cost							(3,852)				3,852
Balance (in shares) at Sep. 30, 2019					7,000	153,571,381
Balance at Sep. 30, 2019	5,693,417		5,670,104		$ 169,302	$ 153,571	3,478,159	1,840,214		56,228	(27,370)	23,313
Balance (in shares) at Dec. 31, 2019					7,000	152,965,571																	7,000	152,965,571
Balance at Dec. 31, 2019	5,727,241		5,707,015		$ 169,302	$ 152,966	3,462,080	1,896,427		54,277	(28,037)	20,226	$ (159,249)		$ (159,323)		$ (159,323)		$ 74		$ 5,567,992	$ 5,547,692	$ 169,302	$ 152,966	$ 3,462,080	$ 1,737,104	$ 54,277	$ (28,037)	$ 20,300
Increase (Decrease) in Equity
Income after income tax (benefit) expense	137,351		131,401					131,401				5,950
Other comprehensive income (loss), net of tax	137,494		137,494							137,494
Net investment by (distribution to) non-controlling interest	$ (4,874)											(4,874)
Repurchases of shares of common stock (in shares)	(873,376)					(873,376)
Repurchases of shares of common stock	$ (33,098)		(33,098)			$ (873)	(32,225)
Dividends on 5.70% Series C Preferred Stock		(7,481)		(7,481)				(7,481)
Dividends on common stock	(160,980)		(160,980)					(160,980)
Stock compensation plans, net of tax (in shares)						287,527
Stock compensation plans, net of tax	22,016		22,016			$ 287	21,729
Change in shares held in trust for deferred compensation plans, at cost							(915)				915
Balance (in shares) at Sep. 30, 2020					7,000	152,379,722
Balance at Sep. 30, 2020	5,658,420		5,637,044		$ 169,302	$ 152,380	3,450,669	1,700,044		191,771	(27,122)	21,376
Balance (in shares) at Jun. 30, 2020					7,000	152,233,106
Balance at Jun. 30, 2020	5,658,555		5,635,255		$ 169,302	$ 152,233	3,441,925	1,700,480		198,408	(27,093)	23,300
Increase (Decrease) in Equity
Income after income tax (benefit) expense	57,302		55,738					55,738				1,564
Other comprehensive income (loss), net of tax	(6,637)		(6,637)					0		(6,637)		0
Net investment by (distribution to) non-controlling interest	$ (3,488)											(3,488)
Repurchases of shares of common stock (in shares)	0
Dividends on 5.70% Series C Preferred Stock		$ (2,494)		$ (2,494)					$ (2,494)
Dividends on common stock	$ (53,680)		(53,680)					(53,680)
Stock compensation plans, net of tax (in shares)						146,616
Stock compensation plans, net of tax	8,862		8,862			$ 147	8,715				0
Change in shares held in trust for deferred compensation plans, at cost							29				(29)
Balance (in shares) at Sep. 30, 2020					7,000	152,379,722
Balance at Sep. 30, 2020	$ 5,658,420		$ 5,637,044		$ 169,302	$ 152,380	$ 3,450,669	$ 1,700,044		$ 191,771	$ (27,122)	$ 21,376

[1] See "Note 3. Summary of Significant Accounting Policies" for further information