TCF Financial 10-Q 8 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 01, 2018
Document and Entity Information
Entity Registrant Name	TCF FINANCIAL CORP
Entity Central Index Key	814,184
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		166,804,795

Consolidated Statements of Fina

Consolidated Statements of Financial Condition - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Assets:
Cash and due from banks		$ 569,968	$ 621,782
Investments		80,672	82,644
Debt securities held to maturity		152,881	161,576
Debt securities available for sale		2,379,546	1,709,018
Loans and leases held for sale		114,198	134,862
Consumer real estate:
First mortgage lien		1,960,756	1,959,387
Junior lien		2,940,701	2,860,309
Total consumer real estate		4,901,457	4,819,696
Commercial		3,741,164	3,561,193
Leasing and equipment finance		4,601,887	4,761,661
Inventory finance		2,880,404	2,739,754
Auto finance		2,275,134	3,199,639
Other		21,107	22,517
Total loans and leases	[1]	18,421,153	19,104,460
Allowance for loan and lease losses		(160,621)	(171,041)
Net loans and leases		18,260,532	18,933,419
Premises and equipment, net		429,648	421,549
Goodwill, net		154,757	154,757
Other assets		762,583	782,552
Total assets		22,904,785	23,002,159
Deposits:
Checking		6,382,667	6,300,127
Savings		5,737,144	5,287,606
Money market		1,504,952	1,764,998
Certificates of deposit		4,871,748	4,982,271
Total deposits		18,496,511	18,335,002
Short-term borrowings		2,324	0
Long-term borrowings		1,171,541	1,249,449
Total borrowings		1,173,865	1,249,449
Accrued expenses and other liabilities		706,397	737,124
Total liabilities		20,376,773	20,321,575
Equity:
Preferred stock, par value $0.01 per share, 30,000,000 shares authorized; 7,000 and 4,007,000 shares issued		169,302	265,821
Common stock, par value $0.01 per share, 280,000,000 shares authorized; 173,589,933 and 172,158,449 shares issued		1,736	1,722
Additional paid-in capital		882,321	877,217
Retained earnings, subject to certain restrictions		1,708,410	1,577,311
Accumulated other comprehensive income (loss)		(65,259)	(18,517)
Treasury stock at cost, 6,777,409 and 489,030 shares and other		189,652	40,797
Total TCF Financial Corporation stockholders' equity		2,506,858	2,662,757
Non-controlling interest in subsidiaries		21,154	17,827
Total equity		2,528,012	2,680,584
Total liabilities and equity		$ 22,904,785	$ 23,002,159
[1]	Loans and leases are reported at historical cost including net direct fees and costs associated with originating and acquiring loans and leases, lease residuals, unearned income and unamortized purchase premiums and discounts. The aggregate amount of these loan and lease adjustments was $9.0 million and $33.3 million at September 30, 2018 and December 31, 2017, respectively.

Consolidated Statements of Fi_2

Consolidated Statements of Financial Condition (Parenthetical) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (shares)	30,000,000	30,000,000
Preferred stock, shares issued (shares)	7,000	4,007,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (shares)	280,000,000	280,000,000
Common stock, shares issued (shares)	173,589,933	172,158,449
Treasury stock, shares (shares)	6,777,409	489,030

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest income:
Loans and leases		$ 264,678	$ 243,973	$ 794,333	$ 697,613
Debt securities available for sale		14,838	8,486	37,477	24,518
Debt securities held to maturity		988	1,073	3,005	3,388
Loans held for sale and other		6,678	4,073	13,952	22,910
Total interest income		287,182	257,605	848,767	748,429
Interest expense:
Deposits		27,335	17,015	73,798	45,166
Borrowings		10,726	6,487	31,850	19,885
Total interest expense		38,061	23,502	105,648	65,051
Net interest income		249,121	234,103	743,119	683,378
Provision for credit losses		2,270	14,545	27,874	46,184
Net interest income after provision for credit losses		246,851	219,558	715,245	637,194
Non-interest income:
Gains on sales of auto loans, net		0	0	0	3,244
Gains on sales of consumer real estate loans, net		8,764	8,049	25,079	25,920
Subtotal		14,796	18,015	46,890	61,511
Leasing and equipment finance		45,045	34,080	129,796	102,208
Other		3,818	2,930	11,468	8,428
Fees and other revenue		116,351	109,041	342,571	327,218
Gains (losses) on debt securities, net		94	189	181	189
Total non-interest income		116,445	109,230	342,752	327,407
Non-interest expense:
Compensation and employee benefits		123,127	114,954	367,542	354,882
Occupancy and equipment		42,337	38,766	123,562	117,331
Other		57,989	61,581	205,892	187,160
Subtotal		223,453	215,301	696,996	659,373
Operating lease depreciation		19,525	15,696	54,744	39,404
Foreclosed real estate and repossessed assets, net		3,881	3,829	12,654	13,017
Other credit costs, net		(436)	209	48	334
Total non-interest expense		246,423	235,035	764,442	712,128
Income before income tax expense		116,873	93,753	293,555	252,473
Income tax expense		28,034	30,704	66,083	77,341
Income after income tax expense		88,839	63,049	227,472	175,132
Income attributable to non-controlling interest		2,643	2,521	8,766	7,894
Net income attributable to TCF Financial Corporation		86,196	60,528	218,706	167,238
Preferred stock dividends		2,494	6,464	9,094	16,158
Impact of preferred stock redemption or notice to redeem preferred stock	[1]	0	5,779	3,481	5,779
Net income available to common stockholders		$ 83,702	$ 48,285	$ 206,131	$ 145,301
Earnings per common share:
Basic (in dollars per share)		$ 0.51	$ 0.29	$ 1.24	$ 0.86
Diluted (in dollars per share)		$ 0.51	$ 0.29	$ 1.23	$ 0.86
Fees and service charges
Non-interest income:
Fee revenue		$ 32,574	$ 34,605	$ 95,995	$ 98,620
Card revenue
Non-interest income:
Fee revenue		15,065	14,177	43,786	41,481
ATM revenue
Non-interest income:
Fee revenue		5,053	5,234	14,636	14,970
Subtotal
Non-interest income:
Fee revenue		52,692	54,016	154,417	155,071
Servicing fee income
Non-interest income:
Fee revenue		$ 6,032	$ 9,966	$ 21,811	$ 32,347
[1]	For the nine months ended September 30, 2018, amount represents the deferred stock issuance costs originally recorded in preferred stock upon the issuance of the Series B Preferred Stock that were reclassified to retained earnings on March 1, 2018, as the Company redeemed all outstanding Series B Preferred Stock. For the quarter and nine months ended September 30, 2017, amount represents the deferred stock issuance costs originally recorded in preferred stock upon the issuance of the 7.50% Series A non-cumulative perpetual preferred stock ("Series A Preferred Stock") that were reclassified to retained earnings on September 15, 2017, the date the Company announced its intent to redeem the outstanding Series A Preferred Stock.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income attributable to TCF Financial Corporation	$ 86,196	$ 60,528	$ 218,706	$ 167,238
Other comprehensive income (loss), net of tax:
Net unrealized gains (losses) on debt securities available for sale and interest-only strips	(13,434)	2,445	(46,059)	17,555
Net unrealized gains (losses) on net investment hedges	(1,904)	(1,682)	3,479	(3,144)
Foreign currency translation adjustment	2,899	2,939	(4,136)	5,527
Recognized postretirement prior service cost	(9)	(8)	(26)	(22)
Total other comprehensive income (loss), net of tax	(12,448)	3,694	(46,742)	19,916
Comprehensive income	$ 73,748	$ 64,222	$ 171,964	$ 187,154

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Thousands	Total	TCF Financial Corporation	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock and Other	Non-controlling Interest	Series A Preferred Stock	Series A Preferred StockTCF Financial Corporation	Series A Preferred StockPreferred Stock	Series A Preferred StockRetained Earnings	Series B Preferred Stock	Series B Preferred StockTCF Financial Corporation	Series B Preferred StockPreferred Stock	Series B Preferred StockRetained Earnings
Increase (Decrease) in Equity
Change in accounting principle	$ 0	$ 0			$ 1,319	$ (1,319)
Adjusted balance after cumulative adjustment related to change in accounting principle	2,444,645	2,427,483	$ 263,240	$ 1,710	864,095	1,381,582	$ (33,725)	$ (49,419)	$ 17,162
Balance (in shares) at Dec. 31, 2016			4,006,900	171,034,506
Balance at Dec. 31, 2016	2,444,645	2,427,483	$ 263,240	$ 1,710	862,776	1,382,901	(33,725)	(49,419)	17,162
Increase (Decrease) in Equity
Net income	175,132	167,238				167,238			7,894
Other comprehensive income (loss), net of tax	19,916	19,916					19,916
Net investment by (distribution to) non-controlling interest	(5,150)								(5,150)
Public offering of Series C preferred stock (in shares)			7,000
Public offering of Series C preferred stock	169,448	169,448	$ 169,448
Redemption of or notice to redeem preferred stock (in shares)												(6,900)
Redemption of or notice to redeem preferred stock										$ (172,500)	$ (172,500)	$ (166,721)	$ (5,779)
Repurchase of 6,288,379 shares of common stock	0
Dividends on preferred stock	(16,158)	(16,158)				(16,158)
Dividends on common stock	(37,917)	(37,917)				(37,917)
Common shares purchased by TCF employee benefit plans (in shares)				1,079,753
Common shares purchased by TCF employee benefit plans	17,702	17,702		$ 11	17,691
Stock compensation plans, net of tax (in shares)				(237,767)
Stock compensation plans, net of tax	1,396	1,396		$ (2)	1,398
Change in shares held in trust for deferred compensation plans, at cost	0	0			(18,552)			18,552
Balance (in shares) at Sep. 30, 2017			4,007,000	171,876,492
Balance at Sep. 30, 2017	2,596,514	2,576,608	$ 265,967	$ 1,719	864,632	1,488,966	(13,809)	(30,867)	19,906
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	2,662,641	$ 265,821	$ 1,722	877,217	1,577,195	(18,517)	(40,797)	17,827
Balance (in shares) at Dec. 31, 2017			4,007,000	172,158,449
Balance at Dec. 31, 2017	2,680,584	2,662,757	$ 265,821	$ 1,722	877,217	1,577,311	(18,517)	(40,797)	17,827
Increase (Decrease) in Equity
Net income	227,472	218,706				218,706			8,766
Other comprehensive income (loss), net of tax	(46,742)	(46,742)					(46,742)
Net investment by (distribution to) non-controlling interest	$ (5,439)								(5,439)
Redemption of or notice to redeem preferred stock (in shares)																(4,000,000)
Redemption of or notice to redeem preferred stock														$ (100,000)	$ (100,000)	$ (96,519)	$ (3,481)
Repurchase of 6,288,379 shares of common stock (in shares)	6,288,379
Repurchase of 6,288,379 shares of common stock	$ (149,912)	(149,912)						(149,912)
Dividends on preferred stock	(9,094)	(9,094)				(9,094)
Dividends on common stock	(74,916)	(74,916)				(74,916)
Common stock warrants exercised (in shares)				1,050,084
Common stock warrants exercised	0	0		$ 11	(11)
Common shares purchased by TCF employee benefit plans (in shares)				34,627
Common shares purchased by TCF employee benefit plans	715	715		$ 0	715
Stock compensation plans, net of tax (in shares)				346,773
Stock compensation plans, net of tax	5,460	5,460		$ 3	5,457
Change in shares held in trust for deferred compensation plans, at cost	0	0			(1,057)			1,057
Balance (in shares) at Sep. 30, 2018			7,000	173,589,933
Balance at Sep. 30, 2018	$ 2,528,012	$ 2,506,858	$ 169,302	$ 1,736	$ 882,321	$ 1,708,410	$ (65,259)	$ (189,652)	$ 21,154

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income	$ 227,472	$ 175,132
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Provision for credit losses	27,874	46,184
Depreciation and amortization	167,058	149,313
Provision for deferred income taxes	33,409	17,685
Proceeds from sales of loans and leases held for sale	264,970	188,756
Originations of loans and leases held for sale, net of repayments	271,793	359,109
Gains on sales of assets, net	(28,977)	(37,023)
Net change in other assets and accrued expenses and other liabilities	13,572	(95,267)
Other, net	(29,668)	(33,057)
Net cash provided by (used in) operating activities	403,917	52,614
Cash flows from investing activities:
Proceeds from maturities of and principal collected on debt securities	131,442	105,561
Purchases of debt securities	(921,832)	(238,586)
Redemption of Federal Home Loan Bank stock	201,001	190,001
Purchases of Federal Home Loan Bank stock	(199,000)	(203,000)
Proceeds from sales of loans and leases	675,164	1,156,854
Principal collected on loans and leases, net of loan and lease originations and purchases	735,840	(1,541,913)
Acquisition of Equipment Financing & Leasing Corporation, net of cash acquired	0	8,120
Purchases of lease equipment	(857,934)	(743,819)
Proceeds from sales of assets	58,879	46,532
Purchases of premises and equipment	(45,460)	(36,376)
Other, net	15,151	22,099
Net cash provided by (used in) investing activities	(206,749)	(1,250,767)
Cash flows from financing activities:
Net change in deposits	163,442	869,029
Net change in short-term borrowings	2,451	(4,746)
Proceeds from long-term borrowings	7,043,458	7,931,686
Payments on long-term borrowings	(7,118,690)	(7,625,170)
Net proceeds from public offering of Series C preferred stock	0	169,448
Redemption of Series B preferred stock	(100,000)	0
Repurchases of common stock	(149,912)	0
Common shares sold to TCF employee benefit plans	715	17,702
Dividends paid on preferred stock	(9,094)	(14,541)
Dividends paid on common stock	(74,916)	(37,917)
Exercise of stock options	(997)	(57)
Net investment by (distribution to) non-controlling interest	(5,439)	(5,150)
Net cash provided by (used in) financing activities	(248,982)	1,300,284
Net change in cash and due from banks	(51,814)	102,131
Cash and due from banks at beginning of period	621,782	609,603
Cash and due from banks at end of period	569,968	711,734
Supplemental disclosures of cash flow information:
Cash paid (received) for interest on deposits and borrowings	99,336	60,561
Cash paid (received) for income taxes, net	(21,035)	53,621
Transfer of loans and leases to other assets	77,704	74,958
Transfer of loans and leases from held for investment to held for sale, net	644,488	965,532
Transfer of mandatorily redeemable Series A preferred stock to accrued expenses and other liabilities	$ 0	$ 172,500

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation TCF Financial Corporation (together with its direct and indirect subsidiaries, "we," "us," "our," "TCF" or the "Company"), a Delaware corporation, is a national bank holding company based in Wayzata, Minnesota. References herein to "TCF Financial" or the "Holding Company" refer to TCF Financial Corporation on an unconsolidated basis. Its principal subsidiary, TCF National Bank ("TCF Bank"), is headquartered in Sioux Falls, South Dakota. TCF Bank operates bank branches in Illinois, Minnesota, Michigan, Colorado, Wisconsin, Arizona and South Dakota (TCF's primary banking markets). Through its direct subsidiaries, TCF Bank provides a full range of consumer facing and commercial services, including consumer banking services, commercial banking services, commercial leasing and equipment financing, and commercial inventory financing. The accompanying unaudited consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles ("GAAP") for interim financial information and in accordance with the instructions to Quarterly Report on Form 10-Q and Article 10 of Regulation S-X as promulgated by the Securities and Exchange Commission. Accordingly, the consolidated financial statements do not include all of the information and notes necessary for complete financial statements in conformity with GAAP. In the opinion of management, the accompanying unaudited consolidated financial statements contain all the significant adjustments, consisting of normal recurring items, considered necessary for fair presentation. The results of operations for interim periods are not necessarily indicative of the results to be expected for the entire year. The information in this Quarterly Report on Form 10-Q is written with the presumption that the users of the interim financial statements have read or have access to the Company's most recent Annual Report on Form 10-K, which contains the latest audited financial statements and notes thereto, together with Management's Discussion and Analysis of Financial Condition and Results of Operations at and for the year ended December 31, 2017 . The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amount of revenues and expenses during the reporting period. These estimates are based on information available to management at the time the estimates are made. Actual results could differ from those estimates. All significant intercompany accounts and transactions have been eliminated in consolidation. Certain reclassifications have been made to prior period financial statements to conform to current period presentation.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Accounting policies in effect at December 31, 2017 remain significantly unchanged and have been followed similarly as in previous periods. New Accounting Pronouncements Adopted Effective January 1, 2018, the Company adopted Accounting Standards Update ("ASU") No. 2017-12: Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities , which expands hedge accounting for nonfinancial and financial risk components and amends measurement methodologies to more closely align hedge accounting with a company’s risk management activities. The ASU decreases the complexity of preparing and understanding hedge results through measurement and reporting of hedge ineffectiveness. In addition, disclosures have been enhanced and the presentation of hedged results changed to align the effects of the hedging instrument and the hedged item. The adoption of this ASU was on a modified retrospective basis and resulted in the Company recording a cumulative effect reduction to the opening balance of retained earnings of $116 thousand . Effective January 1, 2018, the Company adopted ASU No. 2017-09: Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting , which provides guidance about which changes to the terms and conditions of a share-based payment award requires an entity to apply modification accounting in Topic 718. The adoption of this ASU was on a prospective basis and will be applicable to an award modified on or after January 1, 2018. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2017-07: Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost , which changes how employers that sponsor defined benefit pension and/or other postretirement benefit plans present the net periodic benefit cost in the income statement. Under the new guidance, employers present the service cost component of the net periodic benefit cost in the same income statement line item as other employee compensation costs arising from services rendered during the period. Only the service cost component is eligible for capitalization in assets. The other components of net periodic benefit cost are presented separately from the line item that includes service cost and outside of any subtotal of operating income. In addition, disclosure of the line items used to present the other components of net periodic benefit cost is required if the components are not presented separately in the income statement. The adoption of this ASU was on a modified retrospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2017-05: Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets , which provides guidance for recognizing gains and losses from the transfer of nonfinancial assets in contracts with non-customers. The ASU also clarifies that Accounting Standards Codification 610-20 applies to the derecognition of nonfinancial assets and in substance nonfinancial assets unless other specific guidance applies or the sale is to a customer. The guidance does not apply to the derecognition of businesses, nonprofit activities, financial assets, including equity method investments, or to revenue contracts with customers. The adoption of this ASU was on a modified retrospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business , which clarifies the definition of a business with the objective of adding guidance to assist companies with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The ASU provides a more robust framework to use in determining when a set of assets and activities is a business. The adoption of this ASU was on a prospective basis. TCF will evaluate future transactions to determine if they should be accounted for as acquisitions (or disposals) of assets or businesses. Effective January 1, 2018, the Company adopted ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash , which requires entities to show changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. As a result, entities no longer present transfers between cash and cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. The adoption of this ASU was on a retrospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2016-17, Consolidation (Topic 810): Interests Held through Related Parties That Are under Common Control , which changes the way in which a single decision maker considers indirect interests when performing the primary beneficiary analysis under the variable interest model. Under the amended guidance, indirect interests held by a related party would be considered on a proportional basis. The adoption of this ASU was on a retrospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory , which requires the income tax effects of intercompany sales and transfers of assets, other than inventory, to be recognized in the period the transaction occurs. The adoption of this ASU was on a modified retrospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments , which addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice in how certain types of cash receipts and cash payments are presented in the statement of cash flows. The adoption of this ASU was on a retrospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2016-04, Liabilities - Extinguishments of Liabilities (Subtopic 405-20): Recognition of Breakage for Certain Prepaid Stored-Value Products , which requires issuers of prepaid stored-value products redeemable for goods, services or cash at third-party merchants to derecognize liabilities related to those products for breakage. The adoption of this ASU was on a modified retrospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities and ASU No. 2018-03, Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities , which amend the classification and measurement of investments in equity securities, simplify the impairment analysis of equity investments without readily determinable fair values, require separate presentation of certain fair value changes for financial liabilities measured at fair value and eliminate certain disclosure requirements associated with the fair value of financial instruments. The adoption of these ASUs was on a prospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted the following ASUs using the modified retrospective method with no cumulative-effect adjustment to opening retained earnings: ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606); ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date; ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net); ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing; ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients; ASU No. 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers; ASU No. 2017-13 , Revenue Recognition (Topic 605), Revenue from Contracts with Customers (Topic 606), Leases (Topic 840), and Leases (Topic 842): Amendments to SEC Paragraphs and ASU No. 2017-14, Income Statement - Reporting Comprehensive Income (Topic 220), Revenue Recognition (Topic 605), and Revenue from Contracts with Customers (Topic 606) . TCF derives a majority of its revenue from loans and leases, as well as any related servicing fee revenue, which are not within the scope of these ASUs. These ASUs are applicable to most of the fees and service charges, card and ATM revenue earned by TCF, as well as the gains on sales of certain non-financial assets. However, the recognition of these revenue streams does not change in a significant manner as a result of the adoption of these ASUs. The majority of this revenue is both charged to the customer and earned either at a point in time or on a transactional basis. As a result, the revenue expected to be recognized in any future year related to remaining performance obligations, contracts where revenue is recognized when invoiced and contracts with variable consideration related to undelivered performance obligations are not material. In addition, receivables related to fees and service charges and the related bad debt expense are not material. There are no material contract assets, contract liabilities or deferred contract costs recorded in the Company's Consolidated Statements of Financial Condition. As a significant majority of the Company's revenue streams are not included in the scope of these ASUs and the recognition of revenue for the revenue streams within the scope of these ASUs are not significantly changed, the adoption of this guidance did not have a material impact on the Company's consolidated financial statements.

Cash and Due from Banks

Cash and Due from Banks	9 Months Ended
	Sep. 30, 2018
Cash and Cash Equivalents [Abstract]
Cash and Due from Banks	Cash and Due from Banks At September 30, 2018 and December 31, 2017 , TCF Bank was required by Federal Reserve regulations to maintain reserves of $110.1 million and $107.0 million , respectively, in cash on hand or at the Federal Reserve Bank. TCF maintains cash balances that are restricted as to their use in accordance with certain obligations. Cash payments received on loans serviced for third parties are generally held in separate accounts until remitted. TCF may also retain cash balances for collateral on certain borrowings, forward foreign exchange contracts, interest rate contracts and other contracts. TCF maintained restricted cash totaling $47.9 million and $36.5 million at September 30, 2018 and December 31, 2017 , respectively. TCF had cash held in interest-bearing accounts of $263.1 million and $324.2 million at September 30, 2018 and December 31, 2017 , respectively.

Debt Securities Available for S

Debt Securities Available for Sale and Debt Securities Held to Maturity	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Debt Securities Available for Sale and Debt Securities Held to Maturity	Debt Securities Available for Sale and Debt Securities Held to Maturity Debt securities were as follows: At September 30, 2018 At December 31, 2017 (In thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Debt securities available for sale: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ 1,630,465 $ 15 $ 49,796 $ 1,580,684 $ 908,189 $ 308 $ 13,812 $ 894,685 Other 4 — — 4 6 — — 6 Obligations of states and political subdivisions 821,727 28 22,897 798,858 810,159 7,967 3,799 814,327 Total debt securities available for sale $ 2,452,196 $ 43 $ 72,693 $ 2,379,546 $ 1,718,354 $ 8,275 $ 17,611 $ 1,709,018 Debt securities held to maturity: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ 150,081 $ 104 $ 2,321 $ 147,864 $ 158,776 $ 4,462 $ 412 $ 162,826 Other securities 2,800 — — 2,800 2,800 — — 2,800 Total debt securities held to maturity $ 152,881 $ 104 $ 2,321 $ 150,664 $ 161,576 $ 4,462 $ 412 $ 165,626 At September 30, 2018 and December 31, 2017 , mortgage-backed securities with a carrying value of $1.6 million and $0.9 million , respectively, were pledged as collateral to secure certain deposits and borrowings. We have assessed each security with unrealized losses included in the table above for credit impairment. As part of that assessment we evaluated and concluded that we do not intend to sell any of the securities and that it is more likely than not that we will not be required to sell prior to recovery of the amortized cost. Unrealized losses on debt securities available for sale and debt securities held to maturity were due to changes in interest rates. There were no sales or impairment charges for debt securities available for sale and debt securities held to maturity during the third quarter and first nine months of 2018 and 2017 . Net gains (losses) on debt securities were $94 thousand and $181 thousand for the third quarter and first nine months of 2018 , respectively, compared with $189 thousand for both the same periods in 2017 . The net gains were related to recoveries on previously impaired debt securities held to maturity. Gross unrealized losses and fair value of debt securities available for sale and debt securities held to maturity aggregated by investment category and the length of time the securities were in a continuous loss position were as follows: At September 30, 2018 Less than 12 months 12 months or more Total (In thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Debt securities available for sale: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ 967,838 $ 16,402 $ 608,028 $ 33,394 $ 1,575,866 $ 49,796 Obligations of states and political subdivisions 529,164 9,857 262,980 13,040 792,144 22,897 Total debt securities available for sale $ 1,497,002 $ 26,259 $ 871,008 $ 46,434 $ 2,368,010 $ 72,693 Debt securities held to maturity: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ 120,860 $ 1,151 $ 21,910 $ 1,170 $ 142,770 $ 2,321 Total debt securities held to maturity $ 120,860 $ 1,151 $ 21,910 $ 1,170 $ 142,770 $ 2,321 At December 31, 2017 Less than 12 months 12 months or more Total (In thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Debt securities available for sale: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ 406,298 $ 2,686 $ 428,585 $ 11,126 $ 834,883 $ 13,812 Obligations of states and political subdivisions 103,759 486 207,516 3,313 311,275 3,799 Total debt securities available for sale $ 510,057 $ 3,172 $ 636,101 $ 14,439 $ 1,146,158 $ 17,611 Debt securities held to maturity: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ 13,309 $ 132 $ 11,470 $ 280 $ 24,779 $ 412 Total debt securities held to maturity $ 13,309 $ 132 $ 11,470 $ 280 $ 24,779 $ 412 The amortized cost and fair value of debt securities available for sale and debt securities held to maturity by final contractual maturity were as follows. The final contractual maturities do not consider possible prepayments and therefore expected maturities may differ because borrowers may have the right to prepay. At September 30, 2018 At December 31, 2017 (In thousands) Amortized Cost Fair Value Amortized Cost Fair Value Debt securities available for sale: Due in one year or less $ — $ — $ 6 $ 6 Due in 1-5 years 68,368 67,737 15,178 15,312 Due in 5-10 years 692,272 673,804 514,336 517,867 Due after 10 years 1,691,556 1,638,005 1,188,834 1,175,833 Total debt securities available for sale $ 2,452,196 $ 2,379,546 $ 1,718,354 $ 1,709,018 Debt securities held to maturity: Due in one year or less $ — $ — $ 1,000 $ 1,000 Due in 1-5 years 2,400 2,400 1,400 1,400 Due in 5-10 years 431 435 400 400 Due after 10 years 150,050 147,829 158,776 162,826 Total debt securities held to maturity $ 152,881 $ 150,664 $ 161,576 $ 165,626 Interest income attributable to debt securities available for sale was as follows: Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Taxable interest income $ 10,511 $ 4,619 $ 24,487 $ 13,707 Tax-exempt interest income 4,327 3,867 12,990 10,811 Total interest income $ 14,838 $ 8,486 $ 37,477 $ 24,518

Loans and Leases

Loans and Leases	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Loans and Leases	Loans and Leases Loans and leases were as follows: (In thousands) At September 30, 2018 At December 31, 2017 Consumer real estate: First mortgage lien $ 1,960,756 $ 1,959,387 Junior lien 2,940,701 2,860,309 Total consumer real estate 4,901,457 4,819,696 Commercial: Commercial real estate: Permanent 2,362,045 2,385,752 Construction and development 411,610 365,533 Total commercial real estate 2,773,655 2,751,285 Commercial business 967,509 809,908 Total commercial 3,741,164 3,561,193 Leasing and equipment finance 4,601,887 4,761,661 Inventory finance 2,880,404 2,739,754 Auto finance 2,275,134 3,199,639 Other 21,107 22,517 Total loans and leases (1) $ 18,421,153 $ 19,104,460 (1) Loans and leases are reported at historical cost including net direct fees and costs associated with originating and acquiring loans and leases, lease residuals, unearned income and unamortized purchase premiums and discounts. The aggregate amount of these loan and lease adjustments was $9.0 million and $33.3 million at September 30, 2018 and December 31, 2017 , respectively. Loan Sales During the third quarter and first nine months of 2018 , TCF sold $328.0 million and $775.9 million , respectively, of consumer real estate loans, received cash of $346.5 million and $807.5 million , respectively, and recognized net gains of $8.8 million and $25.1 million , respectively. During the third quarter and first nine months of 2017 , TCF sold $291.0 million and $943.8 million , respectively, of consumer real estate loans, received cash of $305.3 million and $987.8 million , respectively, and recognized net gains of $8.0 million and $25.9 million , respectively. Related to these sales, TCF retained no interest-only strips during the third quarter of 2018 and retained interest-only strips of $3.8 million during the first nine months of 2018 . TCF retained interest-only strips of $0.5 million and $2.5 million during the third quarter and first nine months of 2017 , respectively. Included in consumer real estate loans sold in the third quarter and first nine months of 2018 were $34.7 million of non-accrual loans, which were sold servicing released, and $21.8 million and $71.2 million for the same periods in 2017 . TCF generally retains servicing on loans sold. During the third quarter and first nine months of 2018 and the third quarter of 2017 , TCF did not sell any auto finance loans. TCF sold $298.6 million of auto finance loans during the first nine months of 2017 , received cash of $303.3 million and recognized net gains of $3.2 million . No servicing assets or liabilities related to consumer real estate or auto finance loans were recorded within TCF's Consolidated Statements of Financial Condition at September 30, 2018 or December 31, 2017 , as the contractual servicing fees are adequate to compensate TCF for its servicing responsibilities based on the amount demanded by the marketplace. Total interest-only strips and the contractual liabilities related to loan sales were as follows: (In thousands) At September 30, 2018 At December 31, 2017 Interest-only strips attributable to: Consumer real estate loan sales $ 15,619 $ 16,440 Auto finance loan sales 2,093 4,946 Total interest-only strips $ 17,712 $ 21,386 Contractual liabilities attributable to: Consumer real estate loan sales $ 1,540 $ 1,234 TCF recorded no impairment charges on the consumer real estate interest-only strips in the third quarter of 2018 and 2017 and $268 thousand and $875 thousand in the first nine months of 2018 and 2017 , respectively. TCF recorded $45 thousand and $235 thousand of impairment charges on the auto finance interest-only strips in the third quarter of 2018 and 2017 , respectively, and $393 thousand and $400 thousand in the first nine months of 2018 and 2017 , respectively.

Allowance for Loan and Lease Lo

Allowance for Loan and Lease Losses and Credit Quality Information	9 Months Ended
	Sep. 30, 2018
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance for Loan and Lease Losses and Credit Quality Information	Allowance for Loan and Lease Losses and Credit Quality Information The rollforwards of the allowance for loan and lease losses were as follows: (In thousands) Consumer Commercial Leasing and Inventory Auto Other Total At or For the Quarter Ended September 30, 2018: Balance, beginning of period $ 43,954 $ 40,291 $ 22,247 $ 11,840 $ 46,608 $ 679 $ 165,619 Charge-offs (1,519 ) (18 ) (2,608 ) (880 ) (12,460 ) (1,963 ) (19,448 ) Recoveries 7,949 26 678 243 2,975 787 12,658 Net (charge-offs) recoveries 6,430 8 (1,930 ) (637 ) (9,485 ) (1,176 ) (6,790 ) Provision for credit losses (4,827 ) 171 2,822 124 2,729 1,251 2,270 Other (299 ) — (213 ) 34 — — (478 ) Balance, end of period $ 45,258 $ 40,470 $ 22,926 $ 11,361 $ 39,852 $ 754 $ 160,621 At or For the Quarter Ended September 30, 2017: Balance, beginning of period $ 52,408 $ 34,669 $ 21,922 $ 12,129 $ 43,893 $ 599 $ 165,620 Charge-offs (2,940 ) — (1,404 ) (750 ) (11,028 ) (1,877 ) (17,999 ) Recoveries 6,392 196 358 281 1,780 840 9,847 Net (charge-offs) recoveries 3,452 196 (1,046 ) (469 ) (9,248 ) (1,037 ) (8,152 ) Provision for credit losses (5,669 ) 1,479 1,967 240 15,437 1,091 14,545 Other (2,353 ) — (72 ) 78 (1,422 ) — (3,769 ) Balance, end of period $ 47,838 $ 36,344 $ 22,771 $ 11,978 $ 48,660 $ 653 $ 168,244 (In thousands) Consumer Commercial Leasing and Inventory Auto Other Total At or For the Nine Months Ended September 30, 2018: Balance, beginning of period $ 47,168 $ 37,195 $ 22,528 $ 13,233 $ 50,225 $ 692 $ 171,041 Charge-offs (5,729 ) (22 ) (7,257 ) (2,102 ) (36,996 ) (5,395 ) (57,501 ) Recoveries 10,264 71 1,881 539 8,339 2,696 23,790 Net (charge-offs) recoveries 4,535 49 (5,376 ) (1,563 ) (28,657 ) (2,699 ) (33,711 ) Provision for credit losses (2,173 ) 3,226 6,000 (224 ) 18,284 2,761 27,874 Other (4,272 ) — (226 ) (85 ) — — (4,583 ) Balance, end of period $ 45,258 $ 40,470 $ 22,926 $ 11,361 $ 39,852 $ 754 $ 160,621 At or For the Nine Months Ended September 30, 2017: Balance, beginning of period $ 59,448 $ 32,695 $ 21,350 $ 13,932 $ 32,310 $ 534 $ 160,269 Charge-offs (9,205 ) (5,431 ) (5,694 ) (1,856 ) (28,045 ) (4,996 ) (55,227 ) Recoveries 18,783 455 1,718 675 4,680 2,761 29,072 Net (charge-offs) recoveries 9,578 (4,976 ) (3,976 ) (1,181 ) (23,365 ) (2,235 ) (26,155 ) Provision for credit losses (13,553 ) 8,625 5,520 (903 ) 44,141 2,354 46,184 Other (7,635 ) — (123 ) 130 (4,426 ) — (12,054 ) Balance, end of period $ 47,838 $ 36,344 $ 22,771 $ 11,978 $ 48,660 $ 653 $ 168,244 The allowance for loan and lease losses and loans and leases outstanding by type of allowance methodology were as follows: At September 30, 2018 (In thousands) Consumer Commercial Leasing and Inventory Auto Other Total Allowance for loan and lease losses: Collectively evaluated for impairment $ 22,274 $ 38,843 $ 19,021 $ 10,850 $ 39,729 $ 754 $ 131,471 Individually evaluated for impairment 22,984 1,627 3,905 511 123 — 29,150 Total $ 45,258 $ 40,470 $ 22,926 $ 11,361 $ 39,852 $ 754 $ 160,621 Loans and leases outstanding: Collectively evaluated for impairment $ 4,785,131 $ 3,710,229 $ 4,574,620 $ 2,878,764 $ 2,262,966 $ 21,105 $ 18,232,815 Individually evaluated for impairment 116,326 30,935 22,464 1,640 12,168 2 183,535 Loans acquired with deteriorated credit quality — — 4,803 — — — 4,803 Total $ 4,901,457 $ 3,741,164 $ 4,601,887 $ 2,880,404 $ 2,275,134 $ 21,107 $ 18,421,153 At December 31, 2017 (In thousands) Consumer Real Estate Commercial Leasing and Equipment Finance Inventory Finance Auto Finance Other Total Allowance for loan and lease losses: Collectively evaluated for impairment $ 28,851 $ 35,635 $ 19,083 $ 12,945 $ 49,900 $ 691 $ 147,105 Individually evaluated for impairment 18,317 1,560 3,445 288 325 1 23,936 Total $ 47,168 $ 37,195 $ 22,528 $ 13,233 $ 50,225 $ 692 $ 171,041 Loans and leases outstanding: Collectively evaluated for impairment $ 4,675,626 $ 3,524,864 $ 4,721,905 $ 2,735,638 $ 3,188,810 $ 22,513 $ 18,869,356 Individually evaluated for impairment 144,070 36,329 27,912 4,116 10,829 4 223,260 Loans acquired with deteriorated credit quality — — 11,844 — — — 11,844 Total $ 4,819,696 $ 3,561,193 $ 4,761,661 $ 2,739,754 $ 3,199,639 $ 22,517 $ 19,104,460 Accruing and Non-accrual Loans and Leases TCF's key credit quality indicator is the receivable's payment performance status, defined as accruing or non-accruing. Non-accrual loans and leases are those which management believes have a higher risk of loss. Delinquent balances are determined based on the contractual terms of the loan or lease. Loans and leases that are over 60 days delinquent have a higher potential to become non-accrual and generally are a leading indicator for future charge-off trends. TCF's accruing and non-accrual loans and leases were as follows: At September 30, 2018 (In thousands) Current-59 Days Delinquent and Accruing 60-89 Days Delinquent and Accruing 90 Days or More Delinquent and Accruing Total Accruing Non-accrual Total Consumer real estate: First mortgage lien $ 1,921,391 $ 2,720 $ 770 $ 1,924,881 $ 35,875 $ 1,960,756 Junior lien 2,920,365 1,119 — 2,921,484 19,217 2,940,701 Total consumer real estate 4,841,756 3,839 770 4,846,365 55,092 4,901,457 Commercial: Commercial real estate 2,768,445 — — 2,768,445 5,210 2,773,655 Commercial business 962,831 — — 962,831 4,678 967,509 Total commercial 3,731,276 — — 3,731,276 9,888 3,741,164 Leasing and equipment finance 4,574,268 5,054 1,701 4,581,023 16,061 4,597,084 Inventory finance 2,878,684 65 15 2,878,764 1,640 2,880,404 Auto finance 2,258,221 6,318 2,982 2,267,521 7,613 2,275,134 Other 21,042 30 33 21,105 2 21,107 Subtotal 18,305,247 15,306 5,501 18,326,054 90,296 18,416,350 Portfolios acquired with deteriorated credit quality 4,000 — 803 4,803 — 4,803 Total $ 18,309,247 $ 15,306 $ 6,304 $ 18,330,857 $ 90,296 $ 18,421,153 At December 31, 2017 (In thousands) Current-59 Days Delinquent and Accruing 60-89 Days Delinquent and Accruing 90 Days or More Delinquent and Accruing Total Accruing Non-accrual Total Consumer real estate: First mortgage lien $ 1,892,771 $ 4,073 $ 593 $ 1,897,437 $ 61,950 $ 1,959,387 Junior lien 2,837,767 1,268 — 2,839,035 21,274 2,860,309 Total consumer real estate 4,730,538 5,341 593 4,736,472 83,224 4,819,696 Commercial: Commercial real estate 2,744,500 — — 2,744,500 6,785 2,751,285 Commercial business 809,907 1 — 809,908 — 809,908 Total commercial 3,554,407 1 — 3,554,408 6,785 3,561,193 Leasing and equipment finance 4,726,339 4,272 2,117 4,732,728 17,089 4,749,817 Inventory finance 2,735,430 191 17 2,735,638 4,116 2,739,754 Auto finance 3,183,196 6,078 2,999 3,192,273 7,366 3,199,639 Other 22,506 3 6 22,515 2 22,517 Subtotal 18,952,416 15,886 5,732 18,974,034 118,582 19,092,616 Portfolios acquired with deteriorated credit quality 10,283 361 1,200 11,844 — 11,844 Total $ 18,962,699 $ 16,247 $ 6,932 $ 18,985,878 $ 118,582 $ 19,104,460 Interest income recognized on loans and leases in non-accrual status and contractual interest that would have been recorded had the loans and leases performed in accordance with their original contractual terms were as follows: Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Contractual interest due on non-accrual loans and leases $ 2,254 $ 3,529 $ 8,138 $ 11,606 Interest income recognized on non-accrual loans and leases 188 581 1,091 2,274 Unrecognized interest income $ 2,066 $ 2,948 $ 7,047 $ 9,332 Consumer real estate loans to customers currently involved in ongoing Chapter 7 or Chapter 13 bankruptcy proceedings which have not yet been discharged, dismissed or completed were as follows: (In thousands) At September 30, 2018 At December 31, 2017 Consumer real estate loans to customers in bankruptcy: 0-59 days delinquent and accruing $ 4,642 $ 7,324 Non-accrual 8,695 10,552 Total consumer real estate loans to customers in bankruptcy $ 13,337 $ 17,876 Loan Modifications for Borrowers with Financial Difficulties Included within loans and leases in the previous accruing and non-accrual loans and leases tables are certain loans that have been modified in order to maximize collection of loan balances. If, for economic or legal reasons related to the customer's financial difficulties, TCF grants a concession, the modified loan is classified as a troubled debt restructuring ("TDR") loan. All loans classified as TDR loans are considered to be impaired. For purposes of this disclosure, purchased credit impaired ("PCI") loans have been excluded. TDR loans were as follows: At September 30, 2018 At December 31, 2017 (In thousands) Accruing TDR Loans Non-accrual TDR Loans Total TDR Loans Accruing TDR Loans Non-accrual TDR Loans Total TDR Loans Consumer real estate $ 82,317 $ 16,334 $ 98,651 $ 88,092 $ 34,282 $ 122,374 Commercial 4,235 9,874 14,109 12,249 83 12,332 Leasing and equipment finance 6,403 2,085 8,488 10,263 1,413 11,676 Inventory finance — 12 12 — 476 476 Auto finance 4,557 5,309 9,866 3,464 5,351 8,815 Other 2 — 2 3 1 4 Total $ 97,514 $ 33,614 $ 131,128 $ 114,071 $ 41,606 $ 155,677 Consumer real estate TDR loans generally remain on accruing status following modification if they are less than 90 days past due and payment in full under the modified terms of the loan is expected based on a current credit evaluation and historical payment performance. Of the non-accrual TDR balance at September 30, 2018 , $7.9 million , or 48.6% , were loans discharged in Chapter 7 bankruptcy that were not reaffirmed by the borrower, of which 57.1% were current. Of the non-accrual TDR balance at December 31, 2017 , $22.3 million , or 65.0% , were loans discharged in Chapter 7 bankruptcy that were not reaffirmed by the borrower, of which 70.0% were current. All eligible loans are re-aged to current delinquency status upon modification. The allowance on accruing consumer real estate TDR loans was $15.6 million , or 19.0% of the outstanding balance, at September 30, 2018 and $17.1 million , or 19.4% of the outstanding balance, at December 31, 2017 . At September 30, 2018 , 0.3% of accruing consumer real estate TDR loans were more than 60 days delinquent, compared with 0.5% at December 31, 2017 . The allowance on accruing TDRs and the percentage of accruing TDR loans that were 60 days or more delinquent were not material for the remaining classes of finance receivables at September 30, 2018 and December 31, 2017 . Unfunded commitments to consumer real estate loans classified as TDRs were $0.5 million at September 30, 2018 and $0.4 million at December 31, 2017 . There were no unfunded commitments to commercial loans classified as TDRs at September 30, 2018 and $0.5 million at December 31, 2017 . At September 30, 2018 and December 31, 2017 , no additional funds were committed to leasing and equipment finance, inventory finance or auto finance loans classified as TDRs. Interest income on TDR loans is recognized based on the restructured terms. Unrecognized interest represents the financial impact of TDR loans and is the difference between interest income recognized on accruing TDR loans and the contractual interest that would have been recorded had the loans performed in accordance with their original contractual terms. The following table summarizes the financial effects of consumer real estate accruing TDR loans. The financial effects of TDR loans for the remaining classes of finance receivables were not material for the third quarter and first nine months of 2018 and 2017 . Quarter Ended September 30, 2018 2017 (In thousands) Contractual Interest Due Interest Income Unrecognized Interest Contractual Interest Due Interest Income Unrecognized Interest Consumer real estate: First mortgage lien $ 1,034 $ 614 $ 420 $ 1,127 $ 688 $ 439 Junior lien 407 278 129 479 331 148 Total consumer real estate $ 1,441 $ 892 $ 549 $ 1,606 $ 1,019 $ 587 Nine Months Ended September 30, 2018 2017 (In thousands) Contractual Interest Due Interest Income Unrecognized Interest Contractual Interest Due Interest Income Unrecognized Interest Consumer real estate: First mortgage lien $ 3,147 $ 1,870 $ 1,277 $ 3,427 $ 2,059 $ 1,368 Junior lien 1,249 853 396 1,476 1,025 451 Total consumer real estate $ 4,396 $ 2,723 $ 1,673 $ 4,903 $ 3,084 $ 1,819 TCF considers a loan to have defaulted when under the modified terms it becomes 90 or more days delinquent, has been transferred to non-accrual status, has been charged down or has been transferred to other real estate owned or repossessed and returned assets. The following table summarizes the TDR loans that defaulted during the periods presented that were modified during the respective reporting period or within one year of the beginning of the respective reporting period. Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Defaulted TDR loan balances modified during the applicable period: (1) Consumer real estate: First mortgage lien $ 778 $ 856 $ 2,751 $ 2,328 Junior lien 176 317 240 518 Total consumer real estate 954 1,173 2,991 2,846 Commercial: Commercial real estate — — — 6,681 Commercial business — — 4,697 — Total commercial — — 4,697 6,681 Leasing and equipment finance 87 451 87 635 Auto finance 217 260 950 867 Defaulted TDR loan balances modified during the applicable period $ 1,258 $ 1,884 $ 8,725 $ 11,029 (1) The loan balances presented are not materially different than the pre-modification loan balances as TCF's loan modifications generally do not forgive principal amounts. Impaired Loans TCF considers impaired loans to include non-accrual commercial loans, non-accrual equipment finance loans and non-accrual inventory finance loans, as well as all TDR loans. For purposes of this disclosure, PCI loans have been excluded. Non-accrual impaired loans, including non-accrual TDR loans, are included in non-accrual loans and leases within the previous tables. Accruing TDR loans have been disclosed by delinquency status within the previous tables of accruing and non-accrual loans and leases. In the following table, the loan balance of impaired loans represents the amount recorded within loans and leases on the Consolidated Statements of Financial Condition, whereas the unpaid contractual balance represents the balances legally owed by the borrowers. Information on impaired loans was as follows: At September 30, 2018 At December 31, 2017 (In thousands) Unpaid Loan Related Unpaid Loan Related Impaired loans with an allowance recorded: Consumer real estate: First mortgage lien $ 65,528 $ 62,581 $ 13,989 $ 91,624 $ 80,802 $ 13,792 Junior lien 25,972 24,778 8,861 32,327 29,544 4,165 Total consumer real estate 91,500 87,359 22,850 123,951 110,346 17,957 Commercial: Commercial real estate 5,547 5,156 1,000 6,810 6,702 1,000 Commercial business 4,713 4,689 627 7,841 7,841 560 Total commercial 10,260 9,845 1,627 14,651 14,543 1,560 Leasing and equipment finance 15,157 15,157 2,415 17,105 17,105 1,345 Inventory finance 1,435 1,439 511 1,296 1,298 288 Auto finance 538 404 59 1,333 1,016 243 Other 2 2 — 3 4 1 Total impaired loans with an allowance recorded 118,892 114,206 27,462 158,339 144,312 21,394 Impaired loans without an allowance recorded: Consumer real estate: First mortgage lien 12,155 9,765 — 12,898 10,445 — Junior lien 11,087 1,527 — 17,697 1,583 — Total consumer real estate 23,242 11,292 — 30,595 12,028 — Commercial real estate 4,344 4,278 — 4,552 4,491 — Inventory finance 201 201 — 2,810 2,818 — Auto finance 13,357 9,462 — 10,566 7,799 — Other 331 — — 331 — — Total impaired loans without an allowance recorded 41,475 25,233 — 48,854 27,136 — Total impaired loans $ 160,367 $ 139,439 $ 27,462 $ 207,193 $ 171,448 $ 21,394 The average loan balance of impaired loans and interest income recognized on impaired loans were as follows: Quarter Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (In thousands) Average Loan Balance Interest Income Recognized Average Loan Balance Interest Income Recognized Average Loan Balance Interest Income Recognized Average Loan Balance Interest Income Recognized Impaired loans with an allowance recorded: Consumer real estate: First mortgage lien $ 62,411 $ 435 $ 84,126 $ 679 $ 71,692 $ 1,706 $ 92,490 $ 2,097 Junior lien 24,788 246 33,438 382 27,160 841 41,083 1,209 Total consumer real estate 87,199 681 117,564 1,061 98,852 2,547 133,573 3,306 Commercial: Commercial real estate 5,192 — 5,119 — 5,929 — 8,461 16 Commercial business 5,981 13 13 — 6,265 130 13 48 Total commercial 11,173 13 5,132 — 12,194 130 8,474 64 Leasing and equipment finance 15,472 16 11,837 10 16,131 70 11,638 28 Inventory finance 1,464 20 2,078 18 1,369 51 3,120 176 Auto finance 452 — 2,792 55 709 — 3,337 146 Other 2 — 4 — 3 — 6 — Total impaired loans with an allowance recorded 115,762 730 139,407 1,144 129,258 2,798 160,148 3,720 Impaired loans without an allowance recorded: Consumer real estate: First mortgage lien 10,074 171 11,871 212 10,105 527 12,264 736 Junior lien 1,591 44 1,669 71 1,556 152 1,749 392 Total consumer real estate 11,665 215 13,540 283 11,661 679 14,013 1,128 Commercial: Commercial real estate 4,315 58 12,090 95 4,385 174 11,860 438 Commercial business — — 334 2 — — 284 3 Total commercial 4,315 58 12,424 97 4,385 174 12,144 441 Inventory finance 403 31 1,255 62 1,510 136 1,037 136 Auto finance 8,757 77 4,878 — 8,630 211 4,592 — Total impaired loans without an allowance recorded 25,140 381 32,097 442 26,186 1,200 31,786 1,705 Total impaired loans $ 140,902 $ 1,111 $ 171,504 $ 1,586 $ 155,444 $ 3,998 $ 191,934 $ 5,425 Other Real Estate Owned and Repossessed and Returned Assets Other real estate owned and repossessed and returned assets were as follows: (In thousands) At September 30, 2018 At December 31, 2017 Other real estate owned $ 19,079 $ 18,225 Repossessed and returned assets 12,279 12,630 Consumer real estate loans in process of foreclosure 15,190 22,622 Other real estate owned and repossessed and returned assets were written down $0.7 million and $2.7 million in the third quarter and first nine months of 2018 , respectively, and $1.6 million and $5.0 million in the same periods in 2017 .

Long-term Borrowings

Long-term Borrowings	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Long-term Borrowings	Long-term Borrowings Long-term borrowings were as follows: At September 30, 2018 At December 31, 2017 (Dollars in thousands) Stated Maturity Amount Stated Rate Amount Stated Rate Federal Home Loan Bank advances 2019 $ — — % $ 600,000 1.40 % - 1.75 % 2020 825,000 2.29 % - 2.45 275,000 1.76 - 1.78 Subtotal 825,000 875,000 Subordinated bank notes 2022 109,037 6.25 108,867 6.25 2025 148,408 4.60 148,252 4.60 Hedge-related basis adjustment (1) (8,339 ) (2,157 ) Subtotal 249,106 254,962 Discounted lease rentals 2018 11,976 2.78 - 4.20 52,347 2.55 - 7.95 2019 39,853 2.53 - 6.00 34,978 2.53 - 6.00 2020 25,034 2.64 - 6.50 19,736 2.64 - 6.50 2021 13,374 2.88 - 5.80 10,077 2.88 - 5.00 2022 3,844 3.04 - 5.50 2,349 3.04 - 5.43 2023 213 4.90 - 5.78 — — Subtotal 94,294 119,487 Capital lease obligation 2018 20 3.73 — — 2019 83 3.73 — — 2020 86 3.73 — — 2021 89 3.73 — — 2022 93 3.73 — — 2023 - 2038 2,770 3.73 — — Subtotal 3,141 — Total long-term borrowings $ 1,171,541 $ 1,249,449 (1) Related to subordinated bank notes with a stated maturity of 2025. At September 30, 2018 , TCF Bank had pledged loans secured by consumer and commercial real estate and Federal Home Loan Bank ("FHLB") stock with an aggregate carrying value of $4.1 billion as collateral for FHLB advances. At September 30, 2018 , $825.0 million of the FHLB advances outstanding were prepayable at TCF's option.

Equity

Equity	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Equity	Equity Preferred Stock Preferred stock was as follows: (In thousands) At September 30, 2018 At December 31, 2017 Series B non-cumulative perpetual preferred stock $ — $ 96,519 Series C non-cumulative perpetual preferred stock 169,302 169,302 Total preferred stock $ 169,302 $ 265,821 At September 30, 2018 and December 31, 2017 , TCF had 7,000,000 depositary shares outstanding, each representing a 1/1000 th ownership interest in a share of the 5.70% Series C non-cumulative perpetual preferred stock of TCF Financial Corporation, par value $0.01 per share, with a liquidation preference of $25,000 per share (equivalent to $25 per depositary share) (the "Series C Preferred Stock"). Dividends are payable on the Series C Preferred Stock if, as and when declared by TCF's Board of Directors on a non-cumulative basis on March 1, June 1, September 1 and December 1 of each year at a per annum rate of 5.70% . The Series C Preferred Stock was issued on September 14, 2017 and may be redeemed at TCF's option in whole or in part on December 1, 2022 or on any dividend payment date thereafter. On March 1, 2018, TCF redeemed all 4,000,000 of the outstanding shares of the 6.45% Series B non-cumulative perpetual preferred stock of TCF Financial Corporation, par value $0.01 per share, with a liquidation preference of $25 per share (the "Series B Preferred Stock") for $100.0 million . Deferred stock issuance costs of $3.5 million originally recorded as a reduction to preferred stock upon the issuance of the Series B Preferred Stock were reclassified to retained earnings and resulted in a one-time, non-cash reduction to net income available to common stockholders utilized in the computation of earnings per common share and diluted earnings per common share for the first nine months of 2018 . Dividends were payable on the Series B Preferred Stock if, as and when declared by TCF's Board of Directors on a non-cumulative basis on March 1, June 1, September 1 and December 1 of each year at a per annum rate of 6.45% . Treasury Stock and Other Treasury stock and other were as follows: (In thousands) At September 30, 2018 At December 31, 2017 Treasury stock, at cost $ 160,178 $ 10,265 Shares held in trust for deferred compensation plans, at cost 29,474 30,532 Total $ 189,652 $ 40,797 TCF repurchased $24.0 million and $149.9 million of its common stock during the third quarter and first nine months of 2018 , respectively, pursuant to its share repurchase program. These shares were recorded as treasury stock. No repurchases of common stock were made in the first nine months of 2017 . At September 30, 2018 , TCF had the authority to repurchase an additional $141.0 million in aggregate value of shares pursuant to its share repurchase program. Warrants At September 30, 2018 , TCF had 173,296 warrants outstanding with an exercise price of $16.93 per share, which expire on November 14, 2018 . During the first nine months of 2018 , 3,026,692 warrants were exercised.

Regulatory Capital Requirements

Regulatory Capital Requirements	9 Months Ended
	Sep. 30, 2018
Regulatory Capital Requirements [Abstract]
Regulatory Capital Requirements	Regulatory Capital Requirements TCF and TCF Bank are subject to minimum capital requirements administered by the federal banking regulators. Failure to meet minimum capital requirements can initiate certain mandatory, and possible additional discretionary, actions by the federal banking regulators that could have a material adverse effect on TCF. In general, TCF Bank may not declare or pay a dividend to TCF Financial in excess of 100% of its net retained earnings for the current year combined with its net retained earnings for the preceding two calendar years, which was $249.1 million at September 30, 2018 , without prior approval of the Office of the Comptroller of the Currency ("OCC"). The OCC also has the authority to prohibit the payment of dividends by a national bank when it determines such payments would constitute an unsafe and unsound banking practice. TCF Bank's ability to make capital distributions in the future may require regulatory approval and may be restricted by its federal banking regulators. TCF Bank's ability to make any such distributions will also depend on its earnings and ability to meet minimum regulatory capital requirements in effect during future periods. In the future, these capital adequacy standards may be higher than existing minimum regulatory capital requirements. Regulatory capital information for TCF and TCF Bank was as follows: TCF TCF Bank At September 30, At December 31, At September 30, At December 31, Well-capitalized Standard Minimum Capital Requirement (1) (Dollars in thousands) 2018 2017 2018 2017 Regulatory Capital: Common equity Tier 1 capital $ 2,226,820 $ 2,242,410 $ 2,297,245 $ 2,409,027 Tier 1 capital 2,412,869 2,522,178 2,318,399 2,426,854 Total capital 2,754,615 2,889,323 2,696,433 2,837,374 Regulatory Capital Ratios: Common equity Tier 1 capital ratio 11.04 % 10.79 % 11.39 % 11.59 % 6.50 % 4.50 % Tier 1 risk-based capital ratio 11.96 12.14 11.49 11.68 8.00 6.00 Total risk-based capital ratio 13.66 13.90 13.37 13.65 10.00 8.00 Tier 1 leverage ratio 10.58 11.12 10.16 10.70 5.00 4.00 (1) Excludes capital conservation buffer of 1.875% and 1.25% at September 30, 2018 and December 31, 2017 , respectively.

Stock Compensation

Stock Compensation	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Compensation	Stock Compensation TCF's restricted stock award and stock option transactions under the TCF Financial 2015 Omnibus Incentive Plan ("Omnibus Incentive Plan") and the TCF Financial Incentive Stock Program were as follows: Restricted Stock Awards Stock Options Shares Weighted- average Grant Date Fair Value Shares Weighted- average Remaining Contractual Life in Years Weighted- average Exercise Price Outstanding at December 31, 2017 2,639,663 $ 13.65 366,000 0.06 $ 15.75 Granted 747,446 21.71 — — — Exercised — — (366,000 ) — 15.75 Forfeited/canceled (203,751 ) 15.07 — — — Vested (836,323 ) 12.15 — — — Outstanding at September 30, 2018 2,347,035 $ 16.62 — — $ — At September 30, 2018 , there were 264,373 shares of performance-based restricted stock awards outstanding that will vest only if certain performance goals and service conditions are achieved. Failure to achieve the performance goals and service conditions will result in all or a portion of the shares being forfeited. Unrecognized stock compensation expense for restricted stock awards was $21.1 million with a weighted-average remaining amortization period of 1.6 years at September 30, 2018 . At September 30, 2018 , there were 406,575 performance-based restricted stock units granted under the Omnibus Incentive Plan that will vest only if certain performance goals are achieved. The number of restricted stock units granted was at target and the actual restricted stock units that will vest will depend on actual performance with a maximum total payout of 150% of target. Failure to achieve the performance goals will result in all or a portion of the restricted stock units being forfeited. The remaining weighted-average performance period of the restricted stock units was 1.7 years at September 30, 2018 . Compensation expense for restricted stock awards and restricted stock units was $3.5 million and $13.1 million for the third quarter and first nine months of 2018 , respectively, and $2.4 million and $6.5 million for the same periods in 2017 .

Employee Benefit Plans

Employee Benefit Plans	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans The net periodic benefit plan (income) cost included in other non-interest expense for the TCF Cash Balance Pension Plan (the "Pension Plan") and the Postretirement Plan were as follows: Pension Plan Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Interest cost $ 246 $ 284 $ 738 $ 854 Return on plan assets (133 ) (142 ) (397 ) (426 ) Net periodic benefit plan (income) cost $ 113 $ 142 $ 341 $ 428 Postretirement Plan Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Interest cost $ 28 $ 33 $ 83 $ 100 Amortization of prior service cost (12 ) (12 ) (35 ) (35 ) Net periodic benefit plan (income) cost $ 16 $ 21 $ 48 $ 65 TCF made no cash contributions to the Pension Plan in the first nine months of 2018 and 2017 . TCF contributed $0.1 million and $0.3 million to the Postretirement Plan in the third quarter and first nine months of 2018 , respectively, and $0.1 million and $0.2 million in the same periods in 2017 .

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments Derivative instruments, recognized at fair value within other assets or accrued expenses and other liabilities on the Consolidated Statements of Financial Condition, were as follows: At September 30, 2018 Fair Value (In thousands) Notional Amount Derivative Assets Derivative Liabilities Derivatives designated as hedging instruments: Interest rate contracts $ 150,000 $ 111 $ — Forward foreign exchange contracts 163,286 — 2,693 Total derivatives designated as hedging instruments 111 2,693 Derivatives not designated as hedging instruments: Interest rate contracts 837,693 1,118 7,367 Forward foreign exchange contracts 252,829 20 2,482 Interest rate lock commitments 45,254 994 378 Other contracts 13,020 — 658 Total derivatives not designated as hedging instruments 2,132 10,885 Total derivatives before netting 2,243 13,578 Netting (1) (352 ) (2,221 ) Total derivatives, net $ 1,891 $ 11,357 At December 31, 2017 Fair Value (In thousands) Notional Amount Derivative Assets Derivative Liabilities Derivatives designated as hedging instruments: Interest rate contracts $ 150,000 $ 405 $ — Forward foreign exchange contracts 77,879 — 1,744 Total derivatives designated as hedging instruments 405 1,744 Derivatives not designated as hedging instruments: Interest rate contracts 592,383 1,392 1,688 Forward foreign exchange contracts 330,928 — 4,619 Interest rate lock commitments 18,015 223 — Other contracts 13,804 — 615 Total derivatives not designated as hedging instruments 1,615 6,922 Total derivatives before netting 2,020 8,666 Netting (1) (457 ) (7,098 ) Total derivatives, net $ 1,563 $ 1,568 (1) Includes balance sheet netting of derivative asset and derivative liability balances, related cash collateral and portfolio level counterparty valuation adjustments. Derivative instruments may be subject to master netting arrangements and collateral arrangements and qualify for offset in the Consolidated Statements of Financial Condition. A master netting arrangement with a counterparty creates a right of offset for amounts due to and from that same counterparty that is enforceable in the event of a default or bankruptcy. Derivative instruments subject to master netting arrangements and collateral arrangements are recognized on a net basis in the Consolidated Statements of Financial Condition. The gross amounts recognized, gross amounts offset and net amount presented of the derivative instruments were as follows: At September 30, 2018 (In thousands) Gross Amounts Recognized Gross Amounts Offset (1) Net Amount Presented Derivative assets: Interest rate contracts $ 1,229 $ (332 ) $ 897 Interest rate lock commitments 994 — 994 Forward foreign exchange contracts 20 (20 ) — Total derivative assets $ 2,243 $ (352 ) $ 1,891 Derivative liabilities: Forward foreign exchange contracts $ 5,175 $ (1,433 ) $ 3,742 Interest rate contracts 7,367 (130 ) 7,237 Interest rate lock commitments 378 — 378 Other contracts 658 (658 ) — Total derivative liabilities $ 13,578 $ (2,221 ) $ 11,357 At December 31, 2017 (In thousands) Gross Amounts Recognized Gross Amounts Offset (1) Net Amount Presented Derivative assets: Interest rate contracts $ 1,797 $ (457 ) $ 1,340 Interest rate lock commitments 223 — 223 Total derivative assets $ 2,020 $ (457 ) $ 1,563 Derivative liabilities: Forward foreign exchange contracts $ 6,363 $ (6,026 ) $ 337 Interest rate contracts 1,688 (457 ) 1,231 Other contracts 615 (615 ) — Total derivative liabilities $ 8,666 $ (7,098 ) $ 1,568 (1) Includes the amounts with counterparties subject to enforceable master netting arrangements that have been offset in the consolidated balance sheets. Derivatives Designated as Hedging Instruments Interest Rate Contract TCF Bank entered into an interest rate swap agreement which was designated as a fair value hedge of its contemporaneously issued subordinated debt. The interest rate swap agreement effectively converts the fixed interest rate to a floating rate based on the three-month London InterBank Offered Rate plus a fixed number of basis points on the $150.0 million notional amount. The carrying amount of the hedged subordinated debt including the cumulative basis adjustment related to the application of fair value hedge accounting is recorded in Long-term borrowings on the Consolidated Statements of Financial Condition and was as follows: Carrying Amount of the Hedged Liability Cumulative Amount of Fair Value Hedging Adjustments Included in the Carrying Amount of the Hedged Liability (In thousands) At September 30, 2018 At December 31, 2017 At September 30, 2018 At December 31, 2017 Subordinated bank note - 2025 $ 140,069 $ 146,095 $ (8,339 ) $ (2,157 ) The gain (loss) related to the fair value hedge and the line within the Consolidated Statements of Income where the gain (loss) was recorded were as follows: Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Gain (loss) of fair value hedge: Hedged item $ 1,206 $ 146 $ 6,337 $ (601 ) Derivative designated as a hedging instrument (1,165 ) (135 ) (6,621 ) 813 Income statement line where the gain (loss) on the fair value hedge was recorded: Interest expense - borrowings $ 10,726 $ — $ 31,850 $ — Other non-interest income — 2,930 — 8,428 Forward Foreign Exchange Contracts Certain of TCF's forward foreign exchange contracts are used to manage the foreign exchange risk associated with the Company's net investment in TCF Commercial Finance Canada, Inc., a wholly-owned indirect Canadian subsidiary of TCF Bank. These forward foreign exchange contracts have been designated as net investment hedges. The effect of net investment hedges on accumulated other comprehensive income was as follows: Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Forward foreign exchange contracts $ (2,537 ) $ (2,174 ) $ 4,637 $ (5,073 ) Derivatives Not Designated as Hedging Instruments Certain other forward foreign exchange contracts, interest rate lock commitments, other contracts and and interest rate contracts have not been designated as hedging instruments. The effect of these derivatives on the Consolidated Statements of Income was as follows: Quarter Ended September 30, Nine Months Ended September 30, (In thousands) Location of Gain (Loss) 2018 2017 2018 2017 Forward foreign exchange contracts Other non-interest expense $ (3,706 ) $ (10,690 ) $ 8,050 $ (20,323 ) Interest rate lock commitments Gains on sales of consumer real estate loans, net (244 ) (29 ) 798 189 Other contracts Other non-interest expense (292 ) — (274 ) — Interest rate contracts Other non-interest income 51 (155 ) 157 (263 ) Net gain (loss) recognized $ (4,191 ) $ (10,874 ) $ 8,731 $ (20,397 ) TCF executes all of its forward foreign exchange contracts in the over-the-counter market with large financial institutions pursuant to International Swaps and Derivatives Association, Inc. agreements. These agreements include credit risk-related features that enhance the creditworthiness of these instruments, as compared with other obligations of the respective counterparty with whom TCF has transacted, by requiring that additional collateral be posted under certain circumstances. The amount of collateral required depends on the contract and is determined daily based on market and currency exchange rate conditions. At September 30, 2018 and December 31, 2017 , credit risk-related contingent features existed on forward foreign exchange contracts with a notional value of $34.9 million and $39.8 million , respectively. In the event TCF is rated less than BB- by Standard and Poor's, the contracts could be terminated or TCF may be required to provide approximately $0.7 million and $0.8 million in additional collateral at September 30, 2018 and December 31, 2017 , respectively. There were $0.6 million and $0.4 million of forward foreign exchange contracts containing credit risk-related features in a liability position at September 30, 2018 and December 31, 2017 , respectively. At September 30, 2018 , TCF had posted $7.6 million , $1.3 million and $1.2 million of cash collateral related to its interest rate contracts, other contracts and forward foreign exchange contracts, respectively, and received $0.2 million of cash collateral related to its forward foreign exchange contracts.

Fair Values Disclosures

Fair Values Disclosures	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Disclosures	Fair Value Disclosures TCF uses fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures. The Company's fair values are based on the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Debt securities available for sale, certain loans held for sale, interest-only strips, forward foreign exchange contracts, interest rate contracts, other contracts, interest rate lock commitments, forward loan sales commitments, and assets and liabilities held in trust for deferred compensation plans are recorded at fair value on a recurring basis. From time to time we may be required to record at fair value other assets on a non-recurring basis, such as certain debt securities held to maturity, loans, goodwill, other intangible assets, other real estate owned, repossessed and returned assets and the securitization receivable. These non-recurring fair value adjustments typically involve application of lower of cost or fair value accounting or write-downs of individual assets. TCF groups its assets and liabilities measured at fair value in three levels, based on the markets in which the assets and liabilities are traded and the degree and reliability of estimates and assumptions used to determine fair value. The levels are as follows: Level 1, which includes valuations that are based on prices obtained from independent pricing sources for the same instruments traded in active markets; Level 2, which includes valuations that are based on prices obtained from independent pricing sources that are based on observable transactions of similar instruments, but not quoted markets and Level 3, which includes valuations generated from Company model-based techniques that use significant unobservable inputs. Such unobservable inputs reflect estimates of assumptions that market participants would use in pricing the asset or liability. The following is a discussion of the valuation methodologies used to record assets and liabilities at fair value on a recurring or non-recurring basis. Debt Securities Available for Sale Debt securities available for sale consist primarily of securities of U.S. Government sponsored enterprises and federal agencies, and obligations of states and political subdivisions. The fair value of these securities, categorized as Level 2, is recorded using prices obtained from independent asset pricing services that are based on observable transactions, but not quoted markets. Management reviews the prices obtained from independent asset pricing services for unusual fluctuations and comparisons to current market trading activity. Loans Held for Sale Loans held for sale for which the fair value option has been elected are categorized as Level 3. The fair value of these loans is recorded utilizing internal valuation models which use quoted investor prices to estimate the fair value. Loans Loans for which repayment is expected to be provided solely by the value of the underlying collateral, categorized as Level 3 and recorded at fair value on a non-recurring basis, are valued based on the fair value of that collateral less estimated selling costs. Such loans include non-accrual impaired loans as well as certain delinquent non-accrual consumer real estate and auto finance loans. The fair value of the collateral is determined based on internal estimates and assessments provided by third-party appraisers. Interest-only Strips The fair value of interest-only strips, categorized as Level 3, represents the present value of future cash flows expected to be received by TCF on certain assets. TCF uses available market data, along with its own empirical data and discounted cash flow models, to arrive at the fair value of its interest-only strips. The present value of the estimated expected future cash flows to be received is determined by using discount, loss and prepayment rates that TCF believes are commensurate with the risks associated with the cash flows and what a market participant would use. These assumptions are inherently subject to volatility and uncertainty and, as a result, the fair value of the interest-only strips may fluctuate significantly from period to period. Derivative Instruments Forward Foreign Exchange Contracts TCF's forward foreign exchange contracts are currency contracts executed in over-the-counter markets and are recorded at fair value using a cash flow model that includes key inputs such as foreign exchange rates and an assessment of the risk of counterparty non-performance. The risk of counterparty non-performance is based on external assessments of credit risk. The fair value of these contracts, categorized as Level 2, is based on observable transactions, but not quoted markets. Interest Rate Contracts TCF executes interest rate contracts with commercial banking customers to facilitate their respective risk management strategies. Certain of these interest rate contracts are simultaneously hedged by offsetting interest rate contracts TCF executes with a third party, minimizing TCF's net interest rate risk exposure resulting from such transactions. TCF also has an interest rate swap agreement to convert its $150.0 million of fixed-rate subordinated notes to floating rate debt. These derivative instruments are recorded at fair value. The fair value of these interest rate contracts, categorized as Level 2, is determined using a cash flow model which considers the forward curve, the discount curve and credit valuation adjustments related to counterparty and/or borrower non-performance risk. Other Contracts TCF's swap agreement, categorized as Level 3, is related to the sale of TCF's Visa Class B stock. The fair value of the swap agreement is based on TCF's estimated exposure related to the Visa covered litigation through a probability analysis of the funding and estimated settlement amounts. Interest Rate Lock Commitments TCF's interest rate lock commitments are derivative instruments that are recorded at fair value using an internal valuation model that utilizes estimated rates of successful loan closings and quoted investor prices. While this model uses both Level 2 and Level 3 inputs, TCF has determined that the significant inputs used in the valuation of these commitments fall within Level 3 and therefore the interest rate lock commitments are categorized as Level 3. Forward Loan Sales Commitments TCF enters into forward loan sales commitments to sell certain consumer real estate loans. The resulting loans held for sale are recorded at fair value under the elected fair value option. TCF relies on internal valuation models to estimate the fair value of these instruments. The valuation models utilize estimated rates of successful loan closings and quoted investor prices. While these models use both Level 2 and Level 3 inputs, TCF has determined that the significant inputs used in the valuation of these commitments fall within Level 3 and therefore the forward loan sales commitments are categorized as Level 3. Other Real Estate Owned and Repossessed and Returned Assets The fair value of other real estate owned, categorized as Level 3, is based on independent appraisals, real estate brokers' price opinions or automated valuation methods, less estimated selling costs. Certain properties require assumptions that are not observable in an active market in the determination of fair value. The fair value of repossessed and returned assets is based on available pricing guides, auction results or price opinions, less estimated selling costs. Assets acquired through foreclosure, repossession or returned to TCF are initially recorded at the lower of the loan or lease carrying amount or fair value less estimated selling costs at the time of transfer to other real estate owned or repossessed and returned assets. Assets and Liabilities Held in Trust for Deferred Compensation Plans Assets held in trust for deferred compensation plans include investments in publicly traded securities, excluding TCF common stock reported in treasury stock and other equity, and U.S. Treasury notes. The fair value of these assets, categorized as Level 1, is based on prices obtained from independent asset pricing services based on active markets. The fair value of the liabilities equals the fair value of the assets. The balances of assets and liabilities measured at fair value on a recurring and non-recurring basis were as follows: At September 30, 2018 (In thousands) Level 1 Level 2 Level 3 Total Recurring Fair Value Measurements through Net Income: Assets: Loans held for sale $ — $ — $ 18,519 $ 18,519 Forward foreign exchange contracts (1) — 20 — 20 Interest rate contracts (1) — 1,229 — 1,229 Interest rate lock commitments (1) — — 994 994 Forward loan sales commitments — — 665 665 Assets held in trust for deferred compensation plans 34,626 — — 34,626 Total assets $ 34,626 $ 1,249 $ 20,178 $ 56,053 Liabilities: Forward foreign exchange contracts (1) $ — $ 2,482 $ — $ 2,482 Interest rate contracts (1) — 7,367 — 7,367 Interest rate lock commitments (1) — — 378 378 Other contracts (1) — — 658 658 Forward loan sales commitments — — 196 196 Liabilities held in trust for deferred compensation plans 34,626 — — 34,626 Total liabilities $ 34,626 $ 9,849 $ 1,232 $ 45,707 Recurring Fair Value Measurements through Other Comprehensive Income: Assets: Debt securities available for sale: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ — $ 1,580,684 $ — $ 1,580,684 Other — — 4 4 Obligations of states and political subdivisions — 798,858 — 798,858 Interest-only strips — — 17,712 17,712 Total assets $ — $ 2,379,542 $ 17,716 $ 2,397,258 Liabilities: Forward foreign exchange contracts (1) $ — $ 2,693 $ — $ 2,693 Total liabilities $ — $ 2,693 $ — $ 2,693 Non-recurring Fair Value Measurements: Loans $ — $ — $ 48,934 $ 48,934 Other real estate owned — — 11,893 11,893 Repossessed and returned assets — 3,918 3,882 7,800 Total non-recurring fair value measurements $ — $ 3,918 $ 64,709 $ 68,627 (1) As permitted under GAAP, TCF has elected to net derivative assets and derivative liabilities when a legally enforceable master netting agreement exists as well as the related cash collateral received and paid. For purposes of this table, the derivative assets and derivative liabilities are presented gross of this netting adjustment. At December 31, 2017 (In thousands) Level 1 Level 2 Level 3 Total Recurring Fair Value Measurements through Net Income: Assets: Loans held for sale $ — $ — $ 3,356 $ 3,356 Interest rate contracts (1) — 1,797 — 1,797 Interest rate lock commitments (1) — — 223 223 Forward loan sales commitments — — 68 68 Assets held in trust for deferred compensation plans 29,962 — — 29,962 Total assets $ 29,962 $ 1,797 $ 3,647 $ 35,406 Liabilities: Forward foreign exchange contracts (1) $ — $ 4,619 $ — $ 4,619 Interest rate contracts (1) — 1,688 — 1,688 Other contracts (1) — — 615 615 Forward loan sales commitments — — 5 5 Liabilities held in trust for deferred compensation plans 29,962 — — 29,962 Total liabilities $ 29,962 $ 6,307 $ 620 $ 36,889 Recurring Fair Value Measurements through Other Comprehensive Income: Assets: Debt securities available for sale: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ — $ 894,685 $ — $ 894,685 Other — — 6 6 Obligations of states and political subdivisions — 814,327 — 814,327 Interest-only strips — — 21,386 21,386 Total assets $ — $ 1,709,012 $ 21,392 $ 1,730,404 Liabilities: Forward foreign exchange contracts (1) $ — $ 1,744 $ — $ 1,744 Total liabilities $ — $ 1,744 $ — $ 1,744 Non-recurring Fair Value Measurements: Loans $ — $ — $ 72,287 $ 72,287 Other real estate owned — — 14,036 14,036 Repossessed and returned assets — 3,669 4,388 8,057 Total non-recurring fair value measurements $ — $ 3,669 $ 90,711 $ 94,380 (1) As permitted under GAAP, TCF has elected to net derivative assets and derivative liabilities when a legally enforceable master netting agreement exists as well as the related cash collateral received and paid. For purposes of this table, the derivative assets and derivative liabilities are presented gross of this netting adjustment. Management assesses the appropriate classification of financial assets and liabilities within the fair value hierarchy by monitoring the level of available observable market information. Changes in markets or economic conditions, as well as changes to Company valuation models, may require the transfer of financial instruments from one fair value level to another. Such transfers, if any, are recorded at the fair values as of the beginning of the quarter in which the transfers occurred. TCF had no transfers in the first nine months of 2018 and 2017 . The changes in Level 3 assets and liabilities measured at fair value on a recurring basis were as follows: (In thousands) Debt Securities Loans Interest-only Strips Interest Forward Other Contracts At or For the Quarter Ended September 30, 2018: Asset (liability) balance, beginning of period $ 4 $ 18,554 $ 19,887 $ 858 $ 110 $ (441 ) Total net gains (losses) included in: Net income — (184 ) 732 (242 ) 359 (292 ) Other comprehensive income (loss) — — 246 — — — Sales — (97,866 ) — — — — Originations — 98,018 — — — — Principal paydowns / settlements — (3 ) (3,153 ) — — 75 Asset (liability) balance, end of period $ 4 $ 18,519 $ 17,712 $ 616 $ 469 $ (658 ) At or For the Quarter Ended September 30, 2017: Asset (liability) balance, beginning of period $ 11 $ 5,238 $ 32,582 $ 515 $ (67 ) $ (462 ) Total net gains (losses) included in: Net income — 17 1,110 (29 ) 14 — Other comprehensive income (loss) — — (1,063 ) — — — Sales — (59,308 ) — — — — Originations — 58,634 542 — — — Principal paydowns / settlements (3 ) (388 ) (9,374 ) — — 78 Asset (liability) balance, end of period $ 8 $ 4,193 $ 23,797 $ 486 $ (53 ) $ (384 ) (In thousands) Debt Securities Available for Sale Loans Held for Sale Interest-only Strips Interest Rate Lock Commitments Forward Loan Sales Commitments Other Contracts At or For the Nine Months Ended September 30, 2018: Asset (liability) balance, beginning of period $ 6 $ 3,356 $ 21,386 $ 223 $ 63 $ (615 ) Total net gains (losses) included in: Net income — 254 1,913 393 406 (274 ) Other comprehensive income (loss) — — 1,015 — — — Sales — (232,747 ) — — — — Originations — 247,667 3,849 — — — Principal paydowns / settlements (2 ) (11 ) (10,451 ) — — 231 Asset (liability) balance, end of period $ 4 $ 18,519 $ 17,712 $ 616 $ 469 $ (658 ) At or For the Nine Months Ended September 30, 2017: Asset (liability) balance, beginning of period $ 18 $ 6,498 $ 40,152 $ 297 $ 361 $ (619 ) Total net gains (losses) included in: Net income — 155 3,323 189 (414 ) — Other comprehensive income (loss) — — (464 ) — — — Sales — (151,182 ) — — — — Originations — 149,118 2,458 — — — Principal paydowns / settlements (10 ) (396 ) (21,672 ) — — 235 Asset (liability) balance, end of period $ 8 $ 4,193 $ 23,797 $ 486 $ (53 ) $ (384 ) Fair Value Option TCF Bank originates first mortgage lien loans in its primary banking markets and sells the loans through correspondent relationships. TCF elected the fair value option for these loans. This election facilitates the offsetting of changes in fair value of the loans held for sale and the derivative financial instruments used to economically hedge them. The difference between the aggregate fair value and aggregate unpaid principal balance of these loans held for sale was as follows: (In thousands) At September 30, 2018 At December 31, 2017 Fair value carrying amount $ 18,519 $ 3,356 Aggregate unpaid principal amount 18,180 3,268 Fair value carrying amount less aggregate unpaid principal $ 339 $ 88 Differences between the fair value carrying amount and the aggregate unpaid principal balance include changes in fair value recorded at and subsequent to funding and gains and losses on the related loan commitment prior to funding. No loans recorded under the fair value option were delinquent or on non-accrual status at September 30, 2018 and December 31, 2017 . The net gain from initial measurement of the correspondent lending loans held for sale, any subsequent changes in fair value while the loans are outstanding and any actual adjustment to the gains realized upon sales of the loans totaled $2.7 million and $6.9 million for the third quarter and first nine months of 2018 , respectively, and $1.3 million and $3.5 million for the same periods in 2017 , and are included in net gains on sales of consumer real estate loans. These amounts exclude the impacts from the interest rate lock commitments and forward loan sales commitments which are also included in net gains on sales of consumer real estate loans. Disclosures About Fair Value of Financial Instruments Management discloses the estimated fair value of financial instruments, including assets and liabilities on and off the balance sheet, for which it is practicable to estimate fair value. These fair value estimates were made at September 30, 2018 and December 31, 2017 based on relevant market information and information about the financial instruments. Fair value estimates are intended to represent the price at which an asset could be sold or a liability could be settled. However, given there is no active market or observable market transactions for many of the Company's financial instruments, the estimates of fair values are subjective in nature, involve uncertainties and include matters of significant judgment. Changes in assumptions could significantly affect the estimated values. The following is a summary of the fair value classifications used for the financial instruments not recorded at fair value. Investments The estimated fair value of investments in FHLB stock and Federal Reserve Bank stock is categorized as Level 2. Debt Securities Held to Maturity The estimated fair value of mortgage-backed securities of U.S. Government sponsored enterprises and federal agencies is categorized as Level 2. The estimated fair value of other debt securities held to maturity is categorized as Level 3. Loans Held for Sale The estimated fair value of loans held for sale is categorized as Level 3. Loans The estimated fair value of loans is categorized as Level 3. Securitization Receivable The estimated fair value of the securitization receivable is categorized as Level 3. Deposits The estimated fair value of checking, savings and money market deposits is categorized as Level 1. The estimated fair value of certificates of deposit is categorized as Level 2. The intangible value of long-term relationships with depositors is not taken into account in the estimated fair values disclosed. Long-term Borrowings The estimated fair value of TCF's long-term borrowings is categorized as Level 2. Financial Instruments with Off-Balance Sheet Risk The estimated fair value of TCF's commitments to extend credit and standby letters of credit is categorized as Level 2. The carrying amounts and estimated fair values of the Company's financial instruments, excluding short-term financial assets and liabilities as their carrying amounts approximate fair value, and excluding financial instruments recorded at fair value on a recurring basis, were as follows. This information represents only a portion of TCF's balance sheet and not the estimated value of the Company as a whole. Non-financial instruments such as the intangible value of TCF's branches and core deposits, leasing operations, goodwill, premises and equipment and the future revenues from TCF's customers are not reflected in this disclosure. Therefore, this information is of limited use in assessing the value of TCF. At September 30, 2018 Carrying Estimated Fair Value (In thousands) Amount Level 1 Level 2 Level 3 Total Financial instrument assets: Investments $ 80,672 $ — $ 80,672 $ — $ 80,672 Debt securities held to maturity 152,881 — 147,864 2,800 150,664 Loans held for sale 113,879 — — 117,625 117,625 Loans: Consumer real estate 4,901,457 — — 4,949,229 4,949,229 Commercial real estate 2,773,655 — — 2,723,277 2,723,277 Commercial business 967,509 — — 924,862 924,862 Equipment finance 2,146,375 — — 2,087,381 2,087,381 Inventory finance 2,880,404 — — 2,865,539 2,865,539 Auto finance 2,275,134 — — 2,240,463 2,240,463 Other 21,107 — — 16,482 16,482 Allowance for loan losses (1) (160,621 ) — — — — Securitization receivable (2) 19,369 — — 18,917 18,917 Total financial instrument assets $ 16,171,821 $ — $ 228,536 $ 15,946,575 $ 16,175,111 Financial instrument liabilities: Deposits $ 18,496,511 $ 13,624,763 $ 4,900,943 $ — $ 18,525,706 Long-term borrowings 1,171,541 — 1,174,761 — 1,174,761 Total financial instrument liabilities $ 19,668,052 $ 13,624,763 $ 6,075,704 $ — $ 19,700,467 Financial instruments with off-balance sheet risk: (3) Commitments to extend credit $ 18,353 $ — $ 18,353 $ — $ 18,353 Standby letters of credit (93 ) — (93 ) — (93 ) Total financial instruments with off-balance sheet risk $ 18,260 $ — $ 18,260 $ — $ 18,260 (1) Expected credit losses are included in the estimated fair values. (2) Carrying amounts are included in other assets. (3) Positive amounts represent assets, negative amounts represent liabilities. At December 31, 2017 Carrying Estimated Fair Value (In thousands) Amount Level 1 Level 2 Level 3 Total Financial instrument assets: Investments $ 82,644 $ — $ 82,644 $ — $ 82,644 Debt securities held to maturity 161,576 — 162,826 2,800 165,626 Loans held for sale 134,752 — — 139,458 139,458 Loans: Consumer real estate 4,819,696 — — 4,916,475 4,916,475 Commercial real estate 2,751,285 — — 2,710,237 2,710,237 Commercial business 809,908 — — 776,989 776,989 Equipment finance 2,300,479 — — 2,260,692 2,260,692 Inventory finance 2,739,754 — — 2,723,045 2,723,045 Auto finance 3,199,639 — — 3,197,794 3,197,794 Other 22,517 — — 21,129 21,129 Allowance for loan losses (1) (171,041 ) — — — — Securitization receivable (2) 19,179 — — 18,595 18,595 Total financial instrument assets $ 16,870,388 $ — $ 245,470 $ 16,767,214 $ 17,012,684 Financial instrument liabilities: Deposits $ 18,335,002 $ 13,352,731 $ 5,023,526 $ — $ 18,376,257 Long-term borrowings 1,249,449 — 1,255,333 — 1,255,333 Total financial instrument liabilities $ 19,584,451 $ 13,352,731 $ 6,278,859 $ — $ 19,631,590 Financial instruments with off-balance sheet risk: (3) Commitments to extend credit $ 19,423 $ — $ 19,423 $ — $ 19,423 Standby letters of credit (83 ) — (83 ) — (83 ) Total financial instruments with off-balance sheet risk $ 19,340 $ — $ 19,340 $ — $ 19,340 (1) Expected credit losses are included in the estimated fair values. (2) Carrying amounts are included in other assets. (3) Positive amounts represent assets, negative amounts represent liabilities.

Earnings Per Common Share

Earnings Per Common Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Common Share	Earnings Per Common Share The computations of basic and diluted earnings per common share were as follows: Quarter Ended September 30, Nine Months Ended September 30, (Dollars in thousands, except per share data) 2018 2017 2018 2017 Basic Earnings Per Common Share: Net income attributable to TCF Financial Corporation $ 86,196 $ 60,528 $ 218,706 $ 167,238 Preferred stock dividends 2,494 6,464 9,094 16,158 Impact of preferred stock redemption or notice to redeem preferred stock (1) — 5,779 3,481 5,779 Net income available to common stockholders 83,702 48,285 206,131 145,301 Less: Earnings allocated to participating securities 13 8 30 25 Earnings allocated to common stock $ 83,689 $ 48,277 $ 206,101 $ 145,276 Weighted-average common shares outstanding for basic earnings per common share 164,854,622 168,970,543 166,350,173 168,492,877 Basic earnings per common share $ 0.51 $ 0.29 $ 1.24 $ 0.86 Diluted Earnings Per Common Share: Earnings allocated to common stock $ 83,689 $ 48,277 $ 206,101 $ 145,276 Weighted-average common shares outstanding used in basic earnings per common share calculation 164,854,622 168,970,543 166,350,173 168,492,877 Net dilutive effect of: Non-participating restricted stock 589,177 269,394 623,556 312,297 Stock options — 314 3,288 17,654 Warrants 89,426 — 525,360 — Weighted-average common shares outstanding for diluted earnings per common share 165,533,225 169,240,251 167,502,377 168,822,828 Diluted earnings per common share $ 0.51 $ 0.29 $ 1.23 $ 0.86 (1) For the nine months ended September 30, 2018, amount represents the deferred stock issuance costs originally recorded in preferred stock upon the issuance of the Series B Preferred Stock that were reclassified to retained earnings on March 1, 2018, as the Company redeemed all outstanding Series B Preferred Stock. For the quarter and nine months ended September 30, 2017, amount represents the deferred stock issuance costs originally recorded in preferred stock upon the issuance of the 7.50% Series A non-cumulative perpetual preferred stock ("Series A Preferred Stock") that were reclassified to retained earnings on September 15, 2017, the date the Company announced its intent to redeem the outstanding Series A Preferred Stock. For the third quarter and first nine months of 2018 , there were 807,502 and 867,319 , respectively, of outstanding shares related to non-participating restricted stock t hat were not included in the computation of diluted earnings per common share because they were anti-dilutive . For the third quarter and first nine months of 2017 , there were 3,960,511 and 4,079,059 , respectively, of outstanding shares related to warrants and non-participating restricted stock that were not included in the computation of diluted earnings per common share because they were anti-dilutive.

Other Non-interest Expense

Other Non-interest Expense	9 Months Ended
	Sep. 30, 2018
Other Income and Expenses [Abstract]
Other Non-interest Expense	Other Non-interest Expense Other non-interest expense was as follows: Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Bureau of Consumer Financial Protection and OCC settlement charge (1) $ — $ — $ 32,000 $ — Advertising and marketing 7,674 6,060 22,075 19,678 Professional fees 5,949 9,875 16,035 26,295 Outside processing 5,052 5,176 15,936 14,411 Card processing and issuance costs 4,090 4,719 12,759 13,534 FDIC insurance 4,376 4,181 12,165 11,964 Loan and lease processing 3,313 5,304 10,430 17,258 Other 27,535 26,266 84,492 84,020 Total other non-interest expense $ 57,989 $ 61,581 $ 205,892 $ 187,160 (1) See Note 17 . Litigation Contingencies for further information.

Business Segments

Business Segments	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Business Segments	Business Segments The Company's reportable segments are Consumer Banking, Wholesale Banking and Enterprise Services. Consumer Banking is comprised of all of the Company's consumer-facing businesses and includes retail banking, consumer real estate and auto finance. Wholesale Banking is comprised of commercial banking, leasing and equipment finance, and inventory finance. Enterprise Services is comprised of (i) corporate treasury, which includes TCF's investment and borrowing portfolios and management of capital, debt and market risks; (ii) corporate functions, such as information technology, risk and credit management, bank operations, finance, investor relations, corporate development, internal audit, legal and human capital management that provide services to the operating segments; (iii) the Holding Company and (iv) eliminations. TCF evaluates performance and allocates resources based on each reportable segment's net income or loss. The reportable business segments follow GAAP as described in Note 1 . Basis of Presentation , except for the accounting for intercompany interest income and interest expense, which are eliminated in consolidation, and presenting net interest income on a fully tax-equivalent basis. TCF generally accounts for inter-segment sales and transfers at cost. Certain information for each of TCF's reportable segments, including reconciliations of TCF's consolidated totals, was as follows: (In thousands) Consumer Banking Wholesale Banking Enterprise Services Consolidated At or For the Quarter Ended September 30, 2018: Interest income: Loans and leases $ 105,961 $ 159,680 $ (963 ) $ 264,678 Debt securities available for sale — — 14,838 14,838 Debt securities held to maturity — 23 965 988 Loans held for sale and other 4,525 35 2,118 6,678 Funds transfer pricing - credits 101,961 9,017 (110,978 ) — Total interest income 212,447 168,755 (94,020 ) 287,182 Interest expense: Deposits 19,807 2,581 4,947 27,335 Borrowings 10,476 19,635 (19,385 ) 10,726 Funds transfer pricing - charges 42,440 53,377 (95,817 ) — Total interest expense 72,723 75,593 (110,255 ) 38,061 Net interest income 139,724 93,162 16,235 249,121 Provision for credit losses (837 ) 3,107 — 2,270 Net interest income after provision for credit losses 140,561 90,055 16,235 246,851 Non-interest income: Fees and service charges 30,651 1,923 — 32,574 Card revenue 15,051 14 — 15,065 ATM revenue 5,052 1 — 5,053 Subtotal 50,754 1,938 — 52,692 Gains on sales of consumer real estate loans, net 8,764 — — 8,764 Servicing fee income 5,779 253 — 6,032 Subtotal 14,543 253 — 14,796 Leasing and equipment finance — 45,045 — 45,045 Other 2,904 405 509 3,818 Fees and other revenue 68,201 47,641 509 116,351 Gains (losses) on debt securities, net — 94 — 94 Total non-interest income 68,201 47,735 509 116,445 Non-interest expense: Compensation and employee benefits 54,053 23,989 45,085 123,127 Occupancy and equipment 26,523 4,952 10,862 42,337 Other 77,196 30,214 (49,421 ) 57,989 Subtotal 157,772 59,155 6,526 223,453 Operating lease depreciation — 19,525 — 19,525 Foreclosed real estate and repossessed assets, net 3,399 482 — 3,881 Other credit costs, net 32 (468 ) — (436 ) Total non-interest expense 161,203 78,694 6,526 246,423 Income (loss) before income tax expense (benefit) 47,559 59,096 10,218 116,873 Income tax expense (benefit) 11,363 13,063 3,608 28,034 Income (loss) after income tax expense (benefit) 36,196 46,033 6,610 88,839 Income attributable to non-controlling interest — 2,643 — 2,643 Preferred stock dividends — — 2,494 2,494 Net income (loss) available to common stockholders $ 36,196 $ 43,390 $ 4,116 $ 83,702 Revenues from external customers: Interest income $ 110,486 $ 158,775 $ 17,921 $ 287,182 Non-interest income 68,201 47,735 509 116,445 Total $ 178,687 $ 206,510 $ 18,430 $ 403,627 Total assets $ 8,040,163 $ 11,740,613 $ 3,124,009 $ 22,904,785 (In thousands) Consumer Banking Wholesale Banking Enterprise Services Consolidated At or For the Quarter Ended September 30, 2017: Interest income: Loans and leases $ 113,397 $ 132,306 $ (1,730 ) $ 243,973 Debt securities available for sale — — 8,486 8,486 Debt securities held to maturity — 25 1,048 1,073 Loans held for sale and other 2,899 17 1,157 4,073 Funds transfer pricing - credits 93,042 6,942 (99,984 ) — Total interest income 209,338 139,290 (91,023 ) 257,605 Interest expense: Deposits 14,070 888 2,057 17,015 Borrowings 13,236 12,400 (19,149 ) 6,487 Funds transfer pricing - charges 36,671 37,061 (73,732 ) — Total interest expense 63,977 50,349 (90,824 ) 23,502 Net interest income (expense) 145,361 88,941 (199 ) 234,103 Provision for credit losses 11,129 3,416 — 14,545 Net interest income (expense) after provision for credit losses 134,232 85,525 (199 ) 219,558 Non-interest income: Fees and service charges 31,145 3,460 — 34,605 Card revenue 14,176 1 — 14,177 ATM revenue 5,234 — — 5,234 Subtotal 50,555 3,461 — 54,016 Gains on sales of consumer real estate loans, net 8,049 — — 8,049 Servicing fee income 9,620 346 — 9,966 Subtotal 17,669 346 — 18,015 Leasing and equipment finance — 34,080 — 34,080 Other 2,710 196 24 2,930 Fees and other revenue 70,934 38,083 24 109,041 Gains (losses) on securities, net — 189 — 189 Total non-interest income 70,934 38,272 24 109,230 Non-interest expense: Compensation and employee benefits 55,977 19,941 39,036 114,954 Occupancy and equipment 28,137 5,214 5,415 38,766 Other 77,065 28,276 (43,760 ) 61,581 Subtotal 161,179 53,431 691 215,301 Operating lease depreciation — 15,696 — 15,696 Foreclosed real estate and repossessed assets, net 2,829 902 98 3,829 Other credit costs, net 54 155 — 209 Total non-interest expense 164,062 70,184 789 235,035 Income (loss) before income tax expense (benefit) 41,104 53,613 (964 ) 93,753 Income tax expense (benefit) 14,370 17,153 (819 ) 30,704 Income (loss) after income tax expense (benefit) 26,734 36,460 (145 ) 63,049 Income attributable to non-controlling interest — 2,521 — 2,521 Preferred stock dividends — — 6,464 6,464 Impact of notice to redeem preferred stock — — 5,779 5,779 Net income (loss) available to common stockholders $ 26,734 $ 33,939 $ (12,388 ) $ 48,285 Revenues from external customers: Interest income $ 116,296 $ 130,618 $ 10,691 $ 257,605 Non-interest income 70,934 38,272 24 109,230 Total $ 187,230 $ 168,890 $ 10,715 $ 366,835 Total assets $ 9,239,458 $ 11,287,665 $ 2,477,915 $ 23,005,038 (In thousands) Consumer Banking Wholesale Banking Enterprise Services Consolidated At or For the Nine Months Ended September 30, 2018: Interest income: Loans and leases $ 323,280 $ 473,870 $ (2,817 ) $ 794,333 Debt securities available for sale — — 37,477 37,477 Debt securities held to maturity — 70 2,935 3,005 Loans held for sale and other 8,267 80 5,605 13,952 Funds transfer pricing - credits 298,850 24,945 (323,795 ) — Total interest income 630,397 498,965 (280,595 ) 848,767 Interest Expense: Deposits 56,077 5,812 11,909 73,798 Borrowings 34,165 57,920 (60,235 ) 31,850 Funds transfer pricing - charges 121,068 148,100 (269,168 ) — Total interest expense 211,310 211,832 (317,494 ) 105,648 Net interest income 419,087 287,133 36,899 743,119 Provision for credit losses 18,941 8,933 — 27,874 Net interest income after provision for credit losses 400,146 278,200 36,899 715,245 Non-interest income: Fees and service charges 88,389 7,606 — 95,995 Card revenue 43,748 38 — 43,786 ATM revenue 14,634 2 — 14,636 Subtotal 146,771 7,646 — 154,417 Gains on sales of consumer real estate loans, net 25,079 — — 25,079 Servicing fee income 20,751 1,060 — 21,811 Subtotal 45,830 1,060 — 46,890 Leasing and equipment finance — 129,796 — 129,796 Other 9,071 1,489 908 11,468 Fees and other revenue 201,672 139,991 908 342,571 Gains (losses) on debt securities, net — 181 — 181 Total non-interest income 201,672 140,172 908 342,752 Non-interest expense: Compensation and employee benefits 161,960 71,476 134,106 367,542 Occupancy and equipment 78,639 14,905 30,018 123,562 Other 257,747 88,843 (140,698 ) 205,892 Subtotal 498,346 175,224 23,426 696,996 Operating lease depreciation — 54,744 — 54,744 Foreclosed real estate and repossessed assets, net 10,947 1,700 7 12,654 Other credit costs, net 92 (44 ) — 48 Total non-interest expense 509,385 231,624 23,433 764,442 Income (loss) before income tax expense (benefit) 92,433 186,748 14,374 293,555 Income tax expense (benefit) 22,351 41,191 2,541 66,083 Income (loss) after income tax expense (benefit) 70,082 145,557 11,833 227,472 Income attributable to non-controlling interest — 8,766 — 8,766 Preferred stock dividends — — 9,094 9,094 Impact of preferred stock redemption — — 3,481 3,481 Net income (loss) available to common stockholders $ 70,082 $ 136,791 $ (742 ) $ 206,131 Revenues from external customers: Interest income $ 331,547 $ 471,203 $ 46,017 $ 848,767 Non-interest income 201,672 140,172 908 342,752 Total $ 533,219 $ 611,375 $ 46,925 $ 1,191,519 Total assets $ 8,040,163 $ 11,740,613 $ 3,124,009 $ 22,904,785 (In thousands) Consumer Banking Wholesale Banking Enterprise Services Consolidated At or For the Nine Months Ended September 30, 2017: Interest income: Loans and leases $ 317,532 $ 384,757 $ (4,676 ) $ 697,613 Debt securities available for sale — — 24,518 24,518 Debt securities held to maturity — 76 3,312 3,388 Loans held for sale and other 19,811 53 3,046 22,910 Funds transfer pricing - credits 271,971 18,084 (290,055 ) — Total interest income 609,314 402,970 (263,855 ) 748,429 Interest Expense: Deposits 38,504 1,683 4,979 45,166 Borrowings 36,332 33,999 (50,446 ) 19,885 Funds transfer pricing - charges 105,696 102,539 (208,235 ) — Total interest expense 180,532 138,221 (253,702 ) 65,051 Net interest income (expense) 428,782 264,749 (10,153 ) 683,378 Provision for credit losses 33,211 12,973 — 46,184 Net interest income (expense) after provision for credit losses 395,571 251,776 (10,153 ) 637,194 Non-interest income: Fees and service charges 90,792 7,828 — 98,620 Card revenue 41,479 2 — 41,481 ATM revenue 14,968 2 — 14,970 Subtotal 147,239 7,832 — 155,071 Gains on sales of auto loans, net 3,244 — — 3,244 Gains on sales of consumer real estate loans, net 25,920 — — 25,920 Servicing fee income 31,357 990 — 32,347 Subtotal 60,521 990 — 61,511 Leasing and equipment finance — 102,208 — 102,208 Other 7,394 711 323 8,428 Fees and other revenue 215,154 111,741 323 327,218 Gains (losses) on securities, net — 189 — 189 Total non-interest income 215,154 111,930 323 327,407 Non-interest expense: Compensation and employee benefits 172,998 64,237 117,647 354,882 Occupancy and equipment 79,835 15,134 22,362 117,331 Other 230,843 81,714 (125,397 ) 187,160 Subtotal 483,676 161,085 14,612 659,373 Operating lease depreciation — 39,404 — 39,404 Foreclosed real estate and repossessed assets, net 10,551 2,086 380 13,017 Other credit costs, net 222 112 — 334 Total non-interest expense 494,449 202,687 14,992 712,128 Income (loss) before income tax expense (benefit) 116,276 161,019 (24,822 ) 252,473 Income tax expense (benefit) 41,133 52,760 (16,552 ) 77,341 Income (loss) after income tax expense (benefit) 75,143 108,259 (8,270 ) 175,132 Income attributable to non-controlling interest — 7,894 — 7,894 Preferred stock dividends — — 16,158 16,158 Impact of notice to redeem preferred stock — — 5,779 5,779 Net income (loss) available to common stockholders $ 75,143 $ 100,365 $ (30,207 ) $ 145,301 Revenues from external customers: Interest income $ 337,343 $ 380,210 $ 30,876 $ 748,429 Non-interest income 215,154 111,930 323 327,407 Total $ 552,497 $ 492,140 $ 31,199 $ 1,075,836 Total assets $ 9,239,458 $ 11,287,665 $ 2,477,915 $ 23,005,038

Litigation Contingencies

Litigation Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Litigation Contingencies	Litigation Contingencies From time to time TCF is a party to legal proceedings arising out of its lending, leasing and deposit operations, including foreclosure proceedings and other collection actions as part of its lending and leasing collections activities. TCF may also be subject to regulatory examinations and enforcement actions brought by federal regulators, including the Securities and Exchange Commission, the Federal Reserve, the OCC and the Bureau of Consumer Financial Protection ("BCFP") which may impose sanctions on TCF for failures related to regulatory compliance. From time to time borrowers and other customers, and employees and former employees have also brought actions against TCF, in some cases claiming substantial damages. TCF and other financial services companies are subject to the risk of class action litigation. Litigation is often unpredictable and the actual results of litigation cannot be determined and therefore the ultimate resolution of a matter and the possible range of loss associated with certain potential outcomes cannot be established. Based on our current understanding of TCF's pending legal proceedings, management does not believe that judgments or settlements arising from pending or threatened legal matters, individually or in the aggregate, would have a material adverse effect on the consolidated financial position, operating results or cash flows of TCF. On January 19, 2017, the BCFP filed a civil lawsuit against TCF Bank in the United States District Court for the District of Minnesota (the "Court"), captioned Consumer Financial Protection Bureau v. TCF National Bank, alleging violations of the Consumer Financial Protection Act ("CFPA") and Regulation E, §1005.17 in connection with TCF Bank's practices administering checking account overdraft program "opt-in" requirements from 2010 to early 2014. On September 8, 2017, the Court issued a ruling on the motion made by TCF Bank to dismiss the complaint of the BCFP. In its ruling, the Court granted TCF Bank's motion to dismiss the BCFP's Regulation E claims and also dismissed the BCFP's unfair, deceptive and abusive conduct claims under the CFPA for periods prior to July 21, 2011. On July 20, 2018, TCF Bank entered into a Stipulated Final Judgment and Order (the "BCFP Settlement") with the BCFP to resolve the matter and has entered into a Consent Order and a Consent Order For a Civil Money Penalty and related stipulations (collectively, the "OCC Consent Orders") with the OCC to resolve related regulatory issues with the OCC (collectively, the BCFP Settlement and the OCC Consent Orders are referred to herein as the "Consent Agreements"). The Consent Agreements provide, among other things, for TCF Bank to submit a restitution plan to the BCFP and OCC pursuant to which TCF Bank will pay restitution in the total amount of $25.0 million to certain current and former customers and require a notice to certain customers opted-in to overdraft service reminding them of their current opt-in choice. We submitted our restitution plan to the BCFP and OCC on September 10, 2018 and have not yet received confirmation that there is no supervisory objection. Pursuant to the Consent Agreements, TCF Bank paid $5.0 million in civil money penalties, $3.0 million of which was paid to the OCC and $2.0 million of which was paid to the BCFP. In addition, TCF Bank expects to incur approximately $2.0 million in administrative costs related to the administration of the restitution plan required under the Consent Agreements. The financial impact of the Consent Agreements was reflected in TCF Financial Corporation's second quarter results.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2018
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) The components of other comprehensive income (loss), reclassifications from accumulated other comprehensive income (loss) to various financial statement line items and the related tax effects were as follows: Quarter Ended September 30, 2018 2017 (In thousands) Before Tax Tax Effect Net of Tax Before Tax Tax Effect Net of Tax Net unrealized gains (losses) on debt securities available for sale and interest-only strips: Net unrealized gains (losses) arising during the period $ (18,086 ) $ 4,516 $ (13,570 ) $ 4,974 $ (1,892 ) $ 3,082 Reclassification of net (gains) losses from accumulated other comprehensive income (loss) to: Total interest income 263 (65 ) 198 287 (109 ) 178 Other non-interest expense (84 ) 22 (62 ) (1,315 ) 500 (815 ) Amounts reclassified from accumulated other comprehensive income (loss) 179 (43 ) 136 (1,028 ) 391 (637 ) Net unrealized gains (losses) on debt securities available for sale and interest-only strips (17,907 ) 4,473 (13,434 ) 3,946 (1,501 ) 2,445 Net unrealized gains (losses) on net investment hedges (2,537 ) 633 (1,904 ) (2,714 ) 1,032 (1,682 ) Foreign currency translation adjustment (1) 2,899 — 2,899 2,939 — 2,939 Recognized postretirement prior service cost: Reclassification of amortization of prior service cost to Other non-interest expense (12 ) 3 (9 ) (12 ) 4 (8 ) Total other comprehensive income (loss) $ (17,557 ) $ 5,109 $ (12,448 ) $ 4,159 $ (465 ) $ 3,694 Nine Months Ended September 30, 2018 2017 (In thousands) Before Tax Tax Effect Net of Tax Before Tax Tax Effect Net of Tax Net unrealized gains (losses) on debt securities available for sale and interest-only strips: Net unrealized gains (losses) arising during the period $ (62,521 ) $ 15,688 $ (46,833 ) $ 28,562 $ (10,859 ) $ 17,703 Reclassification of net (gains) losses from accumulated other comprehensive income (loss) to: Total interest income 810 (202 ) 608 691 (263 ) 428 Other non-interest expense 221 (55 ) 166 (929 ) 353 (576 ) Amounts reclassified from accumulated other comprehensive income (loss) 1,031 (257 ) 774 (238 ) 90 (148 ) Net unrealized gains (losses) on debt securities available for sale and interest-only strips (61,490 ) 15,431 (46,059 ) 28,324 (10,769 ) 17,555 Net unrealized gains (losses) on net investment hedges 4,637 (1,158 ) 3,479 (5,073 ) 1,929 (3,144 ) Foreign currency translation adjustment (1) (4,136 ) — (4,136 ) 5,527 — 5,527 Recognized postretirement prior service cost: Reclassification of amortization of prior service cost to Other non-interest expense (35 ) 9 (26 ) (35 ) 13 (22 ) Total other comprehensive income (loss) $ (61,024 ) $ 14,282 $ (46,742 ) $ 28,743 $ (8,827 ) $ 19,916 (1) Foreign investments are deemed to be permanent in nature and, therefore, TCF does not provide for taxes on foreign currency translation adjustments. The components of accumulated other comprehensive income (loss) were as follows: (In thousands) Net Unrealized Gains (Losses) on Debt Securities Available for Sale and Interest-only Strips Net Unrealized Gains (Losses) on Net Investment Hedges Foreign Currency Translation Adjustment Recognized Postretirement Prior Service Cost Total At or For the Quarter Ended September 30, 2018: Balance, beginning of period $ (48,978 ) $ 9,919 $ (13,878 ) $ 126 $ (52,811 ) Other comprehensive income (loss) (13,570 ) (1,904 ) 2,899 — (12,575 ) Amounts reclassified from accumulated other comprehensive income (loss) 136 — — (9 ) 127 Net other comprehensive income (loss) (13,434 ) (1,904 ) 2,899 (9 ) (12,448 ) Balance, end of period $ (62,412 ) $ 8,015 $ (10,979 ) $ 117 $ (65,259 ) At or For the Quarter Ended September 30, 2017: Balance, beginning of period $ (13,491 ) $ 5,031 $ (9,176 ) $ 133 $ (17,503 ) Other comprehensive income (loss) 3,082 (1,682 ) 2,939 — 4,339 Amounts reclassified from accumulated other comprehensive income (loss) (637 ) — — (8 ) (645 ) Net other comprehensive income (loss) 2,445 (1,682 ) 2,939 (8 ) 3,694 Balance, end of period $ (11,046 ) $ 3,349 $ (6,237 ) $ 125 $ (13,809 ) (In thousands) Net Unrealized Gains (Losses) on Debt Securities Available for Sale and Interest-only Strips Net Unrealized Gains (Losses) on Net Investment Hedges Foreign Currency Translation Adjustment Recognized Postretirement Prior Service Cost Total At or For the Nine Months Ended September 30, 2018: Balance, beginning of period $ (16,353 ) $ 4,536 $ (6,843 ) $ 143 $ (18,517 ) Other comprehensive income (loss) (46,833 ) 3,479 (4,136 ) — (47,490 ) Amounts reclassified from accumulated other comprehensive income (loss) 774 — — (26 ) 748 Net other comprehensive income (loss) (46,059 ) 3,479 (4,136 ) (26 ) (46,742 ) Balance, end of period $ (62,412 ) $ 8,015 $ (10,979 ) $ 117 $ (65,259 ) At or For the Nine Months Ended September 30, 2017: Balance, beginning of period $ (28,601 ) $ 6,493 $ (11,764 ) $ 147 $ (33,725 ) Other comprehensive income (loss) 17,703 (3,144 ) 5,527 — 20,086 Amounts reclassified from accumulated other comprehensive income (loss) (148 ) — — (22 ) (170 ) Net other comprehensive income (loss) 17,555 (3,144 ) 5,527 (22 ) 19,916 Balance, end of period $ (11,046 ) $ 3,349 $ (6,237 ) $ 125 $ (13,809 )

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business	TCF Financial Corporation (together with its direct and indirect subsidiaries, "we," "us," "our," "TCF" or the "Company"), a Delaware corporation, is a national bank holding company based in Wayzata, Minnesota. References herein to "TCF Financial" or the "Holding Company" refer to TCF Financial Corporation on an unconsolidated basis. Its principal subsidiary, TCF National Bank ("TCF Bank"), is headquartered in Sioux Falls, South Dakota. TCF Bank operates bank branches in Illinois, Minnesota, Michigan, Colorado, Wisconsin, Arizona and South Dakota (TCF's primary banking markets). Through its direct subsidiaries, TCF Bank provides a full range of consumer facing and commercial services, including consumer banking services, commercial banking services, commercial leasing and equipment financing, and commercial inventory financing.
Principles of Consolidation	The accompanying unaudited consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles ("GAAP") for interim financial information and in accordance with the instructions to Quarterly Report on Form 10-Q and Article 10 of Regulation S-X as promulgated by the Securities and Exchange Commission. Accordingly, the consolidated financial statements do not include all of the information and notes necessary for complete financial statements in conformity with GAAP. In the opinion of management, the accompanying unaudited consolidated financial statements contain all the significant adjustments, consisting of normal recurring items, considered necessary for fair presentation. The results of operations for interim periods are not necessarily indicative of the results to be expected for the entire year. The information in this Quarterly Report on Form 10-Q is written with the presumption that the users of the interim financial statements have read or have access to the Company's most recent Annual Report on Form 10-K, which contains the latest audited financial statements and notes thereto, together with Management's Discussion and Analysis of Financial Condition and Results of Operations at and for the year ended December 31, 2017 . The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amount of revenues and expenses during the reporting period. These estimates are based on information available to management at the time the estimates are made. Actual results could differ from those estimates. All significant intercompany accounts and transactions have been eliminated in consolidation. Certain reclassifications have been made to prior period financial statements to conform to current period presentation.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
New Accounting Pronouncements Adopted	New Accounting Pronouncements Adopted Effective January 1, 2018, the Company adopted Accounting Standards Update ("ASU") No. 2017-12: Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities , which expands hedge accounting for nonfinancial and financial risk components and amends measurement methodologies to more closely align hedge accounting with a company’s risk management activities. The ASU decreases the complexity of preparing and understanding hedge results through measurement and reporting of hedge ineffectiveness. In addition, disclosures have been enhanced and the presentation of hedged results changed to align the effects of the hedging instrument and the hedged item. The adoption of this ASU was on a modified retrospective basis and resulted in the Company recording a cumulative effect reduction to the opening balance of retained earnings of $116 thousand . Effective January 1, 2018, the Company adopted ASU No. 2017-09: Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting , which provides guidance about which changes to the terms and conditions of a share-based payment award requires an entity to apply modification accounting in Topic 718. The adoption of this ASU was on a prospective basis and will be applicable to an award modified on or after January 1, 2018. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2017-07: Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost , which changes how employers that sponsor defined benefit pension and/or other postretirement benefit plans present the net periodic benefit cost in the income statement. Under the new guidance, employers present the service cost component of the net periodic benefit cost in the same income statement line item as other employee compensation costs arising from services rendered during the period. Only the service cost component is eligible for capitalization in assets. The other components of net periodic benefit cost are presented separately from the line item that includes service cost and outside of any subtotal of operating income. In addition, disclosure of the line items used to present the other components of net periodic benefit cost is required if the components are not presented separately in the income statement. The adoption of this ASU was on a modified retrospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2017-05: Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets , which provides guidance for recognizing gains and losses from the transfer of nonfinancial assets in contracts with non-customers. The ASU also clarifies that Accounting Standards Codification 610-20 applies to the derecognition of nonfinancial assets and in substance nonfinancial assets unless other specific guidance applies or the sale is to a customer. The guidance does not apply to the derecognition of businesses, nonprofit activities, financial assets, including equity method investments, or to revenue contracts with customers. The adoption of this ASU was on a modified retrospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business , which clarifies the definition of a business with the objective of adding guidance to assist companies with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The ASU provides a more robust framework to use in determining when a set of assets and activities is a business. The adoption of this ASU was on a prospective basis. TCF will evaluate future transactions to determine if they should be accounted for as acquisitions (or disposals) of assets or businesses. Effective January 1, 2018, the Company adopted ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash , which requires entities to show changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. As a result, entities no longer present transfers between cash and cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. The adoption of this ASU was on a retrospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2016-17, Consolidation (Topic 810): Interests Held through Related Parties That Are under Common Control , which changes the way in which a single decision maker considers indirect interests when performing the primary beneficiary analysis under the variable interest model. Under the amended guidance, indirect interests held by a related party would be considered on a proportional basis. The adoption of this ASU was on a retrospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory , which requires the income tax effects of intercompany sales and transfers of assets, other than inventory, to be recognized in the period the transaction occurs. The adoption of this ASU was on a modified retrospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments , which addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice in how certain types of cash receipts and cash payments are presented in the statement of cash flows. The adoption of this ASU was on a retrospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2016-04, Liabilities - Extinguishments of Liabilities (Subtopic 405-20): Recognition of Breakage for Certain Prepaid Stored-Value Products , which requires issuers of prepaid stored-value products redeemable for goods, services or cash at third-party merchants to derecognize liabilities related to those products for breakage. The adoption of this ASU was on a modified retrospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities and ASU No. 2018-03, Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities , which amend the classification and measurement of investments in equity securities, simplify the impairment analysis of equity investments without readily determinable fair values, require separate presentation of certain fair value changes for financial liabilities measured at fair value and eliminate certain disclosure requirements associated with the fair value of financial instruments. The adoption of these ASUs was on a prospective basis. The adoption of this guidance did not have a material impact on our consolidated financial statements. Effective January 1, 2018, the Company adopted the following ASUs using the modified retrospective method with no cumulative-effect adjustment to opening retained earnings: ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606); ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date; ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net); ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing; ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients; ASU No. 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers; ASU No. 2017-13 , Revenue Recognition (Topic 605), Revenue from Contracts with Customers (Topic 606), Leases (Topic 840), and Leases (Topic 842): Amendments to SEC Paragraphs and ASU No. 2017-14, Income Statement - Reporting Comprehensive Income (Topic 220), Revenue Recognition (Topic 605), and Revenue from Contracts with Customers (Topic 606) . TCF derives a majority of its revenue from loans and leases, as well as any related servicing fee revenue, which are not within the scope of these ASUs. These ASUs are applicable to most of the fees and service charges, card and ATM revenue earned by TCF, as well as the gains on sales of certain non-financial assets. However, the recognition of these revenue streams does not change in a significant manner as a result of the adoption of these ASUs. The majority of this revenue is both charged to the customer and earned either at a point in time or on a transactional basis. As a result, the revenue expected to be recognized in any future year related to remaining performance obligations, contracts where revenue is recognized when invoiced and contracts with variable consideration related to undelivered performance obligations are not material. In addition, receivables related to fees and service charges and the related bad debt expense are not material. There are no material contract assets, contract liabilities or deferred contract costs recorded in the Company's Consolidated Statements of Financial Condition. As a significant majority of the Company's revenue streams are not included in the scope of these ASUs and the recognition of revenue for the revenue streams within the scope of these ASUs are not significantly changed, the adoption of this guidance did not have a material impact on the Company's consolidated financial statements.

Debt Securities Available for_2

Debt Securities Available for Sale and Debt Securities Held to Maturity (Tables)	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Debt Securities	Debt securities were as follows: At September 30, 2018 At December 31, 2017 (In thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Debt securities available for sale: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ 1,630,465 $ 15 $ 49,796 $ 1,580,684 $ 908,189 $ 308 $ 13,812 $ 894,685 Other 4 — — 4 6 — — 6 Obligations of states and political subdivisions 821,727 28 22,897 798,858 810,159 7,967 3,799 814,327 Total debt securities available for sale $ 2,452,196 $ 43 $ 72,693 $ 2,379,546 $ 1,718,354 $ 8,275 $ 17,611 $ 1,709,018 Debt securities held to maturity: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ 150,081 $ 104 $ 2,321 $ 147,864 $ 158,776 $ 4,462 $ 412 $ 162,826 Other securities 2,800 — — 2,800 2,800 — — 2,800 Total debt securities held to maturity $ 152,881 $ 104 $ 2,321 $ 150,664 $ 161,576 $ 4,462 $ 412 $ 165,626
Schedule of Gross Unrealized Losses and Fair Value of Debt Securities Available for Sale and Debt Securities Held to Maturity that are in a Loss Position	Gross unrealized losses and fair value of debt securities available for sale and debt securities held to maturity aggregated by investment category and the length of time the securities were in a continuous loss position were as follows: At September 30, 2018 Less than 12 months 12 months or more Total (In thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Debt securities available for sale: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ 967,838 $ 16,402 $ 608,028 $ 33,394 $ 1,575,866 $ 49,796 Obligations of states and political subdivisions 529,164 9,857 262,980 13,040 792,144 22,897 Total debt securities available for sale $ 1,497,002 $ 26,259 $ 871,008 $ 46,434 $ 2,368,010 $ 72,693 Debt securities held to maturity: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ 120,860 $ 1,151 $ 21,910 $ 1,170 $ 142,770 $ 2,321 Total debt securities held to maturity $ 120,860 $ 1,151 $ 21,910 $ 1,170 $ 142,770 $ 2,321 At December 31, 2017 Less than 12 months 12 months or more Total (In thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Debt securities available for sale: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ 406,298 $ 2,686 $ 428,585 $ 11,126 $ 834,883 $ 13,812 Obligations of states and political subdivisions 103,759 486 207,516 3,313 311,275 3,799 Total debt securities available for sale $ 510,057 $ 3,172 $ 636,101 $ 14,439 $ 1,146,158 $ 17,611 Debt securities held to maturity: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ 13,309 $ 132 $ 11,470 $ 280 $ 24,779 $ 412 Total debt securities held to maturity $ 13,309 $ 132 $ 11,470 $ 280 $ 24,779 $ 412
Schedule of Amortized Cost and Fair Value of Debt Securities Available for Sale and Debt Securities Held to Maturity by Contractual Maturity	The amortized cost and fair value of debt securities available for sale and debt securities held to maturity by final contractual maturity were as follows. The final contractual maturities do not consider possible prepayments and therefore expected maturities may differ because borrowers may have the right to prepay. At September 30, 2018 At December 31, 2017 (In thousands) Amortized Cost Fair Value Amortized Cost Fair Value Debt securities available for sale: Due in one year or less $ — $ — $ 6 $ 6 Due in 1-5 years 68,368 67,737 15,178 15,312 Due in 5-10 years 692,272 673,804 514,336 517,867 Due after 10 years 1,691,556 1,638,005 1,188,834 1,175,833 Total debt securities available for sale $ 2,452,196 $ 2,379,546 $ 1,718,354 $ 1,709,018 Debt securities held to maturity: Due in one year or less $ — $ — $ 1,000 $ 1,000 Due in 1-5 years 2,400 2,400 1,400 1,400 Due in 5-10 years 431 435 400 400 Due after 10 years 150,050 147,829 158,776 162,826 Total debt securities held to maturity $ 152,881 $ 150,664 $ 161,576 $ 165,626
Interest Income Attributable to Debt Securities Available for Sale	Interest income attributable to debt securities available for sale was as follows: Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Taxable interest income $ 10,511 $ 4,619 $ 24,487 $ 13,707 Tax-exempt interest income 4,327 3,867 12,990 10,811 Total interest income $ 14,838 $ 8,486 $ 37,477 $ 24,518

Loans and Leases (Tables)

Loans and Leases (Tables)	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Information about Loans and Leases	Loans and leases were as follows: (In thousands) At September 30, 2018 At December 31, 2017 Consumer real estate: First mortgage lien $ 1,960,756 $ 1,959,387 Junior lien 2,940,701 2,860,309 Total consumer real estate 4,901,457 4,819,696 Commercial: Commercial real estate: Permanent 2,362,045 2,385,752 Construction and development 411,610 365,533 Total commercial real estate 2,773,655 2,751,285 Commercial business 967,509 809,908 Total commercial 3,741,164 3,561,193 Leasing and equipment finance 4,601,887 4,761,661 Inventory finance 2,880,404 2,739,754 Auto finance 2,275,134 3,199,639 Other 21,107 22,517 Total loans and leases (1) $ 18,421,153 $ 19,104,460 (1) Loans and leases are reported at historical cost including net direct fees and costs associated with originating and acquiring loans and leases, lease residuals, unearned income and unamortized purchase premiums and discounts. The aggregate amount of these loan and lease adjustments was $9.0 million and $33.3 million at September 30, 2018 and December 31, 2017 , respectively.
Interest-only Strips and Contractual Liabilites	Total interest-only strips and the contractual liabilities related to loan sales were as follows: (In thousands) At September 30, 2018 At December 31, 2017 Interest-only strips attributable to: Consumer real estate loan sales $ 15,619 $ 16,440 Auto finance loan sales 2,093 4,946 Total interest-only strips $ 17,712 $ 21,386 Contractual liabilities attributable to: Consumer real estate loan sales $ 1,540 $ 1,234

Allowance for Loan and Lease _2

Allowance for Loan and Lease Losses and Credit Quality Information (Tables)	9 Months Ended
	Sep. 30, 2018
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Rollforwards of the Allowance for Loan and Lease Losses	The rollforwards of the allowance for loan and lease losses were as follows: (In thousands) Consumer Commercial Leasing and Inventory Auto Other Total At or For the Quarter Ended September 30, 2018: Balance, beginning of period $ 43,954 $ 40,291 $ 22,247 $ 11,840 $ 46,608 $ 679 $ 165,619 Charge-offs (1,519 ) (18 ) (2,608 ) (880 ) (12,460 ) (1,963 ) (19,448 ) Recoveries 7,949 26 678 243 2,975 787 12,658 Net (charge-offs) recoveries 6,430 8 (1,930 ) (637 ) (9,485 ) (1,176 ) (6,790 ) Provision for credit losses (4,827 ) 171 2,822 124 2,729 1,251 2,270 Other (299 ) — (213 ) 34 — — (478 ) Balance, end of period $ 45,258 $ 40,470 $ 22,926 $ 11,361 $ 39,852 $ 754 $ 160,621 At or For the Quarter Ended September 30, 2017: Balance, beginning of period $ 52,408 $ 34,669 $ 21,922 $ 12,129 $ 43,893 $ 599 $ 165,620 Charge-offs (2,940 ) — (1,404 ) (750 ) (11,028 ) (1,877 ) (17,999 ) Recoveries 6,392 196 358 281 1,780 840 9,847 Net (charge-offs) recoveries 3,452 196 (1,046 ) (469 ) (9,248 ) (1,037 ) (8,152 ) Provision for credit losses (5,669 ) 1,479 1,967 240 15,437 1,091 14,545 Other (2,353 ) — (72 ) 78 (1,422 ) — (3,769 ) Balance, end of period $ 47,838 $ 36,344 $ 22,771 $ 11,978 $ 48,660 $ 653 $ 168,244 (In thousands) Consumer Commercial Leasing and Inventory Auto Other Total At or For the Nine Months Ended September 30, 2018: Balance, beginning of period $ 47,168 $ 37,195 $ 22,528 $ 13,233 $ 50,225 $ 692 $ 171,041 Charge-offs (5,729 ) (22 ) (7,257 ) (2,102 ) (36,996 ) (5,395 ) (57,501 ) Recoveries 10,264 71 1,881 539 8,339 2,696 23,790 Net (charge-offs) recoveries 4,535 49 (5,376 ) (1,563 ) (28,657 ) (2,699 ) (33,711 ) Provision for credit losses (2,173 ) 3,226 6,000 (224 ) 18,284 2,761 27,874 Other (4,272 ) — (226 ) (85 ) — — (4,583 ) Balance, end of period $ 45,258 $ 40,470 $ 22,926 $ 11,361 $ 39,852 $ 754 $ 160,621 At or For the Nine Months Ended September 30, 2017: Balance, beginning of period $ 59,448 $ 32,695 $ 21,350 $ 13,932 $ 32,310 $ 534 $ 160,269 Charge-offs (9,205 ) (5,431 ) (5,694 ) (1,856 ) (28,045 ) (4,996 ) (55,227 ) Recoveries 18,783 455 1,718 675 4,680 2,761 29,072 Net (charge-offs) recoveries 9,578 (4,976 ) (3,976 ) (1,181 ) (23,365 ) (2,235 ) (26,155 ) Provision for credit losses (13,553 ) 8,625 5,520 (903 ) 44,141 2,354 46,184 Other (7,635 ) — (123 ) 130 (4,426 ) — (12,054 ) Balance, end of period $ 47,838 $ 36,344 $ 22,771 $ 11,978 $ 48,660 $ 653 $ 168,244
Allowance for Loan and Lease Losses and Balances by Type of Allowance Methodology	The allowance for loan and lease losses and loans and leases outstanding by type of allowance methodology were as follows: At September 30, 2018 (In thousands) Consumer Commercial Leasing and Inventory Auto Other Total Allowance for loan and lease losses: Collectively evaluated for impairment $ 22,274 $ 38,843 $ 19,021 $ 10,850 $ 39,729 $ 754 $ 131,471 Individually evaluated for impairment 22,984 1,627 3,905 511 123 — 29,150 Total $ 45,258 $ 40,470 $ 22,926 $ 11,361 $ 39,852 $ 754 $ 160,621 Loans and leases outstanding: Collectively evaluated for impairment $ 4,785,131 $ 3,710,229 $ 4,574,620 $ 2,878,764 $ 2,262,966 $ 21,105 $ 18,232,815 Individually evaluated for impairment 116,326 30,935 22,464 1,640 12,168 2 183,535 Loans acquired with deteriorated credit quality — — 4,803 — — — 4,803 Total $ 4,901,457 $ 3,741,164 $ 4,601,887 $ 2,880,404 $ 2,275,134 $ 21,107 $ 18,421,153 At December 31, 2017 (In thousands) Consumer Real Estate Commercial Leasing and Equipment Finance Inventory Finance Auto Finance Other Total Allowance for loan and lease losses: Collectively evaluated for impairment $ 28,851 $ 35,635 $ 19,083 $ 12,945 $ 49,900 $ 691 $ 147,105 Individually evaluated for impairment 18,317 1,560 3,445 288 325 1 23,936 Total $ 47,168 $ 37,195 $ 22,528 $ 13,233 $ 50,225 $ 692 $ 171,041 Loans and leases outstanding: Collectively evaluated for impairment $ 4,675,626 $ 3,524,864 $ 4,721,905 $ 2,735,638 $ 3,188,810 $ 22,513 $ 18,869,356 Individually evaluated for impairment 144,070 36,329 27,912 4,116 10,829 4 223,260 Loans acquired with deteriorated credit quality — — 11,844 — — — 11,844 Total $ 4,819,696 $ 3,561,193 $ 4,761,661 $ 2,739,754 $ 3,199,639 $ 22,517 $ 19,104,460
Schedule of Accruing and Non-accruing Loans and Leases	TCF's accruing and non-accrual loans and leases were as follows: At September 30, 2018 (In thousands) Current-59 Days Delinquent and Accruing 60-89 Days Delinquent and Accruing 90 Days or More Delinquent and Accruing Total Accruing Non-accrual Total Consumer real estate: First mortgage lien $ 1,921,391 $ 2,720 $ 770 $ 1,924,881 $ 35,875 $ 1,960,756 Junior lien 2,920,365 1,119 — 2,921,484 19,217 2,940,701 Total consumer real estate 4,841,756 3,839 770 4,846,365 55,092 4,901,457 Commercial: Commercial real estate 2,768,445 — — 2,768,445 5,210 2,773,655 Commercial business 962,831 — — 962,831 4,678 967,509 Total commercial 3,731,276 — — 3,731,276 9,888 3,741,164 Leasing and equipment finance 4,574,268 5,054 1,701 4,581,023 16,061 4,597,084 Inventory finance 2,878,684 65 15 2,878,764 1,640 2,880,404 Auto finance 2,258,221 6,318 2,982 2,267,521 7,613 2,275,134 Other 21,042 30 33 21,105 2 21,107 Subtotal 18,305,247 15,306 5,501 18,326,054 90,296 18,416,350 Portfolios acquired with deteriorated credit quality 4,000 — 803 4,803 — 4,803 Total $ 18,309,247 $ 15,306 $ 6,304 $ 18,330,857 $ 90,296 $ 18,421,153 At December 31, 2017 (In thousands) Current-59 Days Delinquent and Accruing 60-89 Days Delinquent and Accruing 90 Days or More Delinquent and Accruing Total Accruing Non-accrual Total Consumer real estate: First mortgage lien $ 1,892,771 $ 4,073 $ 593 $ 1,897,437 $ 61,950 $ 1,959,387 Junior lien 2,837,767 1,268 — 2,839,035 21,274 2,860,309 Total consumer real estate 4,730,538 5,341 593 4,736,472 83,224 4,819,696 Commercial: Commercial real estate 2,744,500 — — 2,744,500 6,785 2,751,285 Commercial business 809,907 1 — 809,908 — 809,908 Total commercial 3,554,407 1 — 3,554,408 6,785 3,561,193 Leasing and equipment finance 4,726,339 4,272 2,117 4,732,728 17,089 4,749,817 Inventory finance 2,735,430 191 17 2,735,638 4,116 2,739,754 Auto finance 3,183,196 6,078 2,999 3,192,273 7,366 3,199,639 Other 22,506 3 6 22,515 2 22,517 Subtotal 18,952,416 15,886 5,732 18,974,034 118,582 19,092,616 Portfolios acquired with deteriorated credit quality 10,283 361 1,200 11,844 — 11,844 Total $ 18,962,699 $ 16,247 $ 6,932 $ 18,985,878 $ 118,582 $ 19,104,460
Interest Income Recognized on Loans and Leases in Non-accrual Status and Contractual Interest	Interest income recognized on loans and leases in non-accrual status and contractual interest that would have been recorded had the loans and leases performed in accordance with their original contractual terms were as follows: Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Contractual interest due on non-accrual loans and leases $ 2,254 $ 3,529 $ 8,138 $ 11,606 Interest income recognized on non-accrual loans and leases 188 581 1,091 2,274 Unrecognized interest income $ 2,066 $ 2,948 $ 7,047 $ 9,332
Summary of Consumer Real Estate Loans to Customers Involved in Bankruptcy Proceedings	Consumer real estate loans to customers currently involved in ongoing Chapter 7 or Chapter 13 bankruptcy proceedings which have not yet been discharged, dismissed or completed were as follows: (In thousands) At September 30, 2018 At December 31, 2017 Consumer real estate loans to customers in bankruptcy: 0-59 days delinquent and accruing $ 4,642 $ 7,324 Non-accrual 8,695 10,552 Total consumer real estate loans to customers in bankruptcy $ 13,337 $ 17,876
Schedule of TDR Loans	TDR loans were as follows: At September 30, 2018 At December 31, 2017 (In thousands) Accruing TDR Loans Non-accrual TDR Loans Total TDR Loans Accruing TDR Loans Non-accrual TDR Loans Total TDR Loans Consumer real estate $ 82,317 $ 16,334 $ 98,651 $ 88,092 $ 34,282 $ 122,374 Commercial 4,235 9,874 14,109 12,249 83 12,332 Leasing and equipment finance 6,403 2,085 8,488 10,263 1,413 11,676 Inventory finance — 12 12 — 476 476 Auto finance 4,557 5,309 9,866 3,464 5,351 8,815 Other 2 — 2 3 1 4 Total $ 97,514 $ 33,614 $ 131,128 $ 114,071 $ 41,606 $ 155,677
Schedule of Financial Effects of TDRs	The following table summarizes the financial effects of consumer real estate accruing TDR loans. The financial effects of TDR loans for the remaining classes of finance receivables were not material for the third quarter and first nine months of 2018 and 2017 . Quarter Ended September 30, 2018 2017 (In thousands) Contractual Interest Due Interest Income Unrecognized Interest Contractual Interest Due Interest Income Unrecognized Interest Consumer real estate: First mortgage lien $ 1,034 $ 614 $ 420 $ 1,127 $ 688 $ 439 Junior lien 407 278 129 479 331 148 Total consumer real estate $ 1,441 $ 892 $ 549 $ 1,606 $ 1,019 $ 587 Nine Months Ended September 30, 2018 2017 (In thousands) Contractual Interest Due Interest Income Unrecognized Interest Contractual Interest Due Interest Income Unrecognized Interest Consumer real estate: First mortgage lien $ 3,147 $ 1,870 $ 1,277 $ 3,427 $ 2,059 $ 1,368 Junior lien 1,249 853 396 1,476 1,025 451 Total consumer real estate $ 4,396 $ 2,723 $ 1,673 $ 4,903 $ 3,084 $ 1,819
Schedule of Accruing Loans that were Restructured within 12 Months and Defaulted	The following table summarizes the TDR loans that defaulted during the periods presented that were modified during the respective reporting period or within one year of the beginning of the respective reporting period. Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Defaulted TDR loan balances modified during the applicable period: (1) Consumer real estate: First mortgage lien $ 778 $ 856 $ 2,751 $ 2,328 Junior lien 176 317 240 518 Total consumer real estate 954 1,173 2,991 2,846 Commercial: Commercial real estate — — — 6,681 Commercial business — — 4,697 — Total commercial — — 4,697 6,681 Leasing and equipment finance 87 451 87 635 Auto finance 217 260 950 867 Defaulted TDR loan balances modified during the applicable period $ 1,258 $ 1,884 $ 8,725 $ 11,029 (1) The loan balances presented are not materially different than the pre-modification loan balances as TCF's loan modifications generally do not forgive principal amounts.
Information on Impaired Loans	Information on impaired loans was as follows: At September 30, 2018 At December 31, 2017 (In thousands) Unpaid Loan Related Unpaid Loan Related Impaired loans with an allowance recorded: Consumer real estate: First mortgage lien $ 65,528 $ 62,581 $ 13,989 $ 91,624 $ 80,802 $ 13,792 Junior lien 25,972 24,778 8,861 32,327 29,544 4,165 Total consumer real estate 91,500 87,359 22,850 123,951 110,346 17,957 Commercial: Commercial real estate 5,547 5,156 1,000 6,810 6,702 1,000 Commercial business 4,713 4,689 627 7,841 7,841 560 Total commercial 10,260 9,845 1,627 14,651 14,543 1,560 Leasing and equipment finance 15,157 15,157 2,415 17,105 17,105 1,345 Inventory finance 1,435 1,439 511 1,296 1,298 288 Auto finance 538 404 59 1,333 1,016 243 Other 2 2 — 3 4 1 Total impaired loans with an allowance recorded 118,892 114,206 27,462 158,339 144,312 21,394 Impaired loans without an allowance recorded: Consumer real estate: First mortgage lien 12,155 9,765 — 12,898 10,445 — Junior lien 11,087 1,527 — 17,697 1,583 — Total consumer real estate 23,242 11,292 — 30,595 12,028 — Commercial real estate 4,344 4,278 — 4,552 4,491 — Inventory finance 201 201 — 2,810 2,818 — Auto finance 13,357 9,462 — 10,566 7,799 — Other 331 — — 331 — — Total impaired loans without an allowance recorded 41,475 25,233 — 48,854 27,136 — Total impaired loans $ 160,367 $ 139,439 $ 27,462 $ 207,193 $ 171,448 $ 21,394
Average Balance of Impaired Loans and Interest Income Recognized on Impaired Loans	The average loan balance of impaired loans and interest income recognized on impaired loans were as follows: Quarter Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (In thousands) Average Loan Balance Interest Income Recognized Average Loan Balance Interest Income Recognized Average Loan Balance Interest Income Recognized Average Loan Balance Interest Income Recognized Impaired loans with an allowance recorded: Consumer real estate: First mortgage lien $ 62,411 $ 435 $ 84,126 $ 679 $ 71,692 $ 1,706 $ 92,490 $ 2,097 Junior lien 24,788 246 33,438 382 27,160 841 41,083 1,209 Total consumer real estate 87,199 681 117,564 1,061 98,852 2,547 133,573 3,306 Commercial: Commercial real estate 5,192 — 5,119 — 5,929 — 8,461 16 Commercial business 5,981 13 13 — 6,265 130 13 48 Total commercial 11,173 13 5,132 — 12,194 130 8,474 64 Leasing and equipment finance 15,472 16 11,837 10 16,131 70 11,638 28 Inventory finance 1,464 20 2,078 18 1,369 51 3,120 176 Auto finance 452 — 2,792 55 709 — 3,337 146 Other 2 — 4 — 3 — 6 — Total impaired loans with an allowance recorded 115,762 730 139,407 1,144 129,258 2,798 160,148 3,720 Impaired loans without an allowance recorded: Consumer real estate: First mortgage lien 10,074 171 11,871 212 10,105 527 12,264 736 Junior lien 1,591 44 1,669 71 1,556 152 1,749 392 Total consumer real estate 11,665 215 13,540 283 11,661 679 14,013 1,128 Commercial: Commercial real estate 4,315 58 12,090 95 4,385 174 11,860 438 Commercial business — — 334 2 — — 284 3 Total commercial 4,315 58 12,424 97 4,385 174 12,144 441 Inventory finance 403 31 1,255 62 1,510 136 1,037 136 Auto finance 8,757 77 4,878 — 8,630 211 4,592 — Total impaired loans without an allowance recorded 25,140 381 32,097 442 26,186 1,200 31,786 1,705 Total impaired loans $ 140,902 $ 1,111 $ 171,504 $ 1,586 $ 155,444 $ 3,998 $ 191,934 $ 5,425
Schedule of Other Real Estate Owned and Repossessed and Returned Assets	Other real estate owned and repossessed and returned assets were as follows: (In thousands) At September 30, 2018 At December 31, 2017 Other real estate owned $ 19,079 $ 18,225 Repossessed and returned assets 12,279 12,630 Consumer real estate loans in process of foreclosure 15,190 22,622

Long-term Borrowings (Tables)

Long-term Borrowings (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Information about Long-term Borrowings	Long-term borrowings were as follows: At September 30, 2018 At December 31, 2017 (Dollars in thousands) Stated Maturity Amount Stated Rate Amount Stated Rate Federal Home Loan Bank advances 2019 $ — — % $ 600,000 1.40 % - 1.75 % 2020 825,000 2.29 % - 2.45 275,000 1.76 - 1.78 Subtotal 825,000 875,000 Subordinated bank notes 2022 109,037 6.25 108,867 6.25 2025 148,408 4.60 148,252 4.60 Hedge-related basis adjustment (1) (8,339 ) (2,157 ) Subtotal 249,106 254,962 Discounted lease rentals 2018 11,976 2.78 - 4.20 52,347 2.55 - 7.95 2019 39,853 2.53 - 6.00 34,978 2.53 - 6.00 2020 25,034 2.64 - 6.50 19,736 2.64 - 6.50 2021 13,374 2.88 - 5.80 10,077 2.88 - 5.00 2022 3,844 3.04 - 5.50 2,349 3.04 - 5.43 2023 213 4.90 - 5.78 — — Subtotal 94,294 119,487 Capital lease obligation 2018 20 3.73 — — 2019 83 3.73 — — 2020 86 3.73 — — 2021 89 3.73 — — 2022 93 3.73 — — 2023 - 2038 2,770 3.73 — — Subtotal 3,141 — Total long-term borrowings $ 1,171,541 $ 1,249,449 (1) Related to subordinated bank notes with a stated maturity of 2025.

Equity (Tables)

Equity (Tables)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Schedule of Preferred Stock	Preferred stock was as follows: (In thousands) At September 30, 2018 At December 31, 2017 Series B non-cumulative perpetual preferred stock $ — $ 96,519 Series C non-cumulative perpetual preferred stock 169,302 169,302 Total preferred stock $ 169,302 $ 265,821
Schedule of Treasury Stock and Other	Treasury stock and other were as follows: (In thousands) At September 30, 2018 At December 31, 2017 Treasury stock, at cost $ 160,178 $ 10,265 Shares held in trust for deferred compensation plans, at cost 29,474 30,532 Total $ 189,652 $ 40,797

Regulatory Capital Requiremen_2

Regulatory Capital Requirements (Tables)	9 Months Ended
	Sep. 30, 2018
Regulatory Capital Requirements [Abstract]
Schedule of Regulatory Capital Information for TCF and TCF Bank	Regulatory capital information for TCF and TCF Bank was as follows: TCF TCF Bank At September 30, At December 31, At September 30, At December 31, Well-capitalized Standard Minimum Capital Requirement (1) (Dollars in thousands) 2018 2017 2018 2017 Regulatory Capital: Common equity Tier 1 capital $ 2,226,820 $ 2,242,410 $ 2,297,245 $ 2,409,027 Tier 1 capital 2,412,869 2,522,178 2,318,399 2,426,854 Total capital 2,754,615 2,889,323 2,696,433 2,837,374 Regulatory Capital Ratios: Common equity Tier 1 capital ratio 11.04 % 10.79 % 11.39 % 11.59 % 6.50 % 4.50 % Tier 1 risk-based capital ratio 11.96 12.14 11.49 11.68 8.00 6.00 Total risk-based capital ratio 13.66 13.90 13.37 13.65 10.00 8.00 Tier 1 leverage ratio 10.58 11.12 10.16 10.70 5.00 4.00 (1) Excludes capital conservation buffer of 1.875% and 1.25% at September 30, 2018 and December 31, 2017 , respectively.

Stock Compensation (Tables)

Stock Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Restricted Stock Award and Stock Option Transactions	TCF's restricted stock award and stock option transactions under the TCF Financial 2015 Omnibus Incentive Plan ("Omnibus Incentive Plan") and the TCF Financial Incentive Stock Program were as follows: Restricted Stock Awards Stock Options Shares Weighted- average Grant Date Fair Value Shares Weighted- average Remaining Contractual Life in Years Weighted- average Exercise Price Outstanding at December 31, 2017 2,639,663 $ 13.65 366,000 0.06 $ 15.75 Granted 747,446 21.71 — — — Exercised — — (366,000 ) — 15.75 Forfeited/canceled (203,751 ) 15.07 — — — Vested (836,323 ) 12.15 — — — Outstanding at September 30, 2018 2,347,035 $ 16.62 — — $ —

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Schedule of Net Periodic Benefit Cost Included in Non-interest Expense for the TCF Cash Balance Pension Plan and Postretirement Plan	The net periodic benefit plan (income) cost included in other non-interest expense for the TCF Cash Balance Pension Plan (the "Pension Plan") and the Postretirement Plan were as follows: Pension Plan Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Interest cost $ 246 $ 284 $ 738 $ 854 Return on plan assets (133 ) (142 ) (397 ) (426 ) Net periodic benefit plan (income) cost $ 113 $ 142 $ 341 $ 428 Postretirement Plan Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Interest cost $ 28 $ 33 $ 83 $ 100 Amortization of prior service cost (12 ) (12 ) (35 ) (35 ) Net periodic benefit plan (income) cost $ 16 $ 21 $ 48 $ 65

Derivative Instruments (Tables)

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments	Derivative instruments, recognized at fair value within other assets or accrued expenses and other liabilities on the Consolidated Statements of Financial Condition, were as follows: At September 30, 2018 Fair Value (In thousands) Notional Amount Derivative Assets Derivative Liabilities Derivatives designated as hedging instruments: Interest rate contracts $ 150,000 $ 111 $ — Forward foreign exchange contracts 163,286 — 2,693 Total derivatives designated as hedging instruments 111 2,693 Derivatives not designated as hedging instruments: Interest rate contracts 837,693 1,118 7,367 Forward foreign exchange contracts 252,829 20 2,482 Interest rate lock commitments 45,254 994 378 Other contracts 13,020 — 658 Total derivatives not designated as hedging instruments 2,132 10,885 Total derivatives before netting 2,243 13,578 Netting (1) (352 ) (2,221 ) Total derivatives, net $ 1,891 $ 11,357 At December 31, 2017 Fair Value (In thousands) Notional Amount Derivative Assets Derivative Liabilities Derivatives designated as hedging instruments: Interest rate contracts $ 150,000 $ 405 $ — Forward foreign exchange contracts 77,879 — 1,744 Total derivatives designated as hedging instruments 405 1,744 Derivatives not designated as hedging instruments: Interest rate contracts 592,383 1,392 1,688 Forward foreign exchange contracts 330,928 — 4,619 Interest rate lock commitments 18,015 223 — Other contracts 13,804 — 615 Total derivatives not designated as hedging instruments 1,615 6,922 Total derivatives before netting 2,020 8,666 Netting (1) (457 ) (7,098 ) Total derivatives, net $ 1,563 $ 1,568 (1) Includes balance sheet netting of derivative asset and derivative liability balances, related cash collateral and portfolio level counterparty valuation adjustments.
Schedule of Gross Amounts Recognized, Gross Amounts Offset and Net Amount Presented	The gross amounts recognized, gross amounts offset and net amount presented of the derivative instruments were as follows: At September 30, 2018 (In thousands) Gross Amounts Recognized Gross Amounts Offset (1) Net Amount Presented Derivative assets: Interest rate contracts $ 1,229 $ (332 ) $ 897 Interest rate lock commitments 994 — 994 Forward foreign exchange contracts 20 (20 ) — Total derivative assets $ 2,243 $ (352 ) $ 1,891 Derivative liabilities: Forward foreign exchange contracts $ 5,175 $ (1,433 ) $ 3,742 Interest rate contracts 7,367 (130 ) 7,237 Interest rate lock commitments 378 — 378 Other contracts 658 (658 ) — Total derivative liabilities $ 13,578 $ (2,221 ) $ 11,357 At December 31, 2017 (In thousands) Gross Amounts Recognized Gross Amounts Offset (1) Net Amount Presented Derivative assets: Interest rate contracts $ 1,797 $ (457 ) $ 1,340 Interest rate lock commitments 223 — 223 Total derivative assets $ 2,020 $ (457 ) $ 1,563 Derivative liabilities: Forward foreign exchange contracts $ 6,363 $ (6,026 ) $ 337 Interest rate contracts 1,688 (457 ) 1,231 Other contracts 615 (615 ) — Total derivative liabilities $ 8,666 $ (7,098 ) $ 1,568 (1) Includes the amounts with counterparties subject to enforceable master netting arrangements that have been offset in the consolidated balance sheets.
Amounts Recorded in the Consolidated Statements of Financial Condition Related to the Cumulative Basis Adjustment for the Fair Value Hedge	The carrying amount of the hedged subordinated debt including the cumulative basis adjustment related to the application of fair value hedge accounting is recorded in Long-term borrowings on the Consolidated Statements of Financial Condition and was as follows: Carrying Amount of the Hedged Liability Cumulative Amount of Fair Value Hedging Adjustments Included in the Carrying Amount of the Hedged Liability (In thousands) At September 30, 2018 At December 31, 2017 At September 30, 2018 At December 31, 2017 Subordinated bank note - 2025 $ 140,069 $ 146,095 $ (8,339 ) $ (2,157 )
Summary of Gains and Losses Related to the Fair Value of the Interest Rate Swap and the Offsetting Changes in the Fair Value of the Hedged Debt	The gain (loss) related to the fair value hedge and the line within the Consolidated Statements of Income where the gain (loss) was recorded were as follows: Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Gain (loss) of fair value hedge: Hedged item $ 1,206 $ 146 $ 6,337 $ (601 ) Derivative designated as a hedging instrument (1,165 ) (135 ) (6,621 ) 813 Income statement line where the gain (loss) on the fair value hedge was recorded: Interest expense - borrowings $ 10,726 $ — $ 31,850 $ — Other non-interest income — 2,930 — 8,428
Effect of Net Investment Hedges on Accumulated Other Comprehensive Income	The effect of net investment hedges on accumulated other comprehensive income was as follows: Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Forward foreign exchange contracts $ (2,537 ) $ (2,174 ) $ 4,637 $ (5,073 )
Summary of Effects of Derivatives not Designated as Hedging Instruments on the Consolidated Statements of Income	Certain other forward foreign exchange contracts, interest rate lock commitments, other contracts and and interest rate contracts have not been designated as hedging instruments. The effect of these derivatives on the Consolidated Statements of Income was as follows: Quarter Ended September 30, Nine Months Ended September 30, (In thousands) Location of Gain (Loss) 2018 2017 2018 2017 Forward foreign exchange contracts Other non-interest expense $ (3,706 ) $ (10,690 ) $ 8,050 $ (20,323 ) Interest rate lock commitments Gains on sales of consumer real estate loans, net (244 ) (29 ) 798 189 Other contracts Other non-interest expense (292 ) — (274 ) — Interest rate contracts Other non-interest income 51 (155 ) 157 (263 ) Net gain (loss) recognized $ (4,191 ) $ (10,874 ) $ 8,731 $ (20,397 )

Fair Values Disclosures (Tables

Fair Values Disclosures (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Balances of Assets and Liabilities Measured at Fair Value on a Recurring and Non-recurring Basis	The balances of assets and liabilities measured at fair value on a recurring and non-recurring basis were as follows: At September 30, 2018 (In thousands) Level 1 Level 2 Level 3 Total Recurring Fair Value Measurements through Net Income: Assets: Loans held for sale $ — $ — $ 18,519 $ 18,519 Forward foreign exchange contracts (1) — 20 — 20 Interest rate contracts (1) — 1,229 — 1,229 Interest rate lock commitments (1) — — 994 994 Forward loan sales commitments — — 665 665 Assets held in trust for deferred compensation plans 34,626 — — 34,626 Total assets $ 34,626 $ 1,249 $ 20,178 $ 56,053 Liabilities: Forward foreign exchange contracts (1) $ — $ 2,482 $ — $ 2,482 Interest rate contracts (1) — 7,367 — 7,367 Interest rate lock commitments (1) — — 378 378 Other contracts (1) — — 658 658 Forward loan sales commitments — — 196 196 Liabilities held in trust for deferred compensation plans 34,626 — — 34,626 Total liabilities $ 34,626 $ 9,849 $ 1,232 $ 45,707 Recurring Fair Value Measurements through Other Comprehensive Income: Assets: Debt securities available for sale: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ — $ 1,580,684 $ — $ 1,580,684 Other — — 4 4 Obligations of states and political subdivisions — 798,858 — 798,858 Interest-only strips — — 17,712 17,712 Total assets $ — $ 2,379,542 $ 17,716 $ 2,397,258 Liabilities: Forward foreign exchange contracts (1) $ — $ 2,693 $ — $ 2,693 Total liabilities $ — $ 2,693 $ — $ 2,693 Non-recurring Fair Value Measurements: Loans $ — $ — $ 48,934 $ 48,934 Other real estate owned — — 11,893 11,893 Repossessed and returned assets — 3,918 3,882 7,800 Total non-recurring fair value measurements $ — $ 3,918 $ 64,709 $ 68,627 (1) As permitted under GAAP, TCF has elected to net derivative assets and derivative liabilities when a legally enforceable master netting agreement exists as well as the related cash collateral received and paid. For purposes of this table, the derivative assets and derivative liabilities are presented gross of this netting adjustment. At December 31, 2017 (In thousands) Level 1 Level 2 Level 3 Total Recurring Fair Value Measurements through Net Income: Assets: Loans held for sale $ — $ — $ 3,356 $ 3,356 Interest rate contracts (1) — 1,797 — 1,797 Interest rate lock commitments (1) — — 223 223 Forward loan sales commitments — — 68 68 Assets held in trust for deferred compensation plans 29,962 — — 29,962 Total assets $ 29,962 $ 1,797 $ 3,647 $ 35,406 Liabilities: Forward foreign exchange contracts (1) $ — $ 4,619 $ — $ 4,619 Interest rate contracts (1) — 1,688 — 1,688 Other contracts (1) — — 615 615 Forward loan sales commitments — — 5 5 Liabilities held in trust for deferred compensation plans 29,962 — — 29,962 Total liabilities $ 29,962 $ 6,307 $ 620 $ 36,889 Recurring Fair Value Measurements through Other Comprehensive Income: Assets: Debt securities available for sale: Mortgage-backed securities: U.S. Government sponsored enterprises and federal agencies $ — $ 894,685 $ — $ 894,685 Other — — 6 6 Obligations of states and political subdivisions — 814,327 — 814,327 Interest-only strips — — 21,386 21,386 Total assets $ — $ 1,709,012 $ 21,392 $ 1,730,404 Liabilities: Forward foreign exchange contracts (1) $ — $ 1,744 $ — $ 1,744 Total liabilities $ — $ 1,744 $ — $ 1,744 Non-recurring Fair Value Measurements: Loans $ — $ — $ 72,287 $ 72,287 Other real estate owned — — 14,036 14,036 Repossessed and returned assets — 3,669 4,388 8,057 Total non-recurring fair value measurements $ — $ 3,669 $ 90,711 $ 94,380 (1) As permitted under GAAP, TCF has elected to net derivative assets and derivative liabilities when a legally enforceable master netting agreement exists as well as the related cash collateral received and paid. For purposes of this table, the derivative assets and derivative liabilities are presented gross of this netting adjustment.
Schedule of Changes in Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis	The changes in Level 3 assets and liabilities measured at fair value on a recurring basis were as follows: (In thousands) Debt Securities Loans Interest-only Strips Interest Forward Other Contracts At or For the Quarter Ended September 30, 2018: Asset (liability) balance, beginning of period $ 4 $ 18,554 $ 19,887 $ 858 $ 110 $ (441 ) Total net gains (losses) included in: Net income — (184 ) 732 (242 ) 359 (292 ) Other comprehensive income (loss) — — 246 — — — Sales — (97,866 ) — — — — Originations — 98,018 — — — — Principal paydowns / settlements — (3 ) (3,153 ) — — 75 Asset (liability) balance, end of period $ 4 $ 18,519 $ 17,712 $ 616 $ 469 $ (658 ) At or For the Quarter Ended September 30, 2017: Asset (liability) balance, beginning of period $ 11 $ 5,238 $ 32,582 $ 515 $ (67 ) $ (462 ) Total net gains (losses) included in: Net income — 17 1,110 (29 ) 14 — Other comprehensive income (loss) — — (1,063 ) — — — Sales — (59,308 ) — — — — Originations — 58,634 542 — — — Principal paydowns / settlements (3 ) (388 ) (9,374 ) — — 78 Asset (liability) balance, end of period $ 8 $ 4,193 $ 23,797 $ 486 $ (53 ) $ (384 ) (In thousands) Debt Securities Available for Sale Loans Held for Sale Interest-only Strips Interest Rate Lock Commitments Forward Loan Sales Commitments Other Contracts At or For the Nine Months Ended September 30, 2018: Asset (liability) balance, beginning of period $ 6 $ 3,356 $ 21,386 $ 223 $ 63 $ (615 ) Total net gains (losses) included in: Net income — 254 1,913 393 406 (274 ) Other comprehensive income (loss) — — 1,015 — — — Sales — (232,747 ) — — — — Originations — 247,667 3,849 — — — Principal paydowns / settlements (2 ) (11 ) (10,451 ) — — 231 Asset (liability) balance, end of period $ 4 $ 18,519 $ 17,712 $ 616 $ 469 $ (658 ) At or For the Nine Months Ended September 30, 2017: Asset (liability) balance, beginning of period $ 18 $ 6,498 $ 40,152 $ 297 $ 361 $ (619 ) Total net gains (losses) included in: Net income — 155 3,323 189 (414 ) — Other comprehensive income (loss) — — (464 ) — — — Sales — (151,182 ) — — — — Originations — 149,118 2,458 — — — Principal paydowns / settlements (10 ) (396 ) (21,672 ) — — 235 Asset (liability) balance, end of period $ 8 $ 4,193 $ 23,797 $ 486 $ (53 ) $ (384 )
Schedule of Differences Between the Aggregate Fair Value and Aggregate Unpaid Principal Balance on Loans Held for Sale	The difference between the aggregate fair value and aggregate unpaid principal balance of these loans held for sale was as follows: (In thousands) At September 30, 2018 At December 31, 2017 Fair value carrying amount $ 18,519 $ 3,356 Aggregate unpaid principal amount 18,180 3,268 Fair value carrying amount less aggregate unpaid principal $ 339 $ 88
Fair Value of Assets and Liabilities, Including Hierarchy Level	The carrying amounts and estimated fair values of the Company's financial instruments, excluding short-term financial assets and liabilities as their carrying amounts approximate fair value, and excluding financial instruments recorded at fair value on a recurring basis, were as follows. This information represents only a portion of TCF's balance sheet and not the estimated value of the Company as a whole. Non-financial instruments such as the intangible value of TCF's branches and core deposits, leasing operations, goodwill, premises and equipment and the future revenues from TCF's customers are not reflected in this disclosure. Therefore, this information is of limited use in assessing the value of TCF. At September 30, 2018 Carrying Estimated Fair Value (In thousands) Amount Level 1 Level 2 Level 3 Total Financial instrument assets: Investments $ 80,672 $ — $ 80,672 $ — $ 80,672 Debt securities held to maturity 152,881 — 147,864 2,800 150,664 Loans held for sale 113,879 — — 117,625 117,625 Loans: Consumer real estate 4,901,457 — — 4,949,229 4,949,229 Commercial real estate 2,773,655 — — 2,723,277 2,723,277 Commercial business 967,509 — — 924,862 924,862 Equipment finance 2,146,375 — — 2,087,381 2,087,381 Inventory finance 2,880,404 — — 2,865,539 2,865,539 Auto finance 2,275,134 — — 2,240,463 2,240,463 Other 21,107 — — 16,482 16,482 Allowance for loan losses (1) (160,621 ) — — — — Securitization receivable (2) 19,369 — — 18,917 18,917 Total financial instrument assets $ 16,171,821 $ — $ 228,536 $ 15,946,575 $ 16,175,111 Financial instrument liabilities: Deposits $ 18,496,511 $ 13,624,763 $ 4,900,943 $ — $ 18,525,706 Long-term borrowings 1,171,541 — 1,174,761 — 1,174,761 Total financial instrument liabilities $ 19,668,052 $ 13,624,763 $ 6,075,704 $ — $ 19,700,467 Financial instruments with off-balance sheet risk: (3) Commitments to extend credit $ 18,353 $ — $ 18,353 $ — $ 18,353 Standby letters of credit (93 ) — (93 ) — (93 ) Total financial instruments with off-balance sheet risk $ 18,260 $ — $ 18,260 $ — $ 18,260 (1) Expected credit losses are included in the estimated fair values. (2) Carrying amounts are included in other assets. (3) Positive amounts represent assets, negative amounts represent liabilities. At December 31, 2017 Carrying Estimated Fair Value (In thousands) Amount Level 1 Level 2 Level 3 Total Financial instrument assets: Investments $ 82,644 $ — $ 82,644 $ — $ 82,644 Debt securities held to maturity 161,576 — 162,826 2,800 165,626 Loans held for sale 134,752 — — 139,458 139,458 Loans: Consumer real estate 4,819,696 — — 4,916,475 4,916,475 Commercial real estate 2,751,285 — — 2,710,237 2,710,237 Commercial business 809,908 — — 776,989 776,989 Equipment finance 2,300,479 — — 2,260,692 2,260,692 Inventory finance 2,739,754 — — 2,723,045 2,723,045 Auto finance 3,199,639 — — 3,197,794 3,197,794 Other 22,517 — — 21,129 21,129 Allowance for loan losses (1) (171,041 ) — — — — Securitization receivable (2) 19,179 — — 18,595 18,595 Total financial instrument assets $ 16,870,388 $ — $ 245,470 $ 16,767,214 $ 17,012,684 Financial instrument liabilities: Deposits $ 18,335,002 $ 13,352,731 $ 5,023,526 $ — $ 18,376,257 Long-term borrowings 1,249,449 — 1,255,333 — 1,255,333 Total financial instrument liabilities $ 19,584,451 $ 13,352,731 $ 6,278,859 $ — $ 19,631,590 Financial instruments with off-balance sheet risk: (3) Commitments to extend credit $ 19,423 $ — $ 19,423 $ — $ 19,423 Standby letters of credit (83 ) — (83 ) — (83 ) Total financial instruments with off-balance sheet risk $ 19,340 $ — $ 19,340 $ — $ 19,340 (1) Expected credit losses are included in the estimated fair values. (2) Carrying amounts are included in other assets. (3) Positive amounts represent assets, negative amounts represent liabilities.

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings per Common Share	The computations of basic and diluted earnings per common share were as follows: Quarter Ended September 30, Nine Months Ended September 30, (Dollars in thousands, except per share data) 2018 2017 2018 2017 Basic Earnings Per Common Share: Net income attributable to TCF Financial Corporation $ 86,196 $ 60,528 $ 218,706 $ 167,238 Preferred stock dividends 2,494 6,464 9,094 16,158 Impact of preferred stock redemption or notice to redeem preferred stock (1) — 5,779 3,481 5,779 Net income available to common stockholders 83,702 48,285 206,131 145,301 Less: Earnings allocated to participating securities 13 8 30 25 Earnings allocated to common stock $ 83,689 $ 48,277 $ 206,101 $ 145,276 Weighted-average common shares outstanding for basic earnings per common share 164,854,622 168,970,543 166,350,173 168,492,877 Basic earnings per common share $ 0.51 $ 0.29 $ 1.24 $ 0.86 Diluted Earnings Per Common Share: Earnings allocated to common stock $ 83,689 $ 48,277 $ 206,101 $ 145,276 Weighted-average common shares outstanding used in basic earnings per common share calculation 164,854,622 168,970,543 166,350,173 168,492,877 Net dilutive effect of: Non-participating restricted stock 589,177 269,394 623,556 312,297 Stock options — 314 3,288 17,654 Warrants 89,426 — 525,360 — Weighted-average common shares outstanding for diluted earnings per common share 165,533,225 169,240,251 167,502,377 168,822,828 Diluted earnings per common share $ 0.51 $ 0.29 $ 1.23 $ 0.86 (1) For the nine months ended September 30, 2018, amount represents the deferred stock issuance costs originally recorded in preferred stock upon the issuance of the Series B Preferred Stock that were reclassified to retained earnings on March 1, 2018, as the Company redeemed all outstanding Series B Preferred Stock. For the quarter and nine months ended September 30, 2017, amount represents the deferred stock issuance costs originally recorded in preferred stock upon the issuance of the 7.50% Series A non-cumulative perpetual preferred stock ("Series A Preferred Stock") that were reclassified to retained earnings on September 15, 2017, the date the Company announced its intent to redeem the outstanding Series A Preferred Stock.

Other Non-interest Expense (Tab

Other Non-interest Expense (Tables)	9 Months Ended
	Sep. 30, 2018
Other Income and Expenses [Abstract]
Other Non-interest Expense	Other non-interest expense was as follows: Quarter Ended September 30, Nine Months Ended September 30, (In thousands) 2018 2017 2018 2017 Bureau of Consumer Financial Protection and OCC settlement charge (1) $ — $ — $ 32,000 $ — Advertising and marketing 7,674 6,060 22,075 19,678 Professional fees 5,949 9,875 16,035 26,295 Outside processing 5,052 5,176 15,936 14,411 Card processing and issuance costs 4,090 4,719 12,759 13,534 FDIC insurance 4,376 4,181 12,165 11,964 Loan and lease processing 3,313 5,304 10,430 17,258 Other 27,535 26,266 84,492 84,020 Total other non-interest expense $ 57,989 $ 61,581 $ 205,892 $ 187,160 (1) See Note 17 . Litigation Contingencies for further information.

Business Segments (Tables)

Business Segments (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Reportable Segments, Including a Reconciliation of Consolidated Totals	Certain information for each of TCF's reportable segments, including reconciliations of TCF's consolidated totals, was as follows: (In thousands) Consumer Banking Wholesale Banking Enterprise Services Consolidated At or For the Quarter Ended September 30, 2018: Interest income: Loans and leases $ 105,961 $ 159,680 $ (963 ) $ 264,678 Debt securities available for sale — — 14,838 14,838 Debt securities held to maturity — 23 965 988 Loans held for sale and other 4,525 35 2,118 6,678 Funds transfer pricing - credits 101,961 9,017 (110,978 ) — Total interest income 212,447 168,755 (94,020 ) 287,182 Interest expense: Deposits 19,807 2,581 4,947 27,335 Borrowings 10,476 19,635 (19,385 ) 10,726 Funds transfer pricing - charges 42,440 53,377 (95,817 ) — Total interest expense 72,723 75,593 (110,255 ) 38,061 Net interest income 139,724 93,162 16,235 249,121 Provision for credit losses (837 ) 3,107 — 2,270 Net interest income after provision for credit losses 140,561 90,055 16,235 246,851 Non-interest income: Fees and service charges 30,651 1,923 — 32,574 Card revenue 15,051 14 — 15,065 ATM revenue 5,052 1 — 5,053 Subtotal 50,754 1,938 — 52,692 Gains on sales of consumer real estate loans, net 8,764 — — 8,764 Servicing fee income 5,779 253 — 6,032 Subtotal 14,543 253 — 14,796 Leasing and equipment finance — 45,045 — 45,045 Other 2,904 405 509 3,818 Fees and other revenue 68,201 47,641 509 116,351 Gains (losses) on debt securities, net — 94 — 94 Total non-interest income 68,201 47,735 509 116,445 Non-interest expense: Compensation and employee benefits 54,053 23,989 45,085 123,127 Occupancy and equipment 26,523 4,952 10,862 42,337 Other 77,196 30,214 (49,421 ) 57,989 Subtotal 157,772 59,155 6,526 223,453 Operating lease depreciation — 19,525 — 19,525 Foreclosed real estate and repossessed assets, net 3,399 482 — 3,881 Other credit costs, net 32 (468 ) — (436 ) Total non-interest expense 161,203 78,694 6,526 246,423 Income (loss) before income tax expense (benefit) 47,559 59,096 10,218 116,873 Income tax expense (benefit) 11,363 13,063 3,608 28,034 Income (loss) after income tax expense (benefit) 36,196 46,033 6,610 88,839 Income attributable to non-controlling interest — 2,643 — 2,643 Preferred stock dividends — — 2,494 2,494 Net income (loss) available to common stockholders $ 36,196 $ 43,390 $ 4,116 $ 83,702 Revenues from external customers: Interest income $ 110,486 $ 158,775 $ 17,921 $ 287,182 Non-interest income 68,201 47,735 509 116,445 Total $ 178,687 $ 206,510 $ 18,430 $ 403,627 Total assets $ 8,040,163 $ 11,740,613 $ 3,124,009 $ 22,904,785 (In thousands) Consumer Banking Wholesale Banking Enterprise Services Consolidated At or For the Quarter Ended September 30, 2017: Interest income: Loans and leases $ 113,397 $ 132,306 $ (1,730 ) $ 243,973 Debt securities available for sale — — 8,486 8,486 Debt securities held to maturity — 25 1,048 1,073 Loans held for sale and other 2,899 17 1,157 4,073 Funds transfer pricing - credits 93,042 6,942 (99,984 ) — Total interest income 209,338 139,290 (91,023 ) 257,605 Interest expense: Deposits 14,070 888 2,057 17,015 Borrowings 13,236 12,400 (19,149 ) 6,487 Funds transfer pricing - charges 36,671 37,061 (73,732 ) — Total interest expense 63,977 50,349 (90,824 ) 23,502 Net interest income (expense) 145,361 88,941 (199 ) 234,103 Provision for credit losses 11,129 3,416 — 14,545 Net interest income (expense) after provision for credit losses 134,232 85,525 (199 ) 219,558 Non-interest income: Fees and service charges 31,145 3,460 — 34,605 Card revenue 14,176 1 — 14,177 ATM revenue 5,234 — — 5,234 Subtotal 50,555 3,461 — 54,016 Gains on sales of consumer real estate loans, net 8,049 — — 8,049 Servicing fee income 9,620 346 — 9,966 Subtotal 17,669 346 — 18,015 Leasing and equipment finance — 34,080 — 34,080 Other 2,710 196 24 2,930 Fees and other revenue 70,934 38,083 24 109,041 Gains (losses) on securities, net — 189 — 189 Total non-interest income 70,934 38,272 24 109,230 Non-interest expense: Compensation and employee benefits 55,977 19,941 39,036 114,954 Occupancy and equipment 28,137 5,214 5,415 38,766 Other 77,065 28,276 (43,760 ) 61,581 Subtotal 161,179 53,431 691 215,301 Operating lease depreciation — 15,696 — 15,696 Foreclosed real estate and repossessed assets, net 2,829 902 98 3,829 Other credit costs, net 54 155 — 209 Total non-interest expense 164,062 70,184 789 235,035 Income (loss) before income tax expense (benefit) 41,104 53,613 (964 ) 93,753 Income tax expense (benefit) 14,370 17,153 (819 ) 30,704 Income (loss) after income tax expense (benefit) 26,734 36,460 (145 ) 63,049 Income attributable to non-controlling interest — 2,521 — 2,521 Preferred stock dividends — — 6,464 6,464 Impact of notice to redeem preferred stock — — 5,779 5,779 Net income (loss) available to common stockholders $ 26,734 $ 33,939 $ (12,388 ) $ 48,285 Revenues from external customers: Interest income $ 116,296 $ 130,618 $ 10,691 $ 257,605 Non-interest income 70,934 38,272 24 109,230 Total $ 187,230 $ 168,890 $ 10,715 $ 366,835 Total assets $ 9,239,458 $ 11,287,665 $ 2,477,915 $ 23,005,038 (In thousands) Consumer Banking Wholesale Banking Enterprise Services Consolidated At or For the Nine Months Ended September 30, 2018: Interest income: Loans and leases $ 323,280 $ 473,870 $ (2,817 ) $ 794,333 Debt securities available for sale — — 37,477 37,477 Debt securities held to maturity — 70 2,935 3,005 Loans held for sale and other 8,267 80 5,605 13,952 Funds transfer pricing - credits 298,850 24,945 (323,795 ) — Total interest income 630,397 498,965 (280,595 ) 848,767 Interest Expense: Deposits 56,077 5,812 11,909 73,798 Borrowings 34,165 57,920 (60,235 ) 31,850 Funds transfer pricing - charges 121,068 148,100 (269,168 ) — Total interest expense 211,310 211,832 (317,494 ) 105,648 Net interest income 419,087 287,133 36,899 743,119 Provision for credit losses 18,941 8,933 — 27,874 Net interest income after provision for credit losses 400,146 278,200 36,899 715,245 Non-interest income: Fees and service charges 88,389 7,606 — 95,995 Card revenue 43,748 38 — 43,786 ATM revenue 14,634 2 — 14,636 Subtotal 146,771 7,646 — 154,417 Gains on sales of consumer real estate loans, net 25,079 — — 25,079 Servicing fee income 20,751 1,060 — 21,811 Subtotal 45,830 1,060 — 46,890 Leasing and equipment finance — 129,796 — 129,796 Other 9,071 1,489 908 11,468 Fees and other revenue 201,672 139,991 908 342,571 Gains (losses) on debt securities, net — 181 — 181 Total non-interest income 201,672 140,172 908 342,752 Non-interest expense: Compensation and employee benefits 161,960 71,476 134,106 367,542 Occupancy and equipment 78,639 14,905 30,018 123,562 Other 257,747 88,843 (140,698 ) 205,892 Subtotal 498,346 175,224 23,426 696,996 Operating lease depreciation — 54,744 — 54,744 Foreclosed real estate and repossessed assets, net 10,947 1,700 7 12,654 Other credit costs, net 92 (44 ) — 48 Total non-interest expense 509,385 231,624 23,433 764,442 Income (loss) before income tax expense (benefit) 92,433 186,748 14,374 293,555 Income tax expense (benefit) 22,351 41,191 2,541 66,083 Income (loss) after income tax expense (benefit) 70,082 145,557 11,833 227,472 Income attributable to non-controlling interest — 8,766 — 8,766 Preferred stock dividends — — 9,094 9,094 Impact of preferred stock redemption — — 3,481 3,481 Net income (loss) available to common stockholders $ 70,082 $ 136,791 $ (742 ) $ 206,131 Revenues from external customers: Interest income $ 331,547 $ 471,203 $ 46,017 $ 848,767 Non-interest income 201,672 140,172 908 342,752 Total $ 533,219 $ 611,375 $ 46,925 $ 1,191,519 Total assets $ 8,040,163 $ 11,740,613 $ 3,124,009 $ 22,904,785 (In thousands) Consumer Banking Wholesale Banking Enterprise Services Consolidated At or For the Nine Months Ended September 30, 2017: Interest income: Loans and leases $ 317,532 $ 384,757 $ (4,676 ) $ 697,613 Debt securities available for sale — — 24,518 24,518 Debt securities held to maturity — 76 3,312 3,388 Loans held for sale and other 19,811 53 3,046 22,910 Funds transfer pricing - credits 271,971 18,084 (290,055 ) — Total interest income 609,314 402,970 (263,855 ) 748,429 Interest Expense: Deposits 38,504 1,683 4,979 45,166 Borrowings 36,332 33,999 (50,446 ) 19,885 Funds transfer pricing - charges 105,696 102,539 (208,235 ) — Total interest expense 180,532 138,221 (253,702 ) 65,051 Net interest income (expense) 428,782 264,749 (10,153 ) 683,378 Provision for credit losses 33,211 12,973 — 46,184 Net interest income (expense) after provision for credit losses 395,571 251,776 (10,153 ) 637,194 Non-interest income: Fees and service charges 90,792 7,828 — 98,620 Card revenue 41,479 2 — 41,481 ATM revenue 14,968 2 — 14,970 Subtotal 147,239 7,832 — 155,071 Gains on sales of auto loans, net 3,244 — — 3,244 Gains on sales of consumer real estate loans, net 25,920 — — 25,920 Servicing fee income 31,357 990 — 32,347 Subtotal 60,521 990 — 61,511 Leasing and equipment finance — 102,208 — 102,208 Other 7,394 711 323 8,428 Fees and other revenue 215,154 111,741 323 327,218 Gains (losses) on securities, net — 189 — 189 Total non-interest income 215,154 111,930 323 327,407 Non-interest expense: Compensation and employee benefits 172,998 64,237 117,647 354,882 Occupancy and equipment 79,835 15,134 22,362 117,331 Other 230,843 81,714 (125,397 ) 187,160 Subtotal 483,676 161,085 14,612 659,373 Operating lease depreciation — 39,404 — 39,404 Foreclosed real estate and repossessed assets, net 10,551 2,086 380 13,017 Other credit costs, net 222 112 — 334 Total non-interest expense 494,449 202,687 14,992 712,128 Income (loss) before income tax expense (benefit) 116,276 161,019 (24,822 ) 252,473 Income tax expense (benefit) 41,133 52,760 (16,552 ) 77,341 Income (loss) after income tax expense (benefit) 75,143 108,259 (8,270 ) 175,132 Income attributable to non-controlling interest — 7,894 — 7,894 Preferred stock dividends — — 16,158 16,158 Impact of notice to redeem preferred stock — — 5,779 5,779 Net income (loss) available to common stockholders $ 75,143 $ 100,365 $ (30,207 ) $ 145,301 Revenues from external customers: Interest income $ 337,343 $ 380,210 $ 30,876 $ 748,429 Non-interest income 215,154 111,930 323 327,407 Total $ 552,497 $ 492,140 $ 31,199 $ 1,075,836 Total assets $ 9,239,458 $ 11,287,665 $ 2,477,915 $ 23,005,038

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2018
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Summary of Components of Other Comprehensive Income (Loss), Reclassifications from Accumulated Cther Comprehensive Income (Loss) to Various Financial Statement Line Items and the Related Tax Effects	The components of other comprehensive income (loss), reclassifications from accumulated other comprehensive income (loss) to various financial statement line items and the related tax effects were as follows: Quarter Ended September 30, 2018 2017 (In thousands) Before Tax Tax Effect Net of Tax Before Tax Tax Effect Net of Tax Net unrealized gains (losses) on debt securities available for sale and interest-only strips: Net unrealized gains (losses) arising during the period $ (18,086 ) $ 4,516 $ (13,570 ) $ 4,974 $ (1,892 ) $ 3,082 Reclassification of net (gains) losses from accumulated other comprehensive income (loss) to: Total interest income 263 (65 ) 198 287 (109 ) 178 Other non-interest expense (84 ) 22 (62 ) (1,315 ) 500 (815 ) Amounts reclassified from accumulated other comprehensive income (loss) 179 (43 ) 136 (1,028 ) 391 (637 ) Net unrealized gains (losses) on debt securities available for sale and interest-only strips (17,907 ) 4,473 (13,434 ) 3,946 (1,501 ) 2,445 Net unrealized gains (losses) on net investment hedges (2,537 ) 633 (1,904 ) (2,714 ) 1,032 (1,682 ) Foreign currency translation adjustment (1) 2,899 — 2,899 2,939 — 2,939 Recognized postretirement prior service cost: Reclassification of amortization of prior service cost to Other non-interest expense (12 ) 3 (9 ) (12 ) 4 (8 ) Total other comprehensive income (loss) $ (17,557 ) $ 5,109 $ (12,448 ) $ 4,159 $ (465 ) $ 3,694 Nine Months Ended September 30, 2018 2017 (In thousands) Before Tax Tax Effect Net of Tax Before Tax Tax Effect Net of Tax Net unrealized gains (losses) on debt securities available for sale and interest-only strips: Net unrealized gains (losses) arising during the period $ (62,521 ) $ 15,688 $ (46,833 ) $ 28,562 $ (10,859 ) $ 17,703 Reclassification of net (gains) losses from accumulated other comprehensive income (loss) to: Total interest income 810 (202 ) 608 691 (263 ) 428 Other non-interest expense 221 (55 ) 166 (929 ) 353 (576 ) Amounts reclassified from accumulated other comprehensive income (loss) 1,031 (257 ) 774 (238 ) 90 (148 ) Net unrealized gains (losses) on debt securities available for sale and interest-only strips (61,490 ) 15,431 (46,059 ) 28,324 (10,769 ) 17,555 Net unrealized gains (losses) on net investment hedges 4,637 (1,158 ) 3,479 (5,073 ) 1,929 (3,144 ) Foreign currency translation adjustment (1) (4,136 ) — (4,136 ) 5,527 — 5,527 Recognized postretirement prior service cost: Reclassification of amortization of prior service cost to Other non-interest expense (35 ) 9 (26 ) (35 ) 13 (22 ) Total other comprehensive income (loss) $ (61,024 ) $ 14,282 $ (46,742 ) $ 28,743 $ (8,827 ) $ 19,916 (1) Foreign investments are deemed to be permanent in nature and, therefore, TCF does not provide for taxes on foreign currency translation adjustments.
Schedule of Components of Accumulated Other Comprehensive Income (Loss)	The components of accumulated other comprehensive income (loss) were as follows: (In thousands) Net Unrealized Gains (Losses) on Debt Securities Available for Sale and Interest-only Strips Net Unrealized Gains (Losses) on Net Investment Hedges Foreign Currency Translation Adjustment Recognized Postretirement Prior Service Cost Total At or For the Quarter Ended September 30, 2018: Balance, beginning of period $ (48,978 ) $ 9,919 $ (13,878 ) $ 126 $ (52,811 ) Other comprehensive income (loss) (13,570 ) (1,904 ) 2,899 — (12,575 ) Amounts reclassified from accumulated other comprehensive income (loss) 136 — — (9 ) 127 Net other comprehensive income (loss) (13,434 ) (1,904 ) 2,899 (9 ) (12,448 ) Balance, end of period $ (62,412 ) $ 8,015 $ (10,979 ) $ 117 $ (65,259 ) At or For the Quarter Ended September 30, 2017: Balance, beginning of period $ (13,491 ) $ 5,031 $ (9,176 ) $ 133 $ (17,503 ) Other comprehensive income (loss) 3,082 (1,682 ) 2,939 — 4,339 Amounts reclassified from accumulated other comprehensive income (loss) (637 ) — — (8 ) (645 ) Net other comprehensive income (loss) 2,445 (1,682 ) 2,939 (8 ) 3,694 Balance, end of period $ (11,046 ) $ 3,349 $ (6,237 ) $ 125 $ (13,809 ) (In thousands) Net Unrealized Gains (Losses) on Debt Securities Available for Sale and Interest-only Strips Net Unrealized Gains (Losses) on Net Investment Hedges Foreign Currency Translation Adjustment Recognized Postretirement Prior Service Cost Total At or For the Nine Months Ended September 30, 2018: Balance, beginning of period $ (16,353 ) $ 4,536 $ (6,843 ) $ 143 $ (18,517 ) Other comprehensive income (loss) (46,833 ) 3,479 (4,136 ) — (47,490 ) Amounts reclassified from accumulated other comprehensive income (loss) 774 — — (26 ) 748 Net other comprehensive income (loss) (46,059 ) 3,479 (4,136 ) (26 ) (46,742 ) Balance, end of period $ (62,412 ) $ 8,015 $ (10,979 ) $ 117 $ (65,259 ) At or For the Nine Months Ended September 30, 2017: Balance, beginning of period $ (28,601 ) $ 6,493 $ (11,764 ) $ 147 $ (33,725 ) Other comprehensive income (loss) 17,703 (3,144 ) 5,527 — 20,086 Amounts reclassified from accumulated other comprehensive income (loss) (148 ) — — (22 ) (170 ) Net other comprehensive income (loss) 17,555 (3,144 ) 5,527 (22 ) 19,916 Balance, end of period $ (11,046 ) $ 3,349 $ (6,237 ) $ 125 $ (13,809 )

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in Accounting Principle
Cumulative effect reduction to the opening balance of retained earnings		$ (116)	$ 0
Retained Earnings
Change in Accounting Principle
Cumulative effect reduction to the opening balance of retained earnings		$ (116)	$ (1,319)
Accounting Standards Update 2017-12 | Retained Earnings
Change in Accounting Principle
Cumulative effect reduction to the opening balance of retained earnings	$ (116)

Cash and Due from Banks - Cash

Cash and Due from Banks - Cash and Due from Banks (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Cash and Cash Equivalents [Abstract]
Reserve in cash on hand or at the Federal Reserve as required by Federal Reserve regulations	$ 110.1	$ 107
Total restricted cash balance	47.9	36.5
Cash held in interest-bearing accounts	$ 263.1	$ 324.2

Debt Securities Available for_3

Debt Securities Available for Sale and Debt Securities Held to Maturity - Debt Securities Available for Sale and Debt Securities Held to Maturity (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Debt securities available for sale:
Amortized Cost	$ 2,452,196,000		$ 2,452,196,000		$ 1,718,354,000
Gross Unrealized Gains	43,000		43,000		8,275,000
Gross Unrealized Losses	72,693,000		72,693,000		17,611,000
Fair Value	2,379,546,000		2,379,546,000		1,709,018,000
Debt securities available for sale sold during the period	0	$ 0	0	$ 0
Impairment charges on debt securities available for sale	0	0	0	0
Debt securities held to maturity:
Amortized Cost	152,881,000		152,881,000		161,576,000
Gross Unrealized Gains	104,000		104,000		4,462,000
Gross Unrealized Losses	2,321,000		2,321,000		412,000
Fair Value	150,664,000		150,664,000		165,626,000
Debt securities held to maturity sold during the period	0	0	0	0
Impairment charges on debt securities held to maturity	0	0	0	0
Recoveries on previously impaired debt securities held to maturity	94,000	$ 189,000	181,000	$ 189,000
Mortgage-backed securities: | Collateral pledged
Debt securities available for sale:
Debt securities available for sale pledged as collateral	1,600,000		1,600,000		900,000
Mortgage-backed securities, U.S. Government sponsored enterprises and federal agencies
Debt securities available for sale:
Amortized Cost	1,630,465,000		1,630,465,000		908,189,000
Gross Unrealized Gains	15,000		15,000		308,000
Gross Unrealized Losses	49,796,000		49,796,000		13,812,000
Fair Value	1,580,684,000		1,580,684,000		894,685,000
Debt securities held to maturity:
Amortized Cost	150,081,000		150,081,000		158,776,000
Gross Unrealized Gains	104,000		104,000		4,462,000
Gross Unrealized Losses	2,321,000		2,321,000		412,000
Fair Value	147,864,000		147,864,000		162,826,000
Mortgage-backed securities, Other
Debt securities available for sale:
Amortized Cost	4,000		4,000		6,000
Gross Unrealized Gains	0		0		0
Gross Unrealized Losses	0		0		0
Fair Value	4,000		4,000		6,000
Obligations of states and political subdivisions
Debt securities available for sale:
Amortized Cost	821,727,000		821,727,000		810,159,000
Gross Unrealized Gains	28,000		28,000		7,967,000
Gross Unrealized Losses	22,897,000		22,897,000		3,799,000
Fair Value	798,858,000		798,858,000		814,327,000
Other securities
Debt securities held to maturity:
Amortized Cost	2,800,000		2,800,000		2,800,000
Gross Unrealized Gains	0		0		0
Gross Unrealized Losses	0		0		0
Fair Value	$ 2,800,000		$ 2,800,000		$ 2,800,000

Debt Securities Available for_4

Debt Securities Available for Sale and Debt Securities Held to Maturity - Gross Unrealized Losses and Fair Value of Debt Securities Available for Sale and Debt Securities Held to Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Gross unrealized losses and fair value of debt securities available for sale that are in a loss position
Less than 12 months, Fair Value	$ 1,497,002	$ 510,057
Less than 12 months, Unrealized Losses	26,259	3,172
12 months or more, Fair Value	871,008	636,101
12 months or more, Unrealized Losses	46,434	14,439
Total, Fair Value	2,368,010	1,146,158
Total, Unrealized Losses	72,693	17,611
Gross unrealized losses and fair value of debt securities held to maturity that are in a loss position
Less than 12 months, Fair Value	120,860	13,309
Less than 12 months, Unrealized Losses	1,151	132
12 months or more, Fair Value	21,910	11,470
12 months or more, Unrealized Losses	1,170	280
Total, Fair Value	142,770	24,779
Total, Unrealized Losses	2,321	412
Mortgage-backed securities, U.S. Government sponsored enterprises and federal agencies
Gross unrealized losses and fair value of debt securities available for sale that are in a loss position
Less than 12 months, Fair Value	967,838	406,298
Less than 12 months, Unrealized Losses	16,402	2,686
12 months or more, Fair Value	608,028	428,585
12 months or more, Unrealized Losses	33,394	11,126
Total, Fair Value	1,575,866	834,883
Total, Unrealized Losses	49,796	13,812
Gross unrealized losses and fair value of debt securities held to maturity that are in a loss position
Less than 12 months, Fair Value	120,860	13,309
Less than 12 months, Unrealized Losses	1,151	132
12 months or more, Fair Value	21,910	11,470
12 months or more, Unrealized Losses	1,170	280
Total, Fair Value	142,770	24,779
Total, Unrealized Losses	2,321	412
Obligations of states and political subdivisions
Gross unrealized losses and fair value of debt securities available for sale that are in a loss position
Less than 12 months, Fair Value	529,164	103,759
Less than 12 months, Unrealized Losses	9,857	486
12 months or more, Fair Value	262,980	207,516
12 months or more, Unrealized Losses	13,040	3,313
Total, Fair Value	792,144	311,275
Total, Unrealized Losses	$ 22,897	$ 3,799

Debt Securities Available for_5

Debt Securities Available for Sale and Debt Securities Held to Maturity - Amortized Cost and Fair Value of Debt Securities Available for Sale and Debt Securities Held to Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Amortized cost, debt securities available for sale
Due in one year or less	$ 0	$ 6
Due in 1-5 years	68,368	15,178
Due in 5-10 years	692,272	514,336
Due after 10 years	1,691,556	1,188,834
Amortized Cost	2,452,196	1,718,354
Fair value, debt securities available for sale
Due in one year or less	0	6
Due in 1-5 years	67,737	15,312
Due in 5-10 years	673,804	517,867
Due after 10 years	1,638,005	1,175,833
Fair Value	2,379,546	1,709,018
Amortized cost, debt securities held to maturity
Due in one year or less	0	1,000
Due in 1-5 years	2,400	1,400
Due in 5-10 years	431	400
Due after 10 years	150,050	158,776
Amortized Cost	152,881	161,576
Fair value, debt securities held to maturity
Due in one year or less	0	1,000
Due in 1-5 years	2,400	1,400
Due in 5-10 years	435	400
Due after 10 years	147,829	162,826
Fair Value	$ 150,664	$ 165,626

Debt Securities Available for_6

Debt Securities Available for Sale and Debt Securities Held to Maturity - Interest Income Attributable to Debt Securities Available for Sale (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest Income on Debt Securities Available for Sale by Taxable Status
Total interest income	$ 14,838	$ 8,486	$ 37,477	$ 24,518
Debt securities available for sale
Interest Income on Debt Securities Available for Sale by Taxable Status
Taxable interest income	10,511	4,619	24,487	13,707
Tax-exempt interest income	4,327	3,867	12,990	10,811
Total interest income	$ 14,838	$ 8,486	$ 37,477	$ 24,518

Loans and Leases - Loan and Lea

Loans and Leases - Loan and Lease Balances (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Loans and Leases Receivable Disclosure
Loans and leases	[1]	$ 18,421,153	$ 19,104,460
Loan and lease adjustments		9,000	33,300
Consumer real estate
Loans and Leases Receivable Disclosure
Loans and leases		4,901,457	4,819,696
Consumer real estate | First mortgage lien
Loans and Leases Receivable Disclosure
Loans and leases		1,960,756	1,959,387
Consumer real estate | Junior lien
Loans and Leases Receivable Disclosure
Loans and leases		2,940,701	2,860,309
Commercial
Loans and Leases Receivable Disclosure
Loans and leases		3,741,164	3,561,193
Commercial | Commercial real estate
Loans and Leases Receivable Disclosure
Loans and leases		2,773,655	2,751,285
Commercial | Permanent
Loans and Leases Receivable Disclosure
Loans and leases		2,362,045	2,385,752
Commercial | Construction and development
Loans and Leases Receivable Disclosure
Loans and leases		411,610	365,533
Commercial | Commercial business
Loans and Leases Receivable Disclosure
Loans and leases		967,509	809,908
Leasing and equipment finance
Loans and Leases Receivable Disclosure
Loans and leases		4,601,887	4,761,661
Inventory finance
Loans and Leases Receivable Disclosure
Loans and leases		2,880,404	2,739,754
Auto finance
Loans and Leases Receivable Disclosure
Loans and leases		2,275,134	3,199,639
Other
Loans and Leases Receivable Disclosure
Loans and leases		$ 21,107	$ 22,517
[1]	Loans and leases are reported at historical cost including net direct fees and costs associated with originating and acquiring loans and leases, lease residuals, unearned income and unamortized purchase premiums and discounts. The aggregate amount of these loan and lease adjustments was $9.0 million and $33.3 million at September 30, 2018 and December 31, 2017, respectively.

Loans and Leases - Loan Sales (

Loans and Leases - Loan Sales (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable
Proceeds from loan sale			$ 264,970,000	$ 188,756,000
Consumer real estate
Accounts, Notes, Loans and Financing Receivable
Loans sold during the period	$ 328,000,000	$ 291,000,000	775,900,000	943,800,000
Proceeds from loan sale	346,500,000	305,300,000	807,500,000	987,800,000
Net gains recognized	8,800,000	8,000,000	25,100,000	25,900,000
Interest-only strips retained on consumer loan sales	0	500,000	3,800,000	2,500,000
Consumer real estate non-accrual loans sold	34,700,000	$ 21,800,000	34,700,000	71,200,000
Servicing asset	0		0		$ 0
Servicing liability	0		0		0
Auto finance
Accounts, Notes, Loans and Financing Receivable
Loans sold during the period				298,600,000
Proceeds from loan sale				303,300,000
Net gains recognized				$ 3,200,000
Servicing asset	0		0		0
Servicing liability	$ 0		$ 0		$ 0

Loans and Leases - Interest-onl

Loans and Leases - Interest-only Strips and Contractual Liabilities Related to Loan Sales (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable
Interest-only strips	$ 17,712,000		$ 17,712,000		$ 21,386,000
Consumer real estate
Accounts, Notes, Loans and Financing Receivable
Interest-only strips	15,619,000		15,619,000		16,440,000
Contractual liabilities related to sale of loans	1,540,000		1,540,000		1,234,000
Impairment charges on interest-only strips	0	$ 0	268,000	$ 875,000
Auto finance
Accounts, Notes, Loans and Financing Receivable
Interest-only strips	2,093,000		2,093,000		$ 4,946,000
Impairment charges on interest-only strips	$ 45,000	$ 235,000	$ 393,000	$ 400,000

Allowance for Loan and Lease _3

Allowance for Loan and Lease Losses and Credit Quality Information - Rollfowards of the Allowance for Loan and Lease Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Allowance for loan and lease losses
Balance, beginning of period	$ 165,619	$ 165,620	$ 171,041	$ 160,269
Charge-offs	(19,448)	(17,999)	(57,501)	(55,227)
Recoveries	12,658	9,847	23,790	29,072
Net (charge-offs) recoveries	(6,790)	(8,152)	(33,711)	(26,155)
Provision for credit losses	2,270	14,545	27,874	46,184
Other	(478)	(3,769)	(4,583)	(12,054)
Balance, end of period	160,621	168,244	160,621	168,244
Consumer Real Estate
Allowance for loan and lease losses
Balance, beginning of period	43,954	52,408	47,168	59,448
Charge-offs	(1,519)	(2,940)	(5,729)	(9,205)
Recoveries	7,949	6,392	10,264	18,783
Net (charge-offs) recoveries	6,430	3,452	4,535	9,578
Provision for credit losses	(4,827)	(5,669)	(2,173)	(13,553)
Other	(299)	(2,353)	(4,272)	(7,635)
Balance, end of period	45,258	47,838	45,258	47,838
Commercial
Allowance for loan and lease losses
Balance, beginning of period	40,291	34,669	37,195	32,695
Charge-offs	(18)	0	(22)	(5,431)
Recoveries	26	196	71	455
Net (charge-offs) recoveries	8	196	49	(4,976)
Provision for credit losses	171	1,479	3,226	8,625
Other	0	0	0	0
Balance, end of period	40,470	36,344	40,470	36,344
Leasing and Equipment Finance
Allowance for loan and lease losses
Balance, beginning of period	22,247	21,922	22,528	21,350
Charge-offs	(2,608)	(1,404)	(7,257)	(5,694)
Recoveries	678	358	1,881	1,718
Net (charge-offs) recoveries	(1,930)	(1,046)	(5,376)	(3,976)
Provision for credit losses	2,822	1,967	6,000	5,520
Other	(213)	(72)	(226)	(123)
Balance, end of period	22,926	22,771	22,926	22,771
Inventory Finance
Allowance for loan and lease losses
Balance, beginning of period	11,840	12,129	13,233	13,932
Charge-offs	(880)	(750)	(2,102)	(1,856)
Recoveries	243	281	539	675
Net (charge-offs) recoveries	(637)	(469)	(1,563)	(1,181)
Provision for credit losses	124	240	(224)	(903)
Other	34	78	(85)	130
Balance, end of period	11,361	11,978	11,361	11,978
Auto Finance
Allowance for loan and lease losses
Balance, beginning of period	46,608	43,893	50,225	32,310
Charge-offs	(12,460)	(11,028)	(36,996)	(28,045)
Recoveries	2,975	1,780	8,339	4,680
Net (charge-offs) recoveries	(9,485)	(9,248)	(28,657)	(23,365)
Provision for credit losses	2,729	15,437	18,284	44,141
Other	0	(1,422)	0	(4,426)
Balance, end of period	39,852	48,660	39,852	48,660
Other
Allowance for loan and lease losses
Balance, beginning of period	679	599	692	534
Charge-offs	(1,963)	(1,877)	(5,395)	(4,996)
Recoveries	787	840	2,696	2,761
Net (charge-offs) recoveries	(1,176)	(1,037)	(2,699)	(2,235)
Provision for credit losses	1,251	1,091	2,761	2,354
Other	0	0	0	0
Balance, end of period	$ 754	$ 653	$ 754	$ 653

Allowance for Loan and Lease _4

Allowance for Loan and Lease Losses and Credit Quality Information - Allowance for Loan and Lease Losses and Balances Outstanding by Allowance Methodology (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Allowance for loan and lease losses:
Collectively evaluated for impairment		$ 131,471		$ 147,105
Individually evaluated for impairment		29,150		23,936
Total		160,621	$ 165,619	171,041	$ 168,244	$ 165,620	$ 160,269
Loans and leases outstanding:
Collectively evaluated for impairment		18,232,815		18,869,356
Individually evaluated for impairment		183,535		223,260
Loans acquired with deteriorated credit quality		4,803		11,844
Total loans and leases	[1]	18,421,153		19,104,460
Consumer Real Estate
Allowance for loan and lease losses:
Collectively evaluated for impairment		22,274		28,851
Individually evaluated for impairment		22,984		18,317
Total		45,258	43,954	47,168	47,838	52,408	59,448
Loans and leases outstanding:
Collectively evaluated for impairment		4,785,131		4,675,626
Individually evaluated for impairment		116,326		144,070
Loans acquired with deteriorated credit quality		0		0
Total loans and leases		4,901,457		4,819,696
Commercial
Allowance for loan and lease losses:
Collectively evaluated for impairment		38,843		35,635
Individually evaluated for impairment		1,627		1,560
Total		40,470	40,291	37,195	36,344	34,669	32,695
Loans and leases outstanding:
Collectively evaluated for impairment		3,710,229		3,524,864
Individually evaluated for impairment		30,935		36,329
Loans acquired with deteriorated credit quality		0		0
Total loans and leases		3,741,164		3,561,193
Leasing and Equipment Finance
Allowance for loan and lease losses:
Collectively evaluated for impairment		19,021		19,083
Individually evaluated for impairment		3,905		3,445
Total		22,926	22,247	22,528	22,771	21,922	21,350
Loans and leases outstanding:
Collectively evaluated for impairment		4,574,620		4,721,905
Individually evaluated for impairment		22,464		27,912
Loans acquired with deteriorated credit quality		4,803		11,844
Total loans and leases		4,601,887		4,761,661
Inventory Finance
Allowance for loan and lease losses:
Collectively evaluated for impairment		10,850		12,945
Individually evaluated for impairment		511		288
Total		11,361	11,840	13,233	11,978	12,129	13,932
Loans and leases outstanding:
Collectively evaluated for impairment		2,878,764		2,735,638
Individually evaluated for impairment		1,640		4,116
Loans acquired with deteriorated credit quality		0		0
Total loans and leases		2,880,404		2,739,754
Auto finance
Allowance for loan and lease losses:
Collectively evaluated for impairment		39,729		49,900
Individually evaluated for impairment		123		325
Total		39,852	46,608	50,225	48,660	43,893	32,310
Loans and leases outstanding:
Collectively evaluated for impairment		2,262,966		3,188,810
Individually evaluated for impairment		12,168		10,829
Loans acquired with deteriorated credit quality		0		0
Total loans and leases		2,275,134		3,199,639
Other
Allowance for loan and lease losses:
Collectively evaluated for impairment		754		691
Individually evaluated for impairment		0		1
Total		754	$ 679	692	$ 653	$ 599	$ 534
Loans and leases outstanding:
Collectively evaluated for impairment		21,105		22,513
Individually evaluated for impairment		2		4
Loans acquired with deteriorated credit quality		0		0
Total loans and leases		$ 21,107		$ 22,517
[1]	Loans and leases are reported at historical cost including net direct fees and costs associated with originating and acquiring loans and leases, lease residuals, unearned income and unamortized purchase premiums and discounts. The aggregate amount of these loan and lease adjustments was $9.0 million and $33.3 million at September 30, 2018 and December 31, 2017, respectively.

Allowance for Loan and Lease _5

Allowance for Loan and Lease Losses and Credit Quality Information - Accruing and Non-accrual Loans and Leases (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due
Current-59 Days Delinquent and Accruing		$ 18,309,247	$ 18,962,699
60-89 Days Delinquent and Accruing		15,306	16,247
90 Days or More Delinquent and Accruing		6,304	6,932
Total Accruing		18,330,857	18,985,878
Non-accrual		90,296	118,582
Total loans and leases	[1]	18,421,153	19,104,460
Portfolios acquired with deteriorated credit quality
Financing Receivable, Recorded Investment, Past Due
Current-59 Days Delinquent and Accruing		4,000	10,283
60-89 Days Delinquent and Accruing		0	361
90 Days or More Delinquent and Accruing		803	1,200
Total Accruing		4,803	11,844
Non-accrual		0	0
Total loans and leases		4,803	11,844
Consumer real estate
Financing Receivable, Recorded Investment, Past Due
Current-59 Days Delinquent and Accruing		4,841,756	4,730,538
60-89 Days Delinquent and Accruing		3,839	5,341
90 Days or More Delinquent and Accruing		770	593
Total Accruing		4,846,365	4,736,472
Non-accrual		55,092	83,224
Total loans and leases		4,901,457	4,819,696
Consumer real estate | First mortgage lien
Financing Receivable, Recorded Investment, Past Due
Current-59 Days Delinquent and Accruing		1,921,391	1,892,771
60-89 Days Delinquent and Accruing		2,720	4,073
90 Days or More Delinquent and Accruing		770	593
Total Accruing		1,924,881	1,897,437
Non-accrual		35,875	61,950
Total loans and leases		1,960,756	1,959,387
Consumer real estate | Junior lien
Financing Receivable, Recorded Investment, Past Due
Current-59 Days Delinquent and Accruing		2,920,365	2,837,767
60-89 Days Delinquent and Accruing		1,119	1,268
90 Days or More Delinquent and Accruing		0	0
Total Accruing		2,921,484	2,839,035
Non-accrual		19,217	21,274
Total loans and leases		2,940,701	2,860,309
Commercial
Financing Receivable, Recorded Investment, Past Due
Current-59 Days Delinquent and Accruing		3,731,276	3,554,407
60-89 Days Delinquent and Accruing		0	1
90 Days or More Delinquent and Accruing		0	0
Total Accruing		3,731,276	3,554,408
Non-accrual		9,888	6,785
Total loans and leases		3,741,164	3,561,193
Commercial | Commercial real estate
Financing Receivable, Recorded Investment, Past Due
Current-59 Days Delinquent and Accruing		2,768,445	2,744,500
60-89 Days Delinquent and Accruing		0	0
90 Days or More Delinquent and Accruing		0	0
Total Accruing		2,768,445	2,744,500
Non-accrual		5,210	6,785
Total loans and leases		2,773,655	2,751,285
Commercial | Commercial business
Financing Receivable, Recorded Investment, Past Due
Current-59 Days Delinquent and Accruing		962,831	809,907
60-89 Days Delinquent and Accruing		0	1
90 Days or More Delinquent and Accruing		0	0
Total Accruing		962,831	809,908
Non-accrual		4,678	0
Total loans and leases		967,509	809,908
Leasing and equipment finance
Financing Receivable, Recorded Investment, Past Due
Current-59 Days Delinquent and Accruing		4,574,268	4,726,339
60-89 Days Delinquent and Accruing		5,054	4,272
90 Days or More Delinquent and Accruing		1,701	2,117
Total Accruing		4,581,023	4,732,728
Non-accrual		16,061	17,089
Total loans and leases		4,597,084	4,749,817
Inventory finance
Financing Receivable, Recorded Investment, Past Due
Current-59 Days Delinquent and Accruing		2,878,684	2,735,430
60-89 Days Delinquent and Accruing		65	191
90 Days or More Delinquent and Accruing		15	17
Total Accruing		2,878,764	2,735,638
Non-accrual		1,640	4,116
Total loans and leases		2,880,404	2,739,754
Auto finance
Financing Receivable, Recorded Investment, Past Due
Current-59 Days Delinquent and Accruing		2,258,221	3,183,196
60-89 Days Delinquent and Accruing		6,318	6,078
90 Days or More Delinquent and Accruing		2,982	2,999
Total Accruing		2,267,521	3,192,273
Non-accrual		7,613	7,366
Total loans and leases		2,275,134	3,199,639
Other
Financing Receivable, Recorded Investment, Past Due
Current-59 Days Delinquent and Accruing		21,042	22,506
60-89 Days Delinquent and Accruing		30	3
90 Days or More Delinquent and Accruing		33	6
Total Accruing		21,105	22,515
Non-accrual		2	2
Total loans and leases		21,107	22,517
Total loans and leases excluding portfolios acquired with deteriorated credit quality
Financing Receivable, Recorded Investment, Past Due
Current-59 Days Delinquent and Accruing		18,305,247	18,952,416
60-89 Days Delinquent and Accruing		15,306	15,886
90 Days or More Delinquent and Accruing		5,501	5,732
Total Accruing		18,326,054	18,974,034
Non-accrual		90,296	118,582
Total loans and leases		$ 18,416,350	$ 19,092,616
[1]	Loans and leases are reported at historical cost including net direct fees and costs associated with originating and acquiring loans and leases, lease residuals, unearned income and unamortized purchase premiums and discounts. The aggregate amount of these loan and lease adjustments was $9.0 million and $33.3 million at September 30, 2018 and December 31, 2017, respectively.

Allowance for Loan and Lease _6

Allowance for Loan and Lease Losses and Credit Quality Information - Interest Income for Loans and Leases in Non-accrual Status (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Contractual Interest Due and Interest Recognized on Non-accrual Loans
Contractual interest due on non-accrual loans and leases	$ 2,254	$ 3,529	$ 8,138	$ 11,606
Interest income recognized on non-accrual loans and leases	188	581	1,091	2,274
Unrecognized interest income	$ 2,066	$ 2,948	$ 7,047	$ 9,332

Allowance for Loan and Lease _7

Allowance for Loan and Lease Losses and Credit Quality Information - Consumer Real Estate Loans to Customers in Bankruptcy (Details) - Consumer real estate - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Consumer Real Estate Loans to Customers Involved in Bankruptcy
0-59 days delinquent and accruing	$ 4,642	$ 7,324
Non-accrual	8,695	10,552
Total consumer real estate loans to customers in bankruptcy	$ 13,337	$ 17,876

Allowance for Loan and Lease _8

Allowance for Loan and Lease Losses and Credit Quality Information - Loan Modifications to Borrowers with Financial Difficulties (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Loan Modifications for Borrowers with Financial Difficulties
Accruing TDR Loans	$ 97,514,000		$ 97,514,000		$ 114,071,000
Non-accrual TDR Loans	33,614,000		33,614,000		41,606,000
Total TDR loans	131,128,000		$ 131,128,000		$ 155,677,000
Delinquency period of performing loans and leases			60 days		60 days
Interest Income Recognized on Accruing TDR Loans	1,111,000	$ 1,586,000	$ 3,998,000	$ 5,425,000
Consumer real estate
Loan Modifications for Borrowers with Financial Difficulties
Accruing TDR Loans	82,317,000		82,317,000		$ 88,092,000
Non-accrual TDR Loans	16,334,000		16,334,000		34,282,000
Total TDR loans	98,651,000		$ 98,651,000		$ 122,374,000
Maximum period past due to be considered accruing status for consumer real estate TDR loans			90 days		90 days
Portion of non-accrual TDR balance, loans discharged in Chapter 7 bankruptcy that are not reaffirmed	$ 7,900,000		$ 7,900,000		$ 22,300,000
Portion of non-accrual TDR balance, loans discharged in Chapter 7 bankruptcy that are not reaffirmed (as a percent)	48.60%		48.60%		65.00%
Portion of non-accrual TDR balance, loans discharged in Chapter 7 bankruptcy that are not reaffirmed, current (as a percent)	57.10%		57.10%		70.00%
Allowance on accruing TDR loans	$ 15,600,000		$ 15,600,000		$ 17,100,000
Allowance on accruing TDR loans (as a percent)	19.00%		19.00%		19.40%
Percent of accruing TDR loans more than 60 days delinquent	0.30%		0.30%		0.50%
Unfunded commitments to loans classified as TDRs	$ 500,000		$ 500,000		$ 400,000
Consumer real estate | Contractual interest rate reduction
Loan Modifications for Borrowers with Financial Difficulties
Contractual Interest Due on Accruing TDR Loans	1,441,000	1,606,000	4,396,000	4,903,000
Interest Income Recognized on Accruing TDR Loans	892,000	1,019,000	2,723,000	3,084,000
Unrecognized Interest Income on Accruing TDR Loans	549,000	587,000	1,673,000	1,819,000
Consumer real estate | First mortgage lien | Contractual interest rate reduction
Loan Modifications for Borrowers with Financial Difficulties
Contractual Interest Due on Accruing TDR Loans	1,034,000	1,127,000	3,147,000	3,427,000
Interest Income Recognized on Accruing TDR Loans	614,000	688,000	1,870,000	2,059,000
Unrecognized Interest Income on Accruing TDR Loans	420,000	439,000	1,277,000	1,368,000
Consumer real estate | Junior lien | Contractual interest rate reduction
Loan Modifications for Borrowers with Financial Difficulties
Contractual Interest Due on Accruing TDR Loans	407,000	479,000	1,249,000	1,476,000
Interest Income Recognized on Accruing TDR Loans	278,000	331,000	853,000	1,025,000
Unrecognized Interest Income on Accruing TDR Loans	129,000	$ 148,000	396,000	$ 451,000
Commercial
Loan Modifications for Borrowers with Financial Difficulties
Accruing TDR Loans	4,235,000		4,235,000		12,249,000
Non-accrual TDR Loans	9,874,000		9,874,000		83,000
Total TDR loans	14,109,000		14,109,000		12,332,000
Unfunded commitments to loans classified as TDRs	0		0		500,000
Leasing and equipment finance
Loan Modifications for Borrowers with Financial Difficulties
Accruing TDR Loans	6,403,000		6,403,000		10,263,000
Non-accrual TDR Loans	2,085,000		2,085,000		1,413,000
Total TDR loans	8,488,000		8,488,000		11,676,000
Unfunded commitments to loans classified as TDRs	0		0		0
Inventory finance
Loan Modifications for Borrowers with Financial Difficulties
Accruing TDR Loans	0		0		0
Non-accrual TDR Loans	12,000		12,000		476,000
Total TDR loans	12,000		12,000		476,000
Unfunded commitments to loans classified as TDRs	0		0		0
Auto finance
Loan Modifications for Borrowers with Financial Difficulties
Accruing TDR Loans	4,557,000		4,557,000		3,464,000
Non-accrual TDR Loans	5,309,000		5,309,000		5,351,000
Total TDR loans	9,866,000		9,866,000		8,815,000
Unfunded commitments to loans classified as TDRs	0		0		0
Other
Loan Modifications for Borrowers with Financial Difficulties
Accruing TDR Loans	2,000		2,000		3,000
Non-accrual TDR Loans	0		0		1,000
Total TDR loans	$ 2,000		$ 2,000		$ 4,000

Allowance for Loan and Lease _9

Allowance for Loan and Lease Losses and Credit Quality Information - Modified TDR Loan Balances that Defaulted During the Period (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Loan Modifications for Borrowers with Financial Difficulties
Minimum period for loans to be delinquent to be considered in default				90 days	90 days
Defaulted TDR loan balance modified during the period	[1]	$ 1,258	$ 1,884	$ 8,725	$ 11,029
Consumer real estate
Loan Modifications for Borrowers with Financial Difficulties
Defaulted TDR loan balance modified during the period	[1]	954	1,173	2,991	2,846
Consumer real estate | First mortgage lien
Loan Modifications for Borrowers with Financial Difficulties
Defaulted TDR loan balance modified during the period	[1]	778	856	2,751	2,328
Consumer real estate | Junior lien
Loan Modifications for Borrowers with Financial Difficulties
Defaulted TDR loan balance modified during the period	[1]	176	317	240	518
Commercial
Loan Modifications for Borrowers with Financial Difficulties
Defaulted TDR loan balance modified during the period	[1]	0	0	4,697	6,681
Commercial | Commercial real estate
Loan Modifications for Borrowers with Financial Difficulties
Defaulted TDR loan balance modified during the period	[1]	0	0	0	6,681
Commercial | Commercial business
Loan Modifications for Borrowers with Financial Difficulties
Defaulted TDR loan balance modified during the period	[1]	0	0	4,697	0
Leasing and equipment finance
Loan Modifications for Borrowers with Financial Difficulties
Defaulted TDR loan balance modified during the period	[1]	87	451	87	635
Auto Finance
Loan Modifications for Borrowers with Financial Difficulties
Defaulted TDR loan balance modified during the period	[1]	$ 217	$ 260	$ 950	$ 867
[1]	The loan balances presented are not materially different than the pre-modification loan balances as TCF's loan modifications generally do not forgive principal amounts.

Allowance for Loan and Lease_10

Allowance for Loan and Lease Losses and Credit Quality Information - Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Impaired Loans
Unpaid Contractual Balance with an Allowance Recorded	$ 118,892		$ 118,892		$ 158,339
Unpaid Contractual Balance without an Allowance Recorded	41,475		41,475		48,854
Total Unpaid Contractual Balance	160,367		160,367		207,193
Loan Balance with an Allowance Recorded	114,206		114,206		144,312
Loan Balance without an Allowance Recorded	25,233		25,233		27,136
Total Loan Balance	139,439		139,439		171,448
Related Allowance Recorded	27,462		27,462		21,394
Average Loan Balance with an Allowance Recorded	115,762	$ 139,407	129,258	$ 160,148
Average Loan Balance without an Allowance Recorded	25,140	32,097	26,186	31,786
Total Average Loan Balance	140,902	171,504	155,444	191,934
Interest Income Recognized with an Allowance Recorded	730	1,144	2,798	3,720
Interest Income Recognized without an Allowance Recorded	381	442	1,200	1,705
Total Interest Income Recognized	1,111	1,586	3,998	5,425
Consumer real estate
Impaired Loans
Unpaid Contractual Balance with an Allowance Recorded	91,500		91,500		123,951
Unpaid Contractual Balance without an Allowance Recorded	23,242		23,242		30,595
Loan Balance with an Allowance Recorded	87,359		87,359		110,346
Loan Balance without an Allowance Recorded	11,292		11,292		12,028
Related Allowance Recorded	22,850		22,850		17,957
Average Loan Balance with an Allowance Recorded	87,199	117,564	98,852	133,573
Average Loan Balance without an Allowance Recorded	11,665	13,540	11,661	14,013
Interest Income Recognized with an Allowance Recorded	681	1,061	2,547	3,306
Interest Income Recognized without an Allowance Recorded	215	283	679	1,128
Consumer real estate | First mortgage lien
Impaired Loans
Unpaid Contractual Balance with an Allowance Recorded	65,528		65,528		91,624
Unpaid Contractual Balance without an Allowance Recorded	12,155		12,155		12,898
Loan Balance with an Allowance Recorded	62,581		62,581		80,802
Loan Balance without an Allowance Recorded	9,765		9,765		10,445
Related Allowance Recorded	13,989		13,989		13,792
Average Loan Balance with an Allowance Recorded	62,411	84,126	71,692	92,490
Average Loan Balance without an Allowance Recorded	10,074	11,871	10,105	12,264
Interest Income Recognized with an Allowance Recorded	435	679	1,706	2,097
Interest Income Recognized without an Allowance Recorded	171	212	527	736
Consumer real estate | Junior lien
Impaired Loans
Unpaid Contractual Balance with an Allowance Recorded	25,972		25,972		32,327
Unpaid Contractual Balance without an Allowance Recorded	11,087		11,087		17,697
Loan Balance with an Allowance Recorded	24,778		24,778		29,544
Loan Balance without an Allowance Recorded	1,527		1,527		1,583
Related Allowance Recorded	8,861		8,861		4,165
Average Loan Balance with an Allowance Recorded	24,788	33,438	27,160	41,083
Average Loan Balance without an Allowance Recorded	1,591	1,669	1,556	1,749
Interest Income Recognized with an Allowance Recorded	246	382	841	1,209
Interest Income Recognized without an Allowance Recorded	44	71	152	392
Commercial
Impaired Loans
Unpaid Contractual Balance with an Allowance Recorded	10,260		10,260		14,651
Loan Balance with an Allowance Recorded	9,845		9,845		14,543
Related Allowance Recorded	1,627		1,627		1,560
Average Loan Balance with an Allowance Recorded	11,173	5,132	12,194	8,474
Average Loan Balance without an Allowance Recorded	4,315	12,424	4,385	12,144
Interest Income Recognized with an Allowance Recorded	13	0	130	64
Interest Income Recognized without an Allowance Recorded	58	97	174	441
Commercial | Commercial real estate
Impaired Loans
Unpaid Contractual Balance with an Allowance Recorded	5,547		5,547		6,810
Unpaid Contractual Balance without an Allowance Recorded	4,344		4,344		4,552
Loan Balance with an Allowance Recorded	5,156		5,156		6,702
Loan Balance without an Allowance Recorded	4,278		4,278		4,491
Related Allowance Recorded	1,000		1,000		1,000
Average Loan Balance with an Allowance Recorded	5,192	5,119	5,929	8,461
Average Loan Balance without an Allowance Recorded	4,315	12,090	4,385	11,860
Interest Income Recognized with an Allowance Recorded	0	0	0	16
Interest Income Recognized without an Allowance Recorded	58	95	174	438
Commercial | Commercial business
Impaired Loans
Unpaid Contractual Balance with an Allowance Recorded	4,713		4,713		7,841
Loan Balance with an Allowance Recorded	4,689		4,689		7,841
Related Allowance Recorded	627		627		560
Average Loan Balance with an Allowance Recorded	5,981	13	6,265	13
Average Loan Balance without an Allowance Recorded	0	334	0	284
Interest Income Recognized with an Allowance Recorded	13	0	130	48
Interest Income Recognized without an Allowance Recorded	0	2	0	3
Leasing and equipment finance
Impaired Loans
Unpaid Contractual Balance with an Allowance Recorded	15,157		15,157		17,105
Loan Balance with an Allowance Recorded	15,157		15,157		17,105
Related Allowance Recorded	2,415		2,415		1,345
Average Loan Balance with an Allowance Recorded	15,472	11,837	16,131	11,638
Interest Income Recognized with an Allowance Recorded	16	10	70	28
Inventory finance
Impaired Loans
Unpaid Contractual Balance with an Allowance Recorded	1,435		1,435		1,296
Unpaid Contractual Balance without an Allowance Recorded	201		201		2,810
Loan Balance with an Allowance Recorded	1,439		1,439		1,298
Loan Balance without an Allowance Recorded	201		201		2,818
Related Allowance Recorded	511		511		288
Average Loan Balance with an Allowance Recorded	1,464	2,078	1,369	3,120
Average Loan Balance without an Allowance Recorded	403	1,255	1,510	1,037
Interest Income Recognized with an Allowance Recorded	20	18	51	176
Interest Income Recognized without an Allowance Recorded	31	62	136	136
Auto finance
Impaired Loans
Unpaid Contractual Balance with an Allowance Recorded	538		538		1,333
Unpaid Contractual Balance without an Allowance Recorded	13,357		13,357		10,566
Loan Balance with an Allowance Recorded	404		404		1,016
Loan Balance without an Allowance Recorded	9,462		9,462		7,799
Related Allowance Recorded	59		59		243
Average Loan Balance with an Allowance Recorded	452	2,792	709	3,337
Average Loan Balance without an Allowance Recorded	8,757	4,878	8,630	4,592
Interest Income Recognized with an Allowance Recorded	0	55	0	146
Interest Income Recognized without an Allowance Recorded	77	0	211	0
Other
Impaired Loans
Unpaid Contractual Balance with an Allowance Recorded	2		2		3
Unpaid Contractual Balance without an Allowance Recorded	331		331		331
Loan Balance with an Allowance Recorded	2		2		4
Loan Balance without an Allowance Recorded	0		0		0
Related Allowance Recorded	0		0		$ 1
Average Loan Balance with an Allowance Recorded	2	4	3	6
Interest Income Recognized with an Allowance Recorded	$ 0	$ 0	$ 0	$ 0

Allowance for Loan and Lease_11

Allowance for Loan and Lease Losses and Credit Quality Information - Other Real Estate Owned and Repossessed and Returned Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Other Real Estate Owned and Repossessed and Returned Assets
Other real estate owned	$ 19,079		$ 19,079		$ 18,225
Repossessed and returned assets	12,279		12,279		12,630
Consumer real estate loans in process of foreclosure	15,190		15,190		$ 22,622
Other real estate owned and repossessed and returned assets
Other Real Estate Owned and Repossessed and Returned Assets
Amount written down	$ 700	$ 1,600	$ 2,700	$ 5,000

Long-term Borrowings - Long-ter

Long-term Borrowings - Long-term Borrowings (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Debt instrument
Long-term borrowings		$ 1,171,541	$ 1,249,449
Hedged-related basis adjustment		8,339	2,157
FHLB advances, amount prepayable		825,000
Federal Home Loan Bank advances
Debt instrument
Long-term borrowings		825,000	875,000
Federal Home Loan Bank advances | TCF Bank
Debt instrument
Loans pledged as collateral		4,100,000
Federal Home Loan Bank advances | Maturity Year 2019
Debt instrument
Long-term borrowings		$ 0	$ 600,000
Stated Rate		0.00%
Federal Home Loan Bank advances | Maturity Year 2019 | Minimum
Debt instrument
Stated Rate			1.40%
Federal Home Loan Bank advances | Maturity Year 2019 | Maximum
Debt instrument
Stated Rate			1.75%
Federal Home Loan Bank advances | Maturity Year 2020
Debt instrument
Long-term borrowings		$ 825,000	$ 275,000
Federal Home Loan Bank advances | Maturity Year 2020 | Minimum
Debt instrument
Stated Rate		2.29%	1.76%
Federal Home Loan Bank advances | Maturity Year 2020 | Maximum
Debt instrument
Stated Rate		2.45%	1.78%
Subordinated bank notes
Debt instrument
Long-term borrowings		$ 249,106	$ 254,962
Subordinated bank notes | Maturity Year 2022
Debt instrument
Long-term borrowings		$ 109,037	$ 108,867
Stated Rate		6.25%	6.25%
Subordinated bank notes | Maturity Year 2025
Debt instrument
Long-term borrowings		$ 148,408	$ 148,252
Stated Rate		4.60%	4.60%
Subordinated bank notes | Maturity Year 2025, Interest Rate Swap
Debt instrument
Hedged-related basis adjustment	[1]	$ (8,339)	$ (2,157)
Discounted lease rentals
Debt instrument
Long-term borrowings		94,294	119,487
Discounted lease rentals | Maturity Year 2018
Debt instrument
Long-term borrowings		$ 11,976	$ 52,347
Discounted lease rentals | Maturity Year 2018 | Minimum
Debt instrument
Stated Rate		2.78%	2.55%
Discounted lease rentals | Maturity Year 2018 | Maximum
Debt instrument
Stated Rate		4.20%	7.95%
Discounted lease rentals | Maturity Year 2019
Debt instrument
Long-term borrowings		$ 39,853	$ 34,978
Discounted lease rentals | Maturity Year 2019 | Minimum
Debt instrument
Stated Rate		2.53%	2.53%
Discounted lease rentals | Maturity Year 2019 | Maximum
Debt instrument
Stated Rate		6.00%	6.00%
Discounted lease rentals | Maturity Year 2020
Debt instrument
Long-term borrowings		$ 25,034	$ 19,736
Discounted lease rentals | Maturity Year 2020 | Minimum
Debt instrument
Stated Rate		2.64%	2.64%
Discounted lease rentals | Maturity Year 2020 | Maximum
Debt instrument
Stated Rate		6.50%	6.50%
Discounted lease rentals | Maturity Year 2021
Debt instrument
Long-term borrowings		$ 13,374	$ 10,077
Discounted lease rentals | Maturity Year 2021 | Minimum
Debt instrument
Stated Rate		2.88%	2.88%
Discounted lease rentals | Maturity Year 2021 | Maximum
Debt instrument
Stated Rate		5.80%	5.00%
Discounted lease rentals | Maturity Year 2022
Debt instrument
Long-term borrowings		$ 3,844	$ 2,349
Discounted lease rentals | Maturity Year 2022 | Minimum
Debt instrument
Stated Rate		3.04%	3.04%
Discounted lease rentals | Maturity Year 2022 | Maximum
Debt instrument
Stated Rate		5.50%	5.43%
Discounted lease rentals | Maturity Year 2023
Debt instrument
Long-term borrowings		$ 213	$ 0
Stated Rate			0.00%
Discounted lease rentals | Maturity Year 2023 | Minimum
Debt instrument
Stated Rate		4.90%
Discounted lease rentals | Maturity Year 2023 | Maximum
Debt instrument
Stated Rate		5.78%
Capital lease obligation
Debt instrument
Long-term borrowings		$ 3,141	$ 0
Capital lease obligation | Maturity Year 2018
Debt instrument
Long-term borrowings		$ 20	$ 0
Stated Rate		3.73%	0.00%
Capital lease obligation | Maturity Year 2019
Debt instrument
Long-term borrowings		$ 83	$ 0
Stated Rate		3.73%	0.00%
Capital lease obligation | Maturity Year 2020
Debt instrument
Long-term borrowings		$ 86	$ 0
Stated Rate		3.73%	0.00%
Capital lease obligation | Maturity Year 2021
Debt instrument
Long-term borrowings		$ 89	$ 0
Stated Rate		3.73%	0.00%
Capital lease obligation | Maturity Year 2022
Debt instrument
Long-term borrowings		$ 93	$ 0
Stated Rate		3.73%	0.00%
Capital lease obligation | Maturity Year 2023 - 2038
Debt instrument
Long-term borrowings		$ 2,770	$ 0
Stated Rate		3.73%	0.00%
[1]	Related to subordinated bank notes with a stated maturity of 2025

Equity - Preferred Stock (Detai

Equity - Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 01, 2018	Sep. 30, 2018	Dec. 31, 2017
Schedule of Preferred Stock
Preferred stock, value outstanding		$ 169,302	$ 265,821
Preferred stock, par value (in dollars per share)		$ 0.01	$ 0.01
Series B non-cumulative perpetual preferred stock
Schedule of Preferred Stock
Preferred stock, value outstanding		$ 0	$ 96,519
Annual rate of dividend (as a percent)	6.45%
Preferred stock, par value (in dollars per share)	$ 0.01
Preferred stock, liquidation preference per share	$ 25
Redemption of Series B Preferred Stock (in shares)	4,000,000
Redemption of Series B Preferred Stock	$ 100,000	100,000
Deferred stock issuance costs of Series B Preferred Stock	$ 3,500
Series C non-cumulative perpetual preferred stock
Schedule of Preferred Stock
Preferred stock, value outstanding		$ 169,302	$ 169,302
Preferred stock, depositary shares outstanding		7,000,000	7,000,000
Annual rate of dividend (as a percent)		5.70%	5.70%
Preferred stock, par value (in dollars per share)		$ 0.01	$ 0.01
Preferred stock, liquidation preference per share		25,000	25,000
Preferred stock, liquidation preference per depositary share		$ 25	$ 25

Equity - Treasury Stock and Oth

Equity - Treasury Stock and Other (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Treasury Stock and Other
Treasury stock, at cost	$ 160,178	$ 160,178		$ 10,265
Shares held in trust for deferred compensation plans, at cost	29,474	29,474		30,532
Total	189,652	189,652		$ 40,797
Repurchase of common stock (in dollars)	24,000	149,912	$ 0
Aggregate value remaining in the stock repurchase program	$ 141,000	$ 141,000
Warrants
Outstanding warrants to purchase common stock (in shares)	173,296	173,296
Warrants exercise price (in dollars per share)	$ 16.93	$ 16.93
Common stock warrants exercised (in shares)		3,026,692

Regulatory Capital Requiremen_3

Regulatory Capital Requirements - Regulatory Capital Requirements (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2018	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations
Percentage of net retained profits for the current year combined with retained net profits for the preceding two calendar years that can be declared as dividend		100.00%
Number of prior calendar years considered for payment of dividends in excess of net retained profit		2 years
Net profits for the current year combined with retained net profits for preceding two calendar years		$ 249,100
TCF
Regulatory Capital:
Common equity Tier 1 capital		2,226,820	$ 2,242,410
Tier 1 capital		2,412,869	2,522,178
Total capital		$ 2,754,615	$ 2,889,323
Common equity Tier 1 capital ratio
Actual, Ratio		11.04%	10.79%
Tier 1 risk-based capital ratio
Actual, Ratio		11.96%	12.14%
Total risk-based capital ratio
Actual, Ratio		13.66%	13.90%
Tier 1 leverage ratio
Actual, Ratio		10.58%	11.12%
TCF Bank
Compliance with Regulatory Capital Requirements under Banking Regulations
Capital conservation buffer excluded from minimum capital requirement		1.875%	1.25%
Regulatory Capital:
Common equity Tier 1 capital		$ 2,297,245	$ 2,409,027
Tier 1 capital		2,318,399	2,426,854
Total capital		$ 2,696,433	$ 2,837,374
Common equity Tier 1 capital ratio
Actual, Ratio		11.39%	11.59%
Well-Capitalized Capital Requirement, Ratio		6.50%
Minimum Capital Requirement, Ratio	[1]	4.50%
Tier 1 risk-based capital ratio
Actual, Ratio		11.49%	11.68%
Well-Capitalized Capital Requirement, Ratio		8.00%
Minimum Capital Requirement, Ratio	[1]	6.00%
Total risk-based capital ratio
Actual, Ratio		13.37%	13.65%
Well-Capitalized Capital Requirement, Ratio		10.00%
Minimum Capital Requirement, Ratio	[1]	8.00%
Tier 1 leverage ratio
Actual, Ratio		10.16%	10.70%
Well-Capitalized Capital Requirement, Ratio		5.00%
Minimum Capital Requirement, Ratio	[1]	4.00%
[1]	Excludes capital conservation buffer of 1.875% and 1.25% at September 30, 2018 and December 31, 2017, respectively.

Stock Compensation - Restricted

Stock Compensation - Restricted Stock Award and Stock Option Transactions (Details) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Restricted Stock Awards (RSAs)
Restricted Stock Awards, Shares Activity
Outstanding at the beginning of the period (in shares)	2,639,663
Granted (in shares)	747,446
Forfeited/cancelled (in shares)	(203,751)
Vested (in shares)	(836,323)
Outstanding at the end of the period (in shares)	2,347,035	2,639,663
Restricted Stock Awards, Weighted-average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share)	$ 13.65
Granted (in dollars per share)	21.71
Forfeited/cancelled (in dollars per share)	15.07
Vested (in dollars per share)	12.15
Outstanding at the end of the period (in dollars per share)	$ 16.62	$ 13.65
Stock Options
Stock Options, Shares Activity
Outstanding at the beginning of the period (in shares)	366,000
Granted (in shares)	0
Exercised (in shares)	(366,000)
Forfeited/canceled (in shares)	0
Vested (in shares)	0
Outstanding at the end of the period (in shares)	0	366,000
Stock Options, Weighted-average Remaining Contractual Life
Weighted-average Remaining Contractual Life	0 days	22 days
Stock Options, Weighted-average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 15.75
Granted (in dollars per share)	0
Exercised (in dollars per share)	15.75
Forfeited/canceled (in dollars per share)	0
Vested (in dollars per share)	0
Outstanding at the end of the period (in dollars per share)	$ 0	$ 15.75

Stock Compensation - Stock Comp

Stock Compensation - Stock Compensation Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Restricted Stock Awards (RSAs)
Share-based compensation
Outstanding number of shares to vest only if certain performance goals and service conditions are achieved (in shares)	264,373		264,373
Unrecognized stock compensation expense for restricted stock awards	$ 21.1		$ 21.1
Weighted-average remaining amortization period			1 year 7 months 6 days
Restricted Stock Units (RSUs) | Omnibus Incentive Plan
Share-based compensation
Restricted stock units, granted (in shares)	406,575		406,575
Restricted stock, maximum multiplier	150.00%		150.00%
Remaining weighted-average performance period for RSUs			1 year 8 months 12 days
Restricted Stock Awards and Restricted Stock Units
Share-based compensation
Compensation expense for restricted stock awards and restricted stock units	$ 3.5	$ 2.4	$ 13.1	$ 6.5

Employee Benefit Plans - Employ

Employee Benefit Plans - Employee Benefit Plans (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Plan
Net periodic benefit plan (income) cost included in non-interest expense
Interest cost	$ 246,000	$ 284,000	$ 738,000	$ 854,000
Return on plan assets	(133,000)	(142,000)	(397,000)	(426,000)
Net periodic benefit plan (income) cost	113,000	142,000	341,000	428,000
TCF contributions			0	0
Postretirement Plan
Net periodic benefit plan (income) cost included in non-interest expense
Interest cost	28,000	33,000	83,000	100,000
Amortization of prior service cost	(12,000)	(12,000)	(35,000)	(35,000)
Net periodic benefit plan (income) cost	16,000	21,000	48,000	65,000
TCF contributions	$ 100,000	$ 100,000	$ 300,000	$ 200,000

Derivative Instruments - Deriva

Derivative Instruments - Derivative Instruments (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Derivatives
Derivative Assets		$ 2,243	$ 2,020
Derivative Liabilities		13,578	8,666
Total derivative assets, net		1,891	1,563
Total derivative liabilities, net		11,357	1,568
Other assets
Derivatives
Derivative Assets		2,243	2,020
Derivative asset netting	[1]	(352)	(457)
Total derivative assets, net		1,891	1,563
Accrued expenses and other liabilities
Derivatives
Derivative Liabilities		13,578	8,666
Derivative liability netting	[1]	(2,221)	(7,098)
Total derivative liabilities, net		11,357	1,568
Derivatives designated as hedging instruments | Other assets
Derivatives
Derivative Assets		111	405
Derivatives designated as hedging instruments | Accrued expenses and other liabilities
Derivatives
Derivative Liabilities		2,693	1,744
Derivatives not designated as hedging instruments | Other assets
Derivatives
Derivative Assets		2,132	1,615
Derivatives not designated as hedging instruments | Accrued expenses and other liabilities
Derivatives
Derivative Liabilities		10,885	6,922
Interest rate contracts
Derivatives
Derivative Assets		1,229	1,797
Derivative Liabilities		7,367	1,688
Total derivative assets, net		897	1,340
Total derivative liabilities, net		7,237	1,231
Interest rate contracts | Derivatives designated as hedging instruments
Derivatives
Notional Amount		150,000	150,000
Interest rate contracts | Derivatives designated as hedging instruments | Other assets
Derivatives
Derivative Assets		111	405
Interest rate contracts | Derivatives designated as hedging instruments | Accrued expenses and other liabilities
Derivatives
Derivative Liabilities		0	0
Interest rate contracts | Derivatives not designated as hedging instruments
Derivatives
Notional Amount		837,693	592,383
Interest rate contracts | Derivatives not designated as hedging instruments | Other assets
Derivatives
Derivative Assets		1,118	1,392
Interest rate contracts | Derivatives not designated as hedging instruments | Accrued expenses and other liabilities
Derivatives
Derivative Liabilities		7,367	1,688
Forward foreign exchange contracts
Derivatives
Derivative Assets		20
Derivative Liabilities		5,175	6,363
Total derivative assets, net		0
Total derivative liabilities, net		3,742	337
Forward foreign exchange contracts | Derivatives designated as hedging instruments
Derivatives
Notional Amount		163,286	77,879
Forward foreign exchange contracts | Derivatives designated as hedging instruments | Other assets
Derivatives
Derivative Assets		0	0
Forward foreign exchange contracts | Derivatives designated as hedging instruments | Accrued expenses and other liabilities
Derivatives
Derivative Liabilities		2,693	1,744
Forward foreign exchange contracts | Derivatives not designated as hedging instruments
Derivatives
Notional Amount		252,829	330,928
Forward foreign exchange contracts | Derivatives not designated as hedging instruments | Other assets
Derivatives
Derivative Assets		20	0
Forward foreign exchange contracts | Derivatives not designated as hedging instruments | Accrued expenses and other liabilities
Derivatives
Derivative Liabilities		2,482	4,619
Interest rate lock commitments
Derivatives
Derivative Assets		994	223
Derivative Liabilities		378
Total derivative assets, net		994	223
Total derivative liabilities, net		378
Interest rate lock commitments | Derivatives not designated as hedging instruments
Derivatives
Notional Amount		45,254	18,015
Interest rate lock commitments | Derivatives not designated as hedging instruments | Other assets
Derivatives
Derivative Assets		994	223
Interest rate lock commitments | Derivatives not designated as hedging instruments | Accrued expenses and other liabilities
Derivatives
Derivative Liabilities		378	0
Other contracts
Derivatives
Derivative Liabilities		658	615
Total derivative liabilities, net		0	0
Other contracts | Derivatives not designated as hedging instruments
Derivatives
Notional Amount		13,020	13,804
Other contracts | Derivatives not designated as hedging instruments | Other assets
Derivatives
Derivative Assets		0	0
Other contracts | Derivatives not designated as hedging instruments | Accrued expenses and other liabilities
Derivatives
Derivative Liabilities		$ 658	$ 615
[1]	Includes balance sheet netting of derivative asset and derivative liability balances, related cash collateral and portfolio level counterparty valuation adjustments.

Derivative Instruments - Deri_2

Derivative Instruments - Derivatives Gross Amounts Recognized and Offset (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Derivative Assets
Gross amounts recognized		$ 2,243	$ 2,020
Gross amounts offset	[1]	(352)	(457)
Net amount presented		1,891	1,563
Derivative Liabilities
Gross amounts recognized		13,578	8,666
Gross amounts offset	[1]	(2,221)	(7,098)
Net amount presented		11,357	1,568
Interest rate contracts
Derivative Assets
Gross amounts recognized		1,229	1,797
Gross amounts offset	[1]	(332)	(457)
Net amount presented		897	1,340
Derivative Liabilities
Gross amounts recognized		7,367	1,688
Gross amounts offset	[1]	(130)	(457)
Net amount presented		7,237	1,231
Interest rate lock commitments
Derivative Assets
Gross amounts recognized		994	223
Gross amounts offset	[1]	0	0
Net amount presented		994	223
Derivative Liabilities
Gross amounts recognized		378
Gross amounts offset	[1]	0
Net amount presented		378
Forward foreign exchange contracts
Derivative Assets
Gross amounts recognized		20
Gross amounts offset	[1]	(20)
Net amount presented		0
Derivative Liabilities
Gross amounts recognized		5,175	6,363
Gross amounts offset	[1]	(1,433)	(6,026)
Net amount presented		3,742	337
Other contracts
Derivative Liabilities
Gross amounts recognized		658	615
Gross amounts offset	[1]	(658)	(615)
Net amount presented		$ 0	$ 0
[1]	Includes the amounts with counterparties subject to enforceable master netting arrangements that have been offset in the consolidated balance sheets.

Derivative Instruments - Deri_3

Derivative Instruments - Derivatives Designated as Hedging Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Interest Rate Contract
Fixed-rate subordinated notes, face amount	$ 150,000		$ 150,000
Carrying amount of the hedged liability - Subordinated bank note - 2025	140,069		140,069		$ 146,095
Cumulative amount of fair value hedging adjustments included in the carrying amount of the hedged liability - Subordinated bank note - 2025	(8,339)		(8,339)		$ (2,157)
Gains and losses related to changes in the fair vale of the interest rate swap and hedged debt
Total amount presented in the Consolidated Statements of Income - Interest expense - borrowings	10,726	$ 6,487	31,850	$ 19,885
Total amount presented in the Consolidated Statements of Income - Other non-interest income	3,818	2,930	11,468	8,428
Forward Foreign Exchange Contracts
Effect of net investment hedges on accumulated other comprehensive income	(2,537)	(2,714)	4,637	(5,073)
Derivatives designated as hedges | Interest expense - borrowings
Gains and losses related to changes in the fair vale of the interest rate swap and hedged debt
Gain (loss) of fair value hedge: Hedged item	1,206		6,337
Gain (loss) of fair value hedge: Derivative designated as a hedging instrument	(1,165)		(6,621)
Derivatives designated as hedges | Other non-interest income
Gains and losses related to changes in the fair vale of the interest rate swap and hedged debt
Gain (loss) of fair value hedge: Hedged item		146		(601)
Gain (loss) of fair value hedge: Derivative designated as a hedging instrument		(135)		813
Derivatives designated as hedges | Net investment hedge | Forward foreign exchange contracts
Forward Foreign Exchange Contracts
Effect of net investment hedges on accumulated other comprehensive income	$ (2,537)	$ (2,174)	$ 4,637	$ (5,073)

Derivative Instruments - Deri_4

Derivative Instruments - Derivatives Not Designated as Hedging Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Forward foreign exchange contracts
Credit risk-related contingent features
Forward foreign exchange contracts with credit risk-related contingent features, notional value	$ 34,900		$ 34,900		$ 39,800
Additional collateral required, if TCF was rated less than BB- by Standard and Poor's	700		700		800
Forward foreign exchange contracts with credit risk-related contingent features, net liability amount	600		600		$ 400
Derivative, Collateral
Cash collateral posted	1,200		1,200
Cash collateral received	200		200
Other contracts
Derivative, Collateral
Cash collateral posted	1,300		1,300
Interest rate contracts
Derivative, Collateral
Cash collateral posted	7,600		7,600
Derivatives not designated as hedges
Derivative instruments, gain (loss)
Effect of derivatives included in the Consolidated Statements of Income	(4,191)	$ (10,874)	8,731	$ (20,397)
Derivatives not designated as hedges | Forward foreign exchange contracts | Other non-interest expense
Derivative instruments, gain (loss)
Effect of derivatives included in the Consolidated Statements of Income	(3,706)	(10,690)	8,050	(20,323)
Derivatives not designated as hedges | Interest rate lock commitments | Gains on sales of consumer real estate loans, net
Derivative instruments, gain (loss)
Effect of derivatives included in the Consolidated Statements of Income	(244)	(29)	798	189
Derivatives not designated as hedges | Other contracts | Other non-interest expense
Derivative instruments, gain (loss)
Effect of derivatives included in the Consolidated Statements of Income	(292)	0	(274)	0
Derivatives not designated as hedges | Interest rate contracts | Other non-interest income
Derivative instruments, gain (loss)
Effect of derivatives included in the Consolidated Statements of Income	$ 51	$ (155)	$ 157	$ (263)

Fair Values Disclosures - Valua

Fair Values Disclosures - Valuation Methodologies of Assets and Liabilities at Fair Value (Details) $ in Millions	Sep. 30, 2018USD ($)
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Fixed-rate subordinated notes, face amount	$ 150
Subordinated bank notes | Maturity Year 2025
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Fixed-rate subordinated notes, face amount	$ 150

Fair Values Disclosures - Asset

Fair Values Disclosures - Assets and Liabilities Measured at Fair Value (Details) - USD ($)		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Fair Value, Adjustment Disclosure [Abstract]
Transfers between fair value levels		$ 0	$ 0
Measurement of fair value on a recurring basis
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		56,053,000		$ 35,406,000
Liabilities, Fair value carrying amount		45,707,000		36,889,000
Measurement of fair value on a recurring basis | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		34,626,000		29,962,000
Liabilities, Fair value carrying amount		34,626,000		29,962,000
Measurement of fair value on a recurring basis | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		1,249,000		1,797,000
Liabilities, Fair value carrying amount		9,849,000		6,307,000
Measurement of fair value on a recurring basis | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		20,178,000		3,647,000
Liabilities, Fair value carrying amount		1,232,000		620,000
Measurement of fair value on a recurring basis | Loans held for sale
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		18,519,000		3,356,000
Measurement of fair value on a recurring basis | Loans held for sale | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Measurement of fair value on a recurring basis | Loans held for sale | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Measurement of fair value on a recurring basis | Loans held for sale | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		18,519,000		3,356,000
Measurement of fair value on a recurring basis | Forward foreign exchange contracts
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount	[1]	20,000
Liabilities, Fair value carrying amount	[1]	2,482,000		4,619,000
Measurement of fair value on a recurring basis | Forward foreign exchange contracts | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount	[1]	0
Liabilities, Fair value carrying amount	[1]	0		0
Measurement of fair value on a recurring basis | Forward foreign exchange contracts | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount	[1]	20,000
Liabilities, Fair value carrying amount	[1]	2,482,000		4,619,000
Measurement of fair value on a recurring basis | Forward foreign exchange contracts | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount	[1]	0
Liabilities, Fair value carrying amount	[1]	0		0
Measurement of fair value on a recurring basis | Interest rate contracts
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount	[1]	1,229,000		1,797,000
Liabilities, Fair value carrying amount	[1]	7,367,000		1,688,000
Measurement of fair value on a recurring basis | Interest rate contracts | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount	[1]	0		0
Liabilities, Fair value carrying amount	[1]	0		0
Measurement of fair value on a recurring basis | Interest rate contracts | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount	[1]	1,229,000		1,797,000
Liabilities, Fair value carrying amount	[1]	7,367,000		1,688,000
Measurement of fair value on a recurring basis | Interest rate contracts | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount	[1]	0		0
Liabilities, Fair value carrying amount	[1]	0		0
Measurement of fair value on a recurring basis | Interest rate lock commitments
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount	[1]	994,000		223,000
Liabilities, Fair value carrying amount	[1]	378,000
Measurement of fair value on a recurring basis | Interest rate lock commitments | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount	[1]	0		0
Liabilities, Fair value carrying amount	[1]	0
Measurement of fair value on a recurring basis | Interest rate lock commitments | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount	[1]	0		0
Liabilities, Fair value carrying amount	[1]	0
Measurement of fair value on a recurring basis | Interest rate lock commitments | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount	[1]	994,000		223,000
Liabilities, Fair value carrying amount	[1]	378,000
Measurement of fair value on a recurring basis | Forward loan sales commitments
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		665,000		68,000
Liabilities, Fair value carrying amount		196,000		5,000
Measurement of fair value on a recurring basis | Forward loan sales commitments | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Liabilities, Fair value carrying amount		0		0
Measurement of fair value on a recurring basis | Forward loan sales commitments | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Liabilities, Fair value carrying amount		0		0
Measurement of fair value on a recurring basis | Forward loan sales commitments | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		665,000		68,000
Liabilities, Fair value carrying amount		196,000		5,000
Measurement of fair value on a recurring basis | Assets held in trust for deferred compensation plans
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		34,626,000		29,962,000
Measurement of fair value on a recurring basis | Assets held in trust for deferred compensation plans | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		34,626,000		29,962,000
Measurement of fair value on a recurring basis | Assets held in trust for deferred compensation plans | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Measurement of fair value on a recurring basis | Assets held in trust for deferred compensation plans | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Measurement of fair value on a recurring basis | Other contracts
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Liabilities, Fair value carrying amount	[1]	658,000		615,000
Measurement of fair value on a recurring basis | Other contracts | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Liabilities, Fair value carrying amount	[1]	0		0
Measurement of fair value on a recurring basis | Other contracts | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Liabilities, Fair value carrying amount	[1]	0		0
Measurement of fair value on a recurring basis | Other contracts | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Liabilities, Fair value carrying amount	[1]	658,000		615,000
Measurement of fair value on a recurring basis | Liabilities held in trust for deferred compensation plans
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Liabilities, Fair value carrying amount		34,626,000		29,962,000
Measurement of fair value on a recurring basis | Liabilities held in trust for deferred compensation plans | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Liabilities, Fair value carrying amount		34,626,000		29,962,000
Measurement of fair value on a recurring basis | Liabilities held in trust for deferred compensation plans | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Liabilities, Fair value carrying amount		0		0
Measurement of fair value on a recurring basis | Liabilities held in trust for deferred compensation plans | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Liabilities, Fair value carrying amount		0		0
Measurement of fair value on a non-recurring basis
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		68,627,000		94,380,000
Loans		48,934,000		72,287,000
Other real estate owned		11,893,000		14,036,000
Repossessed and returned assets		7,800,000		8,057,000
Measurement of fair value on a non-recurring basis | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Loans		0		0
Other real estate owned		0		0
Repossessed and returned assets		0		0
Measurement of fair value on a non-recurring basis | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		3,918,000		3,669,000
Loans		0		0
Other real estate owned		0		0
Repossessed and returned assets		3,918,000		3,669,000
Measurement of fair value on a non-recurring basis | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		64,709,000		90,711,000
Loans		48,934,000		72,287,000
Other real estate owned		11,893,000		14,036,000
Repossessed and returned assets		3,882,000		4,388,000
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		2,397,258,000		1,730,404,000
Liabilities, Fair value carrying amount		2,693,000		1,744,000
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Liabilities, Fair value carrying amount		0		0
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		2,379,542,000		1,709,012,000
Liabilities, Fair value carrying amount		2,693,000		1,744,000
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		17,716,000		21,392,000
Liabilities, Fair value carrying amount		0		0
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Forward foreign exchange contracts
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Liabilities, Fair value carrying amount	[1]	2,693,000		1,744,000
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Forward foreign exchange contracts | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Liabilities, Fair value carrying amount	[1]	0		0
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Forward foreign exchange contracts | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Liabilities, Fair value carrying amount	[1]	2,693,000		1,744,000
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Forward foreign exchange contracts | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Liabilities, Fair value carrying amount	[1]	0		0
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | U.S. Government sponsored enterprises and federal agencies
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		1,580,684,000		894,685,000
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | U.S. Government sponsored enterprises and federal agencies | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | U.S. Government sponsored enterprises and federal agencies | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		1,580,684,000		894,685,000
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | U.S. Government sponsored enterprises and federal agencies | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Mortgage-backed securities, Other
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		4,000		6,000
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Mortgage-backed securities, Other | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Mortgage-backed securities, Other | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Mortgage-backed securities, Other | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		4,000		6,000
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Obligations of states and political subdivisions
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		798,858,000		814,327,000
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Obligations of states and political subdivisions | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Obligations of states and political subdivisions | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		798,858,000		814,327,000
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Obligations of states and political subdivisions | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Interest-only strips
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		17,712,000		21,386,000
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Interest-only strips | Level 1
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Interest-only strips | Level 2
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		0		0
Other Comprehensive Income (Loss) | Measurement of fair value on a recurring basis | Interest-only strips | Level 3
Fair Value, Assets and liabilities measured at fair value on Recurring and Nonrecurring basis
Assets, Fair value carrying amount		$ 17,712,000		$ 21,386,000
[1]	As permitted under GAAP, TCF has elected to net derivative assets and derivative liabilities when a legally enforceable master netting agreement exists as well as the related cash collateral received and paid. For purposes of this table, the derivative assets and derivative liabilities are presented gross of this netting adjustment.

Fair Values Disclosures - Chang

Fair Values Disclosures - Changes in Level 3 Assets and Liabilities Measured at Fair Value (Details) - Level 3 - Measurement of fair value on a recurring basis - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest Rate Lock Commitments
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ 858	$ 515	$ 223	$ 297
Total net gains (losses) included in net income	(242)	(29)	393	189
Total net gains (losses) include in other comprehensive income (loss)	0	0	0	0
Sales	0	0	0	0
Originations	0	0	0	0
Principal paydowns / settlements	0	0	0	0
Ending balance	616	486	616	486
Forward Loan Sales Commitments
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	110	(67)	63	361
Total net gains (losses) included in net income	359	14	406	(414)
Total net gains (losses) include in other comprehensive income (loss)	0	0	0	0
Sales	0	0	0	0
Originations	0	0	0	0
Principal paydowns / settlements	0	0	0	0
Ending balance	469	(53)	469	(53)
Other Contracts
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	(441)	(462)	(615)	(619)
Total net gains (losses) included in net income	(292)	0	(274)	0
Total net gains (losses) include in other comprehensive income (loss)	0	0	0	0
Sales	0	0	0	0
Originations	0	0	0	0
Principal paydowns / settlements	75	78	231	235
Ending balance	(658)	(384)	(658)	(384)
Debt Securities Available for Sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	4	11	6	18
Total net gains (losses) included in net income	0	0	0	0
Total net gains (losses) included in other comprehensive income (loss)	0	0	0	0
Sales	0	0	0	0
Originations	0	0	0	0
Principal paydowns / settlements	0	(3)	(2)	(10)
Ending balance	4	8	4	8
Loans Held for Sale
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	18,554	5,238	3,356	6,498
Total net gains (losses) included in net income	(184)	17	254	155
Total net gains (losses) included in other comprehensive income (loss)	0	0	0	0
Sales	(97,866)	(59,308)	(232,747)	(151,182)
Originations	98,018	58,634	247,667	149,118
Principal paydowns / settlements	(3)	(388)	(11)	(396)
Ending balance	18,519	4,193	18,519	4,193
Interest-only Strips
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	19,887	32,582	21,386	40,152
Total net gains (losses) included in net income	732	1,110	1,913	3,323
Total net gains (losses) included in other comprehensive income (loss)	246	(1,063)	1,015	(464)
Sales	0	0	0	0
Originations	0	542	3,849	2,458
Principal paydowns / settlements	(3,153)	(9,374)	(10,451)	(21,672)
Ending balance	$ 17,712	$ 23,797	$ 17,712	$ 23,797

Fair Values Disclosures - Fair

Fair Values Disclosures - Fair Value Option (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Fair Value, Option, Quantitative Disclosures
Amount of loans recorded under the fair value option that were delinquent or on non-accrual status	$ 0		$ 0		$ 0
Loans Held for Sale
Fair Value, Option, Quantitative Disclosures
Fair value carrying amount	18,519,000		18,519,000		3,356,000
Aggregate unpaid principal amount	18,180,000		18,180,000		3,268,000
Fair value carrying amount less aggregate unpaid principal	339,000		339,000		$ 88,000
Loans Held for Sale | Gains on sales of consumer real estate loans, net
Fair Value, Option, Quantitative Disclosures
Net gain from initial measurement of the correspondent lending loans held for sale and subsequent changes in fair value for loans outstanding	$ 2,700,000	$ 1,300,000	$ 6,900,000	$ 3,500,000

Fair Values Disclosures - Estim

Fair Values Disclosures - Estimated Fair Value of Financial Instrument Assets, Liabilities, and Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Financial instrument assets:
Debt securities held to maturity		$ 152,881		$ 161,576
Loans:
Consumer real estate		4,901,457		4,819,696
Inventory finance		2,880,404		2,739,754
Auto finance		2,275,134		3,199,639
Other		21,107		22,517
Allowance for loan losses		(160,621)	$ (165,619)	(171,041)	$ (168,244)	$ (165,620)	$ (160,269)
Carrying Amount
Financial instrument assets:
Investments		80,672		82,644
Debt securities held to maturity		152,881		161,576
Loans held for sale		113,879		134,752
Loans:
Consumer real estate		4,901,457		4,819,696
Commercial real estate		2,773,655		2,751,285
Commercial business		967,509		809,908
Equipment finance		2,146,375		2,300,479
Inventory finance		2,880,404		2,739,754
Auto finance		2,275,134		3,199,639
Other		21,107		22,517
Allowance for loan losses	[1]	(160,621)		(171,041)
Securitization receivable	[2]	19,369		19,179
Total financial instrument assets		16,171,821		16,870,388
Financial instrument liabilities:
Deposits		18,496,511		18,335,002
Long-term borrowings		1,171,541		1,249,449
Total financial instrument liabilities		19,668,052		19,584,451
Financial instruments with off-balance sheet risk:
Commitments to extend credit	[3]	18,353		19,423
Standby letters of credit	[3]	(93)		(83)
Total financial instruments with off-balance sheet risk	[3]	18,260		19,340
Estimated Fair Value
Financial instrument assets:
Investments		80,672		82,644
Debt securities held to maturity		150,664		165,626
Loans held for sale		117,625		139,458
Loans:
Consumer real estate		4,949,229		4,916,475
Commercial real estate		2,723,277		2,710,237
Commercial business		924,862		776,989
Equipment finance		2,087,381		2,260,692
Inventory finance		2,865,539		2,723,045
Auto finance		2,240,463		3,197,794
Other		16,482		21,129
Allowance for loan losses	[1]	0		0
Securitization receivable	[2]	18,917		18,595
Total financial instrument assets		16,175,111		17,012,684
Financial instrument liabilities:
Deposits		18,525,706		18,376,257
Long-term borrowings		1,174,761		1,255,333
Total financial instrument liabilities		19,700,467		19,631,590
Financial instruments with off-balance sheet risk:
Commitments to extend credit	[3]	18,353		19,423
Standby letters of credit	[3]	(93)		(83)
Total financial instruments with off-balance sheet risk	[3]	18,260		19,340
Estimated Fair Value | Level 1
Financial instrument assets:
Investments		0		0
Debt securities held to maturity		0		0
Loans held for sale		0		0
Loans:
Consumer real estate		0		0
Commercial real estate		0		0
Commercial business		0		0
Equipment finance		0		0
Inventory finance		0		0
Auto finance		0		0
Other		0		0
Allowance for loan losses	[1]	0		0
Securitization receivable	[2]	0		0
Total financial instrument assets		0		0
Financial instrument liabilities:
Deposits		13,624,763		13,352,731
Long-term borrowings		0		0
Total financial instrument liabilities		13,624,763		13,352,731
Financial instruments with off-balance sheet risk:
Commitments to extend credit	[3]	0		0
Standby letters of credit	[3]	0		0
Total financial instruments with off-balance sheet risk	[3]	0		0
Estimated Fair Value | Level 2
Financial instrument assets:
Investments		80,672		82,644
Debt securities held to maturity		147,864		162,826
Loans held for sale		0		0
Loans:
Consumer real estate		0		0
Commercial real estate		0		0
Commercial business		0		0
Equipment finance		0		0
Inventory finance		0		0
Auto finance		0		0
Other		0		0
Allowance for loan losses	[1]	0		0
Securitization receivable	[2]	0		0
Total financial instrument assets		228,536		245,470
Financial instrument liabilities:
Deposits		4,900,943		5,023,526
Long-term borrowings		1,174,761		1,255,333
Total financial instrument liabilities		6,075,704		6,278,859
Financial instruments with off-balance sheet risk:
Commitments to extend credit	[3]	18,353		19,423
Standby letters of credit	[3]	(93)		(83)
Total financial instruments with off-balance sheet risk	[3]	18,260		19,340
Estimated Fair Value | Level 3
Financial instrument assets:
Investments		0		0
Debt securities held to maturity		2,800		2,800
Loans held for sale		117,625		139,458
Loans:
Consumer real estate		4,949,229		4,916,475
Commercial real estate		2,723,277		2,710,237
Commercial business		924,862		776,989
Equipment finance		2,087,381		2,260,692
Inventory finance		2,865,539		2,723,045
Auto finance		2,240,463		3,197,794
Other		16,482		21,129
Allowance for loan losses	[1]	0		0
Securitization receivable	[2]	18,917		18,595
Total financial instrument assets		15,946,575		16,767,214
Financial instrument liabilities:
Deposits		0		0
Long-term borrowings		0		0
Total financial instrument liabilities		0		0
Financial instruments with off-balance sheet risk:
Commitments to extend credit	[3]	0		0
Standby letters of credit	[3]	0		0
Total financial instruments with off-balance sheet risk	[3]	$ 0		$ 0
[1]	Expected credit losses are included in the estimated fair values.
[2]	Carrying amounts are included in other assets.
[3]	Positive amounts represent assets, negative amounts represent liabilities.

Earnings Per Common Share - Com

Earnings Per Common Share - Computation of basic and diluted earnings per common share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic Earnings Per Common Share:
Net income attributable to TCF Financial Corporation		$ 86,196	$ 60,528	$ 218,706	$ 167,238
Preferred stock dividends		2,494	6,464	9,094	16,158
Impact of preferred stock redemption or notice to redeem preferred stock	[1]	0	5,779	3,481	5,779
Net income available to common stockholders		83,702	48,285	206,131	145,301
Less: Earnings allocated to participating securities		13	8	30	25
Earnings allocated to common stock		$ 83,689	$ 48,277	$ 206,101	$ 145,276
Weighted-average common shares outstanding for basic earnings per common share (in shares)		164,854,622	168,970,543	166,350,173	168,492,877
Basic earnings per common share (in dollars per share)		$ 0.51	$ 0.29	$ 1.24	$ 0.86
Diluted Earnings Per Common Share:
Earnings allocated to common stock		$ 83,689	$ 48,277	$ 206,101	$ 145,276
Weighted-average common shares outstanding used in basic earnings per common share calculation (in shares)		164,854,622	168,970,543	166,350,173	168,492,877
Net dilutive effect of:
Non-participating restricted stock (in shares)		589,177	269,394	623,556	312,297
Stock options (in shares)		0	314	3,288	17,654
Warrants (in shares)		89,426	0	525,360	0
Weighted-average common shares outstanding for diluted earnings per common share (in shares)		165,533,225	169,240,251	167,502,377	168,822,828
Diluted earnings per common share (in dollars per share)		$ 0.51	$ 0.29	$ 1.23	$ 0.86
[1]	For the nine months ended September 30, 2018, amount represents the deferred stock issuance costs originally recorded in preferred stock upon the issuance of the Series B Preferred Stock that were reclassified to retained earnings on March 1, 2018, as the Company redeemed all outstanding Series B Preferred Stock. For the quarter and nine months ended September 30, 2017, amount represents the deferred stock issuance costs originally recorded in preferred stock upon the issuance of the 7.50% Series A non-cumulative perpetual preferred stock ("Series A Preferred Stock") that were reclassified to retained earnings on September 15, 2017, the date the Company announced its intent to redeem the outstanding Series A Preferred Stock.

Earnings Per Common Share - Ant

Earnings Per Common Share - Antidilutive securities excluded from computation of earnings per common share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)	807,502	3,960,511	867,319	4,079,059

Other Non-interest Expense - Ot

Other Non-interest Expense - Other Non-interest Expense (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Other Income and Expenses [Abstract]
Bureau of Consumer Financial Protection and OCC settlement charge	[1]	$ 0	$ 0	$ 32,000	$ 0
Advertising and marketing		7,674	6,060	22,075	19,678
Professional fees		5,949	9,875	16,035	26,295
Outside processing		5,052	5,176	15,936	14,411
Card processing and issuance costs		4,090	4,719	12,759	13,534
FDIC insurance		4,376	4,181	12,165	11,964
Loan and lease processing		3,313	5,304	10,430	17,258
Other		27,535	26,266	84,492	84,020
Total other non-interest expense		$ 57,989	$ 61,581	$ 205,892	$ 187,160
[1]	See Note 17. Litigation Contingencies for further information.

Business Segments - Business Se

Business Segments - Business Segments (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Interest income:
Loans and leases		$ 264,678	$ 243,973	$ 794,333	$ 697,613
Debt securities available for sale		14,838	8,486	37,477	24,518
Debt securities held to maturity		988	1,073	3,005	3,388
Loans held for sale and other		6,678	4,073	13,952	22,910
Funds transfer pricing - credits		0	0	0	0
Total interest income		287,182	257,605	848,767	748,429
Interest expense:
Deposits		27,335	17,015	73,798	45,166
Borrowings		10,726	6,487	31,850	19,885
Funds transfer pricing - charges		0	0	0	0
Total interest expense		38,061	23,502	105,648	65,051
Net interest income		249,121	234,103	743,119	683,378
Provision for credit losses		2,270	14,545	27,874	46,184
Net interest income after provision for credit losses		246,851	219,558	715,245	637,194
Non-interest income:
Gains on sales of auto loans, net		0	0	0	3,244
Gains on sales of consumer real estate loans, net		8,764	8,049	25,079	25,920
Subtotal		14,796	18,015	46,890	61,511
Leasing and equipment finance		45,045	34,080	129,796	102,208
Other		3,818	2,930	11,468	8,428
Fees and other revenue		116,351	109,041	342,571	327,218
Gains (losses) on debt securities, net		94	189	181	189
Total non-interest income		116,445	109,230	342,752	327,407
Non-interest expense:
Compensation and employee benefits		123,127	114,954	367,542	354,882
Occupancy and equipment		42,337	38,766	123,562	117,331
Other		57,989	61,581	205,892	187,160
Subtotal		223,453	215,301	696,996	659,373
Operating lease depreciation		19,525	15,696	54,744	39,404
Foreclosed real estate and repossessed assets, net		3,881	3,829	12,654	13,017
Other credit costs, net		(436)	209	48	334
Total non-interest expense		246,423	235,035	764,442	712,128
Income before income tax expense		116,873	93,753	293,555	252,473
Income tax expense (benefit)		28,034	30,704	66,083	77,341
Income after income tax expense		88,839	63,049	227,472	175,132
Income attributable to non-controlling interest		2,643	2,521	8,766	7,894
Preferred stock dividends		2,494	6,464	9,094	16,158
Impact of preferred stock redemption or notice to redeem preferred stock	[1]	0	5,779	3,481	5,779
Net income available to common stockholders		83,702	48,285	206,131	145,301
Revenues from external customers:
Interest Income		287,182	257,605	848,767	748,429
Non-interest income		116,445	109,230	342,752	327,407
Total		403,627	366,835	1,191,519	1,075,836
Total assets		22,904,785	23,005,038	22,904,785	23,005,038	$ 23,002,159
Fees and service charges
Non-interest income:
Fee revenue		32,574	34,605	95,995	98,620
Card revenue
Non-interest income:
Fee revenue		15,065	14,177	43,786	41,481
ATM revenue
Non-interest income:
Fee revenue		5,053	5,234	14,636	14,970
Subtotal
Non-interest income:
Fee revenue		52,692	54,016	154,417	155,071
Servicing fee income
Non-interest income:
Fee revenue		6,032	9,966	21,811	32,347
Consumer Banking
Interest income:
Loans and leases		105,961	113,397	323,280	317,532
Debt securities available for sale		0	0	0	0
Debt securities held to maturity		0	0	0	0
Loans held for sale and other		4,525	2,899	8,267	19,811
Funds transfer pricing - credits		101,961	93,042	298,850	271,971
Total interest income		212,447	209,338	630,397	609,314
Interest expense:
Deposits		19,807	14,070	56,077	38,504
Borrowings		10,476	13,236	34,165	36,332
Funds transfer pricing - charges		42,440	36,671	121,068	105,696
Total interest expense		72,723	63,977	211,310	180,532
Net interest income		139,724	145,361	419,087	428,782
Provision for credit losses		(837)	11,129	18,941	33,211
Net interest income after provision for credit losses		140,561	134,232	400,146	395,571
Non-interest income:
Gains on sales of auto loans, net					3,244
Gains on sales of consumer real estate loans, net		8,764	8,049	25,079	25,920
Subtotal		14,543	17,669	45,830	60,521
Leasing and equipment finance		0	0	0	0
Other		2,904	2,710	9,071	7,394
Fees and other revenue		68,201	70,934	201,672	215,154
Gains (losses) on debt securities, net		0	0	0	0
Total non-interest income		68,201	70,934	201,672	215,154
Non-interest expense:
Compensation and employee benefits		54,053	55,977	161,960	172,998
Occupancy and equipment		26,523	28,137	78,639	79,835
Other		77,196	77,065	257,747	230,843
Subtotal		157,772	161,179	498,346	483,676
Operating lease depreciation		0	0	0	0
Foreclosed real estate and repossessed assets, net		3,399	2,829	10,947	10,551
Other credit costs, net		32	54	92	222
Total non-interest expense		161,203	164,062	509,385	494,449
Income before income tax expense		47,559	41,104	92,433	116,276
Income tax expense (benefit)		11,363	14,370	22,351	41,133
Income after income tax expense		36,196	26,734	70,082	75,143
Income attributable to non-controlling interest		0	0	0	0
Preferred stock dividends		0	0	0	0
Impact of preferred stock redemption or notice to redeem preferred stock			0	0	0
Net income available to common stockholders		36,196	26,734	70,082	75,143
Revenues from external customers:
Interest Income		110,486	116,296	331,547	337,343
Non-interest income		68,201	70,934	201,672	215,154
Total		178,687	187,230	533,219	552,497
Total assets		8,040,163	9,239,458	8,040,163	9,239,458
Consumer Banking | Fees and service charges
Non-interest income:
Fee revenue		30,651	31,145	88,389	90,792
Consumer Banking | Card revenue
Non-interest income:
Fee revenue		15,051	14,176	43,748	41,479
Consumer Banking | ATM revenue
Non-interest income:
Fee revenue		5,052	5,234	14,634	14,968
Consumer Banking | Subtotal
Non-interest income:
Fee revenue		50,754	50,555	146,771	147,239
Consumer Banking | Servicing fee income
Non-interest income:
Fee revenue		5,779	9,620	20,751	31,357
Wholesale Banking
Interest income:
Loans and leases		159,680	132,306	473,870	384,757
Debt securities available for sale		0	0	0	0
Debt securities held to maturity		23	25	70	76
Loans held for sale and other		35	17	80	53
Funds transfer pricing - credits		9,017	6,942	24,945	18,084
Total interest income		168,755	139,290	498,965	402,970
Interest expense:
Deposits		2,581	888	5,812	1,683
Borrowings		19,635	12,400	57,920	33,999
Funds transfer pricing - charges		53,377	37,061	148,100	102,539
Total interest expense		75,593	50,349	211,832	138,221
Net interest income		93,162	88,941	287,133	264,749
Provision for credit losses		3,107	3,416	8,933	12,973
Net interest income after provision for credit losses		90,055	85,525	278,200	251,776
Non-interest income:
Gains on sales of auto loans, net					0
Gains on sales of consumer real estate loans, net		0	0	0	0
Subtotal		253	346	1,060	990
Leasing and equipment finance		45,045	34,080	129,796	102,208
Other		405	196	1,489	711
Fees and other revenue		47,641	38,083	139,991	111,741
Gains (losses) on debt securities, net		94	189	181	189
Total non-interest income		47,735	38,272	140,172	111,930
Non-interest expense:
Compensation and employee benefits		23,989	19,941	71,476	64,237
Occupancy and equipment		4,952	5,214	14,905	15,134
Other		30,214	28,276	88,843	81,714
Subtotal		59,155	53,431	175,224	161,085
Operating lease depreciation		19,525	15,696	54,744	39,404
Foreclosed real estate and repossessed assets, net		482	902	1,700	2,086
Other credit costs, net		(468)	155	(44)	112
Total non-interest expense		78,694	70,184	231,624	202,687
Income before income tax expense		59,096	53,613	186,748	161,019
Income tax expense (benefit)		13,063	17,153	41,191	52,760
Income after income tax expense		46,033	36,460	145,557	108,259
Income attributable to non-controlling interest		2,643	2,521	8,766	7,894
Preferred stock dividends		0	0	0	0
Impact of preferred stock redemption or notice to redeem preferred stock			0	0	0
Net income available to common stockholders		43,390	33,939	136,791	100,365
Revenues from external customers:
Interest Income		158,775	130,618	471,203	380,210
Non-interest income		47,735	38,272	140,172	111,930
Total		206,510	168,890	611,375	492,140
Total assets		11,740,613	11,287,665	11,740,613	11,287,665
Wholesale Banking | Fees and service charges
Non-interest income:
Fee revenue		1,923	3,460	7,606	7,828
Wholesale Banking | Card revenue
Non-interest income:
Fee revenue		14	1	38	2
Wholesale Banking | ATM revenue
Non-interest income:
Fee revenue		1	0	2	2
Wholesale Banking | Subtotal
Non-interest income:
Fee revenue		1,938	3,461	7,646	7,832
Wholesale Banking | Servicing fee income
Non-interest income:
Fee revenue		253	346	1,060	990
Enterprise Services
Interest income:
Loans and leases		(963)	(1,730)	(2,817)	(4,676)
Debt securities available for sale		14,838	8,486	37,477	24,518
Debt securities held to maturity		965	1,048	2,935	3,312
Loans held for sale and other		2,118	1,157	5,605	3,046
Funds transfer pricing - credits		(110,978)	(99,984)	(323,795)	(290,055)
Total interest income		(94,020)	(91,023)	(280,595)	(263,855)
Interest expense:
Deposits		4,947	2,057	11,909	4,979
Borrowings		(19,385)	(19,149)	(60,235)	(50,446)
Funds transfer pricing - charges		(95,817)	(73,732)	(269,168)	(208,235)
Total interest expense		(110,255)	(90,824)	(317,494)	(253,702)
Net interest income		16,235	(199)	36,899	(10,153)
Provision for credit losses		0	0	0	0
Net interest income after provision for credit losses		16,235	(199)	36,899	(10,153)
Non-interest income:
Gains on sales of auto loans, net					0
Gains on sales of consumer real estate loans, net		0	0	0	0
Subtotal		0	0	0	0
Leasing and equipment finance		0	0	0	0
Other		509	24	908	323
Fees and other revenue		509	24	908	323
Gains (losses) on debt securities, net		0	0	0	0
Total non-interest income		509	24	908	323
Non-interest expense:
Compensation and employee benefits		45,085	39,036	134,106	117,647
Occupancy and equipment		10,862	5,415	30,018	22,362
Other		(49,421)	(43,760)	(140,698)	(125,397)
Subtotal		6,526	691	23,426	14,612
Operating lease depreciation		0	0	0	0
Foreclosed real estate and repossessed assets, net		0	98	7	380
Other credit costs, net		0	0	0	0
Total non-interest expense		6,526	789	23,433	14,992
Income before income tax expense		10,218	(964)	14,374	(24,822)
Income tax expense (benefit)		3,608	(819)	2,541	(16,552)
Income after income tax expense		6,610	(145)	11,833	(8,270)
Income attributable to non-controlling interest		0	0	0	0
Preferred stock dividends		2,494	6,464	9,094	16,158
Impact of preferred stock redemption or notice to redeem preferred stock			5,779	3,481	5,779
Net income available to common stockholders		4,116	(12,388)	(742)	(30,207)
Revenues from external customers:
Interest Income		17,921	10,691	46,017	30,876
Non-interest income		509	24	908	323
Total		18,430	10,715	46,925	31,199
Total assets		3,124,009	2,477,915	3,124,009	2,477,915
Enterprise Services | Fees and service charges
Non-interest income:
Fee revenue		0	0	0	0
Enterprise Services | Card revenue
Non-interest income:
Fee revenue		0	0	0	0
Enterprise Services | ATM revenue
Non-interest income:
Fee revenue		0	0	0	0
Enterprise Services | Subtotal
Non-interest income:
Fee revenue		0	0	0	0
Enterprise Services | Servicing fee income
Non-interest income:
Fee revenue		$ 0	$ 0	$ 0	$ 0
[1]	For the nine months ended September 30, 2018, amount represents the deferred stock issuance costs originally recorded in preferred stock upon the issuance of the Series B Preferred Stock that were reclassified to retained earnings on March 1, 2018, as the Company redeemed all outstanding Series B Preferred Stock. For the quarter and nine months ended September 30, 2017, amount represents the deferred stock issuance costs originally recorded in preferred stock upon the issuance of the 7.50% Series A non-cumulative perpetual preferred stock ("Series A Preferred Stock") that were reclassified to retained earnings on September 15, 2017, the date the Company announced its intent to redeem the outstanding Series A Preferred Stock.

Litigation Contingencies - Liti

Litigation Contingencies - Litigation Contingencies (Details) - Consumer Financial Protection Bureau v. TCF National Bank $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)
Litigation Contingencies
Restitution to certain current and former customers	$ 25
Civil money penalty	5
Administrative settlement costs	2
Office of the Comptroller of the Currency
Litigation Contingencies
Civil money penalty	3
Bureau of Consumer Financial Protection
Litigation Contingencies
Civil money penalty	$ 2

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss)
Total other comprehensive income (loss), before tax		$ (17,557)	$ 4,159	$ (61,024)	$ 28,743
Total other comprehensive income (loss), tax effect		5,109	(465)	14,282	(8,827)
Total other comprehensive income (loss), net of tax		(12,448)	3,694	(46,742)	19,916
Debt securities available for sale and interest-only strips
Net unrealized gains (losses) arising during the period, before tax		(18,086)	4,974	(62,521)	28,562
Net unrealized gains (losses) arising during the period, tax effect		4,516	(1,892)	15,688	(10,859)
Net unrealized gains (losses) arising during the period, net of tax		(13,570)	3,082	(46,833)	17,703
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), before tax		179	(1,028)	1,031	(238)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect		(43)	391	(257)	90
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax		136	(637)	774	(148)
Net unrealized gains (losses) on debt securities available for sale and interest-only strips, before taxes		(17,907)	3,946	(61,490)	28,324
Net unrealized gains (losses) on debt securities available for sale and interest-only strips, tax effect		4,473	(1,501)	15,431	(10,769)
Net unrealized gains (losses) on debt securities available for sale and interest-only strips, net of tax		(13,434)	2,445	(46,059)	17,555
Net investment hedges
Net unrealized gains (losses) on net investment hedges, before tax		(2,537)	(2,714)	4,637	(5,073)
Net unrealized gains (losses) on net investment hedges, tax effect		633	1,032	(1,158)	1,929
Net unrealized gains (losses) on net investment hedges, net of tax		(1,904)	(1,682)	3,479	(3,144)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax [Abstract]
Foreign currency translation adjustment, before tax	[1]	2,899	2,939	(4,136)	5,527
Foreign currency translation adjustment, tax effect	[1]	0	0	0	0
Foreign currency translation adjustment, net of tax	[1]	2,899	2,939	(4,136)	5,527
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax [Abstract]
Reclassification of amortization of prior service cost to Other non-interest expense, before tax		(12)	(12)	(35)	(35)
Reclassification of amortization of prior service cost to Other non-interest expense, tax effect		3	4	9	13
Reclassification of amortization of prior service cost to Other non-interest expense, net of tax		(9)	(8)	(26)	(22)
Total interest income
Debt securities available for sale and interest-only strips
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), before tax		263	287	810	691
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect		(65)	(109)	(202)	(263)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax		198	178	608	428
Other non-interest expense
Debt securities available for sale and interest-only strips
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), before tax		(84)	(1,315)	221	(929)
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), tax effect		22	500	(55)	353
Reclassification of net (gains) losses from accumulated other comprehensive income (loss), net of tax		$ (62)	$ (815)	$ 166	$ (576)
[1]	Foreign investments are deemed to be permanent in nature and, therefore, TCF does not provide for taxes on foreign currency translation adjustments.

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Changes in accumulated other comprehensive income by component
Balance, beginning of period	$ (52,811)	$ (17,503)	$ (18,517)	$ (33,725)
Other comprehensive income (loss)	(12,575)	4,339	(47,490)	20,086
Amounts reclassified from accumulated other comprehensive income (loss)	127	(645)	748	(170)
Total other comprehensive income (loss), net of tax	(12,448)	3,694	(46,742)	19,916
Balance, end of period	(65,259)	(13,809)	(65,259)	(13,809)
Net Unrealized Gains (Losses) on Debt Securities Available for Sale and Interest-Only Strips
Changes in accumulated other comprehensive income by component
Balance, beginning of period	(48,978)	(13,491)	(16,353)	(28,601)
Other comprehensive income (loss)	(13,570)	3,082	(46,833)	17,703
Amounts reclassified from accumulated other comprehensive income (loss)	136	(637)	774	(148)
Total other comprehensive income (loss), net of tax	(13,434)	2,445	(46,059)	17,555
Balance, end of period	(62,412)	(11,046)	(62,412)	(11,046)
Net Unrealized Gains (Losses) on Net Investment Hedges
Changes in accumulated other comprehensive income by component
Balance, beginning of period	9,919	5,031	4,536	6,493
Other comprehensive income (loss)	(1,904)	(1,682)	3,479	(3,144)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Total other comprehensive income (loss), net of tax	(1,904)	(1,682)	3,479	(3,144)
Balance, end of period	8,015	3,349	8,015	3,349
Foreign Currency Translation Adjustment
Changes in accumulated other comprehensive income by component
Balance, beginning of period	(13,878)	(9,176)	(6,843)	(11,764)
Other comprehensive income (loss)	2,899	2,939	(4,136)	5,527
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Total other comprehensive income (loss), net of tax	2,899	2,939	(4,136)	5,527
Balance, end of period	(10,979)	(6,237)	(10,979)	(6,237)
Recognized Postretirement Prior Service Cost
Changes in accumulated other comprehensive income by component
Balance, beginning of period	126	133	143	147
Other comprehensive income (loss)	0	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	(9)	(8)	(26)	(22)
Total other comprehensive income (loss), net of tax	(9)	(8)	(26)	(22)
Balance, end of period	$ 117	$ 125	$ 117	$ 125