Consolidated Statements of Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest income:
Loans and leases		$ 1,065,137	$ 954,246	$ 850,546
Debt securities available for sale		54,574	33,278	26,573
Debt securities held to maturity		3,970	4,436	4,649
Loans held for sale and other		18,583	27,097	48,962
Total interest income		1,142,264	1,019,057	930,730
Interest expense:
Deposits		107,113	66,012	61,788
Borrowings		43,144	27,807	20,836
Total interest expense		150,257	93,819	82,624
Net interest income		992,007	925,238	848,106
Provision for credit losses		46,768	68,443	65,874
Net interest income after provision for credit losses		945,239	856,795	782,232
Non-interest income:
Leasing and equipment finance		185,107	145,039	119,166
Gains on sale of loans, net		33,498	42,787	85,259
Gains (losses) on debt securities, net		348	237	(581)
Other		13,843	11,646	8,883
Total non-interest income		470,885	448,299	465,900
Non-interest expense:
Compensation and employee benefits		497,063	482,512	475,964
Occupancy and equipment		165,812	156,909	149,980
Operating lease depreciation		73,829	55,901	40,359
Foreclosed real estate and repossessed assets, net		17,050	17,756	13,187
Other		260,646	346,856	230,397
Total non-interest expense		1,014,400	1,059,934	909,887
Income before income tax expense (benefit)		401,724	245,160	338,245
Income tax expense (benefit)		86,096	(33,624)	116,528
Income after income tax expense (benefit)		315,628	278,784	221,717
Income attributable to non-controlling interest		11,270	10,147	9,593
Net income attributable to TCF Financial Corporation		304,358	268,637	212,124
Preferred stock dividends		11,588	19,904	19,388
Impact of preferred stock redemption	[1]	3,481	5,779	0
Net income available to common stockholders		$ 289,289	$ 242,954	$ 192,736
Earnings per common share:
Basic (in dollars per share)		$ 1.75	$ 1.44	$ 1.15
Diluted (in dollars per share)		$ 1.74	$ 1.44	$ 1.15
Weighted-average common shares outstanding:
Basic (in shares)		165,585,493	168,679,501	167,219,964
Diluted (in shares)		166,561,705	169,089,244	167,807,451
Fees and service charges
Non-interest income:
Fee revenue		$ 132,201	$ 131,887	$ 137,664
Card revenue
Non-interest income:
Fee revenue		58,864	55,732	54,882
ATM revenue
Non-interest income:
Fee revenue		19,690	19,624	20,445
Servicing fee income
Non-interest income:
Fee revenue		$ 27,334	$ 41,347	$ 40,182

[1] Amounts represent the deferred stock issuance costs originally recorded in preferred stock that were reclassified to retained earnings.