TCF Financial 10-K 28 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Feb. 25, 2019	Jun. 29, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	CHEMICAL FINANCIAL CORP
Entity Central Index Key	19,612
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Public Float			$ 3,870
Entity Common Stock, Shares Outstanding		71,478,598

Consolidated Statements of Fina

Consolidated Statements of Financial Position - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Cash and cash equivalents:
Cash and cash due from banks	$ 228,527	$ 226,003
Interest-bearing deposits with the Federal Reserve Bank and other banks	267,312	229,988
Total cash and cash equivalents	495,839	455,991
Investment securities:
Carried at fair value	3,021,832	1,963,546
Held-to-maturity, at amortized cost (fair value of $618,672 and $662,906, respectively)	624,099	677,093
Total investment securities	3,645,931	2,640,639
Loans held-for-sale, at fair value	85,030	52,133
Loans	15,269,779	14,155,267
Allowance for loan losses	(109,984)	(91,887)
Net loans	15,159,795	14,063,380
Premises and equipment	123,442	126,896
Loan servicing rights, at fair value	71,013	63,841
Goodwill	1,134,568	1,134,568
Other intangible assets	28,556	34,271
Interest receivable and other assets	754,167	709,154
Total assets	21,498,341	19,280,873
Deposits:
Noninterest-bearing	3,809,252	3,725,779
Interest-bearing	11,784,030	9,917,024
Total deposits	15,593,282	13,642,803
Collateralized customer deposits	382,687	415,236
Short-term borrowings	2,035,000	2,000,000
Long-term borrowings	426,002	372,882
Interest payable and other liabilities	225,110	181,203
Total liabilities	18,662,081	16,612,124
Shareholders' equity
Preferred stock	0	0
Common stock	71,460	71,207
Additional paid-in capital	2,209,761	2,203,637
Retained earnings	616,149	419,403
Accumulated other comprehensive loss	(61,110)	(25,498)
Total shareholders' equity	2,836,260	2,668,749
Total liabilities and shareholders' equity	$ 21,498,341	$ 19,280,873

Consolidated Statements of Fi_2

Consolidated Statements of Financial Position (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Held-to-maturity, fair value	$ 618,672	$ 662,906
Preferred stock, no par value (in dollars per share)	$ 0	$ 0
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized	135,000,000	135,000,000
Common stock, shares issued	71,460,119	71,207,114
Common stock, shares outstanding	71,460,119	71,207,114

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest income
Interest and fees on loans	$ 675,875	$ 573,128	$ 383,545
Interest on investment securities:
Taxable	62,231	31,496	10,989
Tax-exempt	24,286	18,343	12,317
Dividends on nonmarketable equity securities	7,877	4,924	1,973
Interest on deposits with the Federal Reserve Bank, other banks and Federal funds sold	5,727	4,244	1,555
Total interest income	775,996	632,135	410,379
Interest expense
Interest on deposits	96,980	46,727	23,021
Interest on collateralized customer deposits	2,607	1,269	303
Interest on short-term borrowings	37,510	19,052	1,357
Interest on long-term borrowings	6,566	7,509	4,617
Total interest expense	143,663	74,557	29,298
Net interest income	632,333	557,578	381,081
Provision for loan losses	30,750	23,300	14,875
Net interest income after provision for loan losses	601,583	534,278	366,206
Noninterest income
Net gain on sale of loans and other mortgage banking revenue	35,193	32,205	21,859
Net gain (loss) on sale of investment securities	224	(7,388)	129
Gain on sale of branch offices	0	0	7,391
Other	28,589	25,918	11,988
Total noninterest income	148,536	144,019	122,350
Operating expenses
Salaries, wages and employee benefits	225,427	215,562	165,862
Occupancy	31,670	30,554	23,525
Equipment and software	31,761	32,248	24,408
Outside processing and service fees	45,387	35,142	21,199
Merger expenses	0	8,522	61,134
Restructuring expenses	0	19,880	0
Other	89,953	80,086	42,290
Total operating expenses	424,198	421,994	338,418
Income before income taxes	325,921	256,303	150,138
Income tax expense	41,901	106,780	42,106
Net income	$ 284,020	$ 149,523	$ 108,032
Earnings per common share:
Basic (in dollars per share)	$ 3.98	$ 2.11	$ 2.21
Diluted (in dollars per share)	$ 3.94	$ 2.08	$ 2.17
Service charges and fees on deposit accounts
Noninterest income
Noninterest income	$ 37,097	$ 38,367	$ 30,724
Wealth management revenue
Noninterest income
Noninterest income	25,996	25,512	22,601
Other charges and fees for customer services
Noninterest income
Noninterest income	$ 21,437	$ 29,405	$ 27,658

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 284,020	$ 149,523	$ 108,032
Other comprehensive income (loss), net of tax:
Unrealized holding gains (losses) on securities carried at fair value arising during the period	(34,054)	1,269	(18,723)
Reclassification adjustment for (gains) losses on realized income	(224)	7,388	(129)
Tax effect	7,198	(3,029)	6,598
Net unrealized gains (losses) on securities carried at fair value, net of tax	(27,080)	5,628	(12,254)
Unrealized gains on interest rate swaps designated as cash flow hedges	2,841	4,263	0
Reclassification adjustment for (gains) losses included in net income	(1,871)	1,633	0
Tax effect	(203)	(2,064)	0
Net unrealized gains on interest rate swaps designated as cash flow hedges, net of tax	767	3,832	0
Plan remeasurement	0	13,011	(707)
Adjustment for pension and other postretirement benefits	(11,339)	1,752	2,630
Tax effect	2,381	(5,167)	(673)
Net adjustment for pension and other postretirement benefits	(8,958)	9,596	1,250
Other comprehensive income (loss), net of tax	(35,271)	19,056	(11,004)
Total comprehensive income, net of tax	$ 248,749	$ 168,579	$ 97,028

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands		Total	Common Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2015		$ 1,015,974	$ 38,168	$ 725,280	$ 281,558	$ (29,032)
Changes in Stockholders' Equity
Comprehensive income		97,028			108,032	(11,004)
Cash dividends declared		(49,389)			(49,389)
Issuance of common stock and common stock equivalents in business combinations		1,504,811	32,074	1,472,737
Net shares issued under share-based compensation plans		(350)	351	(701)
Share-based compensation expense		13,452	6	13,446
Ending balance at Dec. 31, 2016		2,581,526	70,599	2,210,762	340,201	(40,036)
Changes in Stockholders' Equity
Cumulative effect adjustment of change in accounting policy, net of tax impact	[1]	3,659			3,659
Comprehensive income		168,579			149,523	19,056
Cash dividends declared		(78,498)			(78,498)
Net shares issued under share-based compensation plans		(23,863)	608	(24,471)
Share-based compensation expense		17,346	0	17,346
Reclassification of certain income tax effects	[2]	0			4,518	(4,518)
Ending balance at Dec. 31, 2017		2,668,749	71,207	2,203,637	419,403	(25,498)
Changes in Stockholders' Equity
Cumulative effect adjustment of change in accounting policy, net of tax impact	[1]	1,339			1,680	(341)
Comprehensive income		248,749			284,020	(35,271)
Cash dividends declared		(88,954)			(88,954)
Net shares issued under share-based compensation plans		(2,201)	253	(2,454)
Share-based compensation expense		8,578	0	8,578
Ending balance at Dec. 31, 2018		$ 2,836,260	$ 71,460	$ 2,209,761	$ 616,149	$ (61,110)
[1]	Refer to Note 1, Summary of Significant Accounting Policies, Note 4, Investment Securities, Note 7, Other Real Estate Owned and Repossessed Assets and Note 9, Loan Servicing Rights, for further details on the changes in accounting policy.
[2]	The reclassification from accumulated other comprehensive income (loss) to retained earnings was due to the early adoption of ASU 2018-02, refer to Note 1 for further details on the adoption.

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Stockholders' Equity [Abstract]
Cash dividends declared per share (in dollars per share)	$ 0.34	$ 0.34	$ 0.28	$ 0.28	$ 0.28	$ 0.28	$ 0.27	$ 0.27	$ 0.27	$ 0.27	$ 0.26	$ 0.26	$ 1.24	$ 1.10	$ 1.06

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net income	$ 284,020	$ 149,523	$ 108,032
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	30,750	23,300	14,875
Gains on sales of loans	(12,173)	(31,734)	(15,686)
Proceeds from sales of loans	741,902	838,549	723,521
Loans originated for sale	(760,591)	(772,968)	(534,422)
Net losses (gains) on sale of investment securities	(224)	7,388	(129)
Net losses (gains) from sales/writedowns of other real estate and repossessed assets	203	(1,017)	(5,212)
Depreciation of premises and equipment	17,026	17,722	13,270
Amortization of intangible assets	5,716	6,090	10,046
Additions to loan servicing rights	(8,226)	(8,745)	(4,333)
Valuation change in loan servicing rights	1,054	8,880	(4,585)
Net amortization of premiums and discounts on investment securities	19,446	19,262	9,713
Share-based compensation expense	8,578	17,346	13,452
Deferred income tax expense	41,916	93,184	24,091
Change in deferred tax valuation allowance	317	(1,089)	(706)
Net increase in interest receivable and other assets	(74,723)	(150,585)	(24,977)
Net increase (decrease) in interest payable and other liabilities	29,410	59,760	(46,449)
Net cash provided by operating activities	324,401	274,866	280,501
Investment securities — carried at fair value:
Proceeds from maturities, calls and principal reductions	291,008	318,952	248,772
Proceeds from sales and redemptions	4,215	409,220	41,446
Purchases	(1,405,798)	(1,480,524)	(187,702)
Investment securities — held-to-maturity:
Proceeds from maturities, calls and principal reductions	104,535	93,600	90,933
Purchases	(52,752)	(141,489)	(206,023)
Net increase in loans	(1,140,686)	(1,189,865)	(860,135)
Proceeds from sales of other real estate and repossessed assets	13,396	19,879	22,147
Purchases of premises and equipment, net of disposals	(13,572)	(12,852)	(18,098)
Proceeds from returns of investment in equity method investments	326	143	77
Cash acquired, net of cash paid, in business combinations	0	0	325,714
Net cash used in investing activities	(2,199,328)	(1,982,936)	(542,869)
Cash flows from financing activities
Net increase in interest and noninterest-bearing demand deposits and savings accounts	1,111,747	243,110	672,584
Net increase (decrease) in time deposits	838,732	526,571	(550,847)
Net increase in collateralized customer deposits and other short-term borrowings	2,451	1,247,189	401,144
Proceeds from issuance of long-term borrowings	200,000	0	375,000
Repayment of long-term borrowings	(147,000)	(224,850)	(351,018)
Cash dividends paid	(88,954)	(78,498)	(49,389)
Proceeds from directors' stock plans and exercise of stock options, net of shares withheld	3,115	3,991	1,572
Cash paid for payroll taxes upon conversion of share-based awards	(5,316)	(27,854)	(1,065)
Net cash provided by financing activities	1,914,775	1,689,659	497,981
Net increase (decrease) in cash and cash equivalents	39,848	(18,411)	235,613
Cash and cash equivalents at beginning of year	455,991	474,402	238,789
Cash and cash equivalents at end of year	495,839	455,991	474,402
Supplemental disclosures of cash flow information:
Interest paid	136,706	73,643	25,460
Income tax payments, net	4,063	2,252	22,200
Non-cash activities:
Loans transferred to other real estate and repossessed assets	11,486	11,546	12,970
Net transfer of loans held-for-sale to loans held- for-investment	(2,035)	(4,150)	(289)
Closed branch offices transferred to other assets	0	13,246	4,846
Business combinations:
Fair value of tangible assets acquired (noncash)	0	420	6,371,781
Goodwill, loan servicing rights and other identifiable intangible assets acquired	0	1,034	908,217
Liabilities assumed	0	1,454	6,100,901
Common stock and stock options issued	$ 0	$ 0	$ 1,504,811

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Nature of Operations Chemical Financial Corporation ("Corporation" or "Chemical") operates in a single operating segment — commercial banking. The Corporation is a financial holding company, headquartered in Detroit, Michigan, that operates through one commercial bank, Chemical Bank. Chemical Bank operates within Michigan, Ohio and Northern Indiana as a Michigan state-chartered commercial bank. Chemical Bank operates through an internal organizational structure of six regional banking units and offers a full range of traditional banking and fiduciary products and services to the residents and business customers in the Corporation's geographical market areas. The products and services offered by the regional banking units, through branch banking offices, are generally consistent throughout the Corporation, as is the pricing of those products and services. The marketing of products and services throughout the Corporation's regional banking units is generally uniform, as many of the markets served by the regional banking units overlap. The distribution of products and services is generally uniform throughout the Corporation's regional banking units and is achieved primarily through retail branch banking offices, automated teller machines and electronically accessed banking products. The Corporation's primary sources of revenue are interest from its loan products and investment securities, service charges and fees from customer deposit accounts, wealth management revenue, net gain on sale of loans and other mortgage banking revenue. Proposed Merger with TCF Financial Corporation Chemical and TCF Financial Corporation ("TCF") have entered into an Agreement and Plan of Merger, dated as of January 27, 2019, which we refer to as the merger agreement. Under the merger agreement, Chemical and TCF have agreed to combine their respective companies in a merger of equals, pursuant to which TCF will merge with and into Chemical, with Chemical continuing as the surviving entity, in a transaction we refer to as the merger. Immediately following the merger or at such later time as the parties may mutually agree, Chemical Bank will merge with and into TCF National Bank, with TCF National Bank as the surviving bank, in a transaction we refer to as the bank merger. The merger agreement was approved by the boards of directors of Chemical and TCF, and is subject to shareholder and regulatory approval and other customary closing conditions. The transaction is anticipated to close in the second half of 2019. The transaction is discussed in more detail in Note 26. Basis of Presentation and Principles of Consolidation The accounting and reporting policies of the Corporation and its subsidiaries have been prepared in accordance with U.S. Generally Accepted Accounting Principles ("GAAP"), Securities and Exchange Commission ("SEC") rules and interpretive releases and prevailing practices within the banking industry. The Consolidated Financial Statements of the Corporation include the accounts of the Corporation and its wholly owned subsidiaries. All significant income and expenses are recorded on the accrual basis. Intercompany accounts and transactions have been eliminated in preparing the Consolidated Financial Statements. Use of Estimates Management makes estimates and assumptions that affect the amounts reported in the Consolidated Financial Statements and accompanying footnotes. Estimates that are particularly susceptible to significant change include the determination of the allowance for loan losses, expected cash flows from acquired loans, income taxes and the valuation of loan servicing rights. Actual results could differ from these estimates. Business Combinations Pursuant to the guidance of the Financial Accounting Standards Board's ("FASB") Accounting Standards Codification ("ASC") Topic 805, Business Combinations ("ASC 805"), the Corporation recognizes assets acquired, including identified intangible assets, and the liabilities assumed in acquisitions at their fair values as of the acquisition date, with the acquisition-related transaction and restructuring costs expensed in the period incurred. See Note 2 for further information regarding the Corporation's mergers and acquisitions. Cash and Cash Equivalents For purposes of reporting cash flows, cash and cash equivalents include cash on hand and interest-bearing deposits held at the Federal Reserve Bank ("FRB"). Investment Securities Investment securities are classified at the time they are acquired as either available-for-sale, held-to-maturity or carried at fair value based upon various factors, including asset/liability management strategies, liquidity and profitability objectives and regulatory requirements. The Corporation held no trading investment securities at December 31, 2018 or 2017 . Debt securities classified as available-for-sale and equity securities are recorded at fair value. Investment securities carried at fair value may be sold prior to maturity based upon asset/liability management decisions. Unrealized gains or losses on available-for-sale debt securities are recorded as part of accumulated other comprehensive income in stockholders’ equity. Unrealized gains or losses on equity securities were recorded as part of accumulated other comprehensive income in stockholders' equity through December 31, 2017. Effective January 1, 2018, the amendments within FASB Accounting Standard Update ("ASU") 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities, require that equity investments be measured at fair value with changes in fair value recognized in net income. At January 1, 2018, the Corporation's equity securities consisted of $1.8 million in preferred stocks. The Corporation recognized a cumulative effect adjustment in the amount of $344 thousand as of January 1, 2018 to reclassify the fair value position into retained earnings. Beginning January 1, 2018, the fair value changes on equity securities are recognized in net income, rather than in accumulated other comprehensive income. The Corporation sold its remaining position in equity securities during the second quarter of 2018. Designation as an investment security held-to-maturity is based on the Corporation's intent and ability to hold the security to maturity. Investment securities held-to-maturity are carried at amortized cost, adjusted for purchase price premiums and accretion of discounts. Investment securities that are not held-to-maturity are accounted for as securities available-for-sale, and are stated at estimated fair value, with the aggregate unrealized gains and losses classified as a component of accumulated other comprehensive income (loss), net of income taxes. Realized gains and losses on the sale of investment securities charges are determined using the specific identification method and are included within noninterest income in the Consolidated Statements of Income. Premiums and discounts on investment securities are amortized over the estimated lives of the related investment securities based on the effective interest yield method and are included in interest income in the Consolidated Statements of Income. The Corporation assesses debt securities that have fair values below amortized cost basis to determine whether declines (impairment) are other-than-temporary. If the Corporation intends to sell an impaired security or it is more-likely-than-not that the Corporation will be required to sell an impaired security prior to the recovery of its amortized cost, an other-than-temporary impairment ("OTTI") write-down is recognized in earnings equal to the entire difference between the investment security's amortized cost basis and its fair value. In assessing whether OTTI exists, management considers, among other things, (i) the length of time and the extent to which the fair value has been less than cost, (ii) the financial condition and near-term prospects of the issuer, (iii) the potential for impairments in an entire industry or sub-sector and (iv) the potential for impairments in certain economically depressed geographical locations. For the years ended December 31, 2018 , 2017 and 2016 , the Corporation did not recognize OTTI. Nonmarketable Equity Securities The Corporation is required to hold non-marketable equity securities, comprised of Federal Home Loan Bank of Indianapolis ("FHLB") and FRB stock, as a condition of membership. These securities are accounted for at cost, which equals par or redemption value, and included in "interest receivable and other assets" on the Consolidated Statements of Financial Position. These securities do not have a readily determinable fair value as their ownership is restricted and there is no market for these securities. These securities can only be redeemed or sold at their par value and only to the respective issuing government supported institution or to another member institution. FHLB stock can only be redeemed upon giving a five year written notice and FRB stock can only be redeemed upon giving six months written notice, with no more than 25.0% eligible for redemption in any calendar year. The Corporation records these non-marketable equity securities as a component of other assets and they are periodically evaluated for impairment. Management considers these non-marketable equity securities to be long-term investments. Accordingly, when evaluating these securities for impairment, management considers the ultimate recoverability of the par value rather than recognizing temporary declines in value, if applicable. The estimated loss is recognized as a loss from equity investments in other noninterest income in the Consolidated Statements of Income. The Corporation's ownership of FHLB stock totaled $125.2 million at December 31, 2018 and $112.0 million at December 31, 2017 . The Corporation's ownership of FRB stock totaled $68.1 million at both December 31, 2018 and December 31, 2017 . Loans Held for Sale Mortgage and construction loans intended for sale in the secondary market are carried at fair value based on the Corporation's election of the fair value option, as prescribed by ASC Topic 820, Fair Value Measurements and Disclosures. The estimated fair value of loans held for sale are based on quoted market prices for securities backed by similar types of loans, where available, or by discounting estimated cash flows using observable inputs inclusive of interest rates, prepayment speeds and loss assumptions for similar collateral. The fair value includes the servicing value of the loans as well as any accrued interest. These loans are sold both with servicing rights retained and with servicing rights released. Originated Loans Held for Investment Originated loans include the Corporation's entire portfolio loans held for investment, excluding loans acquired in business combinations, as further discussed below. Originated loans are stated at their principal amount outstanding, net of unearned income, charge-offs and unamortized deferred fees and costs. Loan interest income is recognized on the accrual basis. Deferred loan fees and costs are amortized over the loan term based on the level-yield method. Net loan commitment fees are deferred and amortized into fee income on a straight-line basis over the commitment period. If a loan is transferred from the loan held for investment portfolio to the held for sale portfolio, any write-down in the carrying amount of the loan at the date of transfer is recorded as a charge-off. The loans are transferred at fair value determined using the same methods described above for held for sale loans. When loans classified as held for investment are transferred to loans held for sale due to a change in intent, cash flows associated with the loans will be classified in the Consolidated Statements of Cash Flows as operating or investing, as appropriate, in accordance with the initial classification of the loans. The past due status of a loan is based on the loan's contractual terms. A loan is placed in nonaccrual status (accrual of interest is discontinued) when principal or interest is past due 90 days or when doubt exists as to the ultimate collection of principal or interest, unless the loan is both well-secured and in the process of collection, or earlier when, in the opinion of management, there is sufficient reason to doubt the collectibility of principal or interest. Interest previously accrued, but not collected, is reversed and charged against interest income at the time the loan is placed in nonaccrual status. Subsequent receipts of interest while a loan is in nonaccrual status are recorded as a reduction of principal. Loans are returned to accrual status when principal and interest payments are brought current and are anticipated to be fully collectible, payments have been received consistently for a period of time (generally six months) and collectibility is no longer in doubt. Loans Acquired in a Business Combination Loans acquired in a business combination ("acquired loans") consist of loans acquired on August 31, 2016 in the merger with Talmer, on May 31, 2015 in the acquisition of Lake Michigan Financial Corporation ("Lake Michigan"), on April 1, 2015 in the acquisition of Monarch Community Bancorp, Inc. ("Monarch"), on October 31, 2014 in the acquisition of Northwestern Bancorp, Inc. ("Northwestern"), and on April 30, 2010 in the acquisition of O.A.K. Financial Corporation ("OAK"). Acquired loans were recorded at fair value at the date of acquisition, without a carryover of the associated allowance for loan losses related to these loans. At each acquisition date, the Corporation elected to account for acquired loans, which are recorded at fair value at acquisition using an estimate of cash flows deemed to be collectible and an accretable yield, in accordance with ASC Topic 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality ("ASC 310-30"), by analogy. ASC 310-30 allows investors to aggregate loans acquired into loan pools that have common risk characteristics and thereby use a composite interest rate and expectation of cash flows expected to be collected for the loan pools. Under the provisions of ASC 310-30, the Corporation aggregated acquired loans into pools within each merger or acquisition based upon common risk characteristics, including types of loans, commercial type loans with similar risk grades and whether loans were performing or nonperforming. A pool is considered a single unit of accounting for the purposes of applying the guidance prescribed in ASC 310-30. A loan will be removed from a pool of acquired loans only if the loan is sold, foreclosed, paid off or written off, and will be removed from the pool at the carrying value. The estimate of expected credit losses was determined based on due diligence performed by executive and senior officers of the Corporation, with assistance from third-party consultants. The Corporation estimated the cash flows expected to be collected over the life of the pools of loans at acquisition and estimates expected cash flows quarterly thereafter, based on a set of assumptions including expectations as to default rates, prepayment rates and loss severities. The Corporation must make numerous assumptions, interpretations and judgments using internal and third-party credit quality information to determine whether it is probable that the Corporation will be able to collect all contractually required payments. This is a point in time assessment and inherently subjective due to the nature of the available information and judgment involved. The calculation of the fair value of the acquired loan pools entails estimating the amount and timing of cash flows attributable to both principal and interest expected to be collected on such loan pools and then discounting those cash flows at market interest rates. The excess of a loan pool's expected cash flows at the acquisition date over its estimated fair value is referred to as the "accretable yield," which is recognized into interest income over the estimated remaining life of the loan pool on a level-yield basis. The difference between a loan pool's contractually required principal and interest payments at the acquisition date and the cash flows expected to be collected at the acquisition date is referred to as the "nonaccretable difference," which includes an estimate of future credit losses expected to be incurred over the estimated life of the loan pool and interest payments that are not expected to be collected. Decreases to the expected cash flows due to deterioration in credit quality in each loan pool in subsequent periods generally require the Corporation to record a provision for loan losses and an increase to the allowance for loan losses and generally results in a transfer from accretable yield to nonaccretable difference. Decreases in the expected cash flows due to unexpected prepayments and/or payoffs will generally result in a transfer from accretable to nonaccretable difference. Improvements in expected cash flows due to improvements in credit quality in each loan pool in subsequent periods will first reverse any previously established allowance for loan losses and will generally result in reversing a portion of the nonaccretable difference, which is then classified as part of the accretable yield and subsequently recognized into interest income over the estimated remaining life of the loan pool. Loans Modified Under Troubled Debt Restructurings Loans modified under TDRs involve granting a concession to a borrower who is experiencing financial difficulty. Concessions generally include modifications to original loan terms, including changes to a loan's payment schedule, principal forgiveness, interest rate reductions, or other actions intended to minimize our economic loss and to avoid foreclosure or repossession of the collateral, if applicable, which generally would not otherwise be considered. The Corporation's TDRs include accruing TDRs, which consist of originated loans that continue to accrue interest as the Corporation expects to collect the remaining principal and interest on the loan, and nonaccrual TDRs, which include originated loans that are in a nonaccrual status and are no longer accruing interest, as the Corporation does not expect to collect the full amount of principal and interest owed from the borrower on these loans. All TDRs are accounted for as impaired loans and are included in the Corporation's analysis of the allowance for loan losses. A TDR that has been renewed by a borrower who is no longer experiencing financial difficulty and which yields a market rate of interest at the time of a renewal is no longer reported as a TDR, but only if they have been refinanced or restructured at market terms and qualify as a new loan. Loans in the Corporation's commercial loan portfolio (comprised of commercial, commercial real estate, real estate construction and land development loans) that meet the definition of a TDR generally consist of loans where the Corporation has allowed borrowers to defer scheduled principal payments and make interest-only payments for a specified period of time at the stated interest rate of the original loan agreement or reduced payments due to a moderate extension of the loan's contractual term. If the Corporation does not expect to collect all principal and interest on the loan, the modified loan is classified as a nonaccrual TDR and impairment is measured based on collateral values, if the loan is collateral dependent. If the Corporation does not expect to incur a loss on the loan based on its assessment of the borrowers' expected cash flows, as the pre- and post-modification effective yields are approximately the same, the loan is current and a six-month payment history has been sustained, the loan is classified as an accruing TDR. Since no loss is expected to be incurred on these loans, no additional provision for loan losses has been recognized for these loans and they continue to accrue interest at their contractual interest rate. Accruing TDRs are transferred to nonaccrual status if they become 90 days past due as to principal or interest payments or if it is probable that any remaining principal and interest payments due on the loan will not be collected in accordance with the modified terms of the loan. If accruing TDRs are deemed to be collateral dependent, they are measured based on collateral values. Loans in the Corporation's consumer loan portfolio (comprised of residential mortgage, consumer installment and home equity loans) that meet the definition of a TDR include a concession that reduces a borrower's monthly payments by decreasing the interest rate charged on the loan for a specified period of time (generally 24 months) under a formal modification agreement. The Corporation recognizes an additional provision for loan losses related to impairment on these loans on an individual basis based on the present value of expected future cash flows discounted at the loan's original effective interest rate. These loans continue to accrue interest at their effective interest rate, which consists of contractual interest under the terms of the modification agreement in addition to an adjustment for the accretion of computed impairment. TDRs are placed on nonaccrual status if they become 90 days past due as to principal or interest payments, or sooner if conditions warrant and measure impairment based on collateral values, if the loan is collateral dependent. Impaired Loans Impaired loans include loans on nonaccrual status and TDRs. Loans are considered impaired when based on current information and events it is probable the Corporation will be unable to collect all amounts due in accordance with the original contractual terms of the loan agreements. Impaired loans are accounted for at the lower of the present value of expected cash flows discounted at the loan's original effective interest rate or the estimated fair value of the collateral, if the loan is collateral dependent. When the present value of expected cash flows or the fair value of collateral of an impaired loan in the originated loan portfolio is less than the amount of unpaid principal outstanding on the loan, the principal balance of the loan is reduced to its carrying value through either a specific allowance for loan losses or a partial charge-off of the loan balance. Nonperforming Loans Nonperforming loans are comprised of loans for which the accrual of interest has been discontinued (nonaccrual loans, including nonaccrual TDRs). Acquired loans that were classified as nonperforming loans prior to being acquired and acquired loans that are not performing in accordance with contractual terms subsequent to acquisition are not classified as nonperforming loans subsequent to acquisition because the loans are recorded in pools at net realizable value based on the principal and interest the Corporation expects to collect on such loans. They continue to earn interest from accretable yield, independent of performance in accordance of their contractual terms, and are expected to be fully collected under the new carrying values of such loans (that is, the new cost basis arising out of purchase accounting). Allowance for Loan Losses The allowance for credit losses ("allowance") consists of two components: the allowance for loan losses (including both the originated and acquired loan portfolios) and the reserve for unfunded credit commitments. Unfunded credit commitments include items such as letters of credit, financial guarantees and binding unfunded loan commitments. The allowance represents management’s estimate of probable credit losses inherent in the loan and credit commitment portfolios as of period end. The allowance is calculated with the objective of maintaining a reserve sufficient to absorb losses inherent in the loan portfolio. The determination of the amount of the allowance requires significant judgment and the use of estimates related to the amount and timing of expected cash flows on acquired loans and impaired loans, collateral values on impaired loans, and estimated losses on pools of homogeneous loans based on historical loss experience, and consideration of current economic trends and conditions, all of which may be susceptible to significant change. The principal assumption used in deriving the allowance is the estimate of a loss percentage for each type of loan. In determining the allowance for the originated loan portfolio and the related provision for loan losses, the Corporation considers three principal elements: (i) valuation allowances based upon probable losses identified during the review of impaired loans, (ii) reserves, by loan classes, on all other loans based on a six -year historical loan loss experience, loan loss trends and giving consideration to estimated loss emergence periods, and (iii) a reserve for qualitative factors that take into consideration risks inherent in the originated loan portfolio that differ from historical loan loss experience. The first element reflects the Corporation's estimate of probable losses based upon the systematic review of individually impaired loans in the originated loan portfolio. These estimates are based upon a number of objective factors, such as payment history, financial condition of the borrower and discounted collateral exposure. The Corporation measures the investment in an impaired loan based on one of three methods: the loan's observable market price; the fair value of the collateral; or the present value of expected future cash flows discounted at the loan's effective interest rate. Loans in the commercial loan portfolio that were in nonaccrual status (including nonaccrual TDRs) were valued based on the fair value of the collateral securing the loan, while accruing TDRs in the commercial loan portfolio and consumer loans were valued based on the present value of expected future cash flows discounted at the loan's effective interest rate. It is the Corporation's general policy to obtain new appraisals at initial impairment and updated when deemed necessary on nonaccrual loans in the commercial loan portfolio. Appraisals on nonaccrual loans in the consumer loan portfolio are updated at initial impairment and when deemed necessary where there is a delay in the foreclosure process. When the Corporation determines that the fair value of the collateral is less than the carrying value of an impaired loan and a portion is deemed not collectible, the portion of the impairment that is deemed not collectible is charged off (confirmed loss) and deducted from the allowance. The remaining carrying value of the impaired loan is classified as a nonperforming loan. When the Corporation determines that the fair value of the collateral is less than the carrying value of an impaired loan but believes it is probable it will recover this impairment, the Corporation establishes a valuation allowance for such impairment. The second element is determined by assigning allocations based principally upon a six -year historical loan loss experience for each class of loan. Average losses may be adjusted based on current loan loss experience, delinquency trends, estimated loss emergence periods and other industry specific environmental factors. This component considers the lagging impact of historical charge-off ratios in periods where future loan charge-offs are expected to increase or decrease, trends in delinquencies and nonaccrual loans, the changing portfolio mix in terms of collateral, average loan balance, loan growth and the degree of seasoning in the various loan portfolios. Loan loss analyses are performed quarterly and certain inputs and parameters are updated as necessary to reflect the current credit environment. The third element is based on qualitative factors that cannot be associated with a specific credit or loan class and reflects an attempt to ensure that the overall allowance appropriately reflects additional losses that are inherent in the Corporation's loan portfolio. Determination of the probable losses inherent in the portfolio, which are not necessarily captured by the allocation methodology discussed above, involves the exercise of judgment. This qualitative portion of the allowance is judgmentally determined and generally serves to compensate for the uncertainty in estimating inherent losses, particularly in times of changing economic conditions, and also considers the inherent judgment associated with risk rating commercial loans. The qualitative portion of the allowance also takes into consideration, among other things, economic conditions within our geographic areas and nationwide, including unemployment levels, industry-wide and Corporation specific loan delinquency rates, changes in composition of and growth in the Corporation's loan portfolio and changing commercial and residential real estate values. Consumer loans secured by real estate are charged-off to the estimated fair value of the collateral when a loss is confirmed or at 180 days past due, whichever is sooner. Loss confirming events include, but are not limited to, bankruptcy (unsecured), continued delinquency, foreclosure or receipt of an asset valuation indicating a collateral deficiency and the asset is the sole source of repayment. For consumer loans not secured by real estate, the charge-off is taken upon confirmation or 120 days past due. Commercial loans are evaluated on a loan level basis and either charged-off or written down to net realizable value if a loss confirming event has occurred. Loss confirming events include, but are not limited to, bankruptcy (unsecured), continued delinquency, foreclosure, or receipt of an asset valuation indicating a collateral deficiency and that asset is the sole source of repayment. Although the Corporation allocates portions of the allowance to specific loans and loan types, the entire allowance attributable to originated loans is available for any loan losses that occur in the originated portfolio. Loans that are deemed not collectible are charged off and reduce the allowance. The provision for loan losses and recoveries on loans previously charged off increase the allowance. Collection efforts may continue and recoveries may occur after a loan is charged off. Acquired loans are aggregated into pools based upon common risk characteristics. An allowance may be recorded related to an acquired loan pool if it experiences a decrease in expected cash flows, as compared to those projected at the acquisition date. On a quarterly basis, the expected future cash flow of each pool is estimated based on various factors, including changes in property values of collateral dependent loans, default rates, loss severities and prepayment speeds. Decreases in estimates of expected cash flows within a pool generally result in a charge to the provision for loan losses and a corresponding increase in the allowance allocated to acquired loans for the particular pool. Increases in estimates of expected cash flows within a pool generally result in a reduction in the allowance allocated to acquired loans for the particular pool, if applicable, and then an adjustment to the accretable yield for the pool, which will increase amounts recognized in interest income in subsequent periods. Various regulatory agencies, as an integral part of their examination processes, periodically review the allowance. Such agencies may require additions to the allowance, based on their judgment, reflecting information available to them at the time of their examinations. Mortgage Banking Operations The Corporation generally sells conforming long-term fixed interest rate mortgage loans it originates in the secondary market. Gains on the sales of these loans are determined using the specific identification method. The Corporation sells residential mortgage loans in the secondary market primarily on a servicing retained basis. The Corporation elected the fair value measurement option, as prescribed by ASC Topic 820, Fair Value Measurements and Disclosures ("ASC 820"), for all residential mortgage loans held-for-sale originated on or after July 1, 2012. This election allows for a more effective offset of the changes in fair value of residential mortgage loans held-for-sale and the derivative instruments used to economically hedge them without having to apply complex hedge accounting provisions. Residential mortgage loans held-for-sale are carried at fair value, with changes in fair value recorded through earnings. Residential mortgage loan commitments, forward commitments, are generally enter

Mergers and Acquisitions

Mergers and Acquisitions	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Mergers and Acquisitions	Mergers and Acquisitions Merger with Talmer Bancorp, Inc. On August 31, 2016, the Corporation completed the merger with Talmer for total consideration of $1.61 billion . As a result of the merger, the Corporation issued 32.1 million shares of its common stock based on an exchange ratio where each Talmer shareholder received 0.4725 shares of the Corporation's common stock, and $ 1.61 in cash, for each share of Talmer common stock. In conjunction with the merger, the Corporation entered into and drew on a $125.0 million credit facility. The proceeds from the credit facility were used to pay off the Corporation's $25.0 million line-of-credit and a $37.5 million line-of-credit of Talmer, with the remaining proceeds used to partially fund the cash portion of the merger consideration. The credit facility was paid off during the year ended December 31, 2018. The Corporation had no merger and acquisition-related expenses during the year ended December 31, 2018 and incurred $8.5 million and $61.1 million of merger-related expenses during the years ended December 31, 2017 and 2016 , respectively. As a result of the merger, Talmer Bank and Trust became a wholly-owned subsidiary of the Corporation. Talmer Bank and Trust was consolidated with and into Chemical Bank during the fourth quarter of 2016. The Corporation determined that the merger with Talmer constitutes a business combination as defined by ASC 805. Accordingly, the assets acquired and liabilities assumed were recorded at their fair values on the date of acquisition. Fair values were determined in accordance with the guidance provided in ASC Topic 820, Fair Value Measurements, as of the merger date as presented in the following table. (Dollars in thousands) Consideration paid: Stock $ 1,504,811 Cash 107,638 Total consideration $ 1,612,449 Fair value of identifiable assets acquired: Cash and cash equivalents $ 433,352 Investment securities: Available-for-sale 808,894 Held-to-maturity 1,657 Loans held-for-sale 244,916 Loans 4,882,402 Premises and equipment 38,793 Loan servicing rights 42,462 Other intangible assets 19,088 Interest receivable and other assets 395,539 Total identifiable assets acquired $ 6,867,103 Fair value of liabilities assumed: Noninterest-bearing deposits $ 1,236,902 Interest-bearing deposits 4,057,716 Interest payable and other liabilities 100,936 Securities sold under agreements to repurchase with customers 19,704 Short-term borrowings 387,500 Long-term borrowings 299,597 Total liabilities assumed $ 6,102,355 Fair value of net identifiable assets acquired $ 764,748 Goodwill resulting from acquisition $ 847,701 Information regarding loans accounted for under ASC 310-30 at the merger date is as follows: (Dollars in thousands) Accounted for under ASC 310-30: Contractual cash flows $ 5,968,488 Contractual cash flows not expected to be collected (nonaccretable difference) 223,959 Expected cash flows 5,744,529 Interest component of expected cash flows (accretable yield) 862,127 Fair value at acquisition $ 4,882,402 Unaudited Pro Forma Combined Results of Operations The following unaudited pro forma financial information presents the consolidated results of operation of the Corporation and Talmer as if the merger had occurred as of January 1, 2015. The unaudited pro forma combined results of operations are presented solely for information purposes and are not intended to represent or be indicative of the consolidated results of operations that Chemical would have reported had these transactions been completed as of the dates and for the periods presented, nor are they necessarily indicative of future results. In particular, no adjustments have been made to eliminate the amount of Talmer's provision for loan losses incurred prior to the acquisition date that would not have been necessary had the acquired loans been recorded at fair value as of the beginning of each period indicated. In accordance with Article 11 of SEC Regulation S-X, transaction costs directly attributable to the acquisitions have been excluded. Years ended December 31, (In thousands, except per share data) 2018 2017 2016 Net interest and other income $ 780,869 $ 701,597 $ 492,323 Net Income 284,020 149,523 115,847 Earnings per share: Basic $ 3.98 $ 2.11 $ 1.65 Diluted $ 3.94 $ 2.08 $ 1.62

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair value, as defined by GAAP, is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. A fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability. The price in the principal (or most advantageous) market used to measure the fair value of the asset or liability is not adjusted for transaction costs. An orderly transaction is a transaction that assumes exposure to the market for a period prior to the measurement date to allow for market activities that are usual and customary for transactions involving such assets and liabilities; it is not a forced transaction. Market participants are buyers and sellers in the principal market that are (i) independent, (ii) knowledgeable, (iii) able to transact and (iv) willing to transact. The Corporation utilizes fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures. Investment securities — carried at fair value, loans held-for-sale, loan servicing rights and derivatives are recorded at fair value on a recurring basis. Additionally, the Corporation may be required to record other assets, such as impaired loans, goodwill, other intangible assets, other real estate and repossessed assets, at fair value on a nonrecurring basis. These nonrecurring fair value adjustments typically involve the application of lower of cost or market accounting or write-downs of individual assets. The Corporation determines the fair value of its financial instruments based on a three-level hierarchy established by GAAP. The classification and disclosure of assets and liabilities within the hierarchy is based on whether the inputs to the valuation methodology used for measurement are observable or unobservable. Observable inputs reflect market-derived or market-based information obtained from independent sources, while unobservable inputs reflect management's estimates about market data. The three levels of inputs that may be used to measure fair value within the GAAP hierarchy are as follows: Level 1 Valuation is based upon quoted prices for identical instruments traded in active markets. Level 2 Valuation is based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant assumptions are observable in the market. Level 2 valuations for the Corporation include government and government-sponsored enterprise debt obligations, including securities issued by the Federal Home Loan Bank ("FHLB"), Federal Home Loan Mortgage Corporation, Federal National Mortgage Association, Federal Farm Credit Bank, Student Loan Marketing Corporation and the Small Business Administration, securities issued by certain state and political subdivisions, residential mortgage-backed securities, collateralized mortgage obligations, corporate bonds, preferred stock and available-for-sale trust preferred securities. Valuations are obtained from a third-party pricing service for these investment securities. Additionally included in Level 2 valuations are loans held-for-sale and derivative assets and liabilities. Level 3 Valuation is generated from model-based techniques that use at least one significant assumption not observable in the market. These unobservable assumptions reflect estimates of assumptions that market participants would use in pricing the asset or liability. Valuation techniques include use of option pricing models, discounted cash flow models, yield curves and similar techniques. The determination of fair value requires management judgment or estimation and generally is corroborated by external data, which includes third-party pricing services. Level 3 valuations for the Corporation include impaired loans, goodwill, core deposit intangible assets, non-compete intangible assets, LSRs and other real estate and repossessed assets. A description of the valuation methodologies used for instruments measured at fair value, as well as the general classification of such instruments pursuant to the valuation hierarchy, is set forth below. These valuation methodologies were applied to all of the Corporation's financial assets and financial liabilities carried at fair value and all financial instruments disclosed at fair value. Transfers of asset or liabilities between levels of the fair value hierarchy are recognized at the beginning of the reporting period, when applicable. In general, fair value is based upon quoted market prices, where available. If quoted market prices are not available, fair value is based upon third-party pricing services when available. Fair value may also be based on internally developed models that primarily use, as inputs, observable market-based parameters. Valuation adjustments may be required to record financial instruments at fair value. Any such valuation adjustments are applied consistently over time. The Corporation's valuation methodologies may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. While management believes the Corporation's valuation methodologies are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date. Furthermore, the fair value amounts may change significantly after the date of the statement of financial position from the amounts reported in the Consolidated Financial Statements and related notes. Assets and Liabilities Recorded at Fair Value on a Recurring Basis Investment securities: Investment securities are recorded at fair value on a recurring basis with the exception of those classified as held-to-maturity. Fair value measurement is based upon quoted prices, if available. If quoted prices are not available, fair values are generally measured using independent pricing models or other model-based valuation techniques that include market inputs, such as benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, reference data and industry and economic events. Loans held-for-sale: The Corporation has elected the fair value option for all loans held-for-sale. Accordingly, loans held-for-sale are recorded at fair value on a recurring basis. The fair values of loans held-for-sale are based on the market price for similar loans sold in the secondary market, and therefore, are classified as Level 2 valuations. Loan servicing rights: The Corporation elected to account for all LSRs under the fair value measurement method. A third party valuation model is used to determine the fair value at the end of each reporting period utilizing a discounted cash flow analysis using interest rates and prepayment speed assumptions currently quoted for comparable instruments and a discount rate determined by management. Because of the nature of the valuation inputs, the Corporation classifies loan servicing rights as Level 3. Refer to Note 9 , "Loan Servicing Rights", for the assumptions included in the valuation of loan servicing rights. Derivatives: The Corporation enters into interest rate lock commitments with prospective borrowers to be sold into the secondary market and forward commitments for the future delivery of mortgage loans to third party investors, which are carried at fair value on a recurring basis. The fair value of these commitments is based on the fair value of related mortgage loans determined using observable market data. Interest rate lock commitments are adjusted for expectations of exercise and funding. This adjustment is not considered to be a material input. The Corporation classifies interest rate lock commitments and forward contracts related to mortgage loans to be delivered for sale as recurring Level 2. Derivative instruments held or issued for risk management or customer-initiated activities are traded in over-the counter markets where quoted market prices are not readily available. Fair value for over-the-counter derivative instruments is measured on a recurring basis using third party models that use primarily market observable inputs, such as yield curves and option volatilities. The fair value for these derivatives may include a credit valuation adjustment that is determined by applying a credit spread for the counterparty or the Corporation, as appropriate, to the total expected exposure of the derivative after considering collateral and other master netting arrangements. These adjustments, which are considered Level 3 inputs, are based on estimates of current credit spreads to evaluate the likelihood of default. The Corporation assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions at both December 31, 2018 and 2017 and it was determined that the credit valuation adjustments were not significant to the overall valuation of its derivatives. As a result, the Corporation classifies its risk management interest rate swaps designated as cash flow hedges and customer-initiated derivatives valuations in Level 2 of the fair value hierarchy. Written and purchased option derivatives consist of instruments to facilitate an equity-linked time deposit product (the "Power Equity CD"). The Power Equity CD is a time deposit that provides the purchaser a guaranteed return of principal at maturity plus a potential equity return, while the Corporation receives a known stream of funds based on equity returns. The written and purchased options are mirror derivative instruments which are carried at fair value on the Consolidated Statements of Financial Position. Fair value measurements for the Power Equity CD are determined using quoted prices of underlying stocks, along with other terms and features of the derivative instrument. As a result, the Power Equity CD derivatives are classified as Level 2 valuations. Disclosure of Recurring Basis Fair Value Measurements For assets and liabilities measured at fair value on a recurring basis, quantitative disclosures about the fair value measurements for each major category of assets and liabilities follow: (Dollars in thousands) Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total December 31, 2018 Investment securities — carried at fair value: Government and government-sponsored enterprises $ — $ 351,700 $ — $ 351,700 State and political subdivisions — 516,286 — 516,286 Residential mortgage-backed securities — 213,428 — 213,428 Collateralized mortgage obligations — 1,601,298 — 1,601,298 Corporate bonds — 293,063 — 293,063 Trust preferred securities — 46,057 — 46,057 Total investment securities — carried at fair value — 3,021,832 — 3,021,832 Loans held-for-sale — 85,030 — 85,030 Loan servicing rights — — 71,013 71,013 Derivative assets: Customer-initiated derivatives — 26,680 — 26,680 Interest rate lock commitments — 1,049 — 1,049 Power Equity CD — 718 — 718 Risk management derivatives — 10,148 — 10,148 Total derivatives — 38,595 — 38,595 Total assets at fair value $ — $ 3,145,457 $ 71,013 $ 3,216,470 Derivative liabilities: Customer-initiated derivatives $ — $ 27,664 $ — $ 27,664 Forward contracts related to mortgage loans to be delivered for sale — 719 — 719 Power Equity CD — 718 — 718 Risk management derivatives — 3,278 — 3,278 Total derivatives — 32,379 — 32,379 Total liabilities at fair value $ — $ 32,379 $ — $ 32,379 (Dollars in thousands) Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total December 31, 2017 Investment securities — carried at fair value: Government and government-sponsored enterprises $ — $ 202,916 $ — $ 202,916 State and political subdivisions — 345,970 — 345,970 Residential mortgage-backed securities — 150,131 — 150,131 Collateralized mortgage obligations — 1,033,845 — 1,033,845 Corporate bonds — 192,794 — 192,794 Trust preferred securities — 36,066 — 36,066 Preferred stock — 1,824 — 1,824 Total investment securities — carried at fair value — 1,963,546 — 1,963,546 Loans held-for-sale — 52,133 — 52,133 Loan servicing rights — — 63,841 63,841 Derivative assets: Customer-initiated derivatives — 9,376 — 9,376 Interest rate lock commitments — 1,222 — 1,222 Power Equity CD — 2,184 — 2,184 Risk management derivatives — 5,899 — 5,899 Total derivatives — 18,681 — 18,681 Total assets at fair value $ — $ 2,034,360 $ 63,841 $ 2,098,201 Derivative liabilities: Customer-initiated derivatives — 10,139 — 10,139 Forward contracts related to mortgage loans to be delivered for sale — 34 — 34 Power Equity CD — 2,184 — 2,184 Total derivatives — 12,357 — 12,357 Total liabilities at fair value $ — $ 12,357 $ — $ 12,357 There were no transfers between levels within the fair value hierarchy during the years ended December 31, 2018 and 2017 . The following table summarizes the changes in Level 3 assets measured at fair value on a recurring basis. Year Ended December 31, 2018 2017 2016 (Dollars in thousands) Loan servicing rights Balance, beginning of period $ 63,841 $ 48,085 $ — Additions due to acquisition — — 42,462 Transfer in based on new accounting policy election (1) — 15,891 — Gains (losses): Recorded in earnings (realized): Recorded in "Net gain on sale of loans and other mortgage banking revenue" (1,054 ) (8,880 ) 4,593 New originations 8,226 8,745 1,030 Balance, end of period $ 71,013 $ 63,841 $ 48,085 (1) Refer to Note 1, Summary of Significant Accounting Policies, for further details. The Corporation has elected the fair value option for loans held-for-sale. These loans are intended for sale and the Corporation believes that the fair value is the best indicator of the resolution of these loans. Interest income is recorded based on the contractual terms of the loans in accordance with the Corporation's policy on loans held for investment in "Interest and fees on loans" in the Consolidated Statements of Income. There were no loans held-for-sale on nonaccrual status or 90 days past due and on accrual status as of December 31, 2018 and 2017 . The aggregate fair value, contractual balance (including accrued interest), and gain or loss for loans held-for-sale carried at fair value option was as follows: December 31, (Dollars in thousands) 2018 2017 Aggregate fair value $ 85,030 $ 52,133 Contractual balance 82,080 50,597 Unrealized gain 2,950 1,536 The total amount of gains from loans held-for-sale included in the Consolidated Statements of Income was as follows: Year Ended December 31, (Dollars in thousands) 2018 2017 2016 Interest income (1) $ 2,788 $ 2,540 $ 1,606 Change in fair value (2) 1,414 715 39 Net gain on sales of loans (2) 12,173 31,734 15,686 Total included in earnings $ 16,375 $ 34,989 $ 17,331 (1) Included in "Interest and fees on loans" in the Consolidated Statements of Income. (2) Included in "Net gain on sale of loans and other mortgage banking revenue" in the Consolidated Statements of Income. Assets and Liabilities Recorded at Fair Value on a Nonrecurring Basis Investment securities : Investment securities classified as held to maturity are recorded at fair value if the value is below amortized cost and the Corporation has determined that such unrealized loss is an other-than-temporary impairment. Fair value measurement is based upon quoted prices, if available. If quoted prices are not available, fair values are generally measured using independent pricing models or other model-based valuation techniques that include market inputs, such as benchmark yields, reported trades, broker dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, reference data and industry and economic events. Impaired Loans: The Corporation does not record loans held for investment at fair value on a recurring basis. However, from time to time, a loan is considered impaired and an allocation of the allowance (valuation allowance) may be established or a portion of the loan is charged off. Loans for which it is probable that payment of interest and principal will not be made in accordance with the contractual terms of the loan agreement are considered impaired. The fair value of impaired loans is estimated using one of several methods, including the loan's observable market price, the fair value of the collateral or the present value of the expected future cash flows discounted at the loan's effective interest rate. Those impaired loans not requiring a valuation allowance represent loans for which the fair value of the expected repayments or collateral exceed the remaining carrying amount of such loans. Impaired loans where a valuation allowance is established or a portion of the loan is charged off based on the fair value of collateral are subject to nonrecurring fair value measurement and require classification in the fair value hierarchy. The Corporation records impaired loans as Level 3 valuations as there is generally no observable market price or management determines the fair value of the collateral is further impaired below the independent appraised value. When management determines the fair value of the collateral is further impaired below the appraised value, discounts ranging between 20% and 30% of the appraised value are used depending on the nature of the collateral and the age of the most recent appraisal. Goodwill: Goodwill is subject to impairment testing on an annual basis. The assessment of goodwill for impairment requires a significant degree of judgment. In the event the assessment indicates that it is more-likely-than-not that the fair value is less than the carrying value, the asset is considered impaired and recorded at fair value. Goodwill that is impaired and subject to nonrecurring fair value measurements is a Level 3 valuation. At December 31, 2018 and 2017 , no goodwill was impaired. Other intangible assets: Other intangible assets consist of core deposit intangible assets and non-compete intangible assets. These items are recorded at fair value when initially recorded. Subsequently, core deposit intangible assets and non-compete intangible assets are amortized primarily on an accelerated basis over periods ranging from ten to fifteen years for core deposit intangible assets and 1 year for non-compete intangible assets and are subject to impairment testing whenever events or changes in circumstances indicate that the carrying amount exceeds the fair value of the asset. If core deposit intangible asset or non-compete intangible asset impairment is identified, the Corporation classifies impaired core deposit intangible assets and impaired non-compete intangible assets subject to nonrecurring fair value measurements as Level 3 valuations. At December 31, 2018 and 2017 , there was no impairment identified for core deposit intangible assets or non-compete intangible assets. Other real estate owned and repossessed assets : The carrying amounts for other real estate and repossessed assets are reported in the Consolidated Statements of Financial Position under "Interest receivable and other assets." Other real estate and repossessed assets include real estate and other types of assets repossessed by the Corporation. Other real estate and repossessed assets are recorded at the lower of cost or fair value upon the transfer of a loan to other real estate and repossessed assets and, subsequently, continue to be measured and carried at the lower of cost or fair value. Fair value is based upon independent market prices, appraised values of the property or management's estimation of the value of the property. The Corporation records other real estate and repossessed assets as Level 3 valuations as management generally determines that the fair value of the property is impaired below the appraised value. When management determines the fair value of the property is further impaired below appraised value, discounts ranging between 20% and 30% of the appraised value are used depending on the nature of the property and the age of the most recent appraisal. Disclosure of Nonrecurring Basis Fair Value Measurements Certain assets may be required to be measured at fair value on a nonrecurring basis. The carrying value of these assets represent end of period values, which approximate the fair value measurements that occurred on the various measurement dates during the period. For assets measured at fair value on a nonrecurring basis, quantitative disclosures about fair value measurements for each major category of assets follow: (Dollars in thousands) Significant Unobservable Inputs (Level 3) December 31, 2018 Impaired loans $ 63,247 Other real estate and repossessed assets 883 Total $ 64,130 December 31, 2017 Impaired loans $ 70,619 Other real estate and repossessed assets 2,899 Total $ 73,518 There were no liabilities recorded at fair value on a nonrecurring basis at either December 31, 2018 or 2017 . The following table presents additional information about the significant unobservable inputs used in the fair value measurement of financial assets measured on a nonrecurring basis that were categorized within the Level 3 of the fair value hierarchy: (Dollars in thousands) Fair Value at December 31, 2018 Valuation Technique Significant Unobservable Inputs Range Impaired loans $ 63,247 Appraisal of collateral Discount for type of collateral and age of appraisal 20%-30% Other real estate and repossessed assets 883 Appraisal of property Discount for type of property and age of appraisal 20%-30% Disclosures About Fair Value of Financial Instruments GAAP requires disclosures about the estimated fair value of the Corporation's financial instruments, including those financial assets and liabilities that are not measured and reported at fair value on a recurring or nonrecurring basis. The Corporation utilized the fair value hierarchy in computing the fair values of its financial instruments. In cases where quoted market prices were not available, the Corporation employed the exit-price notion following the adoption of ASU 2016-01 on January 1, 2018 and used the present value method prior to the adoption of ASU 2016-01, using unobservable inputs requiring management's judgment to estimate the fair values of its financial instruments, which are considered Level 3 valuations. These Level 3 valuations are affected by the assumptions made and, accordingly, are not necessarily indicative of amounts that would be realized in a current market exchange. It is also the Corporation's general practice and intent to hold the majority of its financial instruments until maturity and, therefore, the Corporation does not expect to realize the estimated amounts disclosed. A summary of carrying amounts and estimated fair values of the Corporation's financial instruments not recorded at fair value in their entirety on a recurring basis on the Consolidated Statements of Financial Position are disclosed in the table below: December 31, Level in Fair Value Measurement Hierarchy 2018 2017 (Dollars in thousands) Carrying Amount Fair Value Carrying Amount Fair Value Financial assets: Investment securities: Held-to-maturity Level 2 $ 623,599 $ 618,232 $ 676,593 $ 662,516 Held-to-maturity Level 3 500 440 500 390 Net loans (1) Level 3 15,159,795 14,907,789 14,063,380 14,114,545 Financial liabilities: Time deposits Level 2 $ 4,074,248 $ 4,041,212 $ 3,217,207 $ 3,225,847 Collateralized customer deposits Level 2 382,687 382,370 415,236 415,236 Short-term borrowings Level 2 2,035,000 2,034,719 2,000,000 1,999,137 Long-term borrowings Level 2 426,002 423,258 372,882 367,984 (1) Included $63.2 million and $70.6 million of impaired loans recorded at fair value on a nonrecurring basis at December 31, 2018 and 2017 , respectively. The short-term nature of certain assets and liabilities result in their carrying value approximating fair value. These include cash and cash equivalents, nonmarketable equity securities, interest receivable, bank owned life insurance, deposits without defined maturities and interest payable.

Investment Securities

Investment Securities	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities The following is a summary of the amortized cost and fair value of investment securities carried at fair value and investment securities held-to-maturity at December 31, 2018 and 2017 : Investment Securities Carried at Fair Value (Dollars in thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2018 Debt securities Government and government-sponsored enterprises $ 354,342 $ 713 $ 3,355 $ 351,700 State and political subdivisions 523,178 1,141 8,033 516,286 Residential mortgage-backed securities 216,990 261 3,823 213,428 Collateralized mortgage obligations 1,623,415 2,903 25,020 1,601,298 Corporate bonds 304,243 259 11,439 293,063 Trust preferred securities 47,477 324 1,744 46,057 Total $ 3,069,645 $ 5,601 $ 53,414 $ 3,021,832 December 31, 2017 Debt securities Government and government-sponsored enterprises $ 203,099 $ 765 $ 948 $ 202,916 State and political subdivisions 350,088 310 4,428 345,970 Residential mortgage-backed securities 151,752 5 1,626 150,131 Collateralized mortgage obligations 1,042,240 89 8,484 1,033,845 Corporate bonds 193,230 1,156 1,592 192,794 Trust preferred securities 34,848 1,280 62 36,066 Total debt securities available-for-sale 1,975,257 3,605 17,140 1,961,722 Equity securities Preferred stock 1,389 435 — 1,824 Total equity securities 1,389 435 — 1,824 Total $ 1,976,646 $ 4,040 $ 17,140 $ 1,963,546 Investment Securities Held-to-Maturity (Dollars in thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2018 State and political subdivisions $ 623,599 $ 2,548 $ 7,915 $ 618,232 Trust preferred securities 500 — 60 440 Total $ 624,099 $ 2,548 $ 7,975 $ 618,672 December 31, 2017 State and political subdivisions $ 676,593 $ 3,856 $ 17,933 $ 662,516 Trust preferred securities 500 — 110 390 Total $ 677,093 $ 3,856 $ 18,043 $ 662,906 Investment securities are classified at the time they are acquired as either available-for-sale, held-to-maturity or carried at fair value based upon various factors, including asset/liability management strategies, liquidity and profitability objectives and regulatory requirements. Debt securities classified as available-for-sale and equity securities are recorded at fair value. Investment securities carried at fair value may be sold prior to maturity based upon asset/liability management decisions. Unrealized gains or losses on available-for-sale debt securities are recorded as part of accumulated other comprehensive income in stockholders’ equity. Unrealized gains or losses on equity securities were recorded as part of accumulated other comprehensive income in stockholders' equity through December 31, 2017. Effective January 1, 2018, the amendments within ASU 2016-01, require that equity investments be measured at fair value with changes in fair value recognized in net income. At January 1, 2018, the Corporation's equity securities consisted of $1.8 million in preferred stocks. The Corporation recognized a cumulative effect adjustment in the amount of $344 thousand as of January 1, 2018 to reclassify the fair value position into retained earnings. Beginning January 1, 2018, the fair value changes on equity securities are recognized in net income, rather than in accumulated other comprehensive income. The Corporation sold its remaining position in equity securities during the year ended December 31, 2018. Held-to-maturity securities are carried at amortized cost, adjusted for amortization of premiums or accretion of discounts. The majority of the Corporation's residential mortgage-backed securities and collateralized mortgage obligations are backed by a U.S. government agency (Government National Mortgage Association) or a government sponsored enterprise (Federal Home Loan Mortgage Corporation or Federal National Mortgage Association). Proceeds from sales of investment securities carried at fair value and the associated gains and losses recorded in earnings are listed below: For the years ended December 31, (Dollars in thousands) 2018 2017 2016 Proceeds $ 4,215 $ 409,220 $ 41,446 Gross gains 263 178 325 Gross losses (39 ) (7,566 ) (196 ) The following is a summary of the amortized cost and fair value of investment securities at December 31, 2018 , by maturity, for both carried at fair value and held-to-maturity. The maturities of residential mortgage-backed securities and collateralized mortgage obligations are based on scheduled principal payments. The maturities of all other debt securities are based on final contractual maturity. December 31, 2018 (Dollars in thousands) Amortized Cost Fair Value Investment Securities Carried at Fair Value: Due in one year or less $ 51,523 $ 51,244 Due after one year through five years 109,918 108,051 Due after five years through ten years 515,050 498,612 Due after ten years 2,393,154 2,363,925 Total $ 3,069,645 $ 3,021,832 Investment Securities Held-to-Maturity: Due in one year or less $ 55,840 $ 55,728 Due after one year through five years 230,154 228,528 Due after five years through ten years 164,325 162,764 Due after ten years 173,780 171,652 Total $ 624,099 $ 618,672 Securities with a carrying value of $1.05 billion and $937.2 million were pledged at December 31, 2018 and 2017 , respectively, to secure borrowings and deposits. At December 31, 2018 and 2017 , there were no holdings of securities of any one issuer, other than the U.S. government and its agencies, in an amount greater than 10% of shareholders' equity. The following schedule summarizes information for debt securities both carried at fair value and held-to-maturity with gross unrealized losses at December 31, 2018 and 2017 , aggregated by category and length of time that individual securities have been in a continuous unrealized loss position. As of December 31, 2018 , the Corporation's securities portfolio consisted of 2,096 securities, 1,408 of which were in an unrealized loss position. Less Than 12 Months 12 Months or More Total (Dollars in thousands) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses December 31, 2018 Government and government-sponsored enterprises $ 167,164 $ 1,672 $ 62,200 $ 1,683 $ 229,364 $ 3,355 State and political subdivisions 190,551 1,932 657,327 14,016 847,878 15,948 Residential mortgage-backed securities 20,679 85 123,757 3,738 144,436 3,823 Collateralized mortgage obligations 496,356 5,268 656,208 19,752 1,152,564 25,020 Corporate bonds 169,431 5,888 103,688 5,551 273,119 11,439 Trust preferred securities 34,623 1,640 2,725 164 37,348 1,804 Total $ 1,078,804 $ 16,485 $ 1,605,905 $ 44,904 $ 2,684,709 $ 61,389 December 31, 2017 Government and government-sponsored enterprises $ 63,818 $ 510 $ 24,621 $ 438 $ 88,439 $ 948 State and political subdivisions 437,407 12,268 349,242 10,093 786,649 22,361 Residential mortgage-backed securities 93,508 383 56,576 1,243 150,084 1,626 Collateralized mortgage obligations 713,525 7,235 73,707 1,249 787,232 8,484 Corporate bonds 71,447 1,138 47,878 454 119,325 1,592 Trust preferred securities — — 11,164 172 11,164 172 Total $ 1,379,705 $ 21,534 $ 563,188 $ 13,649 $ 1,942,893 $ 35,183 An assessment is performed quarterly by the Corporation to determine whether unrealized losses in its debt securities portfolio are temporary or other-than-temporary by carefully considering all reasonably available information. The Corporation reviews factors such as financial statements, credit ratings, news releases and other pertinent information of the underlying issuer or company to make its determination. Management did not believe any individual unrealized loss on any debt security as of December 31, 2018 , represented an other-than-temporary impairment (OTTI) as the unrealized losses for these securities resulted primarily from changes in benchmark U.S. Treasury interest rates and not credit issues. Management believed that the unrealized losses on debt securities at December 31, 2018 were temporary in nature and due primarily to changes in interest rates and reduced market liquidity and not as a result of credit-related issues. At December 31, 2018 , the Corporation did not have the intent to sell any of its impaired debt securities and believed that it was more-likely-than-not that the Corporation will not have to sell any such debt securities before a full recovery of amortized cost. Accordingly, at December 31, 2018 , the Corporation believed the impairments in its debt securities portfolio were temporary in nature. However, there is no assurance that OTTI may not occur in the future.

Loans

Loans	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Loans	Loans Loan portfolio segments are defined as the level at which an entity develops and documents a systematic methodology to determine its allowance. The Corporation has two loan portfolio segments (commercial loans and consumer loans) that it uses in determining the allowance. Both quantitative and qualitative factors are used by management at the loan portfolio segment level in determining the adequacy of the allowance for the Corporation. Classes of loans are a disaggregation of an entity's loan portfolio segments. Classes of loans are defined as a group of loans which share similar initial measurement attributes, risk characteristics and methods for monitoring and assessing credit risk. The Corporation has six classes of loans, which are set forth below. Commercial — Loans and lines of credit to varying types of businesses, including municipalities, school districts and nonprofit organizations, for the purpose of supporting working capital, operational needs and term financing of equipment. Repayment of such loans is generally provided through operating cash flows of the business. Commercial loans are predominately secured by equipment, inventory, accounts receivable, personal guarantees of the owner and other sources of repayment, although the Corporation may also secure commercial loans with real estate. Commercial real estate — Loans secured by real estate occupied by the borrower for ongoing operations (owner-occupied), non-owner occupied real estate leased to one or more tenants (non-owner occupied) and vacant land that has been acquired for investment or future land development (vacant land). Real estate construction and land development — Real estate construction loans represent secured loans for the construction of business properties. Real estate construction loans often convert to a commercial real estate loan at the completion of the construction period. Land development loans represent secured development loans made to borrowers for the purpose of infrastructure improvements to vacant land to create finished marketable residential and commercial lots/land. Most land development loans are originated with the intention that the loans will be paid through the sale of developed lots/land by the developers within twelve months of the completion date. Land development loans at December 31, 2018 and 2017 were primarily comprised of loans to develop residential properties. Residential mortgage — Loans secured by one - to four -family residential properties, generally with fixed interest rates for periods of fifteen years or less. The loan-to-value ratio at the time of origination is generally 80% or less. Residential mortgage loans with a loan-to-value ratio of more than 80% generally require private mortgage insurance. Consumer installment — Loans to consumers primarily for the purpose of acquiring automobiles, recreational vehicles and watercraft and comprised primarily of indirect loans purchased from dealers. These loans generally consist of relatively small amounts that are spread across many individual borrowers. Home equity — Loans and lines of credit whereby consumers utilize equity in their personal residence, generally through a second mortgage, as collateral to secure the loan. Loans held-for-sale, comprised of fixed-rate residential mortgage and construction loans, were $85.0 million at December 31, 2018 and $52.1 million at December 31, 2017 . The Corporation sold loans totaling $741.9 million , $838.5 million and $723.5 million during the years ended December 31, 2018 , 2017 and 2016 , respectively. Commercial, commercial real estate, real estate construction and land development loans are referred to as the Corporation's commercial loan portfolio, while residential mortgage, consumer installment and home equity loans are referred to as the Corporation's consumer loan portfolio. A summary of the Corporation's loans follows: (Dollars in thousands) Originated Acquired (1) Total loans December 31, 2018 Commercial loan portfolio: Commercial $ 3,287,087 $ 715,481 $ 4,002,568 Commercial real estate: Owner-occupied 1,513,532 546,025 2,059,557 Non-owner occupied 1,966,330 818,690 2,785,020 Vacant land 40,295 27,215 67,510 Total commercial real estate 3,520,157 1,391,930 4,912,087 Real estate construction and land development 566,726 30,486 597,212 Subtotal 7,373,970 2,137,897 9,511,867 Consumer loan portfolio: Residential mortgage 2,407,305 1,051,361 3,458,666 Consumer installment 1,451,352 69,722 1,521,074 Home equity 612,129 166,043 778,172 Subtotal 4,470,786 1,287,126 5,757,912 Total loans (2) $ 11,844,756 $ 3,425,023 $ 15,269,779 December 31, 2017 Commercial loan portfolio: Commercial $ 2,407,606 $ 978,036 $ 3,385,642 Commercial real estate: Owner-occupied 1,185,614 627,948 1,813,562 Non-owner occupied 1,518,787 1,087,974 2,606,761 Vacant land 47,024 33,323 80,347 Total commercial real estate 2,751,425 1,749,245 4,500,670 Real estate construction and land development 498,155 76,060 574,215 Subtotal 5,657,186 2,803,341 8,460,527 Consumer loan portfolio: Residential mortgage 1,967,857 1,284,630 3,252,487 Consumer installment 1,510,540 102,468 1,613,008 Home equity 611,846 217,399 829,245 Subtotal 4,090,243 1,604,497 5,694,740 Total loans (2) $ 9,747,429 $ 4,407,838 $ 14,155,267 (1) Loans acquired in the Talmer, Lake Michigan, Monarch, Northwestern and OAK acquisitions were elected to be accounted for under ASC 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality (ASC 310-30), by analogy. See Note 1, Summary of Significant Accounting Policies for further information. (2) Reported net of deferred costs totaling $19.7 million and $26.1 million at December 31, 2018 and 2017 , respectively. The Corporation acquired loans at fair value as of the acquisition date, which includes loans acquired in the acquisitions of Talmer, Lake Michigan, Monarch, Northwestern and OAK. Loans acquired in each of these transactions ("Acquired Loans) were elected to be accounted for under ASC 310-30, by analogy, which recognizes the expected shortfall of expected future cash flows, as compared to the contractual amount due, as nonaccretable difference. Any excess of the net present value of expected future cash flows over the acquisition date fair value is recognized as the accretable discount, or accretable yield. The accretable discount is recognized over the expected remaining life of the acquired loans on a pool basis. In the event an acquired loan is renewed or extended, the loan continues to be accounted for as an acquired loan on a pool basis in accordance with ASC 310-30. Activity for the accretable yield, which includes contractually due expected cash flows for acquired loans that have been renewed or extended since the date of acquisition and continue to be accounted for in loan pools in accordance with ASC 310-30, follows: (Dollars in thousands) Talmer Lake Michigan Monarch North-western OAK Total Year Ended December 31, 2018 Balance at beginning of period $ 731,353 $ 95,124 $ 22,496 $ 60,814 $ 17,110 $ 926,897 Accretion recognized in interest income (164,614 ) (24,722 ) (3,881 ) (17,988 ) (10,214 ) (221,419 ) Net reclassification (to) from nonaccretable difference (1)(2) (61,407 ) 2,730 (783 ) (1,371 ) 2,678 (58,153 ) Balance at end of period $ 505,332 $ 73,132 $ 17,832 $ 41,455 $ 9,574 $ 647,325 Year Ended December 31, 2017 Balance at beginning of period $ 798,210 $ 121,416 $ 27,182 $ 69,847 $ 23,316 $ 1,039,971 Accretion recognized in interest income (175,678 ) (29,077 ) (4,533 ) (20,318 ) (12,563 ) (242,169 ) Net reclassification (to) from nonaccretable difference (1) 108,821 2,785 (153 ) 11,285 6,357 129,095 Balance at end of period $ 731,353 $ 95,124 $ 22,496 $ 60,814 $ 17,110 $ 926,897 Year Ended December 31, 2016 Balance at beginning of period $ — $ 152,999 $ 34,558 $ 82,623 $ 28,077 $ 298,257 Addition attributable to acquisitions 862,127 — — — — 862,127 Accretion recognized in interest income (63,917 ) (33,031 ) (5,468 ) (15,791 ) (13,352 ) (131,559 ) Net reclassification (to) from nonaccretable difference (1) — 1,448 (1,908 ) 3,015 8,591 11,146 Balance at end of period $ 798,210 $ 121,416 $ 27,182 $ 69,847 $ 23,316 $ 1,039,971 (1) The net reclassification results from changes in expected cash flows of the acquired loans which may include increases in the amount of contractual principal and interest expected to be collected due to improvement in credit quality, increases in balances outstanding from advances, renewals, extensions and interest rates; as well as reductions in contractual principal and interest expected to be collected due to credit deterioration, payoffs, and decreases in interest rates. (2) The 2018 net reclassification from accretable to nonaccretable difference in the Talmer portfolio was primarily the result of unexpected prepayments and payoffs. Chemical Bank has extended loans to its directors, executive officers and their affiliates. These loans were made in the ordinary course of business upon normal terms, including collateralization and interest rates prevailing at the time, and did not involve more than the normal risk of repayment by the borrower. The aggregate loans outstanding to the directors, executive officers and their affiliates totaled $3.6 million at December 31, 2018 and $3.8 million at December 31, 2017 . During 2018 and 2017 , there were $3.8 million and $44.1 million , respectively, of new loans and other additions, while repayments and other reductions totaled $4.0 million and $64.2 million , respectively. Credit Quality Monitoring The Corporation maintains loan policies and credit underwriting standards as part of the process of managing credit risk. These standards include making loans generally only within the Corporation's market areas. The Corporation's lending markets generally consist of communities throughout Michigan, Ohio and Northern Indiana. The Corporation, through Chemical Bank, has a commercial loan portfolio approval process involving underwriting and individual and group loan approval authorities to consider credit quality and loss exposure at loan origination. The loans in the Corporation's commercial loan portfolio are risk rated at origination based on the grading system set forth below. The approval authority of relationship managers is established based on experience levels, with credit decisions greater than $1.25 million requiring credit officer approval and credit decisions greater than $3.0 million requiring group loan authority approval, except for six executive and senior officers who have varying loan limits up to $8.0 million . With respect to the group loan authorities, Chemical Bank has various regional loan committees that meet weekly to consider loan ranging in amounts from $3.0 million to $7.0 million , and a senior loan committee, consisting of certain executive and senior officers, that meets weekly to consider loans ranging in amounts from $7.0 million up to Chemical Bank's internal lending limit, depending on risk rating and credit action required. Credit actions exceeding Chemical Bank's internal lending limit require the approval of the board of directors of Chemical Bank. The majority of the Corporation's consumer loan portfolio is comprised of secured loans that are relatively small. The Corporation's consumer loan portfolio has a centralized approval process which utilizes standardized underwriting criteria. The ongoing measurement of credit quality of the consumer loan portfolio is largely done on an exception basis. If payments are made on schedule, as agreed, then no further monitoring is performed. However, if delinquency occurs, the delinquent loans are turned over to the Corporation's collection department for resolution, resulting in repossession or foreclosure if payments are not brought current. Credit quality for the entire consumer loan portfolio is measured by the periodic delinquency rate, nonaccrual amounts and actual losses incurred. Loans in the commercial loan portfolio tend to be larger and more complex than those in the consumer loan portfolio, and therefore, are subject to more intensive monitoring. All loans in the commercial loan portfolio have an assigned relationship manager, and most borrowers provide periodic financial and operating information that allows the relationship managers to stay abreast of credit quality during the life of the loans. The risk ratings of loans in the commercial loan portfolio are reassessed at least annually, with loans below an acceptable risk rating reassessed more frequently and reviewed by various loan committees within the Corporation at least quarterly. The Corporation maintains a centralized independent loan review function that monitors the approval process and ongoing asset quality of the loan portfolio, including the accuracy of loan grades. The Corporation also maintains an independent appraisal review function that participates in the review of all appraisals obtained by the Corporation for loans in the commercial loan portfolio. Credit Quality Indicators Commercial Loan Portfolio Risk categories for the Corporation's commercial loan portfolio establish the credit quality of a borrower by measuring liquidity, debt capacity, coverage and payment behavior as shown in the borrower's financial statements. The risk categories also measure the quality of the borrower's management and the repayment support offered by any guarantors. Risk categories for the Corporation's commercial loan portfolio are described as follows: Pass: Includes all loans without weaknesses or potential weaknesses identified in the categories of special mention, substandard or doubtful. Special Mention: Loans with potential credit weakness or credit deficiency, which, if not corrected, pose an unwarranted financial risk that could weaken the loan by adversely impacting the future repayment ability of the borrower. Substandard: Loans with a well-defined weakness, or weaknesses, such as loans to borrowers who may be experiencing losses from operations or inadequate liquidity of a degree and duration that jeopardizes the orderly repayment of the loan. Substandard loans also are distinguished by the distinct possibility of loss in the future if these weaknesses are not corrected. Doubtful: Loans with all the characteristics of a loan classified as Substandard, with the added characteristic that credit weaknesses make collection in full highly questionable and improbable. The primary source of repayment is nonexistent and there is doubt as to the value of the secondary source of repayments. A doubtful asset has a high probability of total or substantial loss, but because of pending events that may strengthen the asset, its classification as loss is deferred. Loss: An asset classified as loss is considered uncollectible and of such little value that the continuance as a bankable asset is not warranted. This classification does not mean that an asset has absolutely no recovery or salvage value, but rather that it is not practical or desirable to defer writing off this basically worthless asset even through partial recovery may occur in the future. The following schedule presents the recorded investment of loans in the commercial loan portfolio by credit risk categories at December 31, 2018 and 2017 : (Dollars in thousands) Pass Special Mention Substandard Doubtful Total December 31, 2018 Originated Portfolio: Commercial $ 3,118,894 $ 87,222 $ 77,036 $ 3,935 $ 3,287,087 Commercial real estate: Owner-occupied 1,430,948 32,056 50,286 242 1,513,532 Non-owner occupied 1,901,822 39,416 25,092 — 1,966,330 Vacant land 36,499 — 3,741 55 40,295 Total commercial real estate 3,369,269 71,472 79,119 297 3,520,157 Real estate construction and land development 557,040 6,108 3,578 — 566,726 Subtotal 7,045,203 164,802 159,733 4,232 7,373,970 Acquired Portfolio: Commercial 655,883 36,809 22,773 16 715,481 Commercial real estate: Owner-occupied 500,072 28,909 17,033 11 546,025 Non-owner occupied 740,900 52,546 25,244 — 818,690 Vacant land 26,978 237 — — 27,215 Total commercial real estate 1,267,950 81,692 42,277 11 1,391,930 Real estate construction and land development 29,248 97 1,141 — 30,486 Subtotal 1,953,081 118,598 66,191 27 2,137,897 Total $ 8,998,284 $ 283,400 $ 225,924 $ 4,259 $ 9,511,867 December 31, 2017 Originated Portfolio: Commercial $ 2,316,464 $ 41,059 $ 50,083 $ — $ 2,407,606 Commercial real estate: Owner-occupied 1,133,609 19,438 32,567 — 1,185,614 Non-owner occupied 1,504,195 4,728 9,864 — 1,518,787 Vacant land 39,775 38 7,211 — 47,024 Total commercial real estate 2,677,579 24,204 49,642 — 2,751,425 Real estate construction and land development 494,528 837 2,790 — 498,155 Subtotal 5,488,571 66,100 102,515 — 5,657,186 Acquired Portfolio: Commercial 873,861 68,418 35,539 218 978,036 Commercial real estate: Owner-occupied 580,127 23,998 23,036 787 627,948 Non-owner occupied 995,709 43,645 48,620 — 1,087,974 Vacant land 27,849 327 5,147 — 33,323 Total commercial real estate 1,603,685 67,970 76,803 787 1,749,245 Real estate construction and land development 72,346 2,218 1,496 — 76,060 Subtotal 2,549,892 138,606 113,838 1,005 2,803,341 Total $ 8,038,463 $ 204,706 $ 216,353 $ 1,005 $ 8,460,527 Consumer Loan Portfolio The Corporation evaluates the credit quality of loans in the consumer loan portfolio based on the performing or nonperforming status of the loan. Loans in the consumer loan portfolio that are performing in accordance with original contractual terms and are less than 90 days past due and accruing interest are considered to be in a performing status, while those that are in nonaccrual status, contractually past due 90 days or more as to interest or principal payments are considered to be in a nonperforming status. Loans accounted for under ASC 310-30, "Acquired loans", that are not performing in accordance with contractual terms are not reported as nonperforming because these loans are recorded in pools at their net realizable value based on the principal and interest the Corporation expects to collect on these loans. The following schedule presents the recorded investment of loans in the consumer loan portfolio based on loans in a performing status and loans in a nonperforming status at December 31, 2018 and 2017 : (Dollars in thousands) Residential mortgage Consumer installment Home equity Total consumer December 31, 2018 Originated Portfolio: Performing $ 2,399,317 $ 1,450,076 $ 608,525 $ 4,457,918 Nonperforming 7,988 1,276 3,604 12,868 Subtotal 2,407,305 1,451,352 612,129 4,470,786 Acquired Loans 1,051,361 69,722 166,043 1,287,126 Total $ 3,458,666 $ 1,521,074 $ 778,172 $ 5,757,912 December 31, 2017 Originated Portfolio: Performing $ 1,959,222 $ 1,509,698 $ 607,541 $ 4,076,461 Nonperforming 8,635 842 4,305 13,782 Subtotal 1,967,857 1,510,540 611,846 4,090,243 Acquired Loans 1,284,630 102,468 217,399 1,604,497 Total $ 3,252,487 $ 1,613,008 $ 829,245 $ 5,694,740 Nonperforming Assets and Past Due Loans Nonperforming assets consist of loans for which the accrual of interest has been discontinued, other real estate owned acquired through acquisitions, other real estate owned obtained through foreclosure and other repossessed assets. Loans are considered past due or delinquent when the contractual principal or interest due in accordance with the terms of the loan agreement or any portion thereof remains unpaid after the due date of the scheduled payments. Loans outside of those accounted for under ASC 310-30 are classified as nonaccrual when, in the opinion of management, collection of principal or interest is doubtful. The accrual of interest is discontinued when a loan is placed in nonaccrual status and any payments received reduce the carrying value of the loan. A loan may be placed back on accrual status if all contractual payments have been received and collection of future principal and interest payments are no longer doubtful. Acquired loans that are not performing in accordance with contractual terms are not reported as nonperforming because these loans are recorded in pools at their net realizable value based on the principal and interest the Corporation expects to collect on these loans. A summary of nonperforming assets follows: December 31, (Dollars in thousands) 2018 2017 Nonperforming assets Nonaccrual loans: Commercial $ 30,139 $ 19,691 Commercial real estate: Owner-occupied 16,056 19,070 Non-owner occupied 23,021 5,270 Vacant land 3,337 5,205 Total commercial real estate 42,414 29,545 Real estate construction and land development 12 77 Residential mortgage 7,988 8,635 Consumer installment 1,276 842 Home equity 3,604 4,305 Total nonaccrual loans 85,433 63,095 Other real estate owned and repossessed assets 6,256 8,807 Total nonperforming assets $ 91,689 $ 71,902 The Corporation's nonaccrual loans at December 31, 2018 and 2017 included $28.1 million and $29.1 million , respectively, of nonaccrual TDRs. There was no interest income recognized on nonaccrual loans during 2018 , 2017 and 2016 while the loans were in nonaccrual status. During 2018 , 2017 and 2016 , the Corporation recognized $2.1 million , $1.3 million and $0.4 million , respectively, of interest income on these loans while they were in an accruing status. Additional interest income that would have been recorded on nonaccrual loans had they been current in accordance with their original terms was $4.8 million in 2018 , $3.1 million in 2017 and $2.9 million in 2016 . During 2018 , 2017 and 2016 , the Corporation recognized interest income of $2.7 million , $2.6 million and $3.9 million , respectively, on performing TDRs. The Corporation had $4.5 million of residential mortgage loans that were in the process of foreclosure at December 31, 2018 , compared to $4.2 million at December 31, 2017 . Loan delinquency, excluding acquired loans accounted for under ASC 310-30, was as follows: Loans Past Due and Still Accruing (Dollars in thousands) 30-89 days past due 90 days or more past due Total past due Nonaccrual Loans Current Total loans December 31, 2018 Originated Portfolio: Commercial $ 16,835 $ — $ 16,835 $ 30,139 $ 3,240,113 $ 3,287,087 Commercial real estate: Owner-occupied 4,657 52 4,709 16,056 1,492,767 1,513,532 Non-owner occupied 1,793 887 2,680 23,021 1,940,629 1,966,330 Vacant land 160 — 160 3,337 36,798 40,295 Total commercial real estate 6,610 939 7,549 42,414 3,470,194 3,520,157 Real estate construction and land development 247 — 247 12 566,467 566,726 Residential mortgage 1,688 — 1,688 7,988 2,397,629 2,407,305 Consumer installment 4,731 — 4,731 1,276 1,445,345 1,451,352 Home equity 3,843 488 4,331 3,604 604,194 612,129 Total $ 33,954 $ 1,427 $ 35,381 $ 85,433 $ 11,723,942 $ 11,844,756 December 31, 2017 Originated Portfolio: Commercial $ 16,269 $ — $ 16,269 $ 19,691 $ 2,371,646 $ 2,407,606 Commercial real estate: — Owner-occupied 4,078 — 4,078 19,070 1,162,466 1,185,614 Non-owner occupied 1,595 13 1,608 5,270 1,511,909 1,518,787 Vacant land 83 — 83 5,205 41,736 47,024 Total commercial real estate 5,756 13 5,769 29,545 2,716,111 2,751,425 Real estate construction and land development — — — 77 498,078 498,155 Residential mortgage 2,325 — 2,325 8,635 1,956,897 1,967,857 Consumer installment 3,663 — 3,663 842 1,506,035 1,510,540 Home equity 2,891 1,364 4,255 4,305 603,286 611,846 Total $ 30,904 $ 1,377 $ 32,281 $ 63,095 $ 9,652,053 $ 9,747,429 Impaired Loans A loan is impaired when, based on current information and events, it is probable that the Corporation will be unable to collect all amounts due according to the contractual terms of the loan agreement. Impaired loans include nonperforming loans and all TDRs. Impaired loans are accounted for at the lower of the present value of expected cash flows or the estimated fair value of the collateral. When the present value of expected cash flows or the fair value of the collateral of an impaired loan not accounted for under ASC 310-30 is less than the amount of unpaid principal outstanding on the loan, the recorded principal balance of the loan is reduced to its carrying value through either a specific allowance for loan loss or a partial charge-off of the loan balance. The following schedules present impaired loans by classes of loans at December 31, 2018 and December 31, 2017 : (Dollars in thousands) Recorded investment Unpaid principal balance Related valuation allowance December 31, 2018 Impaired loans with a valuation allowance: Commercial $ 20,957 $ 23,781 $ 3,546 Commercial real estate: Owner-occupied 14,702 16,519 1,359 Non-owner occupied 16,833 17,452 462 Vacant land 1,008 1,208 96 Total commercial real estate 32,543 35,179 1,917 Real estate construction and land development 126 126 11 Residential mortgage 10,867 10,867 816 Consumer installment 1,126 1,126 186 Home equity 4,432 4,432 328 Subtotal 70,051 75,511 6,804 Impaired loans with no related valuation allowance: Commercial 25,093 25,934 — Commercial real estate: Owner-occupied 10,971 11,601 — Non-owner occupied 12,412 13,411 — Vacant land 2,825 3,911 — Total commercial real estate 26,208 28,923 — Real estate construction and land development 111 111 — Residential mortgage 7,537 7,537 — Consumer installment 377 377 — Home equity 1,496 1,496 — Subtotal 60,822 64,378 — Total impaired loans: Commercial 46,050 49,715 3,546 Commercial real estate: Owner-occupied 25,673 28,120 1,359 Non-owner occupied 29,245 30,863 462 Vacant land 3,833 5,119 96 Total commercial real estate 58,751 64,102 1,917 Real estate construction and land development 237 237 11 Residential mortgage 18,404 18,404 816 Consumer installment 1,503 1,503 186 Home equity 5,928 5,928 328 Total $ 130,873 $ 139,889 $ 6,804 (Dollars in thousands) Recorded investment Unpaid principal balance Related valuation allowance December 31, 2017 Impaired loans with a valuation allowance: Commercial $ 28,897 $ 31,655 $ 2,296 Commercial real estate: Owner-occupied 17,774 21,588 2,317 Non-owner occupied 5,307 7,870 316 Vacant land 4,922 5,122 594 Total commercial real estate 28,003 34,580 3,227 Real estate construction and land development 313 313 14 Residential mortgage 15,872 15,872 1,487 Consumer installment 966 966 120 Home equity 4,570 4,570 858 Subtotal 78,621 87,956 8,002 Impaired loans with no related valuation allowance: Commercial 8,504 9,291 — Commercial real estate: Owner-occupied 11,351 12,631 — Non-owner occupied 5,977 6,438 — Vacant land 752 792 — Total commercial real estate 18,080 19,861 — Residential mortgage 4,902 4,902 — Home equity 1,770 1,770 — Subtotal 33,256 35,824 — Total impaired loans: Commercial 37,401 40,946 2,296 Commercial real estate: Owner-occupied 29,125 34,219 2,317 Non-owner occupied 11,284 14,308 316 Vacant land 5,674 5,914 594 Total commercial real estate 46,083 54,441 3,227 Real estate construction and land development 313 313 14 Residential mortgage 20,774 20,774 1,487 Consumer installment 966 966 120 Home equity 6,340 6,340 858 Total $ 111,877 $ 123,780 $ 8,002 The following schedule presents additional information regarding impaired loans by classes of loans segregated by those requiring a valuation allowance and those not requiring a valuation allowance at December 31, 2018 , 2017 and 2016 and the respective interest income amounts recognized: For the years ended December 31, 2018 2017 2016 (Dollars in thousands) Average annual recorded investment Interest income recognized while on impaired status Average annual recorded investment Interest income recognized while on impaired status Average annual recorded investment Interest income recognized while on impaired status Impaired loans with a valuation allowance: Commercial $ 17,683 $ 457 $ 25,099 $ 939 $ 7,829 $ — Commercial real estate: Owner-occupied 13,103 352 14,143 531 3,694 583 Non-owner occupied 6,440 48 3,274 89 1,711 139 Vacant land 1,881 47 2,566 57 253 113 Total commercial real estate 21,424 447 19,983 677 5,658 835 Real estate construction and land development 4,619 8 175 10 19 — Residential mortgage 12,179 457 16,390 538 23,958 1,285 Consumer installment 989 8 744 4 359 — Home equity 3,262 80 4,201 82 1,759 — Subtotal 60,156 1,457 66,592 2,250 39,582 2,120 Impaired loans with no related valuation allowance: Commercial 21,954 577 10,196 28 29,559 1,343 Commercial real estate: Owner-occupied 13,807 296 11,999 — 20,306 17 Non-owner occupied 10,681 263 9,143 241 14,306 339 Vacant land 2,730 — 3,516 4 7,034 45 Total commercial real estate 27,218 559 24,658 245 41,646 401 Real estate construction and land development 1,520 7 78 — 585 22 Residential mortgage 7,594 110 4,622 38 1,519 — Consumer installment 304 — 205 — — — Home equity 2,217 25 1,392 14 555 — Subtotal 60,807 1,278 41,151 325 73,864 1,766 Total impaired loans: Commercial 39,637 1,034 35,295 967 37,388 1,343 Commercial real estate: Owner-occupied 26,910 648 26,142 531 24,000 600 Non-owner occupied 17,121 311 12,417 330 16,017 478 Vacant land 4,611 47 6,082 61 7,287 158 Total commercial real estate 48,642 1,006 44,641 922 47,304 1,236 Real estate construction and land development 6,139 15 253 10 604 22 Residential mortgage 19,773 567 21,012 576 25,477 1,285 Consumer installment 1,293 8 949 4 359 — Home equity 5,479 105 5,593 96 2,314 — Total $ 120,963 $ 2,735 $ 107,743 $ 2,575 $ 113,446 $ 3,886 The difference between an impaired loan's recorded investment and the unpaid principal balance for originated loans represents a partial charge-off resulting from a confirmed loss due to the value of the collateral securing the loan being below the loan balance and management's assessment that full collection of the loan balance is not likely. Impaired loans included $45.6 million and $48.8 million at December 31, 2018 and December 31, 2017 , respectively, of accruing TDRs. Loans Modified Under Troubled Debt Restructurings (TDRs) The following tables present the recorded investment of loans modified into TDRs during the years ended December 31, 2018 , 2017 and 2016 by type of concession granted. In cases where more than one type of concession was granted, the loans were categorized based on the most significant concession. Concession type (Dollars in thousands) Principal Principal Interest Forbearance Total Pre- modification recorded investment Post- modification recorded investment For the year ended December 31, 2018 Commercial loan portfolio: Commercial $ 4,967 $ — $ 4,129 $ 1,438 67 $ 10,566 $ 10,534 Commercial real estate: Owner-occupied 981 — 2,945 953 19 5,018 4,879 Non-owner occupied 68 66 — — 2 143 134 Total commercial real estate 1,049 66 2,945 953 21 5,161 5,013 Subtotal 6,016 66 7,074 2,391 88 15,727 15,547 Consumer loan portfolio: Residential mortgage 269 151 147 — 9 577 567 Consumer installment 192 168 113 — 47 492 473 Home equity 469 73 453 — 25 1,076 995 Subtotal 930 392 713 — 81 2,145 2,035 Total loans $ 6,946 $ 458 $ 7,787 $ 2,391 169 $ 17,872 $ 17,582 Concession type (Dollars in thousands) Principal Principal Interest Forbearance Total Pre- modification recorded investment Post- modification recorded investment For the year ended December 31, 2017 Commercial loan portfolio: Commercial $ 2,308 $ — $ 1,827 $ 2,176 36 $ 6,416 $ 6,311 Commercial real estate: Owner-occupied 512 — 311 582 13 1,468 1,405 Non-owner occupied 194 — 27 371 3 629 592 Total commercial real estate 706 — 338 953 16 2,097 1,997 Real estate construction and land development 35 — — — 1 36 35 Subtotal 3,049 — 2,165 3,129 53 8,549 8,343 Consumer loan portfolio: Residential mortgage 297 — 383 — 11 763 680 Consumer installment 118 37 37 — 34 208 192 Home equity 389 — 52 — 14 537 441 Subtotal 804 37 472 — 59 1,508 1,313 Total loans $ 3,853 $ 37 $ 2,637 $ 3,129 112 $ 10,057 $ 9,656 Concession type (Dollars in thousands) Principal Principal A/B Note Restructure (1) Interest Forbearance Total Pre- modification recorded investment Post- modification recorded investment For the year ended December 31, 2016 Commercial loan portfolio: Commercial $ 11,533 $ 1,527 $ 43 $ — $ 1,750 54 $ 14,853 $ 14,853 Commercial real estate: Owner-occupied 2,508 1,866 — — — 13 4,374 4,374 Non-owner occupied 485 — — — — 3 485 485 Total commercial real estate 2,993 1,866 — — — 16 4,859 4,859 Subtotal 14,526 3,393 43 — 1,750 70 19,712 19,712 Consumer loan portfolio: Residential mortgage 477 — — — — 4 477 477 Consumer installment 87 — — — — 14 87 87 Home equity 179 — — 364 — 10 543 543 Subtotal 743 — — 364 — 28 1,107 1,107 Total loans $ 15,269 $ 3,393 $ 43 $ 364 $ 1,750 98 $ 20,819 $ 20,819 (1) Loan restructurings whereby the original loan is restructured into two notes: an "A" note, which generally reflects the portion of the modified loans which is expected to be collected: and a "B" note, which is fully charged off. The pre-modification and post-modification

Premises and Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Premises and Equipment	Premises and Equipment The following table summarizes premises and equipment: December 31, (Dollars in thousands) 2018 2017 Land and land improvements $ 31,357 $ 31,427 Buildings 133,720 130,028 Furniture and equipment 107,660 100,932 Total 272,737 262,387 Less accumulated depreciation (149,295 ) (135,491 ) Premises and equipment, net $ 123,442 $ 126,896 The Corporation leases certain branch properties and equipment under operating leases. Net rent expense was $7.7 million , $6.4 million and $3.3 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. During the years ended December 31, 2018 and 2017 , the Corporation had no transfers and $13.2 million transferred from premises and equipment to other assets, respectively, due to branch or building operation closings/consolidations.

Other Real Estate Owned and Rep

Other Real Estate Owned and Repossessed Assets	12 Months Ended
	Dec. 31, 2018
Other Real Estate [Abstract]
Other Real Estate Owned and Repossessed Assets	Other Real Estate Owned and Repossessed Assets Changes in other real estate owned and repossessed assets, included in interest receivable and other assets on the Consolidated Statements of Financial Position, were as follows: (Dollars in thousands) Other real estate Repossessed Balance at January 1, 2016 $ 9,716 $ 219 Additions due to acquisitions 13,227 313 Other additions (1) 9,938 3,032 Net payments received (1,560 ) (763 ) Disposals (13,873 ) (2,426 ) Write-downs (636 ) — Balance at December 31, 2016 $ 16,812 $ 375 Other additions (1) 6,905 4,641 Net payments received (1,064 ) — Disposals (12,831 ) (4,391 ) Write-downs (1,640 ) — Balance at December 31, 2017 $ 8,182 $ 625 Transfers based on adoption of ASU 2014-09 (2) (189 ) — Other additions (1) 7,179 4,307 Net payments received (249 ) — Disposals (7,825 ) (4,508 ) Write-downs (1,266 ) — Balance at December 31, 2018 $ 5,832 $ 424 (1) Includes loans transferred to other real estate owned and other repossessed assets. (2) In accordance with the updates to Topic 606 adopted by the Corporation effective January 1, 2018, $1.1 million of other real estate owned sold with seller financing were reclassified on the Consolidated Statements of Financial Position to loans and the related $0.9 million of deferred gains were recognized in income as an adjustment to opening retained earnings. Refer to Note 1 , Summary of Significant Accounting Policies for further information. At December 31, 2018 , the Corporation had $1.3 million of other real estate owned and repossessed assets as a result of obtaining physical possession in accordance with ASU No. 2014-04, Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans Upon Foreclosure. In addition, there were $4.5 million of consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings are in process, as of December 31, 2018 . Income and expenses related to other real estate owned and repossessed assets, recorded as a component of "Other" operating expenses in the Consolidated Statements of Income, were as follows: (Dollars in thousands) Other real estate owned Repossessed assets For the year ended December 31, 2018 Net gain (loss) on sale $ 1,372 $ (309 ) Write-downs (1,266 ) — Net operating expenses (858 ) (5 ) Total $ (752 ) $ (314 ) For the year ended December 31, 2017 Net gain (loss) on sale $ 3,038 $ (381 ) Write-downs (1,640 ) — Net operating expenses (1,981 ) (41 ) Total $ (583 ) $ (422 ) For the year ended December 31, 2016 Net gain on sale $ 5,325 $ 523 Write-downs (636 ) — Net operating expenses (740 ) (60 ) Total $ 3,949 $ 463

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill Goodwill was $1.13 billion at both December 31, 2018 and 2017 . The difference between consideration paid for the business and the net fair value of assets and liabilities is recognized as goodwill. The Corporation recorded goodwill in the amount of $847.7 million related to the merger with Talmer completed on August 31, 2016. Goodwill is not amortized but is subject to impairment testing annually as of October 31 and on an interim basis if events or changes in circumstances indicate assets might be impaired. Impairment exists when the carrying value of goodwill exceeds its fair value. The Corporation’s most recent annual goodwill impairment review performed as of October 31, 2018 did not indicate that an impairment of goodwill existed. The Corporation also determined that no triggering events have occurred that indicated impairment from the most recent valuation date through December 31, 2018 and that the Corporation's goodwill was no t impaired at December 31, 2018 .

Loan Servicing Rights

Loan Servicing Rights	12 Months Ended
	Dec. 31, 2018
Transfers and Servicing [Abstract]
Loan Servicing Rights	Loan Servicing Rights LSRs are created as a result of selling residential mortgage and commercial real estate loans in the secondary market while retaining the right to service these loans and receive servicing income over the life of the loan, and from acquisitions of other banks that had LSRs. Loans serviced for others are not reported as assets in the Consolidated Statements of Financial Position. The Corporation elected to account for LSRs acquired related to the merger with Talmer under the fair value measurement method. Prior to January 1, 2017, the Corporation accounted for all other LSRs at the lower of cost or fair value ("Amortized LSRs"). The Corporation elected as of January 1, 2017 to account for all previously amortized LSRs and all other LSRs under the fair value measurement method. This change in accounting policy resulted in a cumulative adjustment to retained earnings as of January 1, 2017 in the amount of $3.7 million . For further information on this election, refer to Note 1 , Summary of Significant Accounting Policies. LSRs are established and recorded at the estimated fair value by calculating the present value of estimated future net servicing cash flows, taking into consideration actual and expected mortgage loan prepayment rates, discount rates, servicing costs, and other economic factors, which are determined based on current market conditions. The following table represents the activity for LSRs and the related fair value changes: (Dollars in thousands) Commercial Real Estate Mortgage Total For the year ended December 31, 2018 Fair value, beginning of period $ 427 $ 63,414 $ 63,841 Additions from loans sold with servicing retained 139 8,087 8,226 Changes in fair value due to: Reductions from pay-offs, pay downs and run-off (115 ) (2,766 ) (2,881 ) Changes in estimates of fair value (1) — 1,827 1,827 Fair value, end of period $ 451 $ 70,562 $ 71,013 Principal balance of loans serviced $ 41,127 $ 6,826,952 $ 6,868,079 For the year ended December 31, 2017 Fair value, beginning of period $ 344 $ 47,741 $ 48,085 Transfers in based on new accounting policy election (2) — 15,891 15,891 Additions from loans sold with servicing retained 188 8,557 8,745 Changes in fair value due to: Reductions from pay-offs, pay downs and run-off (105 ) (2,400 ) (2,505 ) Changes in estimates of fair value (1) — (6,375 ) (6,375 ) Fair value, end of period $ 427 $ 63,414 $ 63,841 Principal balance of loans serviced $ 40,316 $ 7,068,431 $ 7,108,747 For the year ended December 31, 2016 Fair value, beginning of period $ — $ — $ — Acquired in Talmer Bancorp, Inc. merger 365 42,097 42,462 Additions from loans sold with servicing retained — 1,030 1,030 Changes in fair value due to: Reductions from pay-offs, pay downs and run-off (17 ) (502 ) (519 ) Changes in estimates of fair value (1) (4 ) 5,116 5,112 Fair value, end of period $ 344 $ 47,741 $ 48,085 Principal balance of loans serviced under the fair value measurement method $ 64,756 $ 5,235,415 $ 5,300,171 (1) Represents estimated LSR value change resulting primarily from market-driven changes in interest rates and prepayments. Included in "Net gain on sale of loans and other mortgage banking revenue" in the Consolidated Statements of Income. (2) The Corporation elected as of January 1, 2017 to account for all loan servicing rights previously accounted for at the lower of cost or fair value under the fair value measurement method. For further information on this election, refer to Note 1 , Summary of Significant Accounting Policies. The following shows the net carrying value and fair value of LSRs and the total loans that the Corporation serviced for others accounted for at the lower of cost or fair value for the year ended December 31, 2016: Year Ended December 31, (Dollars in thousands) 2016 Net carrying value of LSRs $ 10,230 Fair value of LSRs $ 15,891 Valuation allowance $ 8 Loans serviced for others that have servicing rights capitalized $ 2,074,057 Activity for LSRs accounted for at the lower of cost or fair value and the related valuation allowance for the year ended December 31, 2016 is as follows: Year Ended December 31, (Dollars in thousands) 2016 Balance at beginning of period $ 11,122 Additions 3,303 Amortization (4,187 ) Change in valuation allowance (8 ) Balance at end of period $ 10,230 Expected and actual loan prepayment speeds are the most significant factors driving the fair value of loan servicing rights. The following table presents assumptions utilized in determining the fair value of loan servicing rights as of December 31, 2018 and 2017 . Mortgage As of December 31, 2018 Prepayment speed 0.00 - 26.4% Weighted average ("WA") discount rate 10.1 % WA Cost to service/per year $ 66 WA Ancillary income/per year $ 31 WA float range 2.5 % As of December 31, 2017 Prepayment speed 0.00 - 38.8% WA discount rate 10.1 % WA Cost to service/per year $ 66 Ancillary income/per year $ 31 WA float range 1.6 % The Corporation realized total loan servicing fee income of $17.6 million , $18.2 million and $8.7 million for the years ended December 31, 2018 , 2017 and 2016 , respectively, recorded as a component of "Net gain on sale of loans and other mortgage banking revenue" in the Consolidated Statements of Income.

Other Intangible Assets

Other Intangible Assets	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Other Intangible Assets	Other Intangible Assets The following table shows the net carrying value of the Corporation's other intangible assets. December 31, (Dollars in thousands) 2018 2017 Core deposit intangible assets $ 28,556 $ 34,259 Non-compete intangible assets — 12 Total other intangible assets $ 28,556 $ 34,271 Core Deposit Intangible Assets The Corporation recorded core deposit intangible assets associated with each of its acquisitions and its merger with Talmer. Core deposit intangible assets are amortized on an accelerated basis over their estimated useful lives and have an estimated remaining weighted-average useful life of 6.6 years as of December 31, 2018 . The following table sets forth the carrying amount and accumulated amortization of core deposit intangible assets that are amortizable and arose from business combinations or other acquisitions: December 31, (Dollars in thousands) 2018 2017 Gross original amount $ 56,456 $ 59,143 Accumulated amortization 27,900 24,884 Net carrying amount $ 28,556 $ 34,259 Amortization expense recognized on core deposit intangible assets was $5.7 million , $6.0 million and $5.2 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. The estimated future amortization expense on core deposit intangible assets for the next five years is as follows: (Dollars in thousands) Estimated amortization expense 2019 $ 5,441 2020 4,851 2021 4,471 2022 4,218 2023 3,591

Derivative Instruments and Bala

Derivative Instruments and Balance Sheet Offsetting	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Balance Sheet Offsetting	Derivative Instruments and Balance Sheet Offsetting In the normal course of business, the Corporation enters into various transactions involving derivative instruments to manage exposure to fluctuations in interest rates and to meet the financing needs of customers (customer-initiated derivatives). These financial instruments involve, to varying degrees, elements of market and credit risk. Market and credit risk are included in the determination of fair value. Commitments to fund mortgage loans (interest rate locks) to be sold into the secondary market and forward commitments for the future delivery of mortgage loans to third party investors are considered derivatives. It is the Corporation’s practice to enter into forward commitments for the future delivery of mortgage loans when interest rate lock commitments are entered into in order to economically hedge the effect of changes in interest rates resulting from its commitments to fund the loans. The Corporation enters into interest rate derivatives to provide a service to certain qualifying customers to help facilitate their respective risk management strategies. These customer-initiated derivatives are not used for interest rate risk management purposes and primarily consist of interest rate swaps, interest rate caps and floors and foreign exchange contracts. The Corporation generally takes offsetting positions with dealer counterparts to mitigate the inherent risk. Income primarily results from the spread between the customer derivative and the offsetting dealer positions. Gains and losses on customer-related derivatives are included in other noninterest income. The Corporation utilizes interest rate swaps designated as cash flow hedges for risk management purposes to manage exposure that arises from business activities that result in the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates. These interest rate swaps designated as cash flow hedges are used to manage differences in the amount, timing and duration of the Corporation's known or expected cash receipts and its known or expected cash payments principally related to certain variable rate borrowings. The Corporation assesses the effectiveness of each hedging relationship by comparing the changes in cash flows of the derivative instruments with the changes in cash flows of the designated hedged transactions. The changes in fair value of derivatives designated and that qualify as cash flow hedges are recorded in accumulated other comprehensive income (loss) and are subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. For the Corporation's derivative instruments that are designated and qualify as a cash flow hedge, the gain or loss on the derivative instrument, as well as the offsetting loss or gain on the hedged item attributable to the hedged risk are recognized in current earnings in the same line item as the offsetting loss or gain on the related interest rate swap. The Corporation expects the hedges to remain highly effective during the remaining terms of the swaps. The Corporation additionally has written and purchased option derivatives consisting of instruments to facilitate an equity-linked time deposit product (the "Power Equity CD"). The Power Equity CD is a time deposit that provides the purchaser a guaranteed return of principal at maturity plus a potential equity return (a written option), while the Corporation receives a known stream of funds based on the equity return (a purchased option). The written and purchased options are mirror derivative instruments which are carried at fair value on the Consolidated Statements of Financial Position. The following table presents the notional amount and fair value of the Corporation’s derivative instruments held or issued in connection with customer-initiated and mortgage banking activities. December 31, 2018 2017 Fair Value Fair Value (Dollars in thousands) Notional Amount (1) Gross Derivative Assets (2) Gross Derivative Liabilities (2) Notional Amount (1) Gross Derivative Assets (2) Gross Derivative Liabilities (2) Risk management purposes: Derivatives designated as hedging instruments: Interest rate swaps $ 820,000 $ 10,148 $ 3,278 $ 620,000 $ 5,899 $ — Total risk management purposes 820,000 10,148 3,278 620,000 5,899 — Customer-initiated and mortgage banking derivatives: Customer-initiated derivatives 2,477,640 26,680 27,664 1,365,119 9,376 10,139 Foreign exchange forwards (3) — — — — — — Forward contracts related to mortgage loans to be delivered for sale 127,159 — 719 115,996 — 34 Interest rate lock commitments 54,848 1,049 — 71,003 1,222 — Power Equity CD 36,771 718 718 38,807 2,184 2,184 Total customer-initiated and mortgage banking derivatives 2,696,418 28,447 29,101 1,590,925 12,782 12,357 Total gross derivatives $ 3,516,418 $ 38,595 $ 32,379 $ 2,210,925 $ 18,681 $ 12,357 (1) Notional or contract amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Statements of Financial Position. (2) Derivative assets are included within "Interest receivable and other assets" and derivative liabilities are included within "Interest Payable and other liabilities" on the Consolidated Statements of Financial Position. Included in the fair value of the derivative assets are credit valuation adjustments for counterparty credit risk totaling $0.9 million at December 31, 2018 and $0.8 million at December 31, 2017 . (3) The foreign exchange forwards that were entered into during the years ended December 31, 2018 and 2017 matured prior to each respective year end. In the normal course of business, the Corporation may decide to settle a forward contract rather than fulfill the contract. Cash received or paid in this settlement manner is included in "Net gain on sale of loans and other mortgage banking revenue" in the Consolidated Statements of Income and is considered a cost of executing a forward contract. The following table presents the net gains (losses) related to derivative instruments reflecting the changes in fair value. For the years ended December 31, (Dollars in thousands) Location of Gain (Loss) 2018 2017 2016 Forward contracts related to mortgage loans to be delivered for sale Net gain on sale of loans and other mortgage banking revenue $ (685 ) $ (669 ) $ 692 Interest rate lock commitments Net gain on sale of loans and other mortgage banking revenue (173 ) 266 (1,356 ) Power Equity CD Other noninterest income — — — Foreign exchange forwards Other noninterest income — — — Customer-initiated derivatives Other noninterest income (221 ) (1,028 ) 581 Total gain (loss) recognized in income $ (1,079 ) $ (1,431 ) $ (83 ) The following table presents the net gains (losses) recorded in accumulated other comprehensive income and the Consolidated Statements of Income relating to interest rate swaps designated as cash flow hedges for the years ended December 31, 2018 and 2017 . The Corporation first began entering into interest rate swaps designated as cash flow hedges during the year ended December 31, 2017. (Dollars in thousands) Amount of gain recognized in other comprehensive income Amount of gain (loss) reclassified from other comprehensive income to interest income or expense Year Ended December 31, 2018 Interest rate swaps designated as cash flow hedges $ 2,841 $ 1,871 Year Ended December 31, 2017 Interest rate swaps designated as cash flow hedges $ 4,263 $ (1,633 ) At December 31, 2018 , the Corporation expected $4.5 million of unrealized gains to be reclassified as a decrease to interest expense during the following twelve months. Methods and assumptions used by the Corporation in estimating the fair value of its forward contracts, interest rate lock commitments and customer-initiated derivatives are discussed in Note 3 : Fair Value Measurements. Balance Sheet Offsetting Certain financial instruments, including customer-initiated derivatives and interest rate swaps, may be eligible for offset in the Consolidated Statements of Financial Position and/or subject to master netting arrangements or similar agreements. The Corporation is party to master netting arrangements with its financial institution counterparties; however, the Corporation does not offset assets and liabilities under these arrangements for financial statement presentation purposes based on an accounting policy election. The tables below present information about the Corporation’s financial instruments that are eligible for offset. Gross amounts not offset in the (Dollars in thousands) Gross Gross amounts Net amounts Financial Collateral Net December 31, 2018 Offsetting derivative assets Derivative assets (1) $ 36,791 $ — $ 36,791 $ — $ (16,120 ) $ 20,671 Offsetting derivative liabilities Derivative liabilities (1) 30,822 — 30,822 — 430 30,392 December 31, 2017 Offsetting derivative assets Derivative assets (1) $ 15,228 $ — $ 15,228 $ — $ — $ 15,228 Offsetting derivative liabilities Derivative liabilities 10,139 — 10,139 — 1,081 9,058 (1) Amount does not include participated interest rate swaps, forward contracts, interest rate lock commitments and power equity CDs as these instruments are not subject to master netting or similar arrangements.

Commitments, Contingencies and

Commitments, Contingencies and Guarantees	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments, Contingencies and Guarantees	Commitments, Contingencies and Guarantees Commitments In the normal course of business, the Corporation offers a variety of financial instruments containing credit risk that are not required to be reflected in the Consolidated Statements of Financial Position. These financial instruments include outstanding commitments to extend credit, approved but undisbursed loans (undisbursed loan commitments), credit lines, commercial letters of credit and standby letters of credit. The Corporation has risk management policies to identify, monitor and limit exposure to credit risk. To mitigate credit risk for these financial guarantees, the Corporation generally determines the need for specific covenant, guarantee and collateral requirements on a case-by-case basis, depending on the nature of the financial instrument and the customer's creditworthiness. At December 31, 2018 and 2017 , the Corporation had $119.0 million and $187.6 million , respectively, of outstanding financial and performance standby letters of credit. The majority of these standby letters of credit are collateralized. The Corporation determined that there were no potential losses from standby letters of credit at December 31, 2018 and 2017 . Commitments to extend credit are agreements to lend to a customer provided there is no violation of any condition established in the commitment. Commitments generally have fixed expiration dates or other termination clauses and may not require payment of a fee. Since many commitments expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The Corporation evaluates each customer's creditworthiness on an individual basis. The amount of collateral obtained, if deemed necessary by the Corporation upon extension of credit, is based on management's credit evaluation of the counterparty. The collateral held varies, but may include securities, real estate, accounts receivable, inventory, plant or equipment. Unfunded commitments under commercial lines of credit, revolving credit lines and overdraft protection agreements are included in commitments to extend credit. These lines of credit are generally not collateralized, usually do not contain a specified maturity date and may be drawn upon only to the total extent to which the Corporation is committed. At December 31, 2018 and 2017 , the Corporation had $3.55 billion and $3.03 billion , respectively, of commitments to extend credit. The Corporation had undisbursed loan commitments of $493.3 million and $571.0 million at December 31, 2018 and 2017 , respectively. Undisbursed loan commitments are not included in loans on the Consolidated Statements of Financial Position. The majority of undisbursed loan commitments will be funded and convert to a portfolio loan within a one year period. The allowance for credit losses on lending-related commitments included $1.7 million and $1.2 million at December 31, 2018 and 2017 , respectively, for probable credit losses inherent in the Corporation's unused commitments and was recorded in "Interest payable and other liabilities" in the Consolidated Statements of Financial Position. Contingencies and Guarantees The Corporation has originated and sold certain loans, and additionally acquired the potential liability for those historical originated and sold loans by merged or acquired entities, for which the buyer has limited recourse to us in the event the loans do not perform as specified in the agreements. These loans had an outstanding balance of $11.6 million and $13.3 million at December 31, 2018 and 2017 , respectively. The maximum potential amount of undiscounted future payments that the Corporation could be required to make in the event of nonperformance by the borrower totaled $11.4 million and $12.8 million at December 31, 2018 and 2017 , respectively. In the event of nonperformance, the Corporation has rights to the underlying collateral securing the loans. At December 31, 2018 and 2017 , the Corporation had recorded a liability of $0.1 million and $0.2 million , respectively, in connection with the recourse agreements, recorded in "Interest payable and other liabilities" in the Consolidated Statements of Financial Position. In addition, the Corporation acquired certain SBA guaranteed notes in which the guaranteed portion had been sold to a third party investor prior to the Corporation's acquisition. In the event these loans default and the SBA guaranty is no longer intact (i.e. an issue found to have occurred during the origination or the liquidation of the loans) the Corporation would be liable to make the loan whole to the third party investor. The maximum potential amount of undiscounted future payments that the Corporation could be required to make in the event of default by the borrower totaled $19.1 million and $20.6 million at December 31, 2018 and 2017 , respectively. In the event of default, the Corporation has rights to the underlying collateral securing the loans. At both December 31, 2018 and 2017 , the Corporation had recorded a liability of $1.2 million . Representations and Warranties In connection with the Corporation's mortgage banking loan sales, and the historical sales of merged or acquired entities, the Corporation makes certain representations and warranties that the loans meet certain criteria, such as collateral type and underwriting standards. The Corporation may be required to repurchase individual loans and/or indemnify the purchaser against losses if the loan fails to meet established criteria. At December 31, 2018 and 2017 , respectively, the liability recorded in connection with these representations and warranties totaled $4.1 million and $5.3 million , respectively. A summary of the reserve for representations and warranties of the Corporation is as follows: For the years ended December 31, (Dollars in thousands) 2018 2017 2016 Reserve balance at beginning of period $ 5,349 $ 6,459 $ 4,048 Addition of fair value of representations and warranties due to mergers and acquisitions — — 3,100 Reserve reduction (1,217 ) (1,095 ) (580 ) Charge-offs (48 ) (15 ) (109 ) Ending reserve balance $ 4,084 $ 5,349 $ 6,459 Reserve balance: Liability for specific claims $ 398 $ 531 $ 730 General allowance 3,686 4,818 5,729 Total reserve balance $ 4,084 $ 5,349 $ 6,459 Operating Leases and Other Noncancelable Contractual Obligations The Corporation has operating leases and other noncancelable contractual obligations on buildings, equipment, computer software and other expenses that will require annual payments through 2034 , including renewal option periods for those building leases that the Corporation expects to renew. Future minimum lease payments for operating leases and other noncancelable contractual obligations are as follows: (Dollars in thousands) Future Minimum Lease Payments (1) Other Noncancelable Contracts Total Years ending December 31, 2019 $ 7,251 $ 46,225 $ 53,476 2020 6,239 37,566 43,805 2021 5,135 31,330 36,465 2022 4,775 30,124 34,899 2023 4,375 27,849 32,224 Thereafter 12,107 46,771 58,878 Total $ 39,882 $ 219,865 $ 259,747 (1) Future minimum lease payments are reduced by $632 thousand related to sublease income to be received within the next five years. Minimum payments include estimates, where applicable, of estimated usage and annual Consumer Price Index increases of approximately 1.9% . Total expense recorded under operating leases and other noncancelable contractual obligations was $55.2 million in 2018 , compared to $30.8 million in 2017 and $20.4 million in 2016 . Legal Proceedings The Corporation and Chemical Bank are subject to various pending or threatened legal proceedings arising out of the normal course of business and related to our merger and acquisition history. The Corporation assesses its liabilities and contingencies in connection with outstanding legal proceedings utilizing the latest information available. Where it is probable that the Corporation will incur a loss and the amount of the loss can be reasonably estimated, the Corporation records a liability in the Consolidated Financial Statements. While the ultimate liability with respect to these litigation matters and claims cannot be determined at this time, in the opinion of management, the ultimate disposition of these matters is not expected to have a material adverse effect on the financial position or results of operations of the Corporation.

Investments in Qualified Afford

Investments in Qualified Affordable Housing Projects, Federal Historic Projects and New Market Tax Credits	12 Months Ended
	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Investments in Qualified Affordable Housing Projects, Federal Historic Projects and New Market Tax Credits	Investments in Qualified Affordable Housing Projects, Federal Historic Projects and New Market Tax Credits The Corporation invests in qualified affordable housing projects, federal historic projects, and new market projects for the purpose of community reinvestment and obtaining tax credits. Return on the Corporation's investment in these projects comes in the form of the tax credits and tax losses that pass through to the Corporation. The carrying value of the investments is reflected in "Interest receivable and other assets" on the Consolidated Statements of Financial Position. The Corporation utilizes the proportional amortization method to account for investments in qualified affordable housing projects and the equity method to account for investments in other tax credit projects. Under the proportional amortization method, the Corporation amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits. The Corporation recognized additional income tax expense attributable to the amortization of investments in qualified affordable housing projects of $4.2 million , $3.4 million and $2.6 million during the years ended December 31, 2018 , 2017 and 2016 , respectively. The Corporation's remaining investment in qualified affordable housing projects accounted for under the proportional amortization method totaled $84.9 million at December 31, 2018 and $51.4 million at December 31, 2017 . Under the equity method, the Corporation's share of the earnings or losses is included in "Other" operating expenses on the Consolidated Statements of Income. The Corporation's remaining investment in new market projects accounted for under the equity method totaled $13.3 million and $17.3 million at December 31, 2018 and 2017 , respectively. The Corporation's unfunded equity contributions relating to investments in qualified affordable housing projects, federal historic tax projects and new market projects is recorded in "Interest payable and other liabilities" on the Consolidated Statements of Financial Position. The Corporation's remaining unfunded equity contributions totaled $72.0 million and $48.1 million at December 31, 2018 and 2017 , respectively. Management analyzes these investments for potential impairment when events or changes in circumstances indicate that it is more-likely-than-not that the carrying amount of the investment will not be r ea lized. An impairment loss is measured as the amount by which the carrying amount of an investment exceeds its fair value. During the year ended December 31, 2018 , federal housing tax credits resulted in income tax benefit of $12.9 million , partially offset by impairment expense of $12.3 million , representing $9.7 million net of tax, recorded in "other noninterest expense. " During the year ended December 31, 2017 , federal housing tax credits were placed into service resulting in income tax benefit of $7.9 million , partially offset by impairment expense of $9.3 million , representing $6.0 million net of tax, recorded in "Other" operating expenses. There was no impairment loss recognized as of December 31, 2016 . The Corporation consolidates variable interest entities ("VIEs") in which it is the primary beneficiary. In general, a VIE is an entity that either (i) has an insufficient amount of equity to carry out its principal activities without additional subordinated financial support, (ii) has a group of equity owners that are unable to make significant decisions about its activities or (iii) has a group of equity owners that do not have the obligation to absorb losses or the right to receive returns as generated by its operations. If any of these characteristics are present, the entity is subject to a variable interest consolidation model, and consolidation is based on variable interests, not on ownership of the entity's outstanding voting stock. Variable interests are defined as contractual, ownership, or other monetary interests in an entity that change with fluctuations in the entity's net asset value. The primary beneficiary consolidates the VIE. The primary beneficiary is defined as the enterprise that has the power to direct the activities and absorb losses or the right to receive benefits. The Corporation is a significant limited partner in the qualified affordable housing, federal historic and new market projects it has invested in. These projects meet the definition of VIEs. However, the Corporation is not the primary beneficiary of any of the VIEs in which it holds a limited partnership interest; therefore, the VIEs are not consolidated in the Consolidated Financial Statements.

Deposits

Deposits	12 Months Ended
	Dec. 31, 2018
Deposits [Abstract]
Deposits	Deposits A summary of deposits follows: December 31, (Dollars in thousands) 2018 2017 Noninterest-bearing demand $ 3,809,252 $ 3,725,779 Savings and money market accounts 4,092,082 3,655,671 Interest-bearing demand 3,316,278 2,724,415 Brokered deposits 985,522 453,227 Other time deposits 3,390,148 3,083,711 Total deposits $ 15,593,282 $ 13,642,803 Excluded from total deposits are demand deposit account overdrafts (overdrafts) which have been classified as loans. At December 31, 2018 and 2017 , overdrafts totaled $7.9 million and $5.9 million , respectively. Deposits from executive officers, directors, principal shareholders and their related interests were $9.8 million at December 31, 2018 . Time deposits, including certificates of deposit and certain individual retirement account deposits, of $250 thousand or more totaled $2.1 billion and $1.6 billion at December 31, 2018 and 2017 , respectively. At December 31, 2018 , the scheduled maturities of time deposits for the next five years were as follows: (Dollars in thousands) 2019 $ 2,776,097 2020 1,032,314 2021 148,995 2022 82,076 2023 33,900 Thereafter 866 Total $ 4,074,248

Borrowings and Other Short-term

Borrowings and Other Short-term Liabilities	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Borrowings and Other Short-term Liabilities	Borrowings and Other Short-Term Liabilities A summary of the Corporation's short- and long-term borrowings, and other short-term liabilities follows: December 31, 2018 2017 (Dollars in thousands) Amount Weighted Average Rate (1) Amount Weighted Average Rate (1) Short-term borrowings: FHLB advances: 2.46% - 2.59% fixed-rate notes $ 2,035,000 2.47 % $ 2,000,000 1.39 % Long-term borrowings: FHLB advances: 1.00% - 2.72% fixed-rate notes due 2019 to 2025 (2) 410,102 2.00 % 337,204 1.26 % Line-of-credit: floating-rate based on one-month LIBOR plus 1.75% — — 19,963 3.10 % Subordinated debt obligations: floating-rate based on three-month LIBOR plus 1.45% - 2.85% due 2034 to 2035 (3) 11,572 4.85 % 11,425 3.69 % Subordinated debt obligations: floating-rate based on three-month LIBOR plus 3.25% due in 2032 (4) 4,328 5.65 % 4,290 4.59 % Total long-term borrowings 426,002 2.11 % 372,882 1.47 % Total borrowings $ 2,461,002 2.41 % $ 2,372,882 1.40 % Other short-term liabilities: Collateralized customer deposits $ 382,687 0.75 % $ 415,236 0.44 % (1) Weighted average rate presented is the contractual rate which excludes premiums and discounts related to purchase accounting. (2) The December 31, 2018 balance includes advances payable of $410.0 million and purchase accounting premiums of $0.1 million . The December 31, 2017 balance includes advances payable of $337.0 million and purchase accounting premiums of $0.2 million . (3) The December 31, 2018 balance includes advances payable of $15.0 million and purchase accounting discounts of $3.4 million . The December 31, 2017 balance includes advance payable of $15.0 million and purchase accounting discounts of $3.6 million . (4) The December 31, 2018 balance includes advances payable of $5.0 million and purchase accounting discounts of $0.7 million . The December 31, 2017 balance includes advance payable of $5.0 million and purchase accounting discounts of $0.7 million . Chemical Bank is a member of the FHLB, which provides short- and long-term funding collateralized by mortgage related assets to its members. Each advance is payable at its maturity date, with a prepayment penalty for fixed-rate advances. The Corporation's FHLB advances, including both short-term and long-term, require monthly interest payments and are collateralized by commercial and residential mortgage loans totaling $7.81 billion as of December 31, 2018 . The Corporation's additional borrowing availability through the FHLB, subject to the FHLB's credit requirements and policies and based on the amount of FHLB stock owned by the Corporation, was $230.1 million at December 31, 2018 . Effective January 1, 2018, the Corporation adopted ASU 2016-01. As a result, the Corporation will continue to report FHLB and FRB stock at cost. At December 31, 2018 , the contractual principal payments due and the amortization/accretion of purchase accounting adjustments for the remaining maturities of long-term debt over the next five years and thereafter are as follows: (Dollars in thousands) Long-term Debt by Maturity Years Ending December 31, 2019 $ 100,058 2020 110,044 2021 — 2022 — 2023 — Thereafter 215,900 Total $ 426,002

Revenue from Contracts with Cus

Revenue from Contracts with Customers	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	Revenue from Contracts with Customers The Corporation earns a variety of revenue including interest and fees from customers as well as revenues from non-customers. Certain sources of revenue are recognized within interest income and are outside of the scope of ASC Topic 606, Revenue from Contracts with Customers ("ASC 606"). Other sources of revenue fall within the scope of ASC 606 and are mostly recognized within "Noninterest Income" in the Consolidated Statements of Income. The Corporation recognizes revenue when the performance obligations related to the transfer of goods or services under the terms of a contract are satisfied. Some obligations are satisfied at a point in time while others are satisfied over a period of time. Revenue is recognized as the amount of consideration expected to be received in exchange for transferring goods or services to a customer and is segregated based on the nature of product and services offered as part of contractual arrangements. Revenue within the scope of ASC 606 are discussed below. • Service charges and fees on deposit accounts include fees and other charges the Corporation receives to provide various services, including but not limited to, maintaining an account with a customer, providing overdraft services, wire transfers, transferring funds, and accepting and executing stop-payment orders. The consideration includes both fixed (e.g., account maintenance fees) and transaction fees (i.e., wire-transfer fee). Fixed fees are recognized over the period of time the service is provided while transaction fees are recognized when a specific service is rendered to the customer. • Wealth management revenue includes fee income generated from personal and institutional customers. The Corporation also provides investment management services. Services are rendered over a period of time, over which revenue is recognized. Wealth management revenue also includes commissions that are earned for placing a brokerage transaction for execution, such as stocks or other investments. Revenue is recognized once the transaction is completed and the Corporation is entitled to receive consideration. • Other charges and fees for customer services includes service charges on deposit accounts and other fees including account analysis fees, monthly service fees, check orders, ATM fees and other service charges. The Corporation's performance obligation for account analysis fees and monthly service fees is generally satisfied, and therefore, revenue is recognized over the period in which the service is provided. Check orders and other deposit account related fees are largely transactional based, and therefore, the performance obligation is satisfied and related revenue recognized, at a point in time. • Other noninterest expense includes net gain or loss on sales of other real estate and repossessed assets. Revenue is recognized at the time the sale is complete and the Corporation is entitled to receive consideration, including sales that are seller financed as receipt of all payment is expected. The following table presents total noninterest income segregated between contracts with customers within the scope of ASC 606 and those within the scope of other GAAP Topics. The following additionally presents revenues from customers and non-customers that are included within noninterest income and expense. Year Ended December 31, (Dollars in thousands) 2018 Noninterest income Service charges and fees on deposit accounts $ 22,858 Wealth management revenue 5,099 Other charges and fees for customer services 5,556 Noninterest income from contracts with customers within the scope of ASC 606 33,513 Noninterest income within the scope of other GAAP topics 115,023 Total noninterest income $ 148,536 Noninterest expense Other $ (1,063 ) Contract Balances A contract asset balance occurs when an entity performs a service for a customer before the customer pays consideration (resulting in a contract receivable) or before payment is due (resulting in a contract asset). A contract liability balance is an entity's obligation to transfer a service to a customer for which the entity has already received payment (or payment is due) from the customer. The Corporation's noninterest income streams are largely based on transactional activity, or standard month-end revenue accruals such as asset management fees based on month-end market values. Consideration is most often received immediately or shortly after the Corporation satisfies its performance obligation and revenue is recognized. The Corporation does not typically enter into long-term revenue contracts with customers, and therefore, does not experience significant contract balances. As of December 31, 2018 and December 31, 2017 , the Corporation did not have a material amount of contract balances.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The current and deferred components of the provision for income taxes were as follows: Years Ended December 31, (Dollars in thousands) 2018 2017 2016 Current income tax expense (benefit) Federal $ (653 ) $ 14,665 $ 19,144 State 321 20 (423 ) Total current income tax expense (332 ) 14,685 18,721 Deferred income tax expense Federal 41,687 92,636 23,649 State 229 548 442 Total deferred income tax expense 41,916 93,184 24,091 Change in valuation allowance 317 (1,089 ) (706 ) Income tax provision $ 41,901 $ 106,780 $ 42,106 A reconciliation of expected income tax expense at the federal statutory income tax rate and the amounts recorded in the Consolidated Financial Statements were as follows: Years Ended December 31, 2018 2017 2016 (Dollars in thousands) Amount Rate Amount Rate Amount Rate Tax at statutory rate $ 68,443 21.0 % $ 89,706 35.0 % $ 52,548 35.0 % Changes resulting from: Tax-exempt interest income (6,513 ) (2.0 ) (9,001 ) (3.5 ) (5,320 ) (3.5 ) State taxes, net of federal benefit 434 0.1 369 0.1 13 — Change in valuation allowance 317 0.1 (1,089 ) (0.4 ) (706 ) (0.5 ) Bank-owned life insurance adjustments (838 ) (0.2 ) (1,696 ) (0.7 ) (832 ) (0.6 ) Director plan change in control — — — — (508 ) (0.3 ) Income tax credits, net (16,148 ) (4.9 ) (11,449 ) (4.4 ) (2,454 ) (1.6 ) Nondeductible transaction expenses — 156 0.1 2,100 1.4 Nondeductible FDIC insurance premiums 1,095 0.3 — — — — Tax benefit in excess of compensation costs on share-based payments (1) (1,782 ) (0.5 ) (5,886 ) (2.3 ) (2,240 ) (1.5 ) Impact of the Tax Cuts and Jobs Act (2) (2,939 ) (0.9 ) 46,660 18.2 — — Other, net (168 ) (0.1 ) (990 ) (0.4 ) (495 ) (0.4 ) Income tax expense $ 41,901 12.9 % $ 106,780 41.7 % $ 42,106 28.0 % (1) Represents excess tax benefits resulting from the exercise or settlement of share-based payment transactions. (2) The year ended December 31, 2017 included the initial calculated impact of the enactment of H.R.1 (the "Tax Cuts and Jobs Act"), which required a revaluation of net deferred tax assets and liabilities. The year ended December 31, 2018 included the impact of analyzing additional information in the year following the enactment date of the Tax Cuts and Jobs Act that was not previously available, as allowed by Staff Accounting Bulletin (SAB) No. 118, issued in late December 2017. See below for further details. On December 22, 2017, H.R.1 (known as the "Tax Cuts and Jobs Act") was signed into law. Among other provisions, the Tax Cuts and Jobs Act, reduced the statutory corporate income tax rate from a maximum rate of 35% to a flat tax rate of 21% , effective January 1, 2018. ASC Topic 740 requires the recognition of the effects of tax law changes be recorded in the period in which the law is enacted. Therefore, the Corporation's deferred tax assets and liabilities which were previously valued at a federal rate of 35%, were revalued to the current enacted federal tax rate of 21% as of December 31, 2017. In addition, the SEC issued Staff Accounting Bulletin No. 118 to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available in reasonable detail to complete the accounting for certain income tax effects of the Tax Cuts and Jobs Act, thereby allowing a measurement period to reflect provisional adjustments as information becomes available. The measurement period includes the Tax Cuts and Jobs Acts' enactment date up until one year after. During the year ended December 31, 2017, the impact of the Tax Cuts and Jobs Act resulted in a $46.7 million increase to income tax expense related to continuing operations as a result of the revaluation of the net deferred tax asset of $46.0 million and an acceleration of amortization expense on the low income housing tax credit investment portfolio of $0.7 million . The Corporation did not have any provisional adjustments to its net deferred tax asset as a result of the tax reform at December 31, 2017 under Staff Accounting Bulletin No. 118, but continued to obtain, prepare and analyze information as it became available during 2018 in order to complete the accounting requirements under ASC Topic 740 by utilizing the measurement period afforded under SAB 118. These adjustments were finalized with the filing of the Company's 2017 Federal tax return in the fourth quarter and resulted in a tax benefit of $2.9 million . Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The significant components of the deferred tax assets and liabilities at December 31, 2018 and 2017 were as follows: December 31, (Dollars in thousands) 2018 2017 Deferred tax assets: Allowance for loan losses $ 24,019 $ 20,446 Acquisition-related fair value adjustments 16,511 27,607 Unrealized loss on securities 10,040 2,751 Accrued stock-based compensation 3,239 4,082 Loss and tax credit carry forwards 30,169 57,969 Nonaccrual loan interest 10,830 6,155 Accrued expense 7,397 9,200 Other 4,888 9,330 Total deferred tax assets 107,093 137,540 Deferred tax liabilities: Loan servicing rights 14,941 13,446 Core deposit intangible assets 4,966 6,022 Goodwill 4,281 4,076 Deferred loan fees 4,963 4,551 Prepaid expenses 5,625 7,390 Other 5,894 3,184 Total deferred tax liabilities 40,670 38,669 Net deferred tax asset before valuation allowance 66,423 98,871 Valuation allowance (1,467 ) (1,150 ) Net deferred tax asset $ 64,956 $ 97,721 The valuation allowance against the Corporation’s deferred tax assets at December 31, 2018 and 2017 totaled $1.5 million and $1.2 million respectively. The valuation allowance at December 31, 2018 included management’s estimate of capital loss carry forwards more likely than not to expire unutilized. Included in the valuation allowance at December 31, 2017 was $0.6 million due to IRC Section 382 limitations on the utilization of pre-ownership change loss and tax credit carry forwards associated with previously acquired entities and $0.6 million due to management’s estimate of capital loss carry forwards more likely than not to expire unutilized. Actual outcomes could vary from the Corporation's current estimates, resulting in future increases or decreases in the valuation allowance and corresponding future tax expense or benefit. Management concluded that no valuation allowance was necessary on the remainder of the Corporation's net deferred tax assets at December 31, 2018 and 2017 . This determination was based on the Corporation's history of pre-tax and taxable income over the prior three years, as well as management's expectations for sustainable profitability in the future. Management monitors deferred tax assets quarterly for changes affecting the ability to realize and the valuation allowance could be adjusted in future periods. The following table is a summary of the loss attributes, Section 382 limitations, and tax expiration periods as of December 31, 2018 . From the Acquisition of: Talmer Bancorp and Talmer Bank Prior Ownership Changes (Dollars in thousands) Monarch First Place Holdings/First Place Bank Talmer West Bank First of Huron Corp./Signature Bank From 2009 Ownership change Not Limited by Section 382 Total Tax Loss and Credit Carryforwards as of 12/31/18: Years Expiring (except AMT Credits) 2026-2034 2027-2031 2028-2032 2029-2032 2027-2029 Annual Section 382 limitation-base (1) $ 673 $ 6,650 $ 3,028 $ 365 $ 145 $ — $ N/A Gross Federal Net Operating Losses 12,350 — 41,039 247 1,595 — 55,231 Gross Capital Losses — — — — — 6,987 6,987 Realized Built-in Losses — 61,317 8,936 — — — 70,253 Business Tax Credits 1,651 781 — — — — 2,432 Less amounts not recorded due to Sec 382 Limitation (1,738 ) (140 ) — — (145 ) — (2,023 ) Alternative Minimum Tax Credits - no expiration 106 2,115 — 303 — — 2,524 Valuation Allowance — — — — — (1,467 ) (1,467 ) (1) In respect to the Monarch acquisition, in addition to the statutory "base" Section 382 limitation, recognized built in gain increases the Section 382 limitation during the five year period beginning on the acquisition date. The Corporation estimates that the recognized built in gain will total $1.6 million . At December 31, 2018 , the Corporation had approximately $36.0 million of bad debt reserve in equity for which no provision for federal income taxes was recorded. This amount represents Talmer's qualifying thrift bad debt reserve at December 31, 1987 through its acquisition of First Place Bank, which is only required to be recaptured into taxable income if certain events occur. At December 31, 2018 , the potential tax on the above amount was approximately $7.5 million . The Corporation concluded its audit for Talmer Bancorp's Financial Institutions tax for the years ended December 31, 2013, 2014 and 2015, with no changes. The Corporation's federal tax returns for the years ended December 31, 2015 to present are open to potential examination. Talmer amended its four federal tax returns for the years 2011, 2012, 2013 and 2014 to reflect the impact of changes to First Place Bank due to an IRS settlement in January of 2016. These four amendments were selected for audit which concluded with no changes and all expected refunds were received in 2017.The Corporation's most significant states of operation, Michigan and Ohio, do not impose income-based taxes on financial institutions. The Corporation and/or its subsidiaries are subject to immaterial amounts of income tax in various other states, with varying years open to potential examination. The Corporation concluded its audit for Talmer Bancorp's Ohio Financial Institutions tax for the years ended December 31, 2013, 2014, and 2015, with no changes. The Corporation had no unrecognized tax benefits at December 31, 2018 or 2017 and does not expect to record unrecognized tax benefits of any significance during the next twelve months. The Corporation recognizes interest and/or penalties related to income tax matters in income tax expense, when applicable. There were no liabilities accrued for interest and/or penalties at December 31, 2018 or 2017 .

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	Share-Based Compensation The Corporation maintains share-based compensation plans under which it periodically grants share-based awards for a fixed number of shares to certain officers of the Corporation. The fair value of share-based awards is recognized as compensation expense over the requisite service or performance period. During the years ended December 31, 2018 , 2017 and 2016 , share-based compensation expense related to share-based awards totaled $8.6 million , $17.3 million and $14.7 million , respectively. The excess tax benefit realized from shared-based compensation transactions during the years ended December 31, 2018 , 2017 and 2016 was $1.8 million , $6.1 million and $2.2 million , respectively. During the year ended December 31, 2018 , the Corporation granted 321,043 restricted stock units to certain officers of the Corporation. On April 26, 2017, the shareholders of the Corporation approved the Stock Incentive Plan of 2017, which provides for 1,750,000 shares of the Corporation's common stock to be made available for future equity-based awards and canceled the amount of shares available for future grant under prior share-based compensation plans. At December 31, 2018 , there were 1,301,285 shares of common stock available for future grants under the Stock Incentive Plan of 2017. Stock Options The Corporation issues stock options to certain officers from time to time. The exercise price on stock options equals the current market price of the Corporation's common stock on the date of grant and stock options expire ten years from the date of grant. Stock options granted after 2012 vest ratably over a five -year period. Stock options granted prior to 2013 generally vest ratably over a three -year period. Stock options granted prior to 2016 fully vested upon completion of the merger with Talmer. Stock options assumed by the Corporation in the merger with Talmer were fully vested prior to assumption. The following summarizes information about stock options outstanding and exercisable at December 31, 2018 : Options outstanding Options exercisable Range of exercise prices per share Number outstanding Weighted average exercise price per share Weighted average contractual term (in years) Number exercisable Weighted average exercise price per share Weighted average contractual term (in years) $11.09 - 12.80 32,691 $ 12.37 1.93 32,691 $ 12.37 1.93 $13.20 - 16.24 26,669 15.73 4.00 26,669 15.73 4.00 $19.97 - 21.10 22,955 20.15 1.99 22,955 20.15 1.99 $23.78 - 25.14 162,561 24.59 3.59 162,561 24.59 3.59 $29.45 - 32.81 428,350 31.71 6.64 267,067 31.05 6.33 $46.95 - 53.72 104,217 53.35 8.25 43,842 53.54 8.24 $11.09 - 53.72 777,443 $ 31.42 5.79 555,785 $ 28.65 5.13 The intrinsic value of all outstanding in-the-money stock options and exercisable in-the-money stock options was $5.8 million and $5.2 million , respectively, at December 31, 2018 . The aggregate intrinsic values of outstanding and exercisable options at December 31, 2018 were calculated based on the closing market price of the Corporation's common stock on December 31, 2018 of $36.61 per share less the exercise price. Options with intrinsic values less than zero, or "out-of-the-money" options, are not included in the aggregate intrinsic value reported. The total intrinsic value of stock options for the years ended December 31, 2017 and 2016 was $26.6 million and $80.4 million , respectively. A summary of activity for the Corporation's stock options as of and during the years ended December 31, 2018 , 2017 and 2016 is presented below: Non-vested stock options outstanding Stock options outstanding Number of options Weighted- average exercise price per share Weighted- average grant date fair value per share Number of options Weighted- average exercise price per share Outstanding at December 31, 2015 479,755 $ 28.75 $ 8.49 1,054,739 $ 25.38 Granted 441,167 32.81 6.15 441,167 32.81 Acquired — — — 1,466,408 15.08 Exercised — — — (450,296 ) 20.02 Vested (454,360 ) 28.74 8.49 — — Forfeited/expired (58,623 ) 31.10 7.17 (58,623 ) 31.10 Outstanding at December 31, 2016 407,939 $ 32.81 $ 6.15 2,453,395 $ 21.41 Granted 132,414 53.43 9.94 132,414 53.43 Exercised — — — (1,427,159 ) 17.50 Vested (161,751 ) 37.73 7.07 — — Forfeited/expired (47,732 ) 37.55 7.03 (47,732 ) 37.55 Outstanding at December 31, 2017 330,870 $ 37.97 $ 7.09 1,110,918 $ 29.56 Exercised — — — (302,796 ) 24.00 Vested (78,533 ) 37.16 6.94 — — Forfeited/expired (30,679 ) 37.20 6.97 (30,679 ) 37.20 Outstanding at December 31, 2018 221,658 $ 38.37 $ 7.16 777,443 $ 31.42 Exercisable/vested at December 31, 2018 555,785 $ 28.65 Total cash received from option exercises during the years ended December 31, 2018 , 2017 and 2016 was $2.6 million , $3.2 million and $2.7 million , respectively, resulting in the issuance of 179,887 shares, 621,355 shares and 229,055 shares, respectively. At December 31, 2018 , unrecognized compensation expense related to stock options totaled $1.2 million and is expected to be recognized over a remaining weighted average period of 2.6 years. The fair value of the stock options granted during the years ended December 31, 2017 and 2016 were estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions. The Corporation did not grant any stock options during the year ended December 31, 2018 . 2017 2016 Expected dividend yield 3.31 % 3.30 % Risk-free interest rate 2.05 % 1.39 % Expected stock price volatility 26.7 % 27.9 % Expected life of options — in years 6.0 6.5 Weighted average fair value of options granted $ 9.94 $ 6.15 The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant and the expected life of the options granted. Expected stock volatility was based on historical volatility of the Corporation's common stock over the expected life of the option. The expected life of options represents the period of time that options granted are expected to be outstanding and is based primarily upon historical experience, including option exercise behavior. Because of the unpredictability of the assumptions required, the Black-Scholes (or any other valuation) model is incapable of accurately predicting the Corporation's common stock price or of placing an accurate present value on options to purchase its stock. In addition, the Black-Scholes model was designed to approximate value for types of options that are very different from those issued by the Corporation. In spite of any theoretical value that may be placed on a stock option grant, no value is possible under options issued by the Corporation without an increase in the market price per share of the Corporation's common stock over the market price per share of the Corporation's common stock at the date of grant. Restricted Stock Units The Corporation grants Performance-Based Restricted Stock Units ("PRSUs") and Time-Based Restricted Stock Units ("TRSUs") (collectively referred to as RSUs) to certain officers from time to time. The PRSUs vest based on the Corporation achieving certain performance target levels and the grantee completing the requisite service period. The PRSUs are eligible to vest from 0.5 x to 1.5 x the number of units originally granted depending on which, if any, of the performance target levels are met. However, if the minimum performance target levels are not achieved, no shares will become vested or be issued for that respective year's PRSUs. The TRSUs vest upon satisfaction of a service condition. Upon achievement of the performance target level and/or satisfaction of a service condition, as applicable, the RSUs are converted into shares of the Corporation's common stock on a one-to-one basis. Compensation expense related to RSUs is recognized over the expected requisite performance or service period, as applicable. A summary of the activity for RSUs during the year ended December 31, 2018 is presented below: Number of units Weighted-average grant date fair value per unit Outstanding at December 31, 2017 380,940 $ 41.29 Granted 321,043 54.15 Converted into shares of common stock (102,553 ) 34.77 Forfeited/expired (22,940 ) 47.87 Outstanding at December 31, 2018 576,490 $ 49.35 At December 31, 2018 , unrecognized compensation expense related to RSUs totaled $16.4 million and is expected to be recognized over a remaining weighted average period of 3.1 years . Restricted Stock Awards The Corporation assumed restricted stock awards in the merger with Talmer that vest upon completion of future service requirements. The fair value of these awards is equal to the market price of the Corporation's common stock at the date the awards were assumed with the portion of the fair value related to post-combination service. The Corporation recognizes stock-based compensation expense over the vesting period, using the straight-lined method, based upon the number of shares of restricted stock ultimately expected to vest. If an individual that has been awarded restricted stock awards terminates their employment prior to the end of the vesting period, the unvested portion of the stock is forfeited, with certain exceptions. The following table provides information regarding nonvested restricted stock awards: Nonvested restricted stock awards Number of awards Weighted-average acquisition-date fair value Nonvested at January 1, 2018 83,228 $ 46.23 Vested (41,784 ) 46.23 Forfeited (592 ) 46.23 Nonvested at December 31, 2018 40,852 $ 46.23 At December 31, 2018 , unrecognized compensation expense related to nonvested restricted stock awards totaled $0.3 million and is expected to be recognized over a remaining weighted average period of 0.2 years .

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Retirement Plans	Retirement Plans The Corporation's retirement plans include a qualified defined benefit pension plan, a nonqualified pension plan, a nonqualified postretirement benefit plan, a 401(k) savings plan, and a multi-employer defined benefit plan. Qualified Defined Benefit Pension Plan The Chemical Financial Corporation Employees’ Pension Plan (the "Pension Plan") is a qualified defined benefit, noncontributory pension plan, which provides for postretirement pension benefits for certain salaried employees of the Corporation and its subsidiary, Chemical Bank. Benefits under the Pension Plan were partially frozen effective June 30, 2006. Under the partial freeze of the Pension Plan, benefits for employees with less than 15 years of service or whose combined age plus years of service were less than 65 at June 30, 2006, were based on years of vested service at June 30, 2006 and generally the average of the employee's salary for the five years ended June 30, 2006. In addition, no employee hired after January 1, 2006 was eligible to participate in the Pension Plan. Effective September 30, 2017, the Pension and Compensation Committee approved an amendment to the Pension Plan to cease accruing additional benefits under the existing pension benefit formula after the effective date and all accrued benefits were frozen. Retirement benefits under the Pension Plan are based on years of vested service at September 30, 2017, up to a maximum of thirty years, and the employee's average annual pay for the five highest consecutive years during the ten years preceding September 30, 2017, except for employees whose benefits were previously frozen during 2006. Pension Plan benefits are the present value of estimated future periodic payments that are attributable to services rendered by the employees to the valuation date. Benefits include the benefits expected to be paid to (a) retired or terminated employees or their beneficiaries and (b) present employees or their beneficiaries. The freeze of the Pension Plan effective September 30, 2017, required a remeasurement of the plan's projected benefit obligation. The combined impact of the remeasurement, an increase in fair value of underlying assets, the impact of the freeze and changes to participant's status as a result of the Corporation's restructuring efforts during the year ended December 31, 2017, resulted in an increase of the funded status of the Pension Plan. A discount rate of 3.68% was utilized to remeasure the projected benefit obligation as of December 31, 2017. There was less than $0.1 million of curtailment cost to the Corporation as a result of the amendment. A discount rate of 4.32% was utilized for the projected benefit obligation as of December 31, 2018 . The Pension Plan is fully funded as of December 31, 2018 . At December 31, 2018 , the Corporation had 80 employees who had accrued benefits under the Pension Plan, which contributions are intended to provide benefits attributable to service-to-date employees. Pension Plan expense was a benefit of $3.8 million in 2018 , compared to a benefit of $1.5 million in 2017 and an expense of $0.1 million in 2016 . Nonqualified Pension Plan The Corporation has a supplemental defined benefit nonqualified pension plan, the Chemical Financial Corporation Supplemental Pension Plan ("SERP"). The Corporation established the SERP to provide payments to certain executive officers of the Corporation, as determined by the Compensation and Pension Committee. The Internal Revenue Code limits both the amount of eligible compensation for benefit calculation purposes and the amount of annual benefits that may be paid from a tax-qualified retirement plan. The SERP was designed to provide benefits to executive officers of the Corporation would have been entitled, calculated under the provisions of the Pension Plan, as if the limits imposed by the Internal Revenue Code did not apply. The SERP is an unfunded plan and, therefore, has no assets. Effective September 30, 2017, the Pension and Compensation Committee approved a curtailment to the SERP, due to the retirement of the final remaining participant in the SERP. The curtailment, in addition to changes in valuation of liabilities, resulted in a reduction in obligation during the year ended December 31, 2017. As of December 31, 2018 , a $0.3 million liability included in other liabilities was recorded in the Consolidated Statements of Financial Position related to a former participant of the SERP. As of December 31, 2018 , the SERP had no active participants. Nonqualified Postretirement Benefit Plan The Corporation has a nonqualified postretirement benefit plan ("Postretirement Plan") that provides medical and dental benefits, upon retirement, to a limited number of active and retired employees. The majority of the retirees are required to make contributions toward the cost of their benefits based on their years of credited service and age at retirement. Beginning January 1, 2012, the Corporation amended the Postretirement Plan to extend coverage to employees who were at least age 50 as of January 1, 2012. These employees must also retire at age 60 or older, have at least twenty-five years of service with the Corporation and be participating in the active employee group health insurance plan in order to be eligible to participate in the Corporation's Postretirement Plan. Eligible employees may also cover their spouse until age 65 as long as the spouse is not offered health insurance coverage through his or her employer. Employees and their spouses eligible to participate in the Postretirement Plan will be required to make contributions toward the cost of their benefits upon retirement, with the contribution levels designed to cover the projected overall cost of these benefits over the long-term. Retiree contributions are generally adjusted annually. The accounting for these postretirement benefits anticipates changes in future cost-sharing features such as retiree contributions, deductibles, copayments and coinsurance. The Corporation reserves the right to amend, modify or terminate these benefits at any time. 401(k) Savings Plan The Corporation's 401(k) Savings Plan is available to all employees and provides employees with tax deferred salary deductions and alternative investment options. Effective January 1, 2018, the Corporation provides a safe harbor matching contribution of the participants elective deferrals up to a maximum of 6.0% of eligible compensation up to the maximum amount allowed under the Internal Revenue Code. Prior to January 1, 2018, the Corporation provided an employer match, in addition to a 4.0% contribution for all employees, with the exception of employees participating the Pension Plan discussed above, during the time period they were eligible to earn service credits. The Corporation previously matched 50.0% of the participants' elective deferrals on the first 4.0% of the participants' base compensation up to the maximum amount allowed under the Internal Revenue Code. The 401(k) Savings Plan provides employees with the option to invest in the Corporation's common stock. The Corporation's combined amount of the employer match and 4.0% to the 401(k) Savings Plan totaled $8.4 million in 2018 , $9.1 million in 2017 and $6.5 million in 2016 . Multi-Employer Defined Benefit Plan In conjunction with the April 1, 2015 acquisition of Monarch, the Corporation acquired a participation in the Pentegra Defined Benefit Plan for Financial Institutions (Pentegra DB Plan), a qualified defined benefit plan. Employee benefits for Monarch employees under the Pentegra DB Plan were frozen effective April 1, 2004. The Pentegra DB Plan operates as a multi-employer plan for accounting purposes and as a multiple employer plan under the Employee Retirement Income Security Act of 1974 and the Internal Revenue Code (IRC). The Pentegra DB Plan is a single plan under IRC Section 413(c) and, as a result, all the plan's assets stand behind all of the plan's liabilities. Accordingly, contributions made by a participating employer may be used to provide benefits to participants of other participating employers. No contributions were made to the Pentegra DB Plan during the years ended December 31, 2018 , 2017 and 2016 . The Pentegra DB Plan's Employer Identification Number is 13-5645888 and the Plan Number is 333. Financial information for the Pentegra DB Plan, which maintains a June 30 year end, is made available through the public Form 5500 which is available by April 15th of the year following the plan year end. The Pentegra DB Plan was fully funded as of its most recent year end. The Corporation's allocation of assets and liabilities in the Pentegra DB Plan totaled $3.8 million and $3.7 million respectively, as of December 31, 2018 and 2017 , and the Corporation's allocation of assets comprised 0.1% of the plan's total assets at those dates. Benefit Obligations and Plan Expenses The following schedule sets forth the changes in the projected benefit obligation and plan assets of the Corporation's Plans: Pension Plan Postretirement Plan SERP (Dollars in thousands) 2018 2017 2018 2017 2018 2017 Projected benefit obligation: Benefit obligation at beginning of year $ 121,361 $ 123,968 $ 2,512 $ 2,601 $ 2,423 $ 2,567 Service cost — 639 3 5 — 61 Interest cost 4,356 4,966 82 94 12 69 Net actuarial loss (gain) (7,048 ) 10,131 (208 ) 10 (36 ) (274 ) Benefits paid (7,237 ) (6,432 ) (189 ) (198 ) (2,062 ) — Curtailment — (11,911 ) — — — — Benefit obligation at end of year 111,432 121,361 2,200 2,512 337 2,423 Fair value of plan assets: Fair value of plan assets at beginning of year 145,901 132,751 — — — — Actual return on plan assets (10,312 ) 19,582 — — — — Employer contributions — — — 198 — — Benefits paid (7,237 ) (6,432 ) — (198 ) — — Fair value of plan assets at end of year 128,352 145,901 — — — — Funded (unfunded) status at December 31 $ 16,920 $ 24,540 $ (2,200 ) $ (2,512 ) $ (337 ) $ (2,423 ) Accumulated benefit obligation $ 111,432 $ 121,361 $ 2,200 $ 2,512 $ 337 $ 2,423 The Corporation did not make a contribution to the Pension Plan in either 2018 or 2017 . The Corporation is not required to make a contribution to the Pension Plan in 2019 . Weighted-average rate assumptions of the Corporation's Plans follow: Pension Plan Postretirement Plan SERP 2018 2017 2016 2018 2017 2016 2018 2017 2016 Discount rate used in determining benefit obligation — December 31 4.32 % 3.68 % 4.22 % 4.11 % 3.41 % 3.79 % 4.32 % 3.38 % 3.63 % Discount rate used in determining expense 3.68 4.22 4.55 3.41 3.79 4.23 — — 4.51 Discount rate used in determining expense — prior to remeasurement — 3.81 — — — — 3.38 3.63 2.87 Expected long-term return on Pension Plan assets 6.50 6.75 6.75 — — — — — — Rate of compensation increase used in determining benefit obligation — December 31 — — 3.50 — — — — — 3.50 Rate of compensation increase used in determining pension expense — 3.50 3.50 — — — — 3.50 3.50 Year 1 increase in cost of postretirement benefits — — — 7.50 6.50 7.00 — — — Net periodic pension cost (income) of the Corporation's Plans was as follows for the years ended December 31: Pension Plan Postretirement Plan SERP (Dollars in thousands) 2018 2017 2016 2018 2017 2016 2018 2017 2016 Service cost $ — $ 639 $ 1,041 $ 3 $ 5 $ 9 $ — $ 61 $ 77 Interest cost 4,356 4,966 5,335 82 94 132 12 69 92 Expected return on plan assets (8,879 ) (8,938 ) (8,562 ) — — — — — — Amortization of prior service credit — — — — — 117 — — — Amortization of net actuarial loss (gain) 710 1,837 2,259 (143 ) (162 ) (100 ) (7 ) 77 78 Curtailment — 1 — — — — — — — Settlement (1) — — — — — — — 322 120 Net cost (income) $ (3,813 ) $ (1,495 ) $ 73 $ (58 ) $ (63 ) $ 158 $ 5 $ 529 $ 367 (1) The settlement charge relates to the settlement of liabilities under the SERP for the retirement of the plan participant during the third quarter of 2017 and the change in control as a result of the merger with Talmer as of August 31, 2016. The following schedule presents estimated future benefit payments for the next 10 years under the Corporation's Plans for retirees already receiving benefits and future retirees, assuming they retire and begin receiving unreduced benefits as soon as they are eligible: (Dollars in thousands) Pension Plan Postretirement Plan SERP 2019 $ 6,387 $ 241 $ 22 2020 6,522 237 22 2021 6,680 231 22 2022 6,795 221 22 2023 6,895 209 22 2024 - 2028 35,908 853 106 Total $ 69,187 $ 1,992 $ 216 For measurement purposes for the Postretirement Plan, the annual rates of increase in the per capita cost of covered health care benefits and dental benefits for 2019 were each assumed at 7.5% . These rates were assumed to decrease gradually to 5.0% in 2020 and remain at that level thereafter. The assumed health care and dental cost trend rates could have a significant effect on the amounts reported for the Postretirement Plan. A one percentage-point change in these rates would have the following effects: One Percentage-Point (Dollars in thousands) Increase Decrease Effect on total of service and interest cost component in 2017 $ 7 $ (6 ) Effect on postretirement benefit obligation as of December 31, 2017 157 (143 ) Pension Plan Assets The assets of the Pension Plan are invested by the Wealth Management department of Chemical Bank. The investment policy and allocation of the assets of the pension trust were approved by the Compensation and Pension Committee of the board of directors of the Corporation. The Pension Plan's primary investment objective is long-term growth coupled with income. In consideration of the Pension Plan's fiduciary responsibilities, emphasis is placed on quality investments with sufficient liquidity to meet benefit payments and plan expenses, as well as providing the flexibility to manage the investments to accommodate current economic and financial market conditions. To meet the Pension Plan's long-term objective within the constraints of prudent management, target ranges have been set for the three primary asset classes: an equity securities range from 40.0% to 70.0% , a debt securities range from 20.0% to 60.0% , and a cash and cash equivalents and other range from 0.0% to 10.0% . Modest asset positions outside of these targeted ranges may occur due to the repositioning of assets within industries or other activity in the financial markets. Equity securities are primarily comprised of both individual securities and equity-based mutual funds, invested in either domestic or international markets. The stocks are diversified among the major economic sectors of the market and are selected based on balance sheet strength, expected earnings growth, the management team and position within their industries, among other characteristics. Debt securities are comprised of U.S. dollar denominated bonds issued by the U.S. Treasury, U.S. government agencies and investment grade bonds issued by corporations. The notes and bonds purchased are primarily rated "A" or better by the major bond rating companies from diverse industries. The Pension Plan's asset allocation by asset category was as follows: December 31, Asset Category 2018 2017 Equity securities 67 % 68 % Debt securities 26 28 Other 7 4 Total 100 % 100 % The following schedule sets forth the fair value of the Pension Plan's assets and the level of the valuation inputs used to value those assets at December 31, 2018 and 2017 : (Dollars in thousands) Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total December 31, 2018 Cash $ 8,770 $ — $ — $ 8,770 Equity securities: U.S. large- and mid-cap stocks (1) 63,823 — — 63,823 U.S. small-cap mutual funds 4,713 — — 4,713 International large-cap mutual funds 11,091 — — 11,091 Emerging markets mutual funds 6,439 — — 6,439 Debt securities: U.S. Treasury and government sponsored agency bonds and notes — 547 — 547 Mutual funds (2) 32,969 — — 32,969 Total $ 127,805 $ 547 $ — $ 128,352 December 31, 2017 Cash $ 5,238 $ — $ — $ 5,238 Equity securities: U.S. large- and mid-cap stocks (1) 68,909 — — 68,909 U.S. small-cap mutual funds 5,377 — — 5,377 International large-cap mutual funds 18,341 — — 18,341 Emerging markets mutual funds 7,363 — — 7,363 Debt securities: U.S. Treasury and government sponsored agency bonds and notes — 548 — 548 Mutual funds (2) 40,046 — — 40,046 Other 79 — — 79 Total $ 145,353 $ 548 $ — $ 145,901 (1) Comprised of common stocks and mutual funds traded on U.S. Exchanges whose issuers had market capitalizations exceeding $3 billion . (2) Comprised primarily of fixed-income bonds issued by the U.S. Treasury and government sponsored agencies and bonds of U.S. and foreign issuers from diverse industries. At December 31, 2018 and 2017 , the Pension Plan did not hold any shares of the Corporation's common stock. During 2017 , cash dividends of $0.2 million were paid on the Corporation's common stock held by the Pension Plan. Accumulated Other Comprehensive Loss The following sets forth the changes in accumulated other comprehensive income (loss), net of tax, related to the Corporation's Pension Plan, Postretirement Plan and SERP during 2018 : (Dollars in thousands) Pension Plan Postretirement Plan SERP Total Accumulated other comprehensive income (loss) at beginning of year $ (20,483 ) $ 744 $ (69 ) $ (19,808 ) Comprehensive income (loss) adjustment: Net actuarial income (loss) (9,032 ) 51 23 (8,958 ) Comprehensive income (loss) adjustment (9,032 ) 51 23 (8,958 ) Accumulated other comprehensive income (loss) at end of year $ (29,515 ) $ 795 $ (46 ) $ (28,766 ) The estimated income (loss) that will be amortized from accumulated other comprehensive income (loss) into net periodic cost, net of tax, in 2019 is as follows: (Dollars in thousands) Pension Plan Postretirement Plan SERP Total Net gain (loss) $ (444 ) $ 143 $ (1 ) $ (302 )

Equity

Equity	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Equity	Equity Shelf Registration On May 10, 2017, the Corporation filed an automatic shelf registration statement on Form S-3ASR with the SEC for an indeterminate amount of securities, which became immediately effective. The shelf registration statement provides the Corporation with the ability to raise capital, subject to SEC rules and limitations, if the board of directors of the Corporation decides to do so. Preferred Stock On April 20, 2015, the shareholders of the Corporation approved an amendment to the restated articles of incorporation which eliminated and replaced the previous class of 200,000 shares of preferred stock, approved by shareholders on April 20, 2009, with a new class of 2,000,000 shares of preferred stock. As of December 31, 2018 , no shares of preferred stock were issued and outstanding. Common Stock On July 19, 2016, the shareholders of the Corporation approved an amendment to the restated articles of incorporation to increase the number of authorized shares of common stock from 60,000,000 to 100,000,000 in anticipation of the merger with Talmer. On April 26, 2017, the shareholders of the Corporation approved an amendment to the restated articles of incorporation to increase the number of authorized shares of common stock from 100,000,000 to 135,000,000 .

Regulatory Capital and Reserve

Regulatory Capital and Reserve Requirements	12 Months Ended
	Dec. 31, 2018
Banking and Thrift [Abstract]
Regulatory Capital and Reserve Requirements	Regulatory Capital and Reserve Requirements Federal and state banking regulations place certain restrictions on the transfer of assets, in the form of dividends, loans, or advances, from Chemical Bank to the Corporation. As of December 31, 2018 , substantially all of the assets of Chemical Bank were restricted from transfer to the Corporation in the form of loans or advances. Dividends from Chemical Bank are the principal source of funds for the Corporation. In addition to the statutory limits, the Corporation considers the overall financial and capital position of Chemical Bank prior to making any cash dividend decisions. Banking regulations require that banks maintain cash reserve balances in vault cash, with the Federal Reserve Bank, or with certain other qualifying banks. The aggregate average amount of the regulatory balances required to be maintained by Chemical Bank during 2018 and 2017 were $57.0 million and $71.7 million , respectively. During 2018 , Chemical Bank satisfied its regulatory reserve requirements by maintaining a combination of vault cash balances and cash held with the FRB in excess of regulatory reserve requirements. Chemical Bank was not required to maintain compensating balances with correspondent banks during 2018 or 2017 . The Corporation and Chemical Bank are subject to various regulatory capital requirements administered by federal banking agencies. Under these capital requirements, Chemical Bank must meet specific capital guidelines that involve quantitative measures of assets and certain off-balance sheet items as calculated under regulatory accounting practices. In addition, capital amounts and classifications are subject to qualitative judgments by regulators. Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on the Consolidated Financial Statements. Management believes as of December 31, 2018 , the Corporation and Chemical Bank met all capital adequacy requirements to which they are subject. Quantitative measures established by regulation to ensure capital adequacy require minimum ratios of Tier 1 capital to average assets (Leverage Ratio) and Common Equity Tier 1, Tier 1 and Total capital to risk-weighted assets. These capital guidelines assign risk weights to on- and off-balance sheet items in arriving at total risk-weighted assets. Minimum capital levels are based upon the perceived risk of various asset categories and certain off-balance sheet instruments. Risk-weighted assets for the Corporation and Chemical Bank totaled $16.10 billion and $16.07 billion , respectively, at December 31, 2018 , compared to $14.74 billion and $14.70 billion at December 31, 2017 , respectively. Effective January 1, 2015, the Corporation adopted the Basel III regulatory capital framework as approved by federal banking agencies, which is subject to a multi-year phase-in period. The adoption of this new framework modified the calculation of the various capital ratios, added a new ratio, common equity tier 1, and revised the adequately and well capitalized thresholds. In addition, Basel III establishes a new capital conservation buffer of 2.5% of risk-weighted assets, which is phased-in over a four-year period beginning January 1, 2016. The capital conservation buffer for 2018 is 1.875% and was 1.25% for 2017 . The Corporation has elected to opt-out of including accumulated other comprehensive income in common equity tier 1 capital. At December 31, 2018 and 2017 , Chemical Bank's capital ratios exceeded the quantitative capital ratios required for an institution to be considered "well-capitalized." Significant factors that may affect capital adequacy include, but are not limited to, a disproportionate growth in assets versus capital and a change in mix or credit quality of assets. There are no conditions or events since that notification that management believes have changed the institutions' category. The summary below compares the actual capital amounts and ratios with the quantitative measures established by regulation to ensure capital adequacy: Actual Minimum Required for Capital Adequacy Purposes Minimum Required for Capital Adequacy Purposes Plus Capital Conservation Buffer Required to be Well Capitalized Under Prompt Corrective Action Regulations (Dollars in thousands) Capital Amount Ratio Capital Amount Ratio Capital Amount Ratio Capital Amount Ratio December 31, 2018 Total Capital to Risk-Weighted Assets Corporation $ 1,855,922 11.5 % $ 1,288,363 8.0 % $ 1,590,323 9.9 % N/A N/A Chemical Bank 1,825,742 11.4 1,285,444 8.0 1,586,719 9.9 $ 1,606,804 10.0 % Tier 1 Capital to Risk-Weighted Assets Corporation 1,723,004 10.7 966,272 6.0 1,268,232 7.9 N/A N/A Chemical Bank 1,708,724 10.6 964,083 6.0 1,265,358 7.9 1,285,444 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets Corporation 1,723,004 10.7 724,704 4.5 1,026,664 6.4 N/A N/A Chemical Bank 1,708,724 10.6 723,062 4.5 1,024,338 6.4 1,044,423 6.5 Leverage Ratio Corporation 1,723,004 8.7 793,669 4.0 793,669 4.0 N/A N/A Chemical Bank 1,708,724 8.6 792,184 4.0 792,184 4.0 990,230 5.0 December 31, 2017 Total Capital to Risk-Weighted Assets Corporation $ 1,614,046 11.0 % $ 1,179,076 8.0 % $ 1,363,307 9.3 % N/A N/A Chemical Bank 1,613,087 11.0 1,176,361 8.0 1,360,167 9.3 $ 1,470,451 10.0 % Tier 1 Capital to Risk-Weighted Assets Corporation 1,498,463 10.2 884,307 6.0 1,068,538 7.3 N/A N/A Chemical Bank 1,513,219 10.3 882,271 6.0 1,066,077 7.3 1,176,361 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets Corporation 1,498,463 10.2 663,230 4.5 847,461 5.8 N/A N/A Chemical Bank 1,513,219 10.3 661,703 4.5 845,509 5.8 955,793 6.5 Leverage Ratio Corporation 1,498,463 8.3 720,890 4.0 720,890 4.0 N/A N/A Chemical Bank 1,513,219 8.4 720,043 4.0 720,043 4.0 900,053 5.0 During the years ended December 31, 2018 , 2017 and 2016 , Chemical Bank paid dividends to the Corporation totaling $114.3 million , $165.0 million and $110.5 million , respectively. On January 22, 2019 , a cash dividend on the Corporation's common stock of $0.34 per share was declared. The dividend will be paid on March 15, 2019 to shareholders of record as of March 1, 2019 .

Parent Company Only Financial S

Parent Company Only Financial Statements	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Disclosure [Abstract]
Parent Company Only Financial Statements	Parent Company Only Financial Statements Condensed financial statements of Chemical Financial Corporation (parent company) only follow: Condensed Statements of Financial Position December 31, (Dollars in thousands) 2018 2017 Assets Cash at subsidiary bank $ 11,477 $ 5,761 Investment in subsidiaries 2,820,866 2,673,858 Premises and equipment 3,595 3,931 Goodwill 1,092 1,092 Deferred tax asset 5,865 7,203 Other assets 27,157 31,459 Total assets $ 2,870,052 $ 2,723,304 Liabilities Other liabilities $ 17,892 $ 18,877 Non-revolving line-of-credit — 19,963 Subordinated debentures 15,900 15,715 Total liabilities 33,792 54,555 Shareholders' equity 2,836,260 2,668,749 Total liabilities and shareholders' equity $ 2,870,052 $ 2,723,304 Condensed Statements of Income Years Ended December 31, (Dollars in thousands) 2018 2017 2016 Income Cash dividends from subsidiaries $ 114,300 $ 165,000 $ 110,450 Other (loss) income (269 ) 921 151 Total income 114,031 165,921 110,601 Expenses Interest expense 1,601 3,076 1,816 Operating expenses 13,784 23,298 30,589 Total expenses 15,385 26,374 32,405 Income before income taxes and equity in undistributed net income of subsidiaries 98,646 139,547 78,196 Income tax benefit 4,472 12,670 11,378 Equity in undistributed net income (loss) of subsidiaries 180,902 (2,694 ) 18,458 Net income $ 284,020 $ 149,523 $ 108,032 Condensed Statements of Cash Flows Years Ended December 31, (Dollars in thousands) 2018 2017 2016 Cash Flows From Operating Activities Net income $ 284,020 $ 149,523 $ 108,032 Adjustments to reconcile net income to net cash provided by operating activities: Share-based compensation expense 8,578 17,346 13,452 Depreciation of premises and equipment 435 408 355 Equity in undistributed net (income) loss of subsidiaries (180,902 ) 2,694 (18,458 ) Net decrease in other assets 4,302 1,410 9,752 Net increase (decrease) in other liabilities 537 25,178 (11,830 ) Net cash provided by operating activities 116,970 196,559 101,303 Cash Flows From Investing Activities Cash paid, net of cash assumed, in business combinations — — (107,622 ) Purchases of premises and equipment, net (99 ) (288 ) (774 ) Net cash used in investing activities (99 ) (288 ) (108,396 ) Cash Flows From Financing Activities Cash dividends paid (88,954 ) (78,498 ) (49,389 ) Proceeds from issuance of common stock, net of issuance costs — — — Repayment of subordinated debt obligations — — (18,558 ) Repayments of other borrowings (20,000 ) (105,000 ) (62,500 ) Proceeds from issuance of other borrowings — — 125,000 Proceeds from directors' stock purchase plan and exercise of stock options 3,115 3,991 1,572 Cash paid for payroll taxes upon conversion of restricted stock units (5,316 ) (27,854 ) (1,065 ) Net cash used in financing activities (111,155 ) (207,361 ) (4,940 ) Net increase (decrease) in cash and cash equivalents 5,716 (11,090 ) (12,033 ) Cash and cash equivalents at beginning of year 5,761 16,851 28,884 Cash and cash equivalents at end of year $ 11,477 $ 5,761 $ 16,851 Business combinations: Fair value of assets acquired (noncash) $ — $ — $ 46,898 Liabilities assumed — — 58,309 Common stock and stock options issued — — 1,504,811

Earnings Per Common Share

Earnings Per Common Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Earnings Per Common Share	Earnings Per Common Share The two-class method is used in the calculation of basic and diluted earnings per share. Under the two-class method, earnings available to common shareholders for the period are allocated between common shareholders and participating securities according to dividends declared (or accumulated) and participating rights in undistributed earnings. Average shares of common stock for diluted net income per common share include shares to be issued upon the exercise of stock options granted under the Corporation’s share-based compensation plans, restricted stock units that may be converted to stock, restricted stock awards and stock to be issued under the deferred stock compensation plan for non-employee directors. The factors used in the earnings per share computation follow: For the years ended December 31, (In thousands, except per share data) 2018 2017 2016 Net income $ 284,020 $ 149,523 $ 108,032 Net income allocated to participating securities 186 495 166 Net income allocated to common shareholders (1) $ 283,834 $ 149,028 $ 107,866 Weighted average common shares - issued 71,385 71,103 49,091 Average unvested restricted share awards (47 ) (238 ) (139 ) Weighted average common shares outstanding - basic 71,338 70,865 48,952 Effect of dilutive securities Weighted average common stock equivalents 687 648 651 Weighted average common shares outstanding - diluted 72,025 71,513 49,603 EPS available to common shareholders Basic earnings per common share $ 3.98 $ 2.11 $ 2.21 Diluted earnings per common share $ 3.94 $ 2.08 $ 2.17 (1) Net income allocated to common shareholders for basic and diluted earnings per share may differ under the two-class method as a result of adding common share equivalents for options and warrants to dilutive shares outstanding, which alters the ratio used to allocate net income to common shareholders and participating securities for the purposes of calculating diluted earnings per share. For the effect of dilutive securities, the assumed average stock valuation is $53.70 per share, $50.26 per share and $40.58 per share for the years ended December 31, 2018 , 2017 and 2016 , respectively. The average number of exercisable employee stock option awards outstanding that were "out-of-the-money," whereby the option exercise price per share exceeded the market price per share and, therefore, were not included in the computation of diluted earnings per common share because they would have been anti-dilutive, totaled 61,298 for the year ended December 31, 2018 , 107,272 for the year ended December 31, 2017 and zero for the year ended December 31, 2016 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss The following table summarizes the changes within each component of accumulated other comprehensive income (loss), net of related tax benefit/expense for the years ended December 31, 2018 , 2017 and 2016 : (Dollars in thousands) Unrealized gains (losses) on securities carried at fair value, net of tax Defined Benefit Pension Plans Unrealized gains (losses) on cash flow hedges, net of tax Total For the year ended December 31, 2018 Beginning balance $ (10,348 ) $ (19,808 ) $ 4,658 $ (25,498 ) Cumulative effect adjustment of change in accounting policy, net of tax impact (1) (344 ) — 3 (341 ) Beginning balance at January 1, 2018 (10,692 ) (19,808 ) 4,661 (25,839 ) Other comprehensive income (loss) before reclassifications (26,903 ) — 2,245 (24,658 ) Amounts reclassified from accumulated other comprehensive income (loss) (177 ) (8,958 ) (1,478 ) (10,613 ) Net current period other comprehensive income (loss) (27,080 ) (8,958 ) 767 (35,271 ) Ending balance $ (37,772 ) $ (28,766 ) $ 5,428 $ (61,110 ) For the year ended December 31, 2017 Beginning balance $ (14,142 ) $ (25,894 ) $ — $ (40,036 ) Other comprehensive income before reclassifications 826 8,457 2,771 12,054 Amounts reclassified from accumulated other comprehensive income 4,802 1,139 1,061 7,002 Net current period other comprehensive income 5,628 9,596 3,832 19,056 Reclassification of certain deferred tax effects (2) (1,834 ) (3,510 ) 826 (4,518 ) Ending balance $ (10,348 ) $ (19,808 ) $ 4,658 $ (25,498 ) For the year ended December 31, 2016 Beginning balance $ (1,888 ) $ (27,144 ) $ — $ (29,032 ) Other comprehensive (loss) before reclassifications (12,170 ) (229 ) — (12,399 ) Amounts reclassified from accumulated other comprehensive income (loss) (84 ) 1,479 — 1,395 Net current period other comprehensive income (loss) (12,254 ) 1,250 — (11,004 ) Ending balance $ (14,142 ) $ (25,894 ) $ — $ (40,036 ) (1) Refer to Note 1 , Summary of Significant Accounting Policies and Note 4 , Investment Securities, for further details on the changes in accounting policy. (2) The reclassification from accumulated other comprehensive income (loss) to retained earnings was due to the early adoption of ASU 2018-02, see Note 1 for further information. The following table summarizes the amounts reclassified out of each component of accumulated other comprehensive income (loss) for the years ended December 31, 2018 , 2017 and 2016 : (Dollars in thousands) Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Income Statement December 31, 2018 December 31, 2017 December 31, 2016 Gains and losses on available-for-sale securities $ 224 $ (7,388 ) $ 129 Net gain (loss) on sale of investment securities (noninterest income) (47 ) 2,586 (45 ) Income tax (expense)/benefit $ 177 $ (4,802 ) $ 84 Net income (loss) Amortization of defined benefit pension plan items $ 11,339 $ (1,752 ) $ (2,276 ) Salaries, wages and employee benefits (operating expenses) (2,381 ) 613 797 Income tax expense/(benefit) $ 8,958 $ (1,139 ) $ (1,479 ) Net (income) loss Gains and losses on cash flow hedges (1,871 ) 1,633 — Interest on short-term borrowings (interest expense) 393 (572 ) — Income tax expense/(benefit) $ (1,478 ) $ 1,061 $ — Net (income) loss

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On January 28, 2019, Chemical and TCF Financial Corporation ("TCF") jointly announced the signing of a definitive merger agreement (the "Merger Agreement") under which, the companies will combine in an all-stock merger of equals transaction. Under the terms of the agreement, which was unanimously approved by the boards of directors of both companies, TCF will merge into Chemical, and the combined holding company and bank will operate under the TCF name and brand following the closing of the transaction. TCF is headquartered in Wayzata, Minnesota with reported assets of approximately $23.7 billion as of December 31, 2018 . Under the terms of the Merger Agreement, TCF shareholders will receive 0.5081 shares of Chemical common stock for each share of TCF common stock based on a fixed exchange ratio, equivalent to $21.58 per TCF share based on the closing price as of January 25, 2019. Each outstanding share of 5.70% Series C Non-Cumulative Perpetual Preferred Stock of TCF will be converted into the right to receive one share of a newly created series of preferred stock of Chemical. Upon completion of the deal, TCF and Chemical shareholders will own 54% and 46% of the combined company, respectively, on a fully diluted basis. Subject to receipt of regulatory approvals and satisfaction of other customary closing conditions, including approval of both Chemical and TCF shareholders, the transaction is anticipated to close in the second half of 2019.

Summary of Quarterly Statements

Summary of Quarterly Statements of Income (Unaudited)	12 Months Ended
	Dec. 31, 2018
Selected Quarterly Financial Information [Abstract]
Summary of Quarterly Statements of Income (Unaudited)	Summary of Quarterly Statements of Income (Unaudited) The following is a summary of the unaudited quarterly results of operation for the years ended December 31, 2018 , 2017 and 2016 . In the opinion of management, the information reflects all adjustments that are necessary for the fair presentation of the results of operations for the periods presented. 2018 (Dollars in thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter Total Interest income $ 177,934 $ 189,582 $ 198,377 $ 210,103 $ 775,996 Interest expense 26,071 32,045 38,896 46,651 143,663 Net interest income 151,863 157,537 159,481 163,452 632,333 Provision for loan losses 6,256 9,572 6,028 8,894 30,750 Noninterest income 40,554 38,018 37,917 32,047 148,536 Operating expenses 101,610 104,561 109,661 108,366 424,198 Income before income taxes 84,551 81,422 81,709 78,239 325,921 Income tax expense 12,955 12,434 11,312 5,200 41,901 Net income $ 71,596 $ 68,988 $ 70,397 $ 73,039 $ 284,020 Net income per common share: Basic $ 1.01 $ 0.97 $ 0.99 $ 1.02 $ 3.98 Diluted 0.99 0.96 0.98 1.01 3.94 Cash dividends declared per common share 0.28 0.28 0.34 0.34 1.24 2017 (Dollars in thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter Total Interest income $ 142,896 $ 155,133 $ 164,944 $ 169,162 $ 632,135 Interest expense 12,799 17,185 21,316 23,257 74,557 Net interest income 130,097 137,948 143,628 145,905 557,578 Provision for loan losses 4,050 6,229 5,499 7,522 23,300 Noninterest income 38,010 41,568 32,122 32,319 144,019 Operating expenses 104,196 98,237 119,539 100,022 421,994 Income before income taxes 59,861 75,050 50,712 70,680 256,303 Income tax expense 12,257 23,036 10,253 61,234 106,780 Net income $ 47,604 $ 52,014 $ 40,459 $ 9,446 $ 149,523 Net income per common share: Basic $ 0.67 $ 0.73 $ 0.57 $ 0.13 $ 2.11 Diluted 0.67 0.73 0.56 0.13 2.08 Cash dividends declared per common share 0.27 0.27 0.28 0.28 1.10 2016 (Dollars in thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter Total Interest income $ 79,464 $ 82,937 $ 103,562 $ 144,416 $ 410,379 Interest expense 5,134 5,442 6,753 11,969 29,298 Net interest income 74,330 77,495 96,809 132,447 381,081 Provision for loan losses 1,500 3,000 4,103 6,272 14,875 Noninterest income 19,419 20,897 27,770 54,264 122,350 Operating expenses 58,887 59,085 106,144 114,302 338,418 Income before income taxes 33,362 36,307 14,332 66,137 150,138 Income tax expense 9,757 10,532 2,848 18,969 42,106 Net income $ 23,605 $ 25,775 $ 11,484 $ 47,168 $ 108,032 Net income per common share: Basic $ 0.61 $ 0.67 $ 0.23 $ 0.67 $ 2.21 Diluted 0.60 0.67 0.23 0.66 2.17 Cash dividends declared per common share 0.26 0.26 0.27 0.27 1.06

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations Chemical Financial Corporation ("Corporation" or "Chemical") operates in a single operating segment — commercial banking. The Corporation is a financial holding company, headquartered in Detroit, Michigan, that operates through one commercial bank, Chemical Bank. Chemical Bank operates within Michigan, Ohio and Northern Indiana as a Michigan state-chartered commercial bank. Chemical Bank operates through an internal organizational structure of six regional banking units and offers a full range of traditional banking and fiduciary products and services to the residents and business customers in the Corporation's geographical market areas. The products and services offered by the regional banking units, through branch banking offices, are generally consistent throughout the Corporation, as is the pricing of those products and services. The marketing of products and services throughout the Corporation's regional banking units is generally uniform, as many of the markets served by the regional banking units overlap. The distribution of products and services is generally uniform throughout the Corporation's regional banking units and is achieved primarily through retail branch banking offices, automated teller machines and electronically accessed banking products. The Corporation's primary sources of revenue are interest from its loan products and investment securities, service charges and fees from customer deposit accounts, wealth management revenue, net gain on sale of loans and other mortgage banking revenue.
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accounting and reporting policies of the Corporation and its subsidiaries have been prepared in accordance with U.S. Generally Accepted Accounting Principles ("GAAP"), Securities and Exchange Commission ("SEC") rules and interpretive releases and prevailing practices within the banking industry. The Consolidated Financial Statements of the Corporation include the accounts of the Corporation and its wholly owned subsidiaries. All significant income and expenses are recorded on the accrual basis. Intercompany accounts and transactions have been eliminated in preparing the Consolidated Financial Statements.
Use of Estimates	Use of Estimates Management makes estimates and assumptions that affect the amounts reported in the Consolidated Financial Statements and accompanying footnotes. Estimates that are particularly susceptible to significant change include the determination of the allowance for loan losses, expected cash flows from acquired loans, income taxes and the valuation of loan servicing rights. Actual results could differ from these estimates.
Business Combinations	Business Combinations Pursuant to the guidance of the Financial Accounting Standards Board's ("FASB") Accounting Standards Codification ("ASC") Topic 805, Business Combinations ("ASC 805"), the Corporation recognizes assets acquired, including identified intangible assets, and the liabilities assumed in acquisitions at their fair values as of the acquisition date, with the acquisition-related transaction and restructuring costs expensed in the period incurred. See Note 2 for further information regarding the Corporation's mergers and acquisitions.
Cash and Cash Equivalents	Cash and Cash Equivalents For purposes of reporting cash flows, cash and cash equivalents include cash on hand and interest-bearing deposits held at the Federal Reserve Bank ("FRB").
Investment Securities	Investment Securities Investment securities are classified at the time they are acquired as either available-for-sale, held-to-maturity or carried at fair value based upon various factors, including asset/liability management strategies, liquidity and profitability objectives and regulatory requirements. The Corporation held no trading investment securities at December 31, 2018 or 2017 . Debt securities classified as available-for-sale and equity securities are recorded at fair value. Investment securities carried at fair value may be sold prior to maturity based upon asset/liability management decisions. Unrealized gains or losses on available-for-sale debt securities are recorded as part of accumulated other comprehensive income in stockholders’ equity. Unrealized gains or losses on equity securities were recorded as part of accumulated other comprehensive income in stockholders' equity through December 31, 2017. Effective January 1, 2018, the amendments within FASB Accounting Standard Update ("ASU") 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities, require that equity investments be measured at fair value with changes in fair value recognized in net income. At January 1, 2018, the Corporation's equity securities consisted of $1.8 million in preferred stocks. The Corporation recognized a cumulative effect adjustment in the amount of $344 thousand as of January 1, 2018 to reclassify the fair value position into retained earnings. Beginning January 1, 2018, the fair value changes on equity securities are recognized in net income, rather than in accumulated other comprehensive income. The Corporation sold its remaining position in equity securities during the second quarter of 2018. Designation as an investment security held-to-maturity is based on the Corporation's intent and ability to hold the security to maturity. Investment securities held-to-maturity are carried at amortized cost, adjusted for purchase price premiums and accretion of discounts. Investment securities that are not held-to-maturity are accounted for as securities available-for-sale, and are stated at estimated fair value, with the aggregate unrealized gains and losses classified as a component of accumulated other comprehensive income (loss), net of income taxes. Realized gains and losses on the sale of investment securities charges are determined using the specific identification method and are included within noninterest income in the Consolidated Statements of Income. Premiums and discounts on investment securities are amortized over the estimated lives of the related investment securities based on the effective interest yield method and are included in interest income in the Consolidated Statements of Income. The Corporation assesses debt securities that have fair values below amortized cost basis to determine whether declines (impairment) are other-than-temporary. If the Corporation intends to sell an impaired security or it is more-likely-than-not that the Corporation will be required to sell an impaired security prior to the recovery of its amortized cost, an other-than-temporary impairment ("OTTI") write-down is recognized in earnings equal to the entire difference between the investment security's amortized cost basis and its fair value. In assessing whether OTTI exists, management considers, among other things, (i) the length of time and the extent to which the fair value has been less than cost, (ii) the financial condition and near-term prospects of the issuer, (iii) the potential for impairments in an entire industry or sub-sector and (iv) the potential for impairments in certain economically depressed geographical locations.
Nonmarketable Equity Securities	Nonmarketable Equity Securities The Corporation is required to hold non-marketable equity securities, comprised of Federal Home Loan Bank of Indianapolis ("FHLB") and FRB stock, as a condition of membership. These securities are accounted for at cost, which equals par or redemption value, and included in "interest receivable and other assets" on the Consolidated Statements of Financial Position. These securities do not have a readily determinable fair value as their ownership is restricted and there is no market for these securities. These securities can only be redeemed or sold at their par value and only to the respective issuing government supported institution or to another member institution. FHLB stock can only be redeemed upon giving a five year written notice and FRB stock can only be redeemed upon giving six months written notice, with no more than 25.0% eligible for redemption in any calendar year. The Corporation records these non-marketable equity securities as a component of other assets and they are periodically evaluated for impairment. Management considers these non-marketable equity securities to be long-term investments. Accordingly, when evaluating these securities for impairment, management considers the ultimate recoverability of the par value rather than recognizing temporary declines in value, if applicable. The estimated loss is recognized as a loss from equity investments in other noninterest income in the Consolidated Statements of Income. The Corporation's ownership of FHLB stock totaled $125.2 million at December 31, 2018 and $112.0 million at December 31, 2017 . The Corporation's ownership of FRB stock totaled $68.1 million at both December 31, 2018 and December 31, 2017 .
Loans Held for Sale	Loans Held for Sale Mortgage and construction loans intended for sale in the secondary market are carried at fair value based on the Corporation's election of the fair value option, as prescribed by ASC Topic 820, Fair Value Measurements and Disclosures. The estimated fair value of loans held for sale are based on quoted market prices for securities backed by similar types of loans, where available, or by discounting estimated cash flows using observable inputs inclusive of interest rates, prepayment speeds and loss assumptions for similar collateral. The fair value includes the servicing value of the loans as well as any accrued interest. These loans are sold both with servicing rights retained and with servicing rights released.
Originated Loans Held for Investment	Originated Loans Held for Investment Originated loans include the Corporation's entire portfolio loans held for investment, excluding loans acquired in business combinations, as further discussed below. Originated loans are stated at their principal amount outstanding, net of unearned income, charge-offs and unamortized deferred fees and costs. Loan interest income is recognized on the accrual basis. Deferred loan fees and costs are amortized over the loan term based on the level-yield method. Net loan commitment fees are deferred and amortized into fee income on a straight-line basis over the commitment period. If a loan is transferred from the loan held for investment portfolio to the held for sale portfolio, any write-down in the carrying amount of the loan at the date of transfer is recorded as a charge-off. The loans are transferred at fair value determined using the same methods described above for held for sale loans. When loans classified as held for investment are transferred to loans held for sale due to a change in intent, cash flows associated with the loans will be classified in the Consolidated Statements of Cash Flows as operating or investing, as appropriate, in accordance with the initial classification of the loans. The past due status of a loan is based on the loan's contractual terms. A loan is placed in nonaccrual status (accrual of interest is discontinued) when principal or interest is past due 90 days or when doubt exists as to the ultimate collection of principal or interest, unless the loan is both well-secured and in the process of collection, or earlier when, in the opinion of management, there is sufficient reason to doubt the collectibility of principal or interest. Interest previously accrued, but not collected, is reversed and charged against interest income at the time the loan is placed in nonaccrual status. Subsequent receipts of interest while a loan is in nonaccrual status are recorded as a reduction of principal. Loans are returned to accrual status when principal and interest payments are brought current and are anticipated to be fully collectible, payments have been received consistently for a period of time (generally six months) and collectibility is no longer in doubt.
Loans Acquired in a Business Combination	Loans Acquired in a Business Combination Loans acquired in a business combination ("acquired loans") consist of loans acquired on August 31, 2016 in the merger with Talmer, on May 31, 2015 in the acquisition of Lake Michigan Financial Corporation ("Lake Michigan"), on April 1, 2015 in the acquisition of Monarch Community Bancorp, Inc. ("Monarch"), on October 31, 2014 in the acquisition of Northwestern Bancorp, Inc. ("Northwestern"), and on April 30, 2010 in the acquisition of O.A.K. Financial Corporation ("OAK"). Acquired loans were recorded at fair value at the date of acquisition, without a carryover of the associated allowance for loan losses related to these loans. At each acquisition date, the Corporation elected to account for acquired loans, which are recorded at fair value at acquisition using an estimate of cash flows deemed to be collectible and an accretable yield, in accordance with ASC Topic 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality ("ASC 310-30"), by analogy. ASC 310-30 allows investors to aggregate loans acquired into loan pools that have common risk characteristics and thereby use a composite interest rate and expectation of cash flows expected to be collected for the loan pools. Under the provisions of ASC 310-30, the Corporation aggregated acquired loans into pools within each merger or acquisition based upon common risk characteristics, including types of loans, commercial type loans with similar risk grades and whether loans were performing or nonperforming. A pool is considered a single unit of accounting for the purposes of applying the guidance prescribed in ASC 310-30. A loan will be removed from a pool of acquired loans only if the loan is sold, foreclosed, paid off or written off, and will be removed from the pool at the carrying value. The estimate of expected credit losses was determined based on due diligence performed by executive and senior officers of the Corporation, with assistance from third-party consultants. The Corporation estimated the cash flows expected to be collected over the life of the pools of loans at acquisition and estimates expected cash flows quarterly thereafter, based on a set of assumptions including expectations as to default rates, prepayment rates and loss severities. The Corporation must make numerous assumptions, interpretations and judgments using internal and third-party credit quality information to determine whether it is probable that the Corporation will be able to collect all contractually required payments. This is a point in time assessment and inherently subjective due to the nature of the available information and judgment involved. The calculation of the fair value of the acquired loan pools entails estimating the amount and timing of cash flows attributable to both principal and interest expected to be collected on such loan pools and then discounting those cash flows at market interest rates. The excess of a loan pool's expected cash flows at the acquisition date over its estimated fair value is referred to as the "accretable yield," which is recognized into interest income over the estimated remaining life of the loan pool on a level-yield basis. The difference between a loan pool's contractually required principal and interest payments at the acquisition date and the cash flows expected to be collected at the acquisition date is referred to as the "nonaccretable difference," which includes an estimate of future credit losses expected to be incurred over the estimated life of the loan pool and interest payments that are not expected to be collected. Decreases to the expected cash flows due to deterioration in credit quality in each loan pool in subsequent periods generally require the Corporation to record a provision for loan losses and an increase to the allowance for loan losses and generally results in a transfer from accretable yield to nonaccretable difference. Decreases in the expected cash flows due to unexpected prepayments and/or payoffs will generally result in a transfer from accretable to nonaccretable difference. Improvements in expected cash flows due to improvements in credit quality in each loan pool in subsequent periods will first reverse any previously established allowance for loan losses and will generally result in reversing a portion of the nonaccretable difference, which is then classified as part of the accretable yield and subsequently recognized into interest income over the estimated remaining life of the loan pool.
Loans Modified Under Troubled Debt Restructurings	Loans Modified Under Troubled Debt Restructurings Loans modified under TDRs involve granting a concession to a borrower who is experiencing financial difficulty. Concessions generally include modifications to original loan terms, including changes to a loan's payment schedule, principal forgiveness, interest rate reductions, or other actions intended to minimize our economic loss and to avoid foreclosure or repossession of the collateral, if applicable, which generally would not otherwise be considered. The Corporation's TDRs include accruing TDRs, which consist of originated loans that continue to accrue interest as the Corporation expects to collect the remaining principal and interest on the loan, and nonaccrual TDRs, which include originated loans that are in a nonaccrual status and are no longer accruing interest, as the Corporation does not expect to collect the full amount of principal and interest owed from the borrower on these loans. All TDRs are accounted for as impaired loans and are included in the Corporation's analysis of the allowance for loan losses. A TDR that has been renewed by a borrower who is no longer experiencing financial difficulty and which yields a market rate of interest at the time of a renewal is no longer reported as a TDR, but only if they have been refinanced or restructured at market terms and qualify as a new loan. Loans in the Corporation's commercial loan portfolio (comprised of commercial, commercial real estate, real estate construction and land development loans) that meet the definition of a TDR generally consist of loans where the Corporation has allowed borrowers to defer scheduled principal payments and make interest-only payments for a specified period of time at the stated interest rate of the original loan agreement or reduced payments due to a moderate extension of the loan's contractual term. If the Corporation does not expect to collect all principal and interest on the loan, the modified loan is classified as a nonaccrual TDR and impairment is measured based on collateral values, if the loan is collateral dependent. If the Corporation does not expect to incur a loss on the loan based on its assessment of the borrowers' expected cash flows, as the pre- and post-modification effective yields are approximately the same, the loan is current and a six-month payment history has been sustained, the loan is classified as an accruing TDR. Since no loss is expected to be incurred on these loans, no additional provision for loan losses has been recognized for these loans and they continue to accrue interest at their contractual interest rate. Accruing TDRs are transferred to nonaccrual status if they become 90 days past due as to principal or interest payments or if it is probable that any remaining principal and interest payments due on the loan will not be collected in accordance with the modified terms of the loan. If accruing TDRs are deemed to be collateral dependent, they are measured based on collateral values. Loans in the Corporation's consumer loan portfolio (comprised of residential mortgage, consumer installment and home equity loans) that meet the definition of a TDR include a concession that reduces a borrower's monthly payments by decreasing the interest rate charged on the loan for a specified period of time (generally 24 months) under a formal modification agreement. The Corporation recognizes an additional provision for loan losses related to impairment on these loans on an individual basis based on the present value of expected future cash flows discounted at the loan's original effective interest rate. These loans continue to accrue interest at their effective interest rate, which consists of contractual interest under the terms of the modification agreement in addition to an adjustment for the accretion of computed impairment. TDRs are placed on nonaccrual status if they become 90 days past due as to principal or interest payments, or sooner if conditions warrant and measure impairment based on collateral values, if the loan is collateral dependent.
Impaired Loans	Impaired Loans Impaired loans include loans on nonaccrual status and TDRs. Loans are considered impaired when based on current information and events it is probable the Corporation will be unable to collect all amounts due in accordance with the original contractual terms of the loan agreements. Impaired loans are accounted for at the lower of the present value of expected cash flows discounted at the loan's original effective interest rate or the estimated fair value of the collateral, if the loan is collateral dependent. When the present value of expected cash flows or the fair value of collateral of an impaired loan in the originated loan portfolio is less than the amount of unpaid principal outstanding on the loan, the principal balance of the loan is reduced to its carrying value through either a specific allowance for loan losses or a partial charge-off of the loan balance.
Nonperforming Loans	Nonperforming Loans Nonperforming loans are comprised of loans for which the accrual of interest has been discontinued (nonaccrual loans, including nonaccrual TDRs). Acquired loans that were classified as nonperforming loans prior to being acquired and acquired loans that are not performing in accordance with contractual terms subsequent to acquisition are not classified as nonperforming loans subsequent to acquisition because the loans are recorded in pools at net realizable value based on the principal and interest the Corporation expects to collect on such loans. They continue to earn interest from accretable yield, independent of performance in accordance of their contractual terms, and are expected to be fully collected under the new carrying values of such loans (that is, the new cost basis arising out of purchase accounting).
Allowance for Loan Losses	Allowance for Loan Losses The allowance for credit losses ("allowance") consists of two components: the allowance for loan losses (including both the originated and acquired loan portfolios) and the reserve for unfunded credit commitments. Unfunded credit commitments include items such as letters of credit, financial guarantees and binding unfunded loan commitments. The allowance represents management’s estimate of probable credit losses inherent in the loan and credit commitment portfolios as of period end. The allowance is calculated with the objective of maintaining a reserve sufficient to absorb losses inherent in the loan portfolio. The determination of the amount of the allowance requires significant judgment and the use of estimates related to the amount and timing of expected cash flows on acquired loans and impaired loans, collateral values on impaired loans, and estimated losses on pools of homogeneous loans based on historical loss experience, and consideration of current economic trends and conditions, all of which may be susceptible to significant change. The principal assumption used in deriving the allowance is the estimate of a loss percentage for each type of loan. In determining the allowance for the originated loan portfolio and the related provision for loan losses, the Corporation considers three principal elements: (i) valuation allowances based upon probable losses identified during the review of impaired loans, (ii) reserves, by loan classes, on all other loans based on a six -year historical loan loss experience, loan loss trends and giving consideration to estimated loss emergence periods, and (iii) a reserve for qualitative factors that take into consideration risks inherent in the originated loan portfolio that differ from historical loan loss experience. The first element reflects the Corporation's estimate of probable losses based upon the systematic review of individually impaired loans in the originated loan portfolio. These estimates are based upon a number of objective factors, such as payment history, financial condition of the borrower and discounted collateral exposure. The Corporation measures the investment in an impaired loan based on one of three methods: the loan's observable market price; the fair value of the collateral; or the present value of expected future cash flows discounted at the loan's effective interest rate. Loans in the commercial loan portfolio that were in nonaccrual status (including nonaccrual TDRs) were valued based on the fair value of the collateral securing the loan, while accruing TDRs in the commercial loan portfolio and consumer loans were valued based on the present value of expected future cash flows discounted at the loan's effective interest rate. It is the Corporation's general policy to obtain new appraisals at initial impairment and updated when deemed necessary on nonaccrual loans in the commercial loan portfolio. Appraisals on nonaccrual loans in the consumer loan portfolio are updated at initial impairment and when deemed necessary where there is a delay in the foreclosure process. When the Corporation determines that the fair value of the collateral is less than the carrying value of an impaired loan and a portion is deemed not collectible, the portion of the impairment that is deemed not collectible is charged off (confirmed loss) and deducted from the allowance. The remaining carrying value of the impaired loan is classified as a nonperforming loan. When the Corporation determines that the fair value of the collateral is less than the carrying value of an impaired loan but believes it is probable it will recover this impairment, the Corporation establishes a valuation allowance for such impairment. The second element is determined by assigning allocations based principally upon a six -year historical loan loss experience for each class of loan. Average losses may be adjusted based on current loan loss experience, delinquency trends, estimated loss emergence periods and other industry specific environmental factors. This component considers the lagging impact of historical charge-off ratios in periods where future loan charge-offs are expected to increase or decrease, trends in delinquencies and nonaccrual loans, the changing portfolio mix in terms of collateral, average loan balance, loan growth and the degree of seasoning in the various loan portfolios. Loan loss analyses are performed quarterly and certain inputs and parameters are updated as necessary to reflect the current credit environment. The third element is based on qualitative factors that cannot be associated with a specific credit or loan class and reflects an attempt to ensure that the overall allowance appropriately reflects additional losses that are inherent in the Corporation's loan portfolio. Determination of the probable losses inherent in the portfolio, which are not necessarily captured by the allocation methodology discussed above, involves the exercise of judgment. This qualitative portion of the allowance is judgmentally determined and generally serves to compensate for the uncertainty in estimating inherent losses, particularly in times of changing economic conditions, and also considers the inherent judgment associated with risk rating commercial loans. The qualitative portion of the allowance also takes into consideration, among other things, economic conditions within our geographic areas and nationwide, including unemployment levels, industry-wide and Corporation specific loan delinquency rates, changes in composition of and growth in the Corporation's loan portfolio and changing commercial and residential real estate values. Consumer loans secured by real estate are charged-off to the estimated fair value of the collateral when a loss is confirmed or at 180 days past due, whichever is sooner. Loss confirming events include, but are not limited to, bankruptcy (unsecured), continued delinquency, foreclosure or receipt of an asset valuation indicating a collateral deficiency and the asset is the sole source of repayment. For consumer loans not secured by real estate, the charge-off is taken upon confirmation or 120 days past due. Commercial loans are evaluated on a loan level basis and either charged-off or written down to net realizable value if a loss confirming event has occurred. Loss confirming events include, but are not limited to, bankruptcy (unsecured), continued delinquency, foreclosure, or receipt of an asset valuation indicating a collateral deficiency and that asset is the sole source of repayment. Although the Corporation allocates portions of the allowance to specific loans and loan types, the entire allowance attributable to originated loans is available for any loan losses that occur in the originated portfolio. Loans that are deemed not collectible are charged off and reduce the allowance. The provision for loan losses and recoveries on loans previously charged off increase the allowance. Collection efforts may continue and recoveries may occur after a loan is charged off. Acquired loans are aggregated into pools based upon common risk characteristics. An allowance may be recorded related to an acquired loan pool if it experiences a decrease in expected cash flows, as compared to those projected at the acquisition date. On a quarterly basis, the expected future cash flow of each pool is estimated based on various factors, including changes in property values of collateral dependent loans, default rates, loss severities and prepayment speeds. Decreases in estimates of expected cash flows within a pool generally result in a charge to the provision for loan losses and a corresponding increase in the allowance allocated to acquired loans for the particular pool. Increases in estimates of expected cash flows within a pool generally result in a reduction in the allowance allocated to acquired loans for the particular pool, if applicable, and then an adjustment to the accretable yield for the pool, which will increase amounts recognized in interest income in subsequent periods. Various regulatory agencies, as an integral part of their examination processes, periodically review the allowance. Such agencies may require additions to the allowance, based on their judgment, reflecting information available to them at the time of their examinations.
Mortgage Banking Operations	Mortgage Banking Operations The Corporation generally sells conforming long-term fixed interest rate mortgage loans it originates in the secondary market. Gains on the sales of these loans are determined using the specific identification method. The Corporation sells residential mortgage loans in the secondary market primarily on a servicing retained basis. The Corporation elected the fair value measurement option, as prescribed by ASC Topic 820, Fair Value Measurements and Disclosures ("ASC 820"), for all residential mortgage loans held-for-sale originated on or after July 1, 2012. This election allows for a more effective offset of the changes in fair value of residential mortgage loans held-for-sale and the derivative instruments used to economically hedge them without having to apply complex hedge accounting provisions. Residential mortgage loans held-for-sale are carried at fair value, with changes in fair value recorded through earnings. Residential mortgage loan commitments, forward commitments, are generally entered into at the time interest-rate locks are accepted to protect the value of the mortgage loans from increases in market interest rates during the period held and are generally settled with the investor in the secondary market within 90 days after entering into the forward commitment. Forward loan commitments are accounted for as derivatives and recorded at fair value, with changes in fair value recorded through earnings. The Corporation recognizes revenue associated with the expected future cash flows of servicing loans for loans held-for-sale at the time a forward loan commitment is made to originate a held-for-sale loan, as required under SEC Staff Accounting Bulletin No. 109, Written Loan Commitments Recorded at Fair Value through Earnings. The Corporation purchases and originates loans for sale to the secondary market and sell the loans on either a servicing retained or servicing-released basis. If we retain the right to service the loan, a loan servicing right ("LSR") is created at the time of sale which is recorded at fair value. Effective January 1, 2017, the Corporation elected to account for all LSRs previously accounted for under the lower of cost or fair value method under the fair value method. Management believes this election will provide more comparable results to peers as many of those within our industry group account for loan servicing rights under the fair value method. The change in accounting policy in the first quarter of 2017 resulted in a cumulative adjustment to increase retained earnings in the amount of $3.7 million , net of taxes. LSRs are established and recorded at the estimated fair value by calculating the present fair value of estimated future net servicing cash flows. To determine the fair value of LSRs, the Corporation uses an independent third party valuation model requiring the incorporation of assumptions that market participants would use in estimating future net servicing income, which include estimates of prepayment speeds, discount rate, cost to service and escrow account earnings. Changes in the fair value of LSRs directly impact earnings. Servicing income is recognized in net gain on sale of loans and other mortgage banking revenue in the Consolidated Statements of Income when earned.
Derivatives	Derivatives The Corporation enters into derivatives to manage the fair value changes, exposure to fluctuations exposed to price and interest rate risk, facilitate asset/liability management, minimize the variability of future cash flows on long-term debt, and to provide a service to certain qualifying customers to help facilitate their respective risk management strategies ("customer-initiated derivatives"). All derivatives are recognized on the Consolidated Statements of Financial Condition as other assets and liabilities, as applicable, at their estimated fair value. For derivatives designated as qualified cash flow hedges, changes in the fair value of the derivatives, to the extent effective as a hedge, are recorded in accumulated other comprehensive income, net of income taxes, and reclassified into earnings concurrently with the earnings of the hedged item. For customer-initiated and mortgage banking derivatives, changes in the fair value of the derivative are recognized immediately in earnings. Interest rate swaps are entered into in order to economically hedge the effect of changes and to mitigate the impact of fluctuations in interest rate volatility to manage exposures that arise from business activities that result in the receipt or payment of future known and uncertain cash amounts. These derivatives are designated as cash flow hedges. The changes in fair value of derivatives designated and that qualify as cash flow hedges are recorded in accumulated other comprehensive income (loss) and are subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. For the Corporation's derivative instruments that are designated and qualify as a cash flow hedge, the gain or loss on the derivative instrument, as well as the offsetting loss or gain on the hedged item attributable to the hedged risk are recognized in current earnings in the same line item as the offsetting loss or gain on the related interest rate swap. The Corporation expects the hedges to remain highly effective during the remaining terms of the swaps. Interest rate swaps, are valued based on quoted prices for similar assets in an active market with inputs that are observable. The Corporation utilizes interest rate derivatives to provide a service to certain qualifying customers to help facilitate their respective risk management strategies, customer-initiated derivatives. Therefore, these derivatives are not used to manage interest rate risk in the Corporation's assets or liabilities. The Corporation generally takes offsetting positions with dealer counterparties to mitigate the valuation risk of the customer-initiated derivatives. Income primarily results in the spread between the customer derivatives and offsetting dealer positions. The gains or losses derived from changes in fair value are recognized in current earnings during the period of change in other noninterest income on the Consolidated Statements of Income. The Corporation calculates a credit valuation adjustment by applying a credit spread for the counterparty or the Corporation, as appropriate, to the total expected exposure of the derivative after considering collateral and other master netting arrangements. The Corporation additionally has written and purchased option derivatives consisting of instruments to facilitate an equity-linked time deposit product (the "Power Equity CD"). The Power Equity CD is a time deposit that provides the purchaser a guaranteed return of principal at maturity plus a potential equity return (a written option), while the Corporation receives a known stream of funds based on the equity return (a purchased option). The written and purchased options are mirror derivative instruments which are carried at fair value on the Consolidated Statements of Financial Position.
Premises and Equipment	Premises and Equipment Land is carried at cost. Premises and equipment are stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method with useful lives ranging from 25 to 40 years for buildings and three to ten years for all other depreciable assets. Maintenance and repairs are charged to expense as incurred.
Other Real Estate Owned and Repossessed Assets	Other Real Estate Owned and Repossessed Assets Other real estate owned ("ORE") and repossessed assets represent property acquired by the Corporation as part of an acquisition or subsequently through the loan foreclosure or repossession process, or any other resolution activity that results in partial or total satisfaction of problem loans. ORE is primarily comprised of commercial and residential real estate properties, including vacant land and development properties, obtained in partial or total satisfaction of loan obligations. The acquired properties are recorded at fair value at the date of acquisition. Losses arising at the time of acquisition of properties not acquired as part of an acquisition are charged against the allowance for loan and lease losses. Foreclosed properties are initially recorded at the lower of cost, or the estimated fair value of the property, less estimated costs to sell, based upon the property's appraised value at the date of transfer to ORE and management's estimate of the fair value of the collateral, establishing a new cost basis. Any difference between the net realizable value of the property and the carrying value of the loan is charged to the allowance for loan losses. Subsequently, all other real estate owned is valued at the lower of cost or fair value, less estimated costs to sell, based on periodic valuations performed by management, with any difference between the net realizable value of the property and the carrying value of the loan charged to the allowance for loan losses. If fair value declines subsequent to foreclosure, a valuation allowance is recorded through expense. Subsequent write-downs, for amounts not expected to be recovered, in the carrying value of other real estate owned and repossessed asset properties that may be required are expensed as incurred. Improvements to the properties may be capitalized if the improvements contribute to the overall value of the property. Improvement amounts may not be capitalized in excess of the net realizable value of the property. Any gains or losses realized at the time of disposal are reflected in other noninterest expense on the Consolidated Statements of Income. Other real estate owned and repossessed assets totaling $6.3 million and $8.8 million at December 31, 2018 and 2017 , respectively, was included in "Interest receivable and other assets" in the Consolidated Statements of Financial Position.
Goodwill	Goodwill Goodwill is not amortized, but rather is subject to impairment tests annually or more frequently if triggering events occur and indicate potential impairment. The Corporation's annual goodwill impairment assessment was performed as of October 31, 2018 . The Corporation elected to utilize the qualitative assessment of goodwill impairment allowed under ASC Topic 350-20, Goodwill ("ASC 350-20") that became acceptable as a result of ASU 2011-08, Testing Goodwill for Impairment. In accordance with ASC 350-20, the Corporation assessed qualitative factors to determine whether it is more likely than not that the fair value of its reporting units were less than their carrying amounts. In evaluating whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount, the Corporation assesses relevant events and circumstances, including macroeconomic conditions, industry and market considerations, overall financial performance, changes in the composition or carrying amount of assets and liabilities, the market price of the Corporation's common stock, and other relevant factors. Based on the qualitative assessment performed, the Corporation determined that no goodwill impairment was evident as of the October 31, 2018 assessment date. The Corporation also determined that no triggering events occurred that indicated impairment from the most recent assessment date through December 31, 2018 and that the Corporation's goodwill was not impaired at December 31, 2018 .
Other Intangible Assets	Other Intangible Assets Intangible assets consist of core deposit intangible assets and additionally included non-compete intangible assets at December 31, 2017. Core deposit intangible assets arose as the result of business combinations or other acquisitions and are amortized over periods ranging from 10 to 15 years , primarily on an accelerated basis, as applicable. Non-compete intangible assets arose as the result of business combinations and are amortized over the period of the non-compete agreements. Intangible assets are tested for impairment on an annual basis in accordance with ASC Topic 350, "Intangibles-Goodwill and Other.
Share-based Compensation	Share-based Compensation The Corporation grants stock options, Time-Based Restricted Stock Units ("TRSUs"), Performance-Based Restricted Stock Units ("PRSUs"), and other stock awards to certain executive and senior management employees. The Corporation accounts for share-based compensation expense using the modified-prospective transition method. Under that method, compensation expense is recognized for stock options based on the estimated grant date fair value as computed using the Black-Scholes option pricing model and the probability of issuance. The Corporation accounts for stock awards based on the closing stock price of the Corporation's common stock on the date the award is granted. The fair values of stock options, stock awards and restricted stock awards are recognized as compensation expense on a straight-line basis over the requisite service period. The Corporation accounts for PRSUs based on the closing stock price of the Corporation's common stock on the date of grant, discounted by the present value of estimated future dividends to be declared over the requisite performance or service period. The fair value of PRSUs is recognized as compensation expense over the expected requisite performance period, or requisite service period for awards with multiple performance and service conditions. The Corporation accounts for TRSUs based on the closing stock price of the Corporation's common stock on the date of grant, as these awards accrue dividend equivalents equal to the amount of any cash dividends that would have been payable to a shareholder owning the number of shares of the Corporation's common stock represented by the TRSUs. The fair value of the TRSUs is recognized as compensation expense over the requisite service period.
Bank-Owned Life Insurance	Bank-Owned Life Insurance The Corporation has life insurance policies on certain key officers of Chemical Bank. The majority of the bank-owned life insurance policies of the Corporation were obtained through its acquisition of Lake Michigan and the merger with Talmer. Bank-owned life insurance is recorded at the cash surrender value, net of surrender charges, and is included within "Interest receivable and other assets" on the Consolidated Statements of Financial Position and tax-exempt income from the periodic changes in the cash surrender values are recorded as "Other noninterest income" on the Consolidated Statements of Income.
Collateralized Customer Deposits	Collateralized Customer Deposits Collateralized customer deposits represent funds deposited by customers that are collateralized by investment securities owned by Chemical Bank, as these deposits are not covered by Federal Deposit Insurance Corporation ("FDIC") insurance and are reflected as a liability in the accompanying Consolidated Statements of Financial Position. The Corporation's collateralized customer deposits are considered a stable source of liquidity, much like its core deposit base, and are generally only provided to customers that have an established banking relationship with Chemical Bank.
Short-term Borrowings	Short-term Borrowings Short-term borrowings are comprised of short-term FHLB advances with original scheduled maturities of one year or less. From time to time, the Corporation may also utilized federal funds purchased, which represent unsecured borrowings from nonaffiliated third-party financial institutions, generally on an overnight basis, to cover short-term liquidity needs.
Long-term Borrowings	Long-term Borrowings Long-term borrowings are comprised of securities sold under agreements to repurchase with an unaffiliated third-party financial institution, subordinated debentures and long-term FHLB advances and additionally included a secured non-revolving line-of-credit with an unaffiliated third-party financial institution at December 31, 2017. Securities sold under agreements to repurchase are collateralized financing transactions and the obligations to repurchase securities sold are reflected as a liability in the accompanying Consolidated Statements of Financial Position. The dollar amount of the securities underlying the agreements remains in the Corporation's investment securities portfolio. FHLB advances, both short-term and long-term, are borrowings from the FHLB to fund short-term liquidity needs as well as a portion of the loan and investment securities portfolios. These advances are secured, under a blanket security agreement, by first lien residential mortgage loans with an aggregate book value equal to at least 140.0% of the FHLB advances and the FHLB stock owned by the Corporation. FHLB advances with an original maturity of more than one year are classified as long-term.
Fair Value Measurements	Fair Value Measurements Fair value for assets and liabilities measured at fair value on a recurring or nonrecurring basis refers to the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants in the market in which the reporting entity transacts such sales or transfers based on the assumptions market participants would use when pricing an asset or liability. Assumptions are developed based on prioritizing information within a fair value hierarchy that gives the highest priority to quoted prices in active markets and the lowest priority to unobservable data, such as the reporting entity's own data. The Corporation may choose to measure eligible items at fair value at specified election dates. Unrealized gains and losses on items for which the fair value measurement option has been elected are reported in earnings at each subsequent reporting date. At December 31, 2018 and 2017 , the Corporation had elected the fair value option on all of its loans held-for-sale. In addition, the Corporation elected to account for loan servicing rights under the fair value method effective January 1, 2017. The Corporation has not elected the fair value option for any other financial assets or liabilities as of December 31, 2018 .
Pension and Postretirement Benefit Plan Actuarial Assumptions	Pension and Postretirement Benefit Plan Actuarial Assumptions The Corporation's defined benefit pension, supplemental pension and postretirement benefit obligations and related costs are calculated using actuarial concepts and measurements. Two critical assumptions, the discount rate and the expected long-term rate of return on plan assets, are important elements of expense and/or benefit obligation measurements. Other assumptions involve employee demographic factors such as retirement patterns, mortality, turnover and the rate of future compensation increases, as well as future health care costs. The Corporation evaluates all assumptions annually. The discount rate enables the Corporation to state expected future benefit payments as a present value on the measurement date. The Corporation determined the discount rate at December 31, 2018 and 2017 by utilizing the results from a discount rate model that involves selecting a portfolio of bonds to settle the projected benefit payments of each plan. To determine the expected long-term rate of return on defined benefit pension plan assets, the Corporation considers the current asset allocation of the defined benefit pension plan, as well as historical and expected returns on each asset class. A lower expected rate of return on defined benefit pension plan assets will increase pension expense. The Corporation recognizes the over- or under-funded status of a plan within "Interest receivable and other assets" or "Interest payable and other liabilities" in the Consolidated Statements of Financial Position as measured by the difference between the fair value of the plan assets and the projected benefit obligation. Unrecognized prior service costs and actuarial gains and losses are recognized as a component of accumulated other comprehensive income (loss). The Corporation measures defined benefit plan assets and obligations as of December 31.
Advertising Costs	Advertising Costs Advertising costs are expensed as incurred.
Income and Other Taxes	Income and Other Taxes The Corporation is subject to the income and other tax laws of the United States, the States of Michigan, Ohio and Indiana and other states where nexus has been created. These laws are complex and are subject to different interpretations by the taxpayer and the various taxing authorities. In determining the provision for income and other taxes, management must make judgments and estimates about the application of these inherently complex laws, related regulations and case law. In the process of preparing the Corporation's tax returns, management attempts to make reasonable interpretations of enacted tax laws. These interpretations are subject to challenge by the tax authorities upon audit or to reinterpretation based on management's ongoing assessment of facts and evolving case law. The Corporation and its subsidiaries file a consolidated federal income tax return. The provision for federal income taxes is based on income and expenses, as reported in the Consolidated Financial Statements, rather than amounts reported on the Corporation's federal income tax return. The difference between the federal statutory income tax rate and the Corporation's effective federal income tax rate is primarily a function of the proportion of the Corporation's interest income exempt from federal taxation, nondeductible interest expense and other nondeductible expenses relative to pretax income and tax credits. When income and expenses are recognized in different periods for tax purposes than for book purposes, deferred tax assets and liabilities are recognized for the future tax consequences attributable to the temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Differences in the tax and book carrying amounts of assets and liabilities can also be generated when the Corporation acquires other banks or bank branches. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized as income or expense in the period that includes the enactment date of the change. On December 22, 2017, H.R.1, commonly referred to as the "Tax Cuts and Jobs Act" was signed into law. The Tax Cuts and Jobs Act, among other items, reduced the corporate income tax rate from 35% to 21%, effective January 1, 2018. As such, the Corporation completed a revaluation of the net deferred tax assets and estimated a reduction in the Corporation's deferred tax asset as of December 31, 2018 . On a quarterly basis, management assesses the reasonableness of its effective federal tax rate based upon its estimate of taxable income and the applicable taxes expected for the full year. Deferred tax assets and liabilities are reassessed on a quarterly basis, including the need for a valuation allowance for deferred tax assets. Uncertain income tax positions are evaluated to determine whether it is more-likely-than-not that a tax position will be sustained upon examination based on the technical merits of the tax position. The Corporation records unrecognized tax benefits as liabilities in accordance with ASC Topic 740, Income Taxes, and adjusts these liabilities when management's judgment changes as a result of the evaluation of new information not previously available. The potential for reserves for uncertain tax positions are reviewed quarterly for adequacy based upon developments in tax law and the status of audits or examinations. The Corporation had no unrecognized tax benefits for uncertain tax positions recorded at December 31, 2018 and 2017 .
Investments in Qualified Affordable Housing Projects, Federal Historic Projects and New Market Tax Credits	Investments in Qualified Affordable Housing Projects, Federal Historic Projects and New Market Tax Credits The Corporation invests in qualified affordable housing projects, federal historic projects, and new market projects for the purpose of community reinvestment and obtaining tax credits. Return on the Corporation's investment in these projects comes in the form of the tax credits and tax losses that pass through to the Corporation. The carrying value of the investments is reflected in "Interest receivable and other assets" on the Consolidated Statements of Financial Position. The Corporation utilizes the proportional amortization method to account for investments in qualified affordable housing projects and the equity method to account for investments in other tax credit projects. Management analyzes these investments for potential impairment when events or changes in circumstances indicate that it is more-likely-than-not that the carrying amount of the investment will not be realized. An impairment loss is measured as the amount by which the carrying amount of an investment exceeds its fair value. Under the proportional amortization method, the Corporation amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits. Under the equity method, the Corporation's share of the earnings or losses is included in "Other operating expenses" on the Consolidated Statements of Income. The Corporation's unfunded equity contributions relating to investments in qualified affordable housing projects, federal historic tax projects and new market projects is recorded in "Interest payable and other liabilities" on the Consolidated Statements of Financial Position.
Earnings Per Share	Earnings Per Share The Corporation applies the two-class method of computing earnings per share as the Corporation has unvested restricted stock awards which qualify as participating securities. Under this calculation, all outstanding unvested share-based payment awards that contain rights to nonforfeitable dividends are considered participating securities and earnings per share is determined according to dividends declared and participating right in undistributed earnings.
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Comprehensive income of the Corporation includes net income and adjustments to shareholders' equity for changes in unrealized gains and losses on investment securities available-for-sale, unrealized gains and losses on interest rate swaps designated as cash flow hedges and changes in the net actuarial gain/loss for the Corporation's defined benefit pension and postretirement plans, net of income taxes. The Corporation presents "Comprehensive income" as a component in the Consolidated Statements of Changes in Shareholders' Equity and the components of other comprehensive income (loss) separately in the Consolidated Statements of Comprehensive Income.
Reclassifications	Reclassifications Certain amounts appearing in the Consolidated Financial Statements and notes thereto for prior periods have been reclassified to conform to the current presentation. The reclassification had no effect on net income or shareholders’ equity as previously reported, except in case of the cumulative effect adjustment of change in accounting policy as noted.
Adopted Accounting Pronouncements	Recently Adopted Accounting Principles Standard Description Adoption Date Effect on the financial statements ASU No. 2014-09 - Revenue from Contracts with Customers (Topic 606) ASU No. 2016-08 - Principal versus Agent Considerations ASU No. 2016-10 - Identifying Performance Obligations and Licensing ASU No. 2016-12 - Narrow-scope Improvements and Practical Expedients ("Updates to Topic 606") ASU No. 2016-20 - Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers ASU No. 2017-13 - Revenue from Contracts with Customers (Topic 606): Amendments to SEC Paragraphs Pursuant to the Staff Announcement at the July 20, 2017 EITF Meeting and Rescission of Prior SEC Staff Announcements and Observer Comments ASU No. 2017-14 - Income Statement - Revenue from Contracts with Customers (Topic 606) (SEC Update) The core principle of the Updates to Topic 606 is that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The standard is intended to clarify and converge the revenue recognition principles under GAAP and International Financial Reporting Standards and to streamline revenue recognition requirements in addition to expanding required revenue recognition disclosures. January 1, 2018 under the modified retrospective method A large majority of the Corporation's revenue is derived from net interest income, which is excluded from the scope of the guidance. Following detailed review of the Corporation's revenue streams not derived from net interest income on financial assets and liabilities, management identified the recognition of gains from other real estate sales financed by the Corporation to be in the scope of this amended guidance. Effective January 1, 2018, revenue for new seller financed other real estate owned sales is determined according to the Updates to Topic 606. If all qualifications are met, gains associated with the sales will be recognized into income at the time of closing and therefore not deferred. The cumulative effect of the Updates to Topic 606 increased retained earnings by $1.2 million upon adoption. The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. Additional required disclosures have been included in Note 16, Revenue from Contracts with Customers. The adoption is not expected to have a material impact on the Corporation's net income on an ongoing basis. Refer to Note 7, Other Real Estate Owned and Repossessed Assets, for further detail. Standard Description Adoption Date Effect on the financial statements ASU No. 2016-01 - Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01") ASU 2016-01 amended current guidance by: (i) requiring equity investments with readily determinable fair values to be measured at fair value with changes in fair value recognized in net income, (ii) allowing an entity to measure equity investments that do not have readily determinable fair values at either fair value or cost minus impairment, changes in measurement is recognized in net income, (iii) simplifying impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment, (iv) eliminating the requirement to disclose the methods and assumptions used to estimate the fair value of financial instruments measured at amortized cost; (v) requiring the use of exit price notion when measuring the fair value of financial instruments; (vi) requiring recognition of changes in the fair value related to instrument-specific credit risk in other comprehensive income if financial liabilities are measured at fair value, (vii) requiring separate presentation in financial statements by measurement category, and (viii) clarifying that an entity should evaluate the need for valuation allowance on deferred tax assets related to available-for-sale securities in combination with the entity’s other deferred tax assets. January 1, 2018 using a modified retrospective approach with the exception of disclosure requirements which are adopted on a prospective basis The Corporation identified available-for-sale investment securities qualifying as equity investments in the securities portfolio at January 1, 2018. The adoption resulted in recognizing the unrealized fair value related to the identified equity investments as a cumulative effect to retained earnings of $0.3 million. In addition, the Corporation updated disclosures related to the fair value of financial instruments to the use of the exit price notion. Refer to Note 3, Fair Value Measurements and Note 4, Investment Securities, for further detail. ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts as Cash Payments ("ASU 2016-15") ASU 2016-15 was issued to reduce diversity in practice and prevent financial statement restatements by clarifying the presentation and classification of cash receipts and cash payments within the statement of cash flows. Cash flow issues include: debt prepayment or debt extinguishment costs, settlement of insurance claims, proceeds from the settlement of corporate-owned and bank-owned life insurance policies, distribution received from equity method investees, beneficial interests in securitization transactions and separately identifiable cash flows and application of the predominance principle. January 1, 2018 using retrospective application The adoption did not have a material effect on the presentation of our Consolidated Statements of Cash Flows, as current policies are either already in-line with the clarifications in the updated guidance, or the related cash flows are not material. ASU No. 2017-07 - Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost ("ASU 2017-07") ASU 2017-07 improves the income statement presentation of net periodic benefit cost for an entity's pension and postretirement plans. The standard requires employers to disaggregate current service costs from other components of net benefit cost and present it with other compensation cost. Additionally net benefit cost becomes eligible for capitalization. January 1, 2018 using the retrospective transition method The adoption resulted in a reclassification of $1.7 million and $0.6 million of net periodic income from salaries, wages and employee benefits expense to other expenses on the Consolidated Statements of Income during the year ended December 31, 2017 and 2016, respectively. ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvement to Account for Hedging Activities ("ASU 2017-12") ASU 2017-12 eliminates the separate measurement of hedge ineffectiveness as well as the benchmark interest rate concept when applying hedge risk to variable-rate instruments. It also allows a company to elect to perform subsequent effectiveness assessments qualitatively if the initial quantitative hedge effectiveness assessment is found to be highly effective. January 1, 2018 The early adoption resulted in a cumulative adjustment from opening retained earnings to accumulated other comprehensive income of $3 thousand, which represented all previously recognized hedge ineffectiveness. Standard Description Adoption Date Effect on the financial statements ASU No. 2018-15 - Intangible-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract ("ASU 2018-15") ASU 2018-15 clarifies the accounting treatment for implementation costs for hosting arrangements that are service contracts. The amendments in this update align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal use software in accordance with subtopic 350-40. Under this guidance costs for implementation activities during the development stage shall be capitalized. The said capitalized-costs shall be expensed over the term of the hosting arrangement. Third quarter of 2018 applied retrospectively The early adoption in the third quarter did not have a material effect on the Consolidated Financial Statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	Standard Description Adoption Date Effect on the financial statements ASU No. 2014-09 - Revenue from Contracts with Customers (Topic 606) ASU No. 2016-08 - Principal versus Agent Considerations ASU No. 2016-10 - Identifying Performance Obligations and Licensing ASU No. 2016-12 - Narrow-scope Improvements and Practical Expedients ("Updates to Topic 606") ASU No. 2016-20 - Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers ASU No. 2017-13 - Revenue from Contracts with Customers (Topic 606): Amendments to SEC Paragraphs Pursuant to the Staff Announcement at the July 20, 2017 EITF Meeting and Rescission of Prior SEC Staff Announcements and Observer Comments ASU No. 2017-14 - Income Statement - Revenue from Contracts with Customers (Topic 606) (SEC Update) The core principle of the Updates to Topic 606 is that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The standard is intended to clarify and converge the revenue recognition principles under GAAP and International Financial Reporting Standards and to streamline revenue recognition requirements in addition to expanding required revenue recognition disclosures. January 1, 2018 under the modified retrospective method A large majority of the Corporation's revenue is derived from net interest income, which is excluded from the scope of the guidance. Following detailed review of the Corporation's revenue streams not derived from net interest income on financial assets and liabilities, management identified the recognition of gains from other real estate sales financed by the Corporation to be in the scope of this amended guidance. Effective January 1, 2018, revenue for new seller financed other real estate owned sales is determined according to the Updates to Topic 606. If all qualifications are met, gains associated with the sales will be recognized into income at the time of closing and therefore not deferred. The cumulative effect of the Updates to Topic 606 increased retained earnings by $1.2 million upon adoption. The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. Additional required disclosures have been included in Note 16, Revenue from Contracts with Customers. The adoption is not expected to have a material impact on the Corporation's net income on an ongoing basis. Refer to Note 7, Other Real Estate Owned and Repossessed Assets, for further detail. Standard Description Adoption Date Effect on the financial statements ASU No. 2016-01 - Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01") ASU 2016-01 amended current guidance by: (i) requiring equity investments with readily determinable fair values to be measured at fair value with changes in fair value recognized in net income, (ii) allowing an entity to measure equity investments that do not have readily determinable fair values at either fair value or cost minus impairment, changes in measurement is recognized in net income, (iii) simplifying impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment, (iv) eliminating the requirement to disclose the methods and assumptions used to estimate the fair value of financial instruments measured at amortized cost; (v) requiring the use of exit price notion when measuring the fair value of financial instruments; (vi) requiring recognition of changes in the fair value related to instrument-specific credit risk in other comprehensive income if financial liabilities are measured at fair value, (vii) requiring separate presentation in financial statements by measurement category, and (viii) clarifying that an entity should evaluate the need for valuation allowance on deferred tax assets related to available-for-sale securities in combination with the entity’s other deferred tax assets. January 1, 2018 using a modified retrospective approach with the exception of disclosure requirements which are adopted on a prospective basis The Corporation identified available-for-sale investment securities qualifying as equity investments in the securities portfolio at January 1, 2018. The adoption resulted in recognizing the unrealized fair value related to the identified equity investments as a cumulative effect to retained earnings of $0.3 million. In addition, the Corporation updated disclosures related to the fair value of financial instruments to the use of the exit price notion. Refer to Note 3, Fair Value Measurements and Note 4, Investment Securities, for further detail. ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts as Cash Payments ("ASU 2016-15") ASU 2016-15 was issued to reduce diversity in practice and prevent financial statement restatements by clarifying the presentation and classification of cash receipts and cash payments within the statement of cash flows. Cash flow issues include: debt prepayment or debt extinguishment costs, settlement of insurance claims, proceeds from the settlement of corporate-owned and bank-owned life insurance policies, distribution received from equity method investees, beneficial interests in securitization transactions and separately identifiable cash flows and application of the predominance principle. January 1, 2018 using retrospective application The adoption did not have a material effect on the presentation of our Consolidated Statements of Cash Flows, as current policies are either already in-line with the clarifications in the updated guidance, or the related cash flows are not material. ASU No. 2017-07 - Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost ("ASU 2017-07") ASU 2017-07 improves the income statement presentation of net periodic benefit cost for an entity's pension and postretirement plans. The standard requires employers to disaggregate current service costs from other components of net benefit cost and present it with other compensation cost. Additionally net benefit cost becomes eligible for capitalization. January 1, 2018 using the retrospective transition method The adoption resulted in a reclassification of $1.7 million and $0.6 million of net periodic income from salaries, wages and employee benefits expense to other expenses on the Consolidated Statements of Income during the year ended December 31, 2017 and 2016, respectively. ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvement to Account for Hedging Activities ("ASU 2017-12") ASU 2017-12 eliminates the separate measurement of hedge ineffectiveness as well as the benchmark interest rate concept when applying hedge risk to variable-rate instruments. It also allows a company to elect to perform subsequent effectiveness assessments qualitatively if the initial quantitative hedge effectiveness assessment is found to be highly effective. January 1, 2018 The early adoption resulted in a cumulative adjustment from opening retained earnings to accumulated other comprehensive income of $3 thousand, which represented all previously recognized hedge ineffectiveness. Standard Description Adoption Date Effect on the financial statements ASU No. 2018-15 - Intangible-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract ("ASU 2018-15") ASU 2018-15 clarifies the accounting treatment for implementation costs for hosting arrangements that are service contracts. The amendments in this update align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal use software in accordance with subtopic 350-40. Under this guidance costs for implementation activities during the development stage shall be capitalized. The said capitalized-costs shall be expensed over the term of the hosting arrangement. Third quarter of 2018 applied retrospectively The early adoption in the third quarter did not have a material effect on the Consolidated Financial Statements.

Mergers and Acquisitions (Table

Mergers and Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Summary of assets acquired and liabilities assumed	Fair values were determined in accordance with the guidance provided in ASC Topic 820, Fair Value Measurements, as of the merger date as presented in the following table. (Dollars in thousands) Consideration paid: Stock $ 1,504,811 Cash 107,638 Total consideration $ 1,612,449 Fair value of identifiable assets acquired: Cash and cash equivalents $ 433,352 Investment securities: Available-for-sale 808,894 Held-to-maturity 1,657 Loans held-for-sale 244,916 Loans 4,882,402 Premises and equipment 38,793 Loan servicing rights 42,462 Other intangible assets 19,088 Interest receivable and other assets 395,539 Total identifiable assets acquired $ 6,867,103 Fair value of liabilities assumed: Noninterest-bearing deposits $ 1,236,902 Interest-bearing deposits 4,057,716 Interest payable and other liabilities 100,936 Securities sold under agreements to repurchase with customers 19,704 Short-term borrowings 387,500 Long-term borrowings 299,597 Total liabilities assumed $ 6,102,355 Fair value of net identifiable assets acquired $ 764,748 Goodwill resulting from acquisition $ 847,701
Information regarding acquired loans accounted for under ASC 310-30	Information regarding loans accounted for under ASC 310-30 at the merger date is as follows: (Dollars in thousands) Accounted for under ASC 310-30: Contractual cash flows $ 5,968,488 Contractual cash flows not expected to be collected (nonaccretable difference) 223,959 Expected cash flows 5,744,529 Interest component of expected cash flows (accretable yield) 862,127 Fair value at acquisition $ 4,882,402
Pro forma financial information	The following unaudited pro forma financial information presents the consolidated results of operation of the Corporation and Talmer as if the merger had occurred as of January 1, 2015. The unaudited pro forma combined results of operations are presented solely for information purposes and are not intended to represent or be indicative of the consolidated results of operations that Chemical would have reported had these transactions been completed as of the dates and for the periods presented, nor are they necessarily indicative of future results. In particular, no adjustments have been made to eliminate the amount of Talmer's provision for loan losses incurred prior to the acquisition date that would not have been necessary had the acquired loans been recorded at fair value as of the beginning of each period indicated. In accordance with Article 11 of SEC Regulation S-X, transaction costs directly attributable to the acquisitions have been excluded. Years ended December 31, (In thousands, except per share data) 2018 2017 2016 Net interest and other income $ 780,869 $ 701,597 $ 492,323 Net Income 284,020 149,523 115,847 Earnings per share: Basic $ 3.98 $ 2.11 $ 1.65 Diluted $ 3.94 $ 2.08 $ 1.62

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Summary of assets measured at fair value on a recurring basis	easured at fair value on a recurring basis, quantitative disclosures about the fair value measurements for each major category of assets and liabilities follow: (Dollars in thousands) Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total December 31, 2018 Investment securities — carried at fair value: Government and government-sponsored enterprises $ — $ 351,700 $ — $ 351,700 State and political subdivisions — 516,286 — 516,286 Residential mortgage-backed securities — 213,428 — 213,428 Collateralized mortgage obligations — 1,601,298 — 1,601,298 Corporate bonds — 293,063 — 293,063 Trust preferred securities — 46,057 — 46,057 Total investment securities — carried at fair value — 3,021,832 — 3,021,832 Loans held-for-sale — 85,030 — 85,030 Loan servicing rights — — 71,013 71,013 Derivative assets: Customer-initiated derivatives — 26,680 — 26,680 Interest rate lock commitments — 1,049 — 1,049 Power Equity CD — 718 — 718 Risk management derivatives — 10,148 — 10,148 Total derivatives — 38,595 — 38,595 Total assets at fair value $ — $ 3,145,457 $ 71,013 $ 3,216,470 Derivative liabilities: Customer-initiated derivatives $ — $ 27,664 $ — $ 27,664 Forward contracts related to mortgage loans to be delivered for sale — 719 — 719 Power Equity CD — 718 — 718 Risk management derivatives — 3,278 — 3,278 Total derivatives — 32,379 — 32,379 Total liabilities at fair value $ — $ 32,379 $ — $ 32,379 (Dollars in thousands) Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total December 31, 2017 Investment securities — carried at fair value: Government and government-sponsored enterprises $ — $ 202,916 $ — $ 202,916 State and political subdivisions — 345,970 — 345,970 Residential mortgage-backed securities — 150,131 — 150,131 Collateralized mortgage obligations — 1,033,845 — 1,033,845 Corporate bonds — 192,794 — 192,794 Trust preferred securities — 36,066 — 36,066 Preferred stock — 1,824 — 1,824 Total investment securities — carried at fair value — 1,963,546 — 1,963,546 Loans held-for-sale — 52,133 — 52,133 Loan servicing rights — — 63,841 63,841 Derivative assets: Customer-initiated derivatives — 9,376 — 9,376 Interest rate lock commitments — 1,222 — 1,222 Power Equity CD — 2,184 — 2,184 Risk management derivatives — 5,899 — 5,899 Total derivatives — 18,681 — 18,681 Total assets at fair value $ — $ 2,034,360 $ 63,841 $ 2,098,201 Derivative liabilities: Customer-initiated derivatives — 10,139 — 10,139 Forward contracts related to mortgage loans to be delivered for sale — 34 — 34 Power Equity CD — 2,184 — 2,184 Total derivatives — 12,357 — 12,357 Total liabilities at fair value $ — $ 12,357 $ — $ 12,357 There were no transfers between levels within the fair value hierarchy during the years ended December 31, 2018 and 2017 . The following table summa
Summary of changes in Level 3 assets measured at fair value on a recurring basis	es the changes in Level 3 assets measured at fair value on a recurring basis. Year Ended December 31, 2018 2017 2016 (Dollars in thousands) Loan servicing rights Balance, beginning of period $ 63,841 $ 48,085 $ — Additions due to acquisition — — 42,462 Transfer in based on new accounting policy election (1) — 15,891 — Gains (losses): Recorded in earnings (realized): Recorded in "Net gain on sale of loans and other mortgage banking revenue" (1,054 ) (8,880 ) 4,593 New originations 8,226 8,745 1,030 Balance, end of period $ 71,013 $ 63,841 $ 48,085 (1) Refer to Note 1, Summary of Significant Accounting Policies, for further details. The Corporation has elected
Schedule of aggregate fair value contractual balance and gain (loss) for loans held-for-sale	ntractual balance (including accrued interest), and gain or loss for loans held-for-sale carried at fair value option was as follows: December 31, (Dollars in thousands) 2018 2017 Aggregate fair value $ 85,030 $ 52,133 Contractual balance 82,080 50,597 Unrealized gain 2,950 1,536 The total amount of gains
Amount of gains (losses) from loans held for sale included in the Consolidated Statements of Income	om loans held-for-sale included in the Consolidated Statements of Income was as follows: Year Ended December 31, (Dollars in thousands) 2018 2017 2016 Interest income (1) $ 2,788 $ 2,540 $ 1,606 Change in fair value (2) 1,414 715 39 Net gain on sales of loans (2) 12,173 31,734 15,686 Total included in earnings $ 16,375 $ 34,989 $ 17,331 (1) Included in "Interest and fees on loans" in the Consolidated Statements of Income. (2) Included in "Net gain on sale of loans and other mortgage banking revenue" in the Consolidated Statements of Income. Assets and Liabilities Reco
Summary of assets measured at fair value on a nonrecurring basis	value on a nonrecurring basis, quantitative disclosures about fair value measurements for each major category of assets follow: (Dollars in thousands) Significant Unobservable Inputs (Level 3) December 31, 2018 Impaired loans $ 63,247 Other real estate and repossessed assets 883 Total $ 64,130 December 31, 2017 Impaired loans $ 70,619 Other real estate and repossessed assets 2,899 Total $ 73,518 There were no liabilities
Additional information about significant unobservable inputs used in the fair value measurement of financial assets	additional information about the significant unobservable inputs used in the fair value measurement of financial assets measured on a nonrecurring basis that were categorized within the Level 3 of the fair value hierarchy: (Dollars in thousands) Fair Value at December 31, 2018 Valuation Technique Significant Unobservable Inputs Range Impaired loans $ 63,247 Appraisal of collateral Discount for type of collateral and age of appraisal 20%-30% Other real estate and repossessed assets 883 Appraisal of property Discount for type of property and age of appraisal 20%-30% Disclosures About Fair Valu
Summary of carrying amounts and estimated fair values of the financial instruments	s and estimated fair values of the Corporation's financial instruments not recorded at fair value in their entirety on a recurring basis on the Consolidated Statements of Financial Position are disclosed in the table below: December 31, Level in Fair Value Measurement Hierarchy 2018 2017 (Dollars in thousands) Carrying Amount Fair Value Carrying Amount Fair Value Financial assets: Investment securities: Held-to-maturity Level 2 $ 623,599 $ 618,232 $ 676,593 $ 662,516 Held-to-maturity Level 3 500 440 500 390 Net loans (1) Level 3 15,159,795 14,907,789 14,063,380 14,114,545 Financial liabilities: Time deposits Level 2 $ 4,074,248 $ 4,041,212 $ 3,217,207 $ 3,225,847 Collateralized customer deposits Level 2 382,687 382,370 415,236 415,236 Short-term borrowings Level 2 2,035,000 2,034,719 2,000,000 1,999,137 Long-term borrowings Level 2 426,002 423,258 372,882 367,984 (1) Included $63.2 million and $70.6 million of impaired loans recorded at fair value on a nonrecurring basis at December 31, 2018 and 2017 , respectively. The short-term nature of c

Investment Securities (Tables)

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Available-for-sale Securities	The following is a summary of the amortized cost and fair value of investment securities carried at fair value and investment securities held-to-maturity at December 31, 2018 and 2017 : Investment Securities Carried at Fair Value (Dollars in thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2018 Debt securities Government and government-sponsored enterprises $ 354,342 $ 713 $ 3,355 $ 351,700 State and political subdivisions 523,178 1,141 8,033 516,286 Residential mortgage-backed securities 216,990 261 3,823 213,428 Collateralized mortgage obligations 1,623,415 2,903 25,020 1,601,298 Corporate bonds 304,243 259 11,439 293,063 Trust preferred securities 47,477 324 1,744 46,057 Total $ 3,069,645 $ 5,601 $ 53,414 $ 3,021,832 December 31, 2017 Debt securities Government and government-sponsored enterprises $ 203,099 $ 765 $ 948 $ 202,916 State and political subdivisions 350,088 310 4,428 345,970 Residential mortgage-backed securities 151,752 5 1,626 150,131 Collateralized mortgage obligations 1,042,240 89 8,484 1,033,845 Corporate bonds 193,230 1,156 1,592 192,794 Trust preferred securities 34,848 1,280 62 36,066 Total debt securities available-for-sale 1,975,257 3,605 17,140 1,961,722 Equity securities Preferred stock 1,389 435 — 1,824 Total equity securities 1,389 435 — 1,824 Total $ 1,976,646 $ 4,040 $ 17,140 $ 1,963,546
Held-to-maturity Securities	Investment Securities Held-to-Maturity (Dollars in thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2018 State and political subdivisions $ 623,599 $ 2,548 $ 7,915 $ 618,232 Trust preferred securities 500 — 60 440 Total $ 624,099 $ 2,548 $ 7,975 $ 618,672 December 31, 2017 State and political subdivisions $ 676,593 $ 3,856 $ 17,933 $ 662,516 Trust preferred securities 500 — 110 390 Total $ 677,093 $ 3,856 $ 18,043 $ 662,906
Proceeds from sales of securities and the associated gains and losses recorded in earnings	Proceeds from sales of investment securities carried at fair value and the associated gains and losses recorded in earnings are listed below: For the years ended December 31, (Dollars in thousands) 2018 2017 2016 Proceeds $ 4,215 $ 409,220 $ 41,446 Gross gains 263 178 325 Gross losses (39 ) (7,566 ) (196 )
Amortized cost and fair value of debt securities by contractual maturity	The following is a summary of the amortized cost and fair value of investment securities at December 31, 2018 , by maturity, for both carried at fair value and held-to-maturity. The maturities of residential mortgage-backed securities and collateralized mortgage obligations are based on scheduled principal payments. The maturities of all other debt securities are based on final contractual maturity. December 31, 2018 (Dollars in thousands) Amortized Cost Fair Value Investment Securities Carried at Fair Value: Due in one year or less $ 51,523 $ 51,244 Due after one year through five years 109,918 108,051 Due after five years through ten years 515,050 498,612 Due after ten years 2,393,154 2,363,925 Total $ 3,069,645 $ 3,021,832 Investment Securities Held-to-Maturity: Due in one year or less $ 55,840 $ 55,728 Due after one year through five years 230,154 228,528 Due after five years through ten years 164,325 162,764 Due after ten years 173,780 171,652 Total $ 624,099 $ 618,672
Summary of continuous unrealized loss position of securities	The following schedule summarizes information for debt securities both carried at fair value and held-to-maturity with gross unrealized losses at December 31, 2018 and 2017 , aggregated by category and length of time that individual securities have been in a continuous unrealized loss position. As of December 31, 2018 , the Corporation's securities portfolio consisted of 2,096 securities, 1,408 of which were in an unrealized loss position. Less Than 12 Months 12 Months or More Total (Dollars in thousands) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses December 31, 2018 Government and government-sponsored enterprises $ 167,164 $ 1,672 $ 62,200 $ 1,683 $ 229,364 $ 3,355 State and political subdivisions 190,551 1,932 657,327 14,016 847,878 15,948 Residential mortgage-backed securities 20,679 85 123,757 3,738 144,436 3,823 Collateralized mortgage obligations 496,356 5,268 656,208 19,752 1,152,564 25,020 Corporate bonds 169,431 5,888 103,688 5,551 273,119 11,439 Trust preferred securities 34,623 1,640 2,725 164 37,348 1,804 Total $ 1,078,804 $ 16,485 $ 1,605,905 $ 44,904 $ 2,684,709 $ 61,389 December 31, 2017 Government and government-sponsored enterprises $ 63,818 $ 510 $ 24,621 $ 438 $ 88,439 $ 948 State and political subdivisions 437,407 12,268 349,242 10,093 786,649 22,361 Residential mortgage-backed securities 93,508 383 56,576 1,243 150,084 1,626 Collateralized mortgage obligations 713,525 7,235 73,707 1,249 787,232 8,484 Corporate bonds 71,447 1,138 47,878 454 119,325 1,592 Trust preferred securities — — 11,164 172 11,164 172 Total $ 1,379,705 $ 21,534 $ 563,188 $ 13,649 $ 1,942,893 $ 35,183

Loans (Tables)

Loans (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Summary of loans under portfolio	A summary of the Corporation's loans follows: (Dollars in thousands) Originated Acquired (1) Total loans December 31, 2018 Commercial loan portfolio: Commercial $ 3,287,087 $ 715,481 $ 4,002,568 Commercial real estate: Owner-occupied 1,513,532 546,025 2,059,557 Non-owner occupied 1,966,330 818,690 2,785,020 Vacant land 40,295 27,215 67,510 Total commercial real estate 3,520,157 1,391,930 4,912,087 Real estate construction and land development 566,726 30,486 597,212 Subtotal 7,373,970 2,137,897 9,511,867 Consumer loan portfolio: Residential mortgage 2,407,305 1,051,361 3,458,666 Consumer installment 1,451,352 69,722 1,521,074 Home equity 612,129 166,043 778,172 Subtotal 4,470,786 1,287,126 5,757,912 Total loans (2) $ 11,844,756 $ 3,425,023 $ 15,269,779 December 31, 2017 Commercial loan portfolio: Commercial $ 2,407,606 $ 978,036 $ 3,385,642 Commercial real estate: Owner-occupied 1,185,614 627,948 1,813,562 Non-owner occupied 1,518,787 1,087,974 2,606,761 Vacant land 47,024 33,323 80,347 Total commercial real estate 2,751,425 1,749,245 4,500,670 Real estate construction and land development 498,155 76,060 574,215 Subtotal 5,657,186 2,803,341 8,460,527 Consumer loan portfolio: Residential mortgage 1,967,857 1,284,630 3,252,487 Consumer installment 1,510,540 102,468 1,613,008 Home equity 611,846 217,399 829,245 Subtotal 4,090,243 1,604,497 5,694,740 Total loans (2) $ 9,747,429 $ 4,407,838 $ 14,155,267 (1) Loans acquired in the Talmer, Lake Michigan, Monarch, Northwestern and OAK acquisitions were elected to be accounted for under ASC 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality (ASC 310-30), by analogy. See Note 1, Summary of Significant Accounting Policies for further information. (2) Reported net of deferred costs totaling $19.7 million and $26.1 million at December 31, 2018 and 2017 , respectively.
Schedule of activity for accretable yield	Activity for the accretable yield, which includes contractually due expected cash flows for acquired loans that have been renewed or extended since the date of acquisition and continue to be accounted for in loan pools in accordance with ASC 310-30, follows: (Dollars in thousands) Talmer Lake Michigan Monarch North-western OAK Total Year Ended December 31, 2018 Balance at beginning of period $ 731,353 $ 95,124 $ 22,496 $ 60,814 $ 17,110 $ 926,897 Accretion recognized in interest income (164,614 ) (24,722 ) (3,881 ) (17,988 ) (10,214 ) (221,419 ) Net reclassification (to) from nonaccretable difference (1)(2) (61,407 ) 2,730 (783 ) (1,371 ) 2,678 (58,153 ) Balance at end of period $ 505,332 $ 73,132 $ 17,832 $ 41,455 $ 9,574 $ 647,325 Year Ended December 31, 2017 Balance at beginning of period $ 798,210 $ 121,416 $ 27,182 $ 69,847 $ 23,316 $ 1,039,971 Accretion recognized in interest income (175,678 ) (29,077 ) (4,533 ) (20,318 ) (12,563 ) (242,169 ) Net reclassification (to) from nonaccretable difference (1) 108,821 2,785 (153 ) 11,285 6,357 129,095 Balance at end of period $ 731,353 $ 95,124 $ 22,496 $ 60,814 $ 17,110 $ 926,897 Year Ended December 31, 2016 Balance at beginning of period $ — $ 152,999 $ 34,558 $ 82,623 $ 28,077 $ 298,257 Addition attributable to acquisitions 862,127 — — — — 862,127 Accretion recognized in interest income (63,917 ) (33,031 ) (5,468 ) (15,791 ) (13,352 ) (131,559 ) Net reclassification (to) from nonaccretable difference (1) — 1,448 (1,908 ) 3,015 8,591 11,146 Balance at end of period $ 798,210 $ 121,416 $ 27,182 $ 69,847 $ 23,316 $ 1,039,971 (1) The net reclassification results from changes in expected cash flows of the acquired loans which may include increases in the amount of contractual principal and interest expected to be collected due to improvement in credit quality, increases in balances outstanding from advances, renewals, extensions and interest rates; as well as reductions in contractual principal and interest expected to be collected due to credit deterioration, payoffs, and decreases in interest rates. (2) The 2018 net reclassification from accretable to nonaccretable difference in the Talmer portfolio was primarily the result of unexpected prepayments and payoffs.
Recorded investment of loans in the commercial loan portfolio by risk rating categories	The following schedule presents the recorded investment of loans in the commercial loan portfolio by credit risk categories at December 31, 2018 and 2017 : (Dollars in thousands) Pass Special Mention Substandard Doubtful Total December 31, 2018 Originated Portfolio: Commercial $ 3,118,894 $ 87,222 $ 77,036 $ 3,935 $ 3,287,087 Commercial real estate: Owner-occupied 1,430,948 32,056 50,286 242 1,513,532 Non-owner occupied 1,901,822 39,416 25,092 — 1,966,330 Vacant land 36,499 — 3,741 55 40,295 Total commercial real estate 3,369,269 71,472 79,119 297 3,520,157 Real estate construction and land development 557,040 6,108 3,578 — 566,726 Subtotal 7,045,203 164,802 159,733 4,232 7,373,970 Acquired Portfolio: Commercial 655,883 36,809 22,773 16 715,481 Commercial real estate: Owner-occupied 500,072 28,909 17,033 11 546,025 Non-owner occupied 740,900 52,546 25,244 — 818,690 Vacant land 26,978 237 — — 27,215 Total commercial real estate 1,267,950 81,692 42,277 11 1,391,930 Real estate construction and land development 29,248 97 1,141 — 30,486 Subtotal 1,953,081 118,598 66,191 27 2,137,897 Total $ 8,998,284 $ 283,400 $ 225,924 $ 4,259 $ 9,511,867 December 31, 2017 Originated Portfolio: Commercial $ 2,316,464 $ 41,059 $ 50,083 $ — $ 2,407,606 Commercial real estate: Owner-occupied 1,133,609 19,438 32,567 — 1,185,614 Non-owner occupied 1,504,195 4,728 9,864 — 1,518,787 Vacant land 39,775 38 7,211 — 47,024 Total commercial real estate 2,677,579 24,204 49,642 — 2,751,425 Real estate construction and land development 494,528 837 2,790 — 498,155 Subtotal 5,488,571 66,100 102,515 — 5,657,186 Acquired Portfolio: Commercial 873,861 68,418 35,539 218 978,036 Commercial real estate: Owner-occupied 580,127 23,998 23,036 787 627,948 Non-owner occupied 995,709 43,645 48,620 — 1,087,974 Vacant land 27,849 327 5,147 — 33,323 Total commercial real estate 1,603,685 67,970 76,803 787 1,749,245 Real estate construction and land development 72,346 2,218 1,496 — 76,060 Subtotal 2,549,892 138,606 113,838 1,005 2,803,341 Total $ 8,038,463 $ 204,706 $ 216,353 $ 1,005 $ 8,460,527
Recorded investment of loans in the consumer loan portfolio based on the credit risk profile of loans in a performing and nonperforming status	The following schedule presents the recorded investment of loans in the consumer loan portfolio based on loans in a performing status and loans in a nonperforming status at December 31, 2018 and 2017 : (Dollars in thousands) Residential mortgage Consumer installment Home equity Total consumer December 31, 2018 Originated Portfolio: Performing $ 2,399,317 $ 1,450,076 $ 608,525 $ 4,457,918 Nonperforming 7,988 1,276 3,604 12,868 Subtotal 2,407,305 1,451,352 612,129 4,470,786 Acquired Loans 1,051,361 69,722 166,043 1,287,126 Total $ 3,458,666 $ 1,521,074 $ 778,172 $ 5,757,912 December 31, 2017 Originated Portfolio: Performing $ 1,959,222 $ 1,509,698 $ 607,541 $ 4,076,461 Nonperforming 8,635 842 4,305 13,782 Subtotal 1,967,857 1,510,540 611,846 4,090,243 Acquired Loans 1,284,630 102,468 217,399 1,604,497 Total $ 3,252,487 $ 1,613,008 $ 829,245 $ 5,694,740
Summary of nonperforming loans	A summary of nonperforming assets follows: December 31, (Dollars in thousands) 2018 2017 Nonperforming assets Nonaccrual loans: Commercial $ 30,139 $ 19,691 Commercial real estate: Owner-occupied 16,056 19,070 Non-owner occupied 23,021 5,270 Vacant land 3,337 5,205 Total commercial real estate 42,414 29,545 Real estate construction and land development 12 77 Residential mortgage 7,988 8,635 Consumer installment 1,276 842 Home equity 3,604 4,305 Total nonaccrual loans 85,433 63,095 Other real estate owned and repossessed assets 6,256 8,807 Total nonperforming assets $ 91,689 $ 71,902
Schedule representing the aging status of the recorded investment in loans by classes	Loan delinquency, excluding acquired loans accounted for under ASC 310-30, was as follows: Loans Past Due and Still Accruing (Dollars in thousands) 30-89 days past due 90 days or more past due Total past due Nonaccrual Loans Current Total loans December 31, 2018 Originated Portfolio: Commercial $ 16,835 $ — $ 16,835 $ 30,139 $ 3,240,113 $ 3,287,087 Commercial real estate: Owner-occupied 4,657 52 4,709 16,056 1,492,767 1,513,532 Non-owner occupied 1,793 887 2,680 23,021 1,940,629 1,966,330 Vacant land 160 — 160 3,337 36,798 40,295 Total commercial real estate 6,610 939 7,549 42,414 3,470,194 3,520,157 Real estate construction and land development 247 — 247 12 566,467 566,726 Residential mortgage 1,688 — 1,688 7,988 2,397,629 2,407,305 Consumer installment 4,731 — 4,731 1,276 1,445,345 1,451,352 Home equity 3,843 488 4,331 3,604 604,194 612,129 Total $ 33,954 $ 1,427 $ 35,381 $ 85,433 $ 11,723,942 $ 11,844,756 December 31, 2017 Originated Portfolio: Commercial $ 16,269 $ — $ 16,269 $ 19,691 $ 2,371,646 $ 2,407,606 Commercial real estate: — Owner-occupied 4,078 — 4,078 19,070 1,162,466 1,185,614 Non-owner occupied 1,595 13 1,608 5,270 1,511,909 1,518,787 Vacant land 83 — 83 5,205 41,736 47,024 Total commercial real estate 5,756 13 5,769 29,545 2,716,111 2,751,425 Real estate construction and land development — — — 77 498,078 498,155 Residential mortgage 2,325 — 2,325 8,635 1,956,897 1,967,857 Consumer installment 3,663 — 3,663 842 1,506,035 1,510,540 Home equity 2,891 1,364 4,255 4,305 603,286 611,846 Total $ 30,904 $ 1,377 $ 32,281 $ 63,095 $ 9,652,053 $ 9,747,429
Schedule of Impaired loans by classes	The following schedules present impaired loans by classes of loans at December 31, 2018 and December 31, 2017 : (Dollars in thousands) Recorded investment Unpaid principal balance Related valuation allowance December 31, 2018 Impaired loans with a valuation allowance: Commercial $ 20,957 $ 23,781 $ 3,546 Commercial real estate: Owner-occupied 14,702 16,519 1,359 Non-owner occupied 16,833 17,452 462 Vacant land 1,008 1,208 96 Total commercial real estate 32,543 35,179 1,917 Real estate construction and land development 126 126 11 Residential mortgage 10,867 10,867 816 Consumer installment 1,126 1,126 186 Home equity 4,432 4,432 328 Subtotal 70,051 75,511 6,804 Impaired loans with no related valuation allowance: Commercial 25,093 25,934 — Commercial real estate: Owner-occupied 10,971 11,601 — Non-owner occupied 12,412 13,411 — Vacant land 2,825 3,911 — Total commercial real estate 26,208 28,923 — Real estate construction and land development 111 111 — Residential mortgage 7,537 7,537 — Consumer installment 377 377 — Home equity 1,496 1,496 — Subtotal 60,822 64,378 — Total impaired loans: Commercial 46,050 49,715 3,546 Commercial real estate: Owner-occupied 25,673 28,120 1,359 Non-owner occupied 29,245 30,863 462 Vacant land 3,833 5,119 96 Total commercial real estate 58,751 64,102 1,917 Real estate construction and land development 237 237 11 Residential mortgage 18,404 18,404 816 Consumer installment 1,503 1,503 186 Home equity 5,928 5,928 328 Total $ 130,873 $ 139,889 $ 6,804 (Dollars in thousands) Recorded investment Unpaid principal balance Related valuation allowance December 31, 2017 Impaired loans with a valuation allowance: Commercial $ 28,897 $ 31,655 $ 2,296 Commercial real estate: Owner-occupied 17,774 21,588 2,317 Non-owner occupied 5,307 7,870 316 Vacant land 4,922 5,122 594 Total commercial real estate 28,003 34,580 3,227 Real estate construction and land development 313 313 14 Residential mortgage 15,872 15,872 1,487 Consumer installment 966 966 120 Home equity 4,570 4,570 858 Subtotal 78,621 87,956 8,002 Impaired loans with no related valuation allowance: Commercial 8,504 9,291 — Commercial real estate: Owner-occupied 11,351 12,631 — Non-owner occupied 5,977 6,438 — Vacant land 752 792 — Total commercial real estate 18,080 19,861 — Residential mortgage 4,902 4,902 — Home equity 1,770 1,770 — Subtotal 33,256 35,824 — Total impaired loans: Commercial 37,401 40,946 2,296 Commercial real estate: Owner-occupied 29,125 34,219 2,317 Non-owner occupied 11,284 14,308 316 Vacant land 5,674 5,914 594 Total commercial real estate 46,083 54,441 3,227 Real estate construction and land development 313 313 14 Residential mortgage 20,774 20,774 1,487 Consumer installment 966 966 120 Home equity 6,340 6,340 858 Total $ 111,877 $ 123,780 $ 8,002 The following schedule presents additional information regarding impaired loans by classes of loans segregated by those requiring a valuation allowance and those not requiring a valuation allowance at December 31, 2018 , 2017 and 2016 and the respective interest income amounts recognized: For the years ended December 31, 2018 2017 2016 (Dollars in thousands) Average annual recorded investment Interest income recognized while on impaired status Average annual recorded investment Interest income recognized while on impaired status Average annual recorded investment Interest income recognized while on impaired status Impaired loans with a valuation allowance: Commercial $ 17,683 $ 457 $ 25,099 $ 939 $ 7,829 $ — Commercial real estate: Owner-occupied 13,103 352 14,143 531 3,694 583 Non-owner occupied 6,440 48 3,274 89 1,711 139 Vacant land 1,881 47 2,566 57 253 113 Total commercial real estate 21,424 447 19,983 677 5,658 835 Real estate construction and land development 4,619 8 175 10 19 — Residential mortgage 12,179 457 16,390 538 23,958 1,285 Consumer installment 989 8 744 4 359 — Home equity 3,262 80 4,201 82 1,759 — Subtotal 60,156 1,457 66,592 2,250 39,582 2,120 Impaired loans with no related valuation allowance: Commercial 21,954 577 10,196 28 29,559 1,343 Commercial real estate: Owner-occupied 13,807 296 11,999 — 20,306 17 Non-owner occupied 10,681 263 9,143 241 14,306 339 Vacant land 2,730 — 3,516 4 7,034 45 Total commercial real estate 27,218 559 24,658 245 41,646 401 Real estate construction and land development 1,520 7 78 — 585 22 Residential mortgage 7,594 110 4,622 38 1,519 — Consumer installment 304 — 205 — — — Home equity 2,217 25 1,392 14 555 — Subtotal 60,807 1,278 41,151 325 73,864 1,766 Total impaired loans: Commercial 39,637 1,034 35,295 967 37,388 1,343 Commercial real estate: Owner-occupied 26,910 648 26,142 531 24,000 600 Non-owner occupied 17,121 311 12,417 330 16,017 478 Vacant land 4,611 47 6,082 61 7,287 158 Total commercial real estate 48,642 1,006 44,641 922 47,304 1,236 Real estate construction and land development 6,139 15 253 10 604 22 Residential mortgage 19,773 567 21,012 576 25,477 1,285 Consumer installment 1,293 8 949 4 359 — Home equity 5,479 105 5,593 96 2,314 — Total $ 120,963 $ 2,735 $ 107,743 $ 2,575 $ 113,446 $ 3,886
Schedule providing information on performing and nonperforming TDRs	The following tables present the recorded investment of loans modified into TDRs during the years ended December 31, 2018 , 2017 and 2016 by type of concession granted. In cases where more than one type of concession was granted, the loans were categorized based on the most significant concession. Concession type (Dollars in thousands) Principal Principal Interest Forbearance Total Pre- modification recorded investment Post- modification recorded investment For the year ended December 31, 2018 Commercial loan portfolio: Commercial $ 4,967 $ — $ 4,129 $ 1,438 67 $ 10,566 $ 10,534 Commercial real estate: Owner-occupied 981 — 2,945 953 19 5,018 4,879 Non-owner occupied 68 66 — — 2 143 134 Total commercial real estate 1,049 66 2,945 953 21 5,161 5,013 Subtotal 6,016 66 7,074 2,391 88 15,727 15,547 Consumer loan portfolio: Residential mortgage 269 151 147 — 9 577 567 Consumer installment 192 168 113 — 47 492 473 Home equity 469 73 453 — 25 1,076 995 Subtotal 930 392 713 — 81 2,145 2,035 Total loans $ 6,946 $ 458 $ 7,787 $ 2,391 169 $ 17,872 $ 17,582 Concession type (Dollars in thousands) Principal Principal Interest Forbearance Total Pre- modification recorded investment Post- modification recorded investment For the year ended December 31, 2017 Commercial loan portfolio: Commercial $ 2,308 $ — $ 1,827 $ 2,176 36 $ 6,416 $ 6,311 Commercial real estate: Owner-occupied 512 — 311 582 13 1,468 1,405 Non-owner occupied 194 — 27 371 3 629 592 Total commercial real estate 706 — 338 953 16 2,097 1,997 Real estate construction and land development 35 — — — 1 36 35 Subtotal 3,049 — 2,165 3,129 53 8,549 8,343 Consumer loan portfolio: Residential mortgage 297 — 383 — 11 763 680 Consumer installment 118 37 37 — 34 208 192 Home equity 389 — 52 — 14 537 441 Subtotal 804 37 472 — 59 1,508 1,313 Total loans $ 3,853 $ 37 $ 2,637 $ 3,129 112 $ 10,057 $ 9,656 Concession type (Dollars in thousands) Principal Principal A/B Note Restructure (1) Interest Forbearance Total Pre- modification recorded investment Post- modification recorded investment For the year ended December 31, 2016 Commercial loan portfolio: Commercial $ 11,533 $ 1,527 $ 43 $ — $ 1,750 54 $ 14,853 $ 14,853 Commercial real estate: Owner-occupied 2,508 1,866 — — — 13 4,374 4,374 Non-owner occupied 485 — — — — 3 485 485 Total commercial real estate 2,993 1,866 — — — 16 4,859 4,859 Subtotal 14,526 3,393 43 — 1,750 70 19,712 19,712 Consumer loan portfolio: Residential mortgage 477 — — — — 4 477 477 Consumer installment 87 — — — — 14 87 87 Home equity 179 — — 364 — 10 543 543 Subtotal 743 — — 364 — 28 1,107 1,107 Total loans $ 15,269 $ 3,393 $ 43 $ 364 $ 1,750 98 $ 20,819 $ 20,819 (1) Loan restructurings whereby the original loan is restructured into two notes: an "A" note, which generally reflects the portion of the modified loans which is expected to be collected: and a "B" note, which is fully charged off.
Schedule of Corporation's TDRs	The following schedule presents the Corporation's TDRs at December 31, 2018 and 2017 : (Dollars in thousands) Accruing TDRs Nonaccrual TDRs Total December 31, 2018 Commercial loan portfolio $ 32,508 $ 24,343 $ 56,851 Consumer loan portfolio 13,072 3,732 16,804 Total $ 45,580 $ 28,075 $ 73,655 December 31, 2017 Commercial loan portfolio $ 34,484 $ 24,358 $ 58,842 Consumer loan portfolio 14,298 4,748 19,046 Total $ 48,782 $ 29,106 $ 77,888
Troubled debt restructurings on financing receivables with defaults payment	The following schedule includes TDRs for which there was a payment default during the years ended December 31, 2018 , 2017 and 2016 , whereby the borrower was past due with respect to principal and/or interest for 90 days or more, and the loan became a TDR during the twelve-month period prior to the default: For the years ended December 31, 2018 2017 2016 Number of loans Principal balance at year end Number of loans Principal balance at year end Number of loans Principal balance at year end (Dollars in thousands) Commercial loan portfolio: Commercial 6 $ 700 5 $ 1,617 — $ — Commercial real estate 3 508 — — 2 1,721 Commercial loan portfolio 9 $ 1,208 5 $ 1,617 2 $ 1,721 Consumer loan portfolio (residential mortgage) 18 413 17 434 14 259 Total 27 $ 1,621 22 $ 2,051 16 $ 1,980
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment	The following schedule presents, by loan portfolio segment, the changes in the allowance for the originated loan portfolio for the years ended December 31, 2018 , 2017 and 2016 . (Dollars in thousands) Commercial loan portfolio Consumer loan portfolio Total Originated Loan Portfolio Changes in allowance for loan losses for the year ended December 31, 2018: Beginning balance $ 66,133 $ 25,754 $ 91,887 Provision for loan losses 22,656 7,674 30,330 Charge-offs (9,563 ) (8,901 ) (18,464 ) Recoveries 3,533 2,278 5,811 Ending balance $ 82,759 $ 26,805 $ 109,564 Changes in allowance for loan losses for the year ended December 31, 2017: Beginning balance $ 51,201 $ 27,067 $ 78,268 Provision for loan losses 19,007 4,293 23,300 Charge-offs (8,570 ) (8,297 ) (16,867 ) Recoveries 4,495 2,691 7,186 Ending balance $ 66,133 $ 25,754 $ 91,887 Changes in allowance for loan losses for the year ended December 31, 2016: Beginning balance $ 47,234 $ 26,094 $ 73,328 Provision for loan losses 9,788 5,087 14,875 Charge-offs (8,906 ) (6,396 ) (15,302 ) Recoveries 3,085 2,282 5,367 Ending balance $ 51,201 $ 27,067 $ 78,268 The following schedule presents, by loan portfolio segment, the changes in the allowance for the acquired loan portfolio for the year ended December 31, 2018 . There was no allowance established for the acquired loan portfolio for the years ended December 31, 2017 and 2016 . (Dollars in thousands) Commercial loan portfolio Consumer loan portfolio Total Acquired Loan Portfolio Changes in allowance for loan losses for the year ended December 31, 2018: Beginning balance $ — $ — $ — Provision for loan losses 420 — 420 Charge-offs — — — Recoveries — — — Ending balance $ 420 $ — $ 420 The following schedule presents by loan portfolio segment, details regarding the balance in the allowance and the recorded investment in loans at December 31, 2018 and 2017 by impairment evaluation method. (Dollars in thousands) Commercial Consumer Total Allowance for loan losses balance at December 31, 2018 attributable to: Loans individually evaluated for impairment $ 5,474 $ 1,330 $ 6,804 Loans collectively evaluated for impairment 77,285 25,475 102,760 Loans accounted for under ASC 310-30 420 — 420 Total $ 83,179 $ 26,805 $ 109,984 Recorded investment (loan balance) at December 31, 2018: Loans individually evaluated for impairment $ 105,038 $ 25,835 $ 130,873 Loans collectively evaluated for impairment 7,268,932 4,444,951 11,713,883 Loans accounted for under ASC 310-30 2,137,897 1,287,126 3,425,023 Total $ 9,511,867 $ 5,757,912 $ 15,269,779 Allowance for loan losses balance at December 31, 2017 attributable to: Loans individually evaluated for impairment $ 5,537 $ 2,465 $ 8,002 Loans collectively evaluated for impairment 60,596 23,289 83,885 Loans accounted for under ASC 310-30 — — — Total $ 66,133 $ 25,754 $ 91,887 Recorded investment (loan balance) at December 31, 2017: Loans individually evaluated for impairment $ 83,797 $ 28,080 $ 111,877 Loans collectively evaluated for impairment 5,573,389 4,062,163 9,635,552 Loans accounted for under ASC 310-30 2,803,341 1,604,497 4,407,838 Total $ 8,460,527 $ 5,694,740 $ 14,155,267

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Summary of premises and equipment	The following table summarizes premises and equipment: December 31, (Dollars in thousands) 2018 2017 Land and land improvements $ 31,357 $ 31,427 Buildings 133,720 130,028 Furniture and equipment 107,660 100,932 Total 272,737 262,387 Less accumulated depreciation (149,295 ) (135,491 ) Premises and equipment, net $ 123,442 $ 126,896

Other Real Estate Owned and R_2

Other Real Estate Owned and Repossessed Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Other Real Estate [Abstract]
Tabular disclosure of the changes in non-covered and covered other real estate on properties owned	Changes in other real estate owned and repossessed assets, included in interest receivable and other assets on the Consolidated Statements of Financial Position, were as follows: (Dollars in thousands) Other real estate Repossessed Balance at January 1, 2016 $ 9,716 $ 219 Additions due to acquisitions 13,227 313 Other additions (1) 9,938 3,032 Net payments received (1,560 ) (763 ) Disposals (13,873 ) (2,426 ) Write-downs (636 ) — Balance at December 31, 2016 $ 16,812 $ 375 Other additions (1) 6,905 4,641 Net payments received (1,064 ) — Disposals (12,831 ) (4,391 ) Write-downs (1,640 ) — Balance at December 31, 2017 $ 8,182 $ 625 Transfers based on adoption of ASU 2014-09 (2) (189 ) — Other additions (1) 7,179 4,307 Net payments received (249 ) — Disposals (7,825 ) (4,508 ) Write-downs (1,266 ) — Balance at December 31, 2018 $ 5,832 $ 424 (1) Includes loans transferred to other real estate owned and other repossessed assets. (2) In accordance with the updates to Topic 606 adopted by the Corporation effective January 1, 2018, $1.1 million of other real estate owned sold with seller financing were reclassified on the Consolidated Statements of Financial Position to loans and the related $0.9 million of deferred gains were recognized in income as an adjustment to opening retained earnings. Refer to Note 1 , Summary of Significant Accounting Policies for further information.
Schedule of income and expenses related to other real estate owned	Income and expenses related to other real estate owned and repossessed assets, recorded as a component of "Other" operating expenses in the Consolidated Statements of Income, were as follows: (Dollars in thousands) Other real estate owned Repossessed assets For the year ended December 31, 2018 Net gain (loss) on sale $ 1,372 $ (309 ) Write-downs (1,266 ) — Net operating expenses (858 ) (5 ) Total $ (752 ) $ (314 ) For the year ended December 31, 2017 Net gain (loss) on sale $ 3,038 $ (381 ) Write-downs (1,640 ) — Net operating expenses (1,981 ) (41 ) Total $ (583 ) $ (422 ) For the year ended December 31, 2016 Net gain on sale $ 5,325 $ 523 Write-downs (636 ) — Net operating expenses (740 ) (60 ) Total $ 3,949 $ 463

Loan Servicing Rights (Tables)

Loan Servicing Rights (Tables)	12 Months Ended
	Dec. 31, 2018
Transfers and Servicing [Abstract]
Schedule of activity for loan servicing rights and the related fair value changes	The following table represents the activity for LSRs and the related fair value changes: (Dollars in thousands) Commercial Real Estate Mortgage Total For the year ended December 31, 2018 Fair value, beginning of period $ 427 $ 63,414 $ 63,841 Additions from loans sold with servicing retained 139 8,087 8,226 Changes in fair value due to: Reductions from pay-offs, pay downs and run-off (115 ) (2,766 ) (2,881 ) Changes in estimates of fair value (1) — 1,827 1,827 Fair value, end of period $ 451 $ 70,562 $ 71,013 Principal balance of loans serviced $ 41,127 $ 6,826,952 $ 6,868,079 For the year ended December 31, 2017 Fair value, beginning of period $ 344 $ 47,741 $ 48,085 Transfers in based on new accounting policy election (2) — 15,891 15,891 Additions from loans sold with servicing retained 188 8,557 8,745 Changes in fair value due to: Reductions from pay-offs, pay downs and run-off (105 ) (2,400 ) (2,505 ) Changes in estimates of fair value (1) — (6,375 ) (6,375 ) Fair value, end of period $ 427 $ 63,414 $ 63,841 Principal balance of loans serviced $ 40,316 $ 7,068,431 $ 7,108,747 For the year ended December 31, 2016 Fair value, beginning of period $ — $ — $ — Acquired in Talmer Bancorp, Inc. merger 365 42,097 42,462 Additions from loans sold with servicing retained — 1,030 1,030 Changes in fair value due to: Reductions from pay-offs, pay downs and run-off (17 ) (502 ) (519 ) Changes in estimates of fair value (1) (4 ) 5,116 5,112 Fair value, end of period $ 344 $ 47,741 $ 48,085 Principal balance of loans serviced under the fair value measurement method $ 64,756 $ 5,235,415 $ 5,300,171 (1) Represents estimated LSR value change resulting primarily from market-driven changes in interest rates and prepayments. Included in "Net gain on sale of loans and other mortgage banking revenue" in the Consolidated Statements of Income. (2) The Corporation elected as of January 1, 2017 to account for all loan servicing rights previously accounted for at the lower of cost or fair value under the fair value measurement method. For further information on this election, refer to Note 1 , Summary of Significant Accounting Policies.
Net carrying value, fair value of mortgage servicing rights and loans Corporation servicing for others	The following shows the net carrying value and fair value of LSRs and the total loans that the Corporation serviced for others accounted for at the lower of cost or fair value for the year ended December 31, 2016: Year Ended December 31, (Dollars in thousands) 2016 Net carrying value of LSRs $ 10,230 Fair value of LSRs $ 15,891 Valuation allowance $ 8 Loans serviced for others that have servicing rights capitalized $ 2,074,057
Activity for capitalized loan servicing rights	Activity for LSRs accounted for at the lower of cost or fair value and the related valuation allowance for the year ended December 31, 2016 is as follows: Year Ended December 31, (Dollars in thousands) 2016 Balance at beginning of period $ 11,122 Additions 3,303 Amortization (4,187 ) Change in valuation allowance (8 ) Balance at end of period $ 10,230
Schedule of assumptions included in loan servicing rights	Expected and actual loan prepayment speeds are the most significant factors driving the fair value of loan servicing rights. The following table presents assumptions utilized in determining the fair value of loan servicing rights as of December 31, 2018 and 2017 . Mortgage As of December 31, 2018 Prepayment speed 0.00 - 26.4% Weighted average ("WA") discount rate 10.1 % WA Cost to service/per year $ 66 WA Ancillary income/per year $ 31 WA float range 2.5 % As of December 31, 2017 Prepayment speed 0.00 - 38.8% WA discount rate 10.1 % WA Cost to service/per year $ 66 Ancillary income/per year $ 31 WA float range 1.6 %

Other Intangible Assets (Tables

Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Net carrying value of other intangible assets	The following table shows the net carrying value of the Corporation's other intangible assets. December 31, (Dollars in thousands) 2018 2017 Core deposit intangible assets $ 28,556 $ 34,259 Non-compete intangible assets — 12 Total other intangible assets $ 28,556 $ 34,271
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets	The following table sets forth the carrying amount and accumulated amortization of core deposit intangible assets that are amortizable and arose from business combinations or other acquisitions: December 31, (Dollars in thousands) 2018 2017 Gross original amount $ 56,456 $ 59,143 Accumulated amortization 27,900 24,884 Net carrying amount $ 28,556 $ 34,259
Estimated future amortization expense on CDIs	The estimated future amortization expense on core deposit intangible assets for the next five years is as follows: (Dollars in thousands) Estimated amortization expense 2019 $ 5,441 2020 4,851 2021 4,471 2022 4,218 2023 3,591

Derivative Instruments and Ba_2

Derivative Instruments and Balance Sheet Offsetting (Tables)	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule reflecting the amount and fair value of risk management derivatives and mortgage banking and customer initiated derivatives	The following table presents the notional amount and fair value of the Corporation’s derivative instruments held or issued in connection with customer-initiated and mortgage banking activities. December 31, 2018 2017 Fair Value Fair Value (Dollars in thousands) Notional Amount (1) Gross Derivative Assets (2) Gross Derivative Liabilities (2) Notional Amount (1) Gross Derivative Assets (2) Gross Derivative Liabilities (2) Risk management purposes: Derivatives designated as hedging instruments: Interest rate swaps $ 820,000 $ 10,148 $ 3,278 $ 620,000 $ 5,899 $ — Total risk management purposes 820,000 10,148 3,278 620,000 5,899 — Customer-initiated and mortgage banking derivatives: Customer-initiated derivatives 2,477,640 26,680 27,664 1,365,119 9,376 10,139 Foreign exchange forwards (3) — — — — — — Forward contracts related to mortgage loans to be delivered for sale 127,159 — 719 115,996 — 34 Interest rate lock commitments 54,848 1,049 — 71,003 1,222 — Power Equity CD 36,771 718 718 38,807 2,184 2,184 Total customer-initiated and mortgage banking derivatives 2,696,418 28,447 29,101 1,590,925 12,782 12,357 Total gross derivatives $ 3,516,418 $ 38,595 $ 32,379 $ 2,210,925 $ 18,681 $ 12,357 (1) Notional or contract amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Statements of Financial Position. (2) Derivative assets are included within "Interest receivable and other assets" and derivative liabilities are included within "Interest Payable and other liabilities" on the Consolidated Statements of Financial Position. Included in the fair value of the derivative assets are credit valuation adjustments for counterparty credit risk totaling $0.9 million at December 31, 2018 and $0.8 million at December 31, 2017 . (3) The foreign exchange forwards that were entered into during the years ended December 31, 2018 and 2017 matured prior to each respective year end.
Schedule reflecting the net gains (losses) relating to derivative instruments related to the changes in fair value	The following table presents the net gains (losses) related to derivative instruments reflecting the changes in fair value. For the years ended December 31, (Dollars in thousands) Location of Gain (Loss) 2018 2017 2016 Forward contracts related to mortgage loans to be delivered for sale Net gain on sale of loans and other mortgage banking revenue $ (685 ) $ (669 ) $ 692 Interest rate lock commitments Net gain on sale of loans and other mortgage banking revenue (173 ) 266 (1,356 ) Power Equity CD Other noninterest income — — — Foreign exchange forwards Other noninterest income — — — Customer-initiated derivatives Other noninterest income (221 ) (1,028 ) 581 Total gain (loss) recognized in income $ (1,079 ) $ (1,431 ) $ (83 ) The following table presents the net gains (losses) recorded in accumulated other comprehensive income and the Consolidated Statements of Income relating to interest rate swaps designated as cash flow hedges for the years ended December 31, 2018 and 2017 . The Corporation first began entering into interest rate swaps designated as cash flow hedges during the year ended December 31, 2017. (Dollars in thousands) Amount of gain recognized in other comprehensive income Amount of gain (loss) reclassified from other comprehensive income to interest income or expense Year Ended December 31, 2018 Interest rate swaps designated as cash flow hedges $ 2,841 $ 1,871 Year Ended December 31, 2017 Interest rate swaps designated as cash flow hedges $ 4,263 $ (1,633 )
Schedule of the Company's financial instruments eligible for offset, offsetting assets	The tables below present information about the Corporation’s financial instruments that are eligible for offset. Gross amounts not offset in the (Dollars in thousands) Gross Gross amounts Net amounts Financial Collateral Net December 31, 2018 Offsetting derivative assets Derivative assets (1) $ 36,791 $ — $ 36,791 $ — $ (16,120 ) $ 20,671 Offsetting derivative liabilities Derivative liabilities (1) 30,822 — 30,822 — 430 30,392 December 31, 2017 Offsetting derivative assets Derivative assets (1) $ 15,228 $ — $ 15,228 $ — $ — $ 15,228 Offsetting derivative liabilities Derivative liabilities 10,139 — 10,139 — 1,081 9,058 (1) Amount does not include participated interest rate swaps, forward contracts, interest rate lock commitments and power equity CDs as these instruments are not subject to master netting or similar arrangements.
Schedule of the Company's financial instruments eligible for offset, offsetting liabilities	The tables below present information about the Corporation’s financial instruments that are eligible for offset. Gross amounts not offset in the (Dollars in thousands) Gross Gross amounts Net amounts Financial Collateral Net December 31, 2018 Offsetting derivative assets Derivative assets (1) $ 36,791 $ — $ 36,791 $ — $ (16,120 ) $ 20,671 Offsetting derivative liabilities Derivative liabilities (1) 30,822 — 30,822 — 430 30,392 December 31, 2017 Offsetting derivative assets Derivative assets (1) $ 15,228 $ — $ 15,228 $ — $ — $ 15,228 Offsetting derivative liabilities Derivative liabilities 10,139 — 10,139 — 1,081 9,058 (1) Amount does not include participated interest rate swaps, forward contracts, interest rate lock commitments and power equity CDs as these instruments are not subject to master netting or similar arrangements.

Commitments, Contingencies an_2

Commitments, Contingencies and Guarantees (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of activity related to liability recorded in connection with representation and warranties	A summary of the reserve for representations and warranties of the Corporation is as follows: For the years ended December 31, (Dollars in thousands) 2018 2017 2016 Reserve balance at beginning of period $ 5,349 $ 6,459 $ 4,048 Addition of fair value of representations and warranties due to mergers and acquisitions — — 3,100 Reserve reduction (1,217 ) (1,095 ) (580 ) Charge-offs (48 ) (15 ) (109 ) Ending reserve balance $ 4,084 $ 5,349 $ 6,459 Reserve balance: Liability for specific claims $ 398 $ 531 $ 730 General allowance 3,686 4,818 5,729 Total reserve balance $ 4,084 $ 5,349 $ 6,459
Schedule of future minimum lease payments for operating leases	Future minimum lease payments for operating leases and other noncancelable contractual obligations are as follows: (Dollars in thousands) Future Minimum Lease Payments (1) Other Noncancelable Contracts Total Years ending December 31, 2019 $ 7,251 $ 46,225 $ 53,476 2020 6,239 37,566 43,805 2021 5,135 31,330 36,465 2022 4,775 30,124 34,899 2023 4,375 27,849 32,224 Thereafter 12,107 46,771 58,878 Total $ 39,882 $ 219,865 $ 259,747 (1) Future minimum lease payments are reduced by $632 thousand related to sublease income to be received within the next five years.

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2018
Deposits [Abstract]
Schedule of Deposits	t December 31, 2018 , the scheduled maturities of time deposits for the next five years were as follows: (Dollars in thousands) 2019 $ 2,776,097 2020 1,032,314 2021 148,995 2022 82,076 2023 33,900 Thereafter 866 Total $ 4,074,248 A summary of deposits follows: December 31, (Dollars in thousands) 2018 2017 Noninterest-bearing demand $ 3,809,252 $ 3,725,779 Savings and money market accounts 4,092,082 3,655,671 Interest-bearing demand 3,316,278 2,724,415 Brokered deposits 985,522 453,227 Other time deposits 3,390,148 3,083,711 Total deposits $ 15,593,282 $ 13,642,803

Borrowings and Other Short-te_2

Borrowings and Other Short-term Liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Short- and Long-term Borrowings	A summary of the Corporation's short- and long-term borrowings, and other short-term liabilities follows: December 31, 2018 2017 (Dollars in thousands) Amount Weighted Average Rate (1) Amount Weighted Average Rate (1) Short-term borrowings: FHLB advances: 2.46% - 2.59% fixed-rate notes $ 2,035,000 2.47 % $ 2,000,000 1.39 % Long-term borrowings: FHLB advances: 1.00% - 2.72% fixed-rate notes due 2019 to 2025 (2) 410,102 2.00 % 337,204 1.26 % Line-of-credit: floating-rate based on one-month LIBOR plus 1.75% — — 19,963 3.10 % Subordinated debt obligations: floating-rate based on three-month LIBOR plus 1.45% - 2.85% due 2034 to 2035 (3) 11,572 4.85 % 11,425 3.69 % Subordinated debt obligations: floating-rate based on three-month LIBOR plus 3.25% due in 2032 (4) 4,328 5.65 % 4,290 4.59 % Total long-term borrowings 426,002 2.11 % 372,882 1.47 % Total borrowings $ 2,461,002 2.41 % $ 2,372,882 1.40 % Other short-term liabilities: Collateralized customer deposits $ 382,687 0.75 % $ 415,236 0.44 % (1) Weighted average rate presented is the contractual rate which excludes premiums and discounts related to purchase accounting. (2) The December 31, 2018 balance includes advances payable of $410.0 million and purchase accounting premiums of $0.1 million . The December 31, 2017 balance includes advances payable of $337.0 million and purchase accounting premiums of $0.2 million . (3) The December 31, 2018 balance includes advances payable of $15.0 million and purchase accounting discounts of $3.4 million . The December 31, 2017 balance includes advance payable of $15.0 million and purchase accounting discounts of $3.6 million . (4) The December 31, 2018 balance includes advances payable of $5.0 million and purchase accounting discounts of $0.7 million . The December 31, 2017 balance includes advance payable of $5.0 million and purchase accounting discounts of $0.7 million .
Long-term Debt by Maturity	At December 31, 2018 , the contractual principal payments due and the amortization/accretion of purchase accounting adjustments for the remaining maturities of long-term debt over the next five years and thereafter are as follows: (Dollars in thousands) Long-term Debt by Maturity Years Ending December 31, 2019 $ 100,058 2020 110,044 2021 — 2022 — 2023 — Thereafter 215,900 Total $ 426,002

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Segregation of Noninterest Income	The following table presents total noninterest income segregated between contracts with customers within the scope of ASC 606 and those within the scope of other GAAP Topics. The following additionally presents revenues from customers and non-customers that are included within noninterest income and expense. Year Ended December 31, (Dollars in thousands) 2018 Noninterest income Service charges and fees on deposit accounts $ 22,858 Wealth management revenue 5,099 Other charges and fees for customer services 5,556 Noninterest income from contracts with customers within the scope of ASC 606 33,513 Noninterest income within the scope of other GAAP topics 115,023 Total noninterest income $ 148,536 Noninterest expense Other $ (1,063 )

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Provision for Federal Income Taxes Components	The current and deferred components of the provision for income taxes were as follows: Years Ended December 31, (Dollars in thousands) 2018 2017 2016 Current income tax expense (benefit) Federal $ (653 ) $ 14,665 $ 19,144 State 321 20 (423 ) Total current income tax expense (332 ) 14,685 18,721 Deferred income tax expense Federal 41,687 92,636 23,649 State 229 548 442 Total deferred income tax expense 41,916 93,184 24,091 Change in valuation allowance 317 (1,089 ) (706 ) Income tax provision $ 41,901 $ 106,780 $ 42,106
Schedule of Federal Effective Income Tax Rate Reconciliation	A reconciliation of expected income tax expense at the federal statutory income tax rate and the amounts recorded in the Consolidated Financial Statements were as follows: Years Ended December 31, 2018 2017 2016 (Dollars in thousands) Amount Rate Amount Rate Amount Rate Tax at statutory rate $ 68,443 21.0 % $ 89,706 35.0 % $ 52,548 35.0 % Changes resulting from: Tax-exempt interest income (6,513 ) (2.0 ) (9,001 ) (3.5 ) (5,320 ) (3.5 ) State taxes, net of federal benefit 434 0.1 369 0.1 13 — Change in valuation allowance 317 0.1 (1,089 ) (0.4 ) (706 ) (0.5 ) Bank-owned life insurance adjustments (838 ) (0.2 ) (1,696 ) (0.7 ) (832 ) (0.6 ) Director plan change in control — — — — (508 ) (0.3 ) Income tax credits, net (16,148 ) (4.9 ) (11,449 ) (4.4 ) (2,454 ) (1.6 ) Nondeductible transaction expenses — 156 0.1 2,100 1.4 Nondeductible FDIC insurance premiums 1,095 0.3 — — — — Tax benefit in excess of compensation costs on share-based payments (1) (1,782 ) (0.5 ) (5,886 ) (2.3 ) (2,240 ) (1.5 ) Impact of the Tax Cuts and Jobs Act (2) (2,939 ) (0.9 ) 46,660 18.2 — — Other, net (168 ) (0.1 ) (990 ) (0.4 ) (495 ) (0.4 ) Income tax expense $ 41,901 12.9 % $ 106,780 41.7 % $ 42,106 28.0 % (1) Represents excess tax benefits resulting from the exercise or settlement of share-based payment transactions. (2) The year ended December 31, 2017 included the initial calculated impact of the enactment of H.R.1 (the "Tax Cuts and Jobs Act"), which required a revaluation of net deferred tax assets and liabilities. The year ended December 31, 2018 included the impact of analyzing additional information in the year following the enactment date of the Tax Cuts and Jobs Act that was not previously available, as allowed by Staff Accounting Bulletin (SAB) No. 118, issued in late December 2017. See below for further details.
Schedule of Deferred Tax Assets and Liabilities	The significant components of the deferred tax assets and liabilities at December 31, 2018 and 2017 were as follows: December 31, (Dollars in thousands) 2018 2017 Deferred tax assets: Allowance for loan losses $ 24,019 $ 20,446 Acquisition-related fair value adjustments 16,511 27,607 Unrealized loss on securities 10,040 2,751 Accrued stock-based compensation 3,239 4,082 Loss and tax credit carry forwards 30,169 57,969 Nonaccrual loan interest 10,830 6,155 Accrued expense 7,397 9,200 Other 4,888 9,330 Total deferred tax assets 107,093 137,540 Deferred tax liabilities: Loan servicing rights 14,941 13,446 Core deposit intangible assets 4,966 6,022 Goodwill 4,281 4,076 Deferred loan fees 4,963 4,551 Prepaid expenses 5,625 7,390 Other 5,894 3,184 Total deferred tax liabilities 40,670 38,669 Net deferred tax asset before valuation allowance 66,423 98,871 Valuation allowance (1,467 ) (1,150 ) Net deferred tax asset $ 64,956 $ 97,721
Summary of the loss attributes, Section 382 limitations, and tax expiration periods	The following table is a summary of the loss attributes, Section 382 limitations, and tax expiration periods as of December 31, 2018 . From the Acquisition of: Talmer Bancorp and Talmer Bank Prior Ownership Changes (Dollars in thousands) Monarch First Place Holdings/First Place Bank Talmer West Bank First of Huron Corp./Signature Bank From 2009 Ownership change Not Limited by Section 382 Total Tax Loss and Credit Carryforwards as of 12/31/18: Years Expiring (except AMT Credits) 2026-2034 2027-2031 2028-2032 2029-2032 2027-2029 Annual Section 382 limitation-base (1) $ 673 $ 6,650 $ 3,028 $ 365 $ 145 $ — $ N/A Gross Federal Net Operating Losses 12,350 — 41,039 247 1,595 — 55,231 Gross Capital Losses — — — — — 6,987 6,987 Realized Built-in Losses — 61,317 8,936 — — — 70,253 Business Tax Credits 1,651 781 — — — — 2,432 Less amounts not recorded due to Sec 382 Limitation (1,738 ) (140 ) — — (145 ) — (2,023 ) Alternative Minimum Tax Credits - no expiration 106 2,115 — 303 — — 2,524 Valuation Allowance — — — — — (1,467 ) (1,467 ) (1) In respect to the Monarch acquisition, in addition to the statutory "base" Section 382 limitation, recognized built in gain increases the Section 382 limitation during the five year period beginning on the acquisition date. The Corporation estimates that the recognized built in gain will total $1.6 million .

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of stock options outstanding by exercise price range	The following summarizes information about stock options outstanding and exercisable at December 31, 2018 : Options outstanding Options exercisable Range of exercise prices per share Number outstanding Weighted average exercise price per share Weighted average contractual term (in years) Number exercisable Weighted average exercise price per share Weighted average contractual term (in years) $11.09 - 12.80 32,691 $ 12.37 1.93 32,691 $ 12.37 1.93 $13.20 - 16.24 26,669 15.73 4.00 26,669 15.73 4.00 $19.97 - 21.10 22,955 20.15 1.99 22,955 20.15 1.99 $23.78 - 25.14 162,561 24.59 3.59 162,561 24.59 3.59 $29.45 - 32.81 428,350 31.71 6.64 267,067 31.05 6.33 $46.95 - 53.72 104,217 53.35 8.25 43,842 53.54 8.24 $11.09 - 53.72 777,443 $ 31.42 5.79 555,785 $ 28.65 5.13
Summary of activity for Corporation's stock options	A summary of activity for the Corporation's stock options as of and during the years ended December 31, 2018 , 2017 and 2016 is presented below: Non-vested stock options outstanding Stock options outstanding Number of options Weighted- average exercise price per share Weighted- average grant date fair value per share Number of options Weighted- average exercise price per share Outstanding at December 31, 2015 479,755 $ 28.75 $ 8.49 1,054,739 $ 25.38 Granted 441,167 32.81 6.15 441,167 32.81 Acquired — — — 1,466,408 15.08 Exercised — — — (450,296 ) 20.02 Vested (454,360 ) 28.74 8.49 — — Forfeited/expired (58,623 ) 31.10 7.17 (58,623 ) 31.10 Outstanding at December 31, 2016 407,939 $ 32.81 $ 6.15 2,453,395 $ 21.41 Granted 132,414 53.43 9.94 132,414 53.43 Exercised — — — (1,427,159 ) 17.50 Vested (161,751 ) 37.73 7.07 — — Forfeited/expired (47,732 ) 37.55 7.03 (47,732 ) 37.55 Outstanding at December 31, 2017 330,870 $ 37.97 $ 7.09 1,110,918 $ 29.56 Exercised — — — (302,796 ) 24.00 Vested (78,533 ) 37.16 6.94 — — Forfeited/expired (30,679 ) 37.20 6.97 (30,679 ) 37.20 Outstanding at December 31, 2018 221,658 $ 38.37 $ 7.16 777,443 $ 31.42 Exercisable/vested at December 31, 2018 555,785 $ 28.65
Assumptions of Black-Scholes option pricing model	The fair value of the stock options granted during the years ended December 31, 2017 and 2016 were estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions. The Corporation did not grant any stock options during the year ended December 31, 2018 . 2017 2016 Expected dividend yield 3.31 % 3.30 % Risk-free interest rate 2.05 % 1.39 % Expected stock price volatility 26.7 % 27.9 % Expected life of options — in years 6.0 6.5 Weighted average fair value of options granted $ 9.94 $ 6.15
Summary of activity for restricted stock units and awards	The following table provides information regarding nonvested restricted stock awards: Nonvested restricted stock awards Number of awards Weighted-average acquisition-date fair value Nonvested at January 1, 2018 83,228 $ 46.23 Vested (41,784 ) 46.23 Forfeited (592 ) 46.23 Nonvested at December 31, 2018 40,852 $ 46.23 A summary of the activity for RSUs during the year ended December 31, 2018 is presented below: Number of units Weighted-average grant date fair value per unit Outstanding at December 31, 2017 380,940 $ 41.29 Granted 321,043 54.15 Converted into shares of common stock (102,553 ) 34.77 Forfeited/expired (22,940 ) 47.87 Outstanding at December 31, 2018 576,490 $ 49.35

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Schedule of Changes in the Projected Benefit Obligation and Plan Assets of the Corporation’s Pension and Postretirement Plans	The following schedule sets forth the changes in the projected benefit obligation and plan assets of the Corporation's Plans: Pension Plan Postretirement Plan SERP (Dollars in thousands) 2018 2017 2018 2017 2018 2017 Projected benefit obligation: Benefit obligation at beginning of year $ 121,361 $ 123,968 $ 2,512 $ 2,601 $ 2,423 $ 2,567 Service cost — 639 3 5 — 61 Interest cost 4,356 4,966 82 94 12 69 Net actuarial loss (gain) (7,048 ) 10,131 (208 ) 10 (36 ) (274 ) Benefits paid (7,237 ) (6,432 ) (189 ) (198 ) (2,062 ) — Curtailment — (11,911 ) — — — — Benefit obligation at end of year 111,432 121,361 2,200 2,512 337 2,423 Fair value of plan assets: Fair value of plan assets at beginning of year 145,901 132,751 — — — — Actual return on plan assets (10,312 ) 19,582 — — — — Employer contributions — — — 198 — — Benefits paid (7,237 ) (6,432 ) — (198 ) — — Fair value of plan assets at end of year 128,352 145,901 — — — — Funded (unfunded) status at December 31 $ 16,920 $ 24,540 $ (2,200 ) $ (2,512 ) $ (337 ) $ (2,423 ) Accumulated benefit obligation $ 111,432 $ 121,361 $ 2,200 $ 2,512 $ 337 $ 2,423
Schedule of Weighted-average rate assumptions of the Pension and Postretirement Plans	Weighted-average rate assumptions of the Corporation's Plans follow: Pension Plan Postretirement Plan SERP 2018 2017 2016 2018 2017 2016 2018 2017 2016 Discount rate used in determining benefit obligation — December 31 4.32 % 3.68 % 4.22 % 4.11 % 3.41 % 3.79 % 4.32 % 3.38 % 3.63 % Discount rate used in determining expense 3.68 4.22 4.55 3.41 3.79 4.23 — — 4.51 Discount rate used in determining expense — prior to remeasurement — 3.81 — — — — 3.38 3.63 2.87 Expected long-term return on Pension Plan assets 6.50 6.75 6.75 — — — — — — Rate of compensation increase used in determining benefit obligation — December 31 — — 3.50 — — — — — 3.50 Rate of compensation increase used in determining pension expense — 3.50 3.50 — — — — 3.50 3.50 Year 1 increase in cost of postretirement benefits — — — 7.50 6.50 7.00 — — —
Schedule of Net periodic Pension Cost (Income) of the Pension and Postretirement Plans	Net periodic pension cost (income) of the Corporation's Plans was as follows for the years ended December 31: Pension Plan Postretirement Plan SERP (Dollars in thousands) 2018 2017 2016 2018 2017 2016 2018 2017 2016 Service cost $ — $ 639 $ 1,041 $ 3 $ 5 $ 9 $ — $ 61 $ 77 Interest cost 4,356 4,966 5,335 82 94 132 12 69 92 Expected return on plan assets (8,879 ) (8,938 ) (8,562 ) — — — — — — Amortization of prior service credit — — — — — 117 — — — Amortization of net actuarial loss (gain) 710 1,837 2,259 (143 ) (162 ) (100 ) (7 ) 77 78 Curtailment — 1 — — — — — — — Settlement (1) — — — — — — — 322 120 Net cost (income) $ (3,813 ) $ (1,495 ) $ 73 $ (58 ) $ (63 ) $ 158 $ 5 $ 529 $ 367 (1) The settlement charge relates to the settlement of liabilities under the SERP for the retirement of the plan participant during the third quarter of 2017 and the change in control as a result of the merger with Talmer as of August 31, 2016.
Schedule of Estimated Future Benefit Payments Under the Pension and Postretirement Plans	The following schedule presents estimated future benefit payments for the next 10 years under the Corporation's Plans for retirees already receiving benefits and future retirees, assuming they retire and begin receiving unreduced benefits as soon as they are eligible: (Dollars in thousands) Pension Plan Postretirement Plan SERP 2019 $ 6,387 $ 241 $ 22 2020 6,522 237 22 2021 6,680 231 22 2022 6,795 221 22 2023 6,895 209 22 2024 - 2028 35,908 853 106 Total $ 69,187 $ 1,992 $ 216
Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates	A one percentage-point change in these rates would have the following effects: One Percentage-Point (Dollars in thousands) Increase Decrease Effect on total of service and interest cost component in 2017 $ 7 $ (6 ) Effect on postretirement benefit obligation as of December 31, 2017 157 (143 )
Schedule of Allocation of Plan Assets	The Pension Plan's asset allocation by asset category was as follows: December 31, Asset Category 2018 2017 Equity securities 67 % 68 % Debt securities 26 28 Other 7 4 Total 100 % 100 % The following schedule sets forth the fair value of the Pension Plan's assets and the level of the valuation inputs used to value those assets at December 31, 2018 and 2017 : (Dollars in thousands) Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total December 31, 2018 Cash $ 8,770 $ — $ — $ 8,770 Equity securities: U.S. large- and mid-cap stocks (1) 63,823 — — 63,823 U.S. small-cap mutual funds 4,713 — — 4,713 International large-cap mutual funds 11,091 — — 11,091 Emerging markets mutual funds 6,439 — — 6,439 Debt securities: U.S. Treasury and government sponsored agency bonds and notes — 547 — 547 Mutual funds (2) 32,969 — — 32,969 Total $ 127,805 $ 547 $ — $ 128,352 December 31, 2017 Cash $ 5,238 $ — $ — $ 5,238 Equity securities: U.S. large- and mid-cap stocks (1) 68,909 — — 68,909 U.S. small-cap mutual funds 5,377 — — 5,377 International large-cap mutual funds 18,341 — — 18,341 Emerging markets mutual funds 7,363 — — 7,363 Debt securities: U.S. Treasury and government sponsored agency bonds and notes — 548 — 548 Mutual funds (2) 40,046 — — 40,046 Other 79 — — 79 Total $ 145,353 $ 548 $ — $ 145,901 (1) Comprised of common stocks and mutual funds traded on U.S. Exchanges whose issuers had market capitalizations exceeding $3 billion . (2) Comprised primarily of fixed-income bonds issued by the U.S. Treasury and government sponsored agencies and bonds of U.S. and foreign issuers from diverse industries.
Schedule of Changes in Accumulated Other Comprehensive Income (Loss), Net of Tax, Related to the Corporation’s Pension, Postretirement and Supplemental Plans	The following sets forth the changes in accumulated other comprehensive income (loss), net of tax, related to the Corporation's Pension Plan, Postretirement Plan and SERP during 2018 : (Dollars in thousands) Pension Plan Postretirement Plan SERP Total Accumulated other comprehensive income (loss) at beginning of year $ (20,483 ) $ 744 $ (69 ) $ (19,808 ) Comprehensive income (loss) adjustment: Net actuarial income (loss) (9,032 ) 51 23 (8,958 ) Comprehensive income (loss) adjustment (9,032 ) 51 23 (8,958 ) Accumulated other comprehensive income (loss) at end of year $ (29,515 ) $ 795 $ (46 ) $ (28,766 )
Schedule of Estimated Income (Loss) That Will Be Amortized From Accumulated Other Comprehensive Income (Loss) Into Net Periodic Cost	The estimated income (loss) that will be amortized from accumulated other comprehensive income (loss) into net periodic cost, net of tax, in 2019 is as follows: (Dollars in thousands) Pension Plan Postretirement Plan SERP Total Net gain (loss) $ (444 ) $ 143 $ (1 ) $ (302 )

Regulatory Capital and Reserv_2

Regulatory Capital and Reserve Requirements (Tables)	12 Months Ended
	Dec. 31, 2018
Banking and Thrift [Abstract]
Corporation's and Chemical Bank's actual capital amounts and ratios with the quantitative measures established by regulation to ensure capital adequacy	The summary below compares the actual capital amounts and ratios with the quantitative measures established by regulation to ensure capital adequacy: Actual Minimum Required for Capital Adequacy Purposes Minimum Required for Capital Adequacy Purposes Plus Capital Conservation Buffer Required to be Well Capitalized Under Prompt Corrective Action Regulations (Dollars in thousands) Capital Amount Ratio Capital Amount Ratio Capital Amount Ratio Capital Amount Ratio December 31, 2018 Total Capital to Risk-Weighted Assets Corporation $ 1,855,922 11.5 % $ 1,288,363 8.0 % $ 1,590,323 9.9 % N/A N/A Chemical Bank 1,825,742 11.4 1,285,444 8.0 1,586,719 9.9 $ 1,606,804 10.0 % Tier 1 Capital to Risk-Weighted Assets Corporation 1,723,004 10.7 966,272 6.0 1,268,232 7.9 N/A N/A Chemical Bank 1,708,724 10.6 964,083 6.0 1,265,358 7.9 1,285,444 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets Corporation 1,723,004 10.7 724,704 4.5 1,026,664 6.4 N/A N/A Chemical Bank 1,708,724 10.6 723,062 4.5 1,024,338 6.4 1,044,423 6.5 Leverage Ratio Corporation 1,723,004 8.7 793,669 4.0 793,669 4.0 N/A N/A Chemical Bank 1,708,724 8.6 792,184 4.0 792,184 4.0 990,230 5.0 December 31, 2017 Total Capital to Risk-Weighted Assets Corporation $ 1,614,046 11.0 % $ 1,179,076 8.0 % $ 1,363,307 9.3 % N/A N/A Chemical Bank 1,613,087 11.0 1,176,361 8.0 1,360,167 9.3 $ 1,470,451 10.0 % Tier 1 Capital to Risk-Weighted Assets Corporation 1,498,463 10.2 884,307 6.0 1,068,538 7.3 N/A N/A Chemical Bank 1,513,219 10.3 882,271 6.0 1,066,077 7.3 1,176,361 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets Corporation 1,498,463 10.2 663,230 4.5 847,461 5.8 N/A N/A Chemical Bank 1,513,219 10.3 661,703 4.5 845,509 5.8 955,793 6.5 Leverage Ratio Corporation 1,498,463 8.3 720,890 4.0 720,890 4.0 N/A N/A Chemical Bank 1,513,219 8.4 720,043 4.0 720,043 4.0 900,053 5.0

Parent Company Only Financial_2

Parent Company Only Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Disclosure [Abstract]
Parent Company Condensed Statement of Financial Position	Condensed financial statements of Chemical Financial Corporation (parent company) only follow: Condensed Statements of Financial Position December 31, (Dollars in thousands) 2018 2017 Assets Cash at subsidiary bank $ 11,477 $ 5,761 Investment in subsidiaries 2,820,866 2,673,858 Premises and equipment 3,595 3,931 Goodwill 1,092 1,092 Deferred tax asset 5,865 7,203 Other assets 27,157 31,459 Total assets $ 2,870,052 $ 2,723,304 Liabilities Other liabilities $ 17,892 $ 18,877 Non-revolving line-of-credit — 19,963 Subordinated debentures 15,900 15,715 Total liabilities 33,792 54,555 Shareholders' equity 2,836,260 2,668,749 Total liabilities and shareholders' equity $ 2,870,052 $ 2,723,304
Parent Company Condensed Statement of Income	Condensed Statements of Income Years Ended December 31, (Dollars in thousands) 2018 2017 2016 Income Cash dividends from subsidiaries $ 114,300 $ 165,000 $ 110,450 Other (loss) income (269 ) 921 151 Total income 114,031 165,921 110,601 Expenses Interest expense 1,601 3,076 1,816 Operating expenses 13,784 23,298 30,589 Total expenses 15,385 26,374 32,405 Income before income taxes and equity in undistributed net income of subsidiaries 98,646 139,547 78,196 Income tax benefit 4,472 12,670 11,378 Equity in undistributed net income (loss) of subsidiaries 180,902 (2,694 ) 18,458 Net income $ 284,020 $ 149,523 $ 108,032
Parent Company Condensed Statement of Cash Flows	Condensed Statements of Cash Flows Years Ended December 31, (Dollars in thousands) 2018 2017 2016 Cash Flows From Operating Activities Net income $ 284,020 $ 149,523 $ 108,032 Adjustments to reconcile net income to net cash provided by operating activities: Share-based compensation expense 8,578 17,346 13,452 Depreciation of premises and equipment 435 408 355 Equity in undistributed net (income) loss of subsidiaries (180,902 ) 2,694 (18,458 ) Net decrease in other assets 4,302 1,410 9,752 Net increase (decrease) in other liabilities 537 25,178 (11,830 ) Net cash provided by operating activities 116,970 196,559 101,303 Cash Flows From Investing Activities Cash paid, net of cash assumed, in business combinations — — (107,622 ) Purchases of premises and equipment, net (99 ) (288 ) (774 ) Net cash used in investing activities (99 ) (288 ) (108,396 ) Cash Flows From Financing Activities Cash dividends paid (88,954 ) (78,498 ) (49,389 ) Proceeds from issuance of common stock, net of issuance costs — — — Repayment of subordinated debt obligations — — (18,558 ) Repayments of other borrowings (20,000 ) (105,000 ) (62,500 ) Proceeds from issuance of other borrowings — — 125,000 Proceeds from directors' stock purchase plan and exercise of stock options 3,115 3,991 1,572 Cash paid for payroll taxes upon conversion of restricted stock units (5,316 ) (27,854 ) (1,065 ) Net cash used in financing activities (111,155 ) (207,361 ) (4,940 ) Net increase (decrease) in cash and cash equivalents 5,716 (11,090 ) (12,033 ) Cash and cash equivalents at beginning of year 5,761 16,851 28,884 Cash and cash equivalents at end of year $ 11,477 $ 5,761 $ 16,851 Business combinations: Fair value of assets acquired (noncash) $ — $ — $ 46,898 Liabilities assumed — — 58,309 Common stock and stock options issued — — 1,504,811

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Numerator and denominator of the basic and diluted earnings per common share computations	The factors used in the earnings per share computation follow: For the years ended December 31, (In thousands, except per share data) 2018 2017 2016 Net income $ 284,020 $ 149,523 $ 108,032 Net income allocated to participating securities 186 495 166 Net income allocated to common shareholders (1) $ 283,834 $ 149,028 $ 107,866 Weighted average common shares - issued 71,385 71,103 49,091 Average unvested restricted share awards (47 ) (238 ) (139 ) Weighted average common shares outstanding - basic 71,338 70,865 48,952 Effect of dilutive securities Weighted average common stock equivalents 687 648 651 Weighted average common shares outstanding - diluted 72,025 71,513 49,603 EPS available to common shareholders Basic earnings per common share $ 3.98 $ 2.11 $ 2.21 Diluted earnings per common share $ 3.94 $ 2.08 $ 2.17 (1) Net income allocated to common shareholders for basic and diluted earnings per share may differ under the two-class method as a result of adding common share equivalents for options and warrants to dilutive shares outstanding, which alters the ratio used to allocate net income to common shareholders and participating securities for the purposes of calculating diluted earnings per share.

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Components of accumulated other comprehensive loss, net of related tax benefit/expense	The following table summarizes the changes within each component of accumulated other comprehensive income (loss), net of related tax benefit/expense for the years ended December 31, 2018 , 2017 and 2016 : (Dollars in thousands) Unrealized gains (losses) on securities carried at fair value, net of tax Defined Benefit Pension Plans Unrealized gains (losses) on cash flow hedges, net of tax Total For the year ended December 31, 2018 Beginning balance $ (10,348 ) $ (19,808 ) $ 4,658 $ (25,498 ) Cumulative effect adjustment of change in accounting policy, net of tax impact (1) (344 ) — 3 (341 ) Beginning balance at January 1, 2018 (10,692 ) (19,808 ) 4,661 (25,839 ) Other comprehensive income (loss) before reclassifications (26,903 ) — 2,245 (24,658 ) Amounts reclassified from accumulated other comprehensive income (loss) (177 ) (8,958 ) (1,478 ) (10,613 ) Net current period other comprehensive income (loss) (27,080 ) (8,958 ) 767 (35,271 ) Ending balance $ (37,772 ) $ (28,766 ) $ 5,428 $ (61,110 ) For the year ended December 31, 2017 Beginning balance $ (14,142 ) $ (25,894 ) $ — $ (40,036 ) Other comprehensive income before reclassifications 826 8,457 2,771 12,054 Amounts reclassified from accumulated other comprehensive income 4,802 1,139 1,061 7,002 Net current period other comprehensive income 5,628 9,596 3,832 19,056 Reclassification of certain deferred tax effects (2) (1,834 ) (3,510 ) 826 (4,518 ) Ending balance $ (10,348 ) $ (19,808 ) $ 4,658 $ (25,498 ) For the year ended December 31, 2016 Beginning balance $ (1,888 ) $ (27,144 ) $ — $ (29,032 ) Other comprehensive (loss) before reclassifications (12,170 ) (229 ) — (12,399 ) Amounts reclassified from accumulated other comprehensive income (loss) (84 ) 1,479 — 1,395 Net current period other comprehensive income (loss) (12,254 ) 1,250 — (11,004 ) Ending balance $ (14,142 ) $ (25,894 ) $ — $ (40,036 ) (1) Refer to Note 1 , Summary of Significant Accounting Policies and Note 4 , Investment Securities, for further details on the changes in accounting policy. (2) The reclassification from accumulated other comprehensive income (loss) to retained earnings was due to the early adoption of ASU 2018-02, see Note 1 for further information.
Summary of amounts reclassified out of accumulated other comprehensive income (loss)	The following table summarizes the amounts reclassified out of each component of accumulated other comprehensive income (loss) for the years ended December 31, 2018 , 2017 and 2016 : (Dollars in thousands) Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Income Statement December 31, 2018 December 31, 2017 December 31, 2016 Gains and losses on available-for-sale securities $ 224 $ (7,388 ) $ 129 Net gain (loss) on sale of investment securities (noninterest income) (47 ) 2,586 (45 ) Income tax (expense)/benefit $ 177 $ (4,802 ) $ 84 Net income (loss) Amortization of defined benefit pension plan items $ 11,339 $ (1,752 ) $ (2,276 ) Salaries, wages and employee benefits (operating expenses) (2,381 ) 613 797 Income tax expense/(benefit) $ 8,958 $ (1,139 ) $ (1,479 ) Net (income) loss Gains and losses on cash flow hedges (1,871 ) 1,633 — Interest on short-term borrowings (interest expense) 393 (572 ) — Income tax expense/(benefit) $ (1,478 ) $ 1,061 $ — Net (income) loss

Summary of Quarterly Statemen_2

Summary of Quarterly Statements of Income (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Selected Quarterly Financial Information [Abstract]
Schedule of Quarterly Financial Information	The following is a summary of the unaudited quarterly results of operation for the years ended December 31, 2018 , 2017 and 2016 . In the opinion of management, the information reflects all adjustments that are necessary for the fair presentation of the results of operations for the periods presented. 2018 (Dollars in thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter Total Interest income $ 177,934 $ 189,582 $ 198,377 $ 210,103 $ 775,996 Interest expense 26,071 32,045 38,896 46,651 143,663 Net interest income 151,863 157,537 159,481 163,452 632,333 Provision for loan losses 6,256 9,572 6,028 8,894 30,750 Noninterest income 40,554 38,018 37,917 32,047 148,536 Operating expenses 101,610 104,561 109,661 108,366 424,198 Income before income taxes 84,551 81,422 81,709 78,239 325,921 Income tax expense 12,955 12,434 11,312 5,200 41,901 Net income $ 71,596 $ 68,988 $ 70,397 $ 73,039 $ 284,020 Net income per common share: Basic $ 1.01 $ 0.97 $ 0.99 $ 1.02 $ 3.98 Diluted 0.99 0.96 0.98 1.01 3.94 Cash dividends declared per common share 0.28 0.28 0.34 0.34 1.24 2017 (Dollars in thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter Total Interest income $ 142,896 $ 155,133 $ 164,944 $ 169,162 $ 632,135 Interest expense 12,799 17,185 21,316 23,257 74,557 Net interest income 130,097 137,948 143,628 145,905 557,578 Provision for loan losses 4,050 6,229 5,499 7,522 23,300 Noninterest income 38,010 41,568 32,122 32,319 144,019 Operating expenses 104,196 98,237 119,539 100,022 421,994 Income before income taxes 59,861 75,050 50,712 70,680 256,303 Income tax expense 12,257 23,036 10,253 61,234 106,780 Net income $ 47,604 $ 52,014 $ 40,459 $ 9,446 $ 149,523 Net income per common share: Basic $ 0.67 $ 0.73 $ 0.57 $ 0.13 $ 2.11 Diluted 0.67 0.73 0.56 0.13 2.08 Cash dividends declared per common share 0.27 0.27 0.28 0.28 1.10 2016 (Dollars in thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter Total Interest income $ 79,464 $ 82,937 $ 103,562 $ 144,416 $ 410,379 Interest expense 5,134 5,442 6,753 11,969 29,298 Net interest income 74,330 77,495 96,809 132,447 381,081 Provision for loan losses 1,500 3,000 4,103 6,272 14,875 Noninterest income 19,419 20,897 27,770 54,264 122,350 Operating expenses 58,887 59,085 106,144 114,302 338,418 Income before income taxes 33,362 36,307 14,332 66,137 150,138 Income tax expense 9,757 10,532 2,848 18,969 42,106 Net income $ 23,605 $ 25,775 $ 11,484 $ 47,168 $ 108,032 Net income per common share: Basic $ 0.61 $ 0.67 $ 0.23 $ 0.67 $ 2.21 Diluted 0.60 0.67 0.23 0.66 2.17 Cash dividends declared per common share 0.26 0.26 0.27 0.27 1.06

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Nature of Operations) (Details)	12 Months Ended
	Dec. 31, 2018Bank
Nature of Operations
Number of banks through which company operates (in bank)	1
Number of regional banking units Chemical Bank operates through (in bank)	6

Summary of Significant Accoun_5

Summary of Significant Accounting Policies (Investment Securities) (Details) - USD ($)	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Retained Earnings Adjustments [Line Items]
Debt Securities, Trading	$ 0
Equity securities	3,021,832,000		$ 1,963,546,000
Retained earnings	$ 616,149,000		419,403,000
Accounting Standards Update 2016-01
Retained Earnings Adjustments [Line Items]
Retained earnings		$ (344,000)	(300,000)
Preferred stock
Retained Earnings Adjustments [Line Items]
Equity securities			$ 1,824,000
Preferred stock | Accounting Standards Update 2016-01
Retained Earnings Adjustments [Line Items]
Equity securities		$ 1,800,000

Summary of Significant Accoun_6

Summary of Significant Accounting Policies (Nonmarketable Equity Securities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
FHLB stock minimum redemption period	5 years
FRB stock minimum redemption period	6 months
FRB stock minimum annual amount redeemable	25.00%
Corporation's ownership in FHLB stock	$ 125.2	$ 112
Corporation's ownership in FRB stock	$ 68.1

Summary of Significant Accoun_7

Summary of Significant Accounting Policies (Originated Loans Held for Investment) (Details)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Number of minimum days when principal or interest is past due is placed in nonaccrual category	90 days
Time period in which payments receive consistently and loans are returned to accrual status	6 months

Summary of Significant Accoun_8

Summary of Significant Accounting Policies (Loans Modified Under Troubled Debt Restructuring) (Details)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Number of minimum days when principal or interest is past due is placed in nonaccrual category	90 days
Time period of real estate residential troubled debt restructurings reducing borrower's monthly payments by decreasing the interest rate charged on the loan	24 months

Summary of Significant Accoun_9

Summary of Significant Accounting Policies (Allowance for Loan Losses) (Details)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Period of weighted average losses for the calculation of the allowance for loan losses	6 years

Summary of Significant Accou_10

Summary of Significant Accounting Policies (Mortgage Banking Operations) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Change in accounting policy for ASC Subtopic 860-50
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cumulative adjustment to retained earnings	$ 3.7
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forward commitment term	90 days

Summary of Significant Accou_11

Summary of Significant Accounting Policies (Premises and Equipment) (Details)	12 Months Ended
	Dec. 31, 2018
Buildings | Minimum
Property, Plant and Equipment [Line Items]
Premises and equipment, estimated useful lives	25 years
Buildings | Maximum
Property, Plant and Equipment [Line Items]
Premises and equipment, estimated useful lives	40 years
All other depreciable assets | Minimum
Property, Plant and Equipment [Line Items]
Premises and equipment, estimated useful lives	3 years
All other depreciable assets | Maximum
Property, Plant and Equipment [Line Items]
Premises and equipment, estimated useful lives	10 years

Summary of Significant Accou_12

Summary of Significant Accounting Policies (Other Real Estate Owned and Repossessed Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Interest receivable and other assets
Other real estate owned and repossessed assets	$ 6.3	$ 8.8

Summary of Significant Accou_13

Summary of Significant Accounting Policies (Other Intangible Assets) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Goodwill, Impairment Loss	$ 0	$ 0
Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization period	10 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization period	15 years
Core deposit intangible assets | Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization period	10 years
Core deposit intangible assets | Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization period	15 years

Summary of Significant Accou_14

Summary of Significant Accounting Policies (Bank-Owned Life Insurance) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Bank-owned life insurance	$ 152.1	$ 147.6
Bank owned life insurance income	$ 4	$ 4.8	$ 1.8

Summary of Significant Accou_15

Summary of Significant Accounting Policies (Long-Term Borrowings) (Details)	Dec. 31, 2018
Accounting Policies [Abstract]
Percentage of FHLB advances secured by first lien real estate residential loans	140.00%

Summary of Significant Accou_16

Summary of Significant Accounting Policies (Advertising Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Advertising and marketing	$ 8.2	$ 5.9	$ 3.7

Summary of Significant Accou_17

Summary of Significant Accounting Policies (Income Taxes and Investment in Tax Credit Projects) (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Contingent income tax liabilities recorded	$ 0	$ 0

Summary of Significant Accou_18

Summary of Significant Accounting Policies (Adopted Accounting Pronouncements) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Jan. 01, 2018
New Accounting Pronouncement, Early Adoption [Line Items]
Retained earnings adjustment		$ (419,403)		$ (616,149)
Reclassification of certain income tax effects	[1]	0
Retained Earnings
New Accounting Pronouncement, Early Adoption [Line Items]
Reclassification of certain income tax effects	[1]	(4,518)
Accounting Standards Update 2014-09
New Accounting Pronouncement, Early Adoption [Line Items]
Retained earnings adjustment		(1,200)
Accounting Standards Update 2016-01
New Accounting Pronouncement, Early Adoption [Line Items]
Retained earnings adjustment		300			$ 344
Accounting Standards Update 2017-07
New Accounting Pronouncement, Early Adoption [Line Items]
Pension plan expense		1,700	$ 600
Adjustments for New Accounting Principle, Early Adoption | Accounting Standards Update 2017-12
New Accounting Pronouncement, Early Adoption [Line Items]
Retained earnings adjustment		$ 3
[1]	The reclassification from accumulated other comprehensive income (loss) to retained earnings was due to the early adoption of ASU 2018-02, refer to Note 1 for further details on the adoption.

Mergers and Acquisitions (Textu

Mergers and Acquisitions (Textual) (Details) $ / shares in Units, $ in Thousands, shares in Millions	Aug. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Business Acquisition
Credit facility drawn		$ 426,002	$ 372,882
Merger expenses		0	8,522	$ 61,134
Line of Credit
Business Acquisition
Credit facility drawn	$ 125,000	$ 0	$ 19,963
Repayments of lines of credit	25,000
Talmer
Business Acquisition
Acquisition purchase price	$ 1,612,449
Stock consideration given (in shares) | shares	32.1
Exchange ratio of common stock issued	0.4725
Share price (in dollars per share) | $ / shares	$ 1.61
Repayments of lines of credit	$ 37,500

Mergers and Acquisitions (Asset

Mergers and Acquisitions (Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	Aug. 31, 2016	Dec. 31, 2018	Dec. 31, 2017
Fair value of liabilities assumed:
Goodwill resulting from acquisition		$ 1,134,568	$ 1,134,568
Talmer
Consideration paid:
Stock	$ 1,504,811
Cash	107,638
Total consideration	1,612,449
Fair value of identifiable assets acquired:
Cash and cash equivalents	433,352
Investment securities:
Available-for-sale	808,894
Held-to-maturity	1,657
Loans held-for-sale	244,916
Loans	4,882,402
Premises and equipment	38,793
Loan servicing rights	42,462
Other intangible assets	19,088
Interest receivable and other assets	395,539
Total identifiable assets acquired	6,867,103
Fair value of liabilities assumed:
Noninterest-bearing deposits	1,236,902
Interest-bearing deposits	4,057,716
Interest payable and other liabilities	100,936
Securities sold under agreements to repurchase with customers	19,704
Short-term borrowings	387,500
Long-term borrowings	299,597
Total liabilities assumed	6,102,355
Fair value of net identifiable assets acquired	764,748
Goodwill resulting from acquisition	$ 847,701

Mergers and Acquisitions (Loans

Mergers and Acquisitions (Loans Accounted for Under ASC 310-30) (Details) - Talmer $ in Thousands	Aug. 31, 2016USD ($)
Accounted for under ASC 310-30:
Contractual cash flows	$ 5,968,488
Contractual cash flows not expected to be collected (nonaccretable difference)	223,959
Expected cash flows	5,744,529
Interest component of expected cash flows (accretable yield)	862,127
Fair value at acquisition	$ 4,882,402

Mergers and Acquisitions (Pro F

Mergers and Acquisitions (Pro Forma Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Combinations [Abstract]
Net interest and other income	$ 780,869	$ 701,597	$ 492,323
Net Income	$ 284,020	$ 149,523	$ 115,847
Earnings per share:
Basic (in dollars per share)	$ 3.98	$ 2.11	$ 1.65
Diluted (in dollars per share)	$ 3.94	$ 2.08	$ 1.62

Fair Value Measurements (Recurr

Fair Value Measurements (Recurring Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	$ 3,021,832	$ 1,963,546
Carried at fair value		1,963,546
Loans held-for-sale	85,030	52,133
Loan servicing rights	71,013	63,841	$ 48,085	$ 0
Derivative assets	38,595	18,681
Total assets at fair value	3,216,470	2,098,201
Derivative liabilities	32,379	12,357
Total liabilities at fair value	32,379	12,357
Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	0	0
Loans held-for-sale	0	0
Loan servicing rights	0	0
Derivative assets	0	0
Total assets at fair value	0	0
Derivative liabilities	0	0
Total liabilities at fair value	0	0
Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	3,021,832	1,963,546
Loans held-for-sale	85,030	52,133
Loan servicing rights	0	0
Derivative assets	38,595	18,681
Total assets at fair value	3,145,457	2,034,360
Derivative liabilities	32,379	12,357
Total liabilities at fair value	32,379	12,357
Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	0	0
Loans held-for-sale	0	0
Loan servicing rights	71,013	63,841
Derivative assets	0	0
Total assets at fair value	71,013	63,841
Derivative liabilities	0	0
Total liabilities at fair value	0	0
Customer-initiated derivatives
Summary of assets measured at fair value on a recurring basis
Derivative assets	26,680	9,376
Derivative liabilities	27,664	10,139
Customer-initiated derivatives | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0	0
Derivative liabilities	0	0
Customer-initiated derivatives | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Derivative assets	26,680	9,376
Derivative liabilities	27,664	10,139
Customer-initiated derivatives | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0	0
Derivative liabilities	0	0
Forward contracts related to mortgage loans to be delivered for sale
Summary of assets measured at fair value on a recurring basis
Derivative liabilities	719	34
Forward contracts related to mortgage loans to be delivered for sale | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Derivative liabilities	0	0
Forward contracts related to mortgage loans to be delivered for sale | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Derivative liabilities	719	34
Forward contracts related to mortgage loans to be delivered for sale | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Derivative liabilities	0	0
Interest rate lock commitments
Summary of assets measured at fair value on a recurring basis
Derivative assets	1,049	1,222
Interest rate lock commitments | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0	0
Interest rate lock commitments | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Derivative assets	1,049	1,222
Interest rate lock commitments | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0	0
Power Equity CD
Summary of assets measured at fair value on a recurring basis
Derivative assets	718	2,184
Derivative liabilities	718	2,184
Power Equity CD | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0	0
Derivative liabilities	0	0
Power Equity CD | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Derivative assets	718	2,184
Derivative liabilities	718	2,184
Power Equity CD | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0	0
Derivative liabilities	0	0
Risk management derivatives
Summary of assets measured at fair value on a recurring basis
Derivative assets	10,148	5,899
Derivative liabilities	3,278
Risk management derivatives | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0	0
Derivative liabilities	0
Risk management derivatives | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Derivative assets	10,148	5,899
Derivative liabilities	3,278
Risk management derivatives | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0	0
Derivative liabilities	0
Government and government-sponsored enterprises
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	351,700	202,916
Government and government-sponsored enterprises | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	0	0
Government and government-sponsored enterprises | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	351,700	202,916
Government and government-sponsored enterprises | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	0	0
State and political subdivisions
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	516,286	345,970
State and political subdivisions | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	0	0
State and political subdivisions | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	516,286	345,970
State and political subdivisions | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	0	0
Residential mortgage-backed securities
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	213,428
Residential mortgage-backed securities | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	0
Residential mortgage-backed securities | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	213,428
Residential mortgage-backed securities | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	0
Residential mortgage-backed securities
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value		150,131
Residential mortgage-backed securities | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value		0
Residential mortgage-backed securities | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value		150,131
Residential mortgage-backed securities | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value		0
Collateralized mortgage obligations
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	1,601,298	1,033,845
Collateralized mortgage obligations | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	0	0
Collateralized mortgage obligations | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	1,601,298	1,033,845
Collateralized mortgage obligations | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	0	0
Corporate bonds
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	293,063	192,794
Corporate bonds | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	0	0
Corporate bonds | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	293,063	192,794
Corporate bonds | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	0	0
Preferred stock
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value		1,824
Preferred stock | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value		0
Preferred stock | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value		1,824
Preferred stock | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value		0
Trust preferred securities
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	46,057	36,066
Trust preferred securities | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	0	0
Trust preferred securities | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	46,057	36,066
Trust preferred securities | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Total investment securities — carried at fair value	$ 0	$ 0

Fair Value Measurements (Change

Fair Value Measurements (Changes in Level 3 Assets) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	$ 0
Loan servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	63,841,000	$ 48,085,000	$ 0
Additions due to acquisition	0	0	42,462,000
Transfer in based on new accounting policy election	0	15,891,000	0
Gains (losses) recorded in earnings (realized) recorded in Net gain on sale of loans and other mortgage banking revenue	(1,054,000)	(8,880,000)	4,593,000
New originations	8,226,000	8,745,000	1,030,000
Balance, end of period	$ 71,013,000	$ 63,841,000	$ 48,085,000

Fair Value Measurements (Aggreg

Fair Value Measurements (Aggregate Fair Value, Contractual Balance, and Gain or Loss for Loans Held-For-Sale) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Aggregate fair value	$ 85,030	$ 52,133
Contractual balance	82,080	50,597
Unrealized gain	$ 2,950	$ 1,536

Fair Value Measurements (Gains

Fair Value Measurements (Gains (Losses) from Loans Held-for-Sale Included in the Consolidated Statements of Income) (Details) - Loans held for sale - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total included in earnings	$ 16,375	$ 34,989	$ 17,331
Interest income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total included in earnings	2,788	2,540	1,606
Net gain on sale of loans and other mortgage banking revenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total included in earnings	1,414	715	39
Net gain on sales of loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total included in earnings	$ 12,173	$ 31,734	$ 15,686

Fair Value Measurements (Nonrec

Fair Value Measurements (Nonrecurring Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	$ 3,216,470	$ 2,098,201
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	71,013	63,841
Nonrecurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	64,130	73,518
Nonrecurring | Impaired loans | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	63,247	70,619
Nonrecurring | Other real estate and repossessed assets | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	$ 883	$ 2,899

Fair Value Measurements (Textua

Fair Value Measurements (Textual) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	$ 3,216,470,000	$ 2,098,201,000
Loans held for sale on nonaccrual status	0	0
Impairment of goodwill	0	0
Impairment identified for intangible assets	0	0
Liabilities recorded at fair value	32,379,000	12,357,000
Loans held for sale 90 days past due and on accrual status	0	0
Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities recorded at fair value	$ 0	$ 0
Non-compete intangible assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Finite-lived intangible assets amortization period	1 year
Loan Servicing Rights
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Valuation allowance related to impairment			$ 8,000
Minimum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Discount factors used to determine fair value	20.00%
Finite-lived intangible assets amortization period	10 years
Minimum | Other Real Estate and Repossessed Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Discount factors used to determine fair value	20.00%
Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Discount factors used to determine fair value	30.00%
Finite-lived intangible assets amortization period	15 years
Maximum | Other Real Estate and Repossessed Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Discount factors used to determine fair value	30.00%

Fair Value Measurements (Level

Fair Value Measurements (Level 3 Assets Measured on a Nonrecurring Basis) (Details) $ in Thousands	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Assets, fair value disclosure	$ 3,216,470	$ 2,098,201
Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Assets, fair value disclosure	$ 71,013	$ 63,841
Discount rate | Level 3 | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Impaired originated loans, measurement input		0.20
Other real estate assets, measurement input		0.20
Discount rate | Level 3 | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Impaired originated loans, measurement input		0.30
Other real estate assets, measurement input		0.30

Fair Value Measurements (Carryi

Fair Value Measurements (Carrying Amounts and Estimated Fair Values) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Investment securities:
Held-to-maturity	$ 618,672	$ 662,906
Financial liabilities:
Short-term borrowings	2,035,000	2,000,000
Long-term borrowings	426,002	372,882
Assets, fair value disclosure	3,216,470	2,098,201
Level 1
Financial liabilities:
Assets, fair value disclosure	0	0
Level 2
Financial liabilities:
Assets, fair value disclosure	3,145,457	2,034,360
Level 3
Financial liabilities:
Assets, fair value disclosure	71,013	63,841
Carrying Amount | Level 2
Investment securities:
Held-to-maturity	623,599	676,593
Financial liabilities:
Time deposits	4,074,248	3,217,207
Collateralized customer deposits	382,687	415,236
Short-term borrowings	2,035,000	2,000,000
Long-term borrowings	426,002	372,882
Carrying Amount | Level 3
Investment securities:
Held-to-maturity	500	500
Net loans	15,159,795	14,063,380
Fair Value | Level 2
Investment securities:
Held-to-maturity	618,232	662,516
Financial liabilities:
Time deposits	4,041,212	3,225,847
Collateralized customer deposits	382,370	415,236
Short-term borrowings	2,034,719	1,999,137
Long-term borrowings	423,258	367,984
Fair Value | Level 3
Investment securities:
Held-to-maturity	440	390
Net loans	$ 14,907,789	$ 14,114,545

Investment Securities (Summary

Investment Securities (Summary of Amortized Cost and Fair Value of Available-for-Sale Investment Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Debt securities
Total	$ 3,069,645		$ 1,975,257
Unrealized Gains	5,601		3,605
Unrealized Losses	53,414		17,140
Fair Value	3,021,832		1,961,722
Equity securities
Total			1,389
Unrealized Gains			435
Unrealized Losses			0
Fair Value			1,824
Amortized Cost			1,976,646
Unrealized Gains			4,040
Unrealized Losses			17,140
Fair Value			1,963,546
Government and government-sponsored enterprises
Debt securities
Total	354,342		203,099
Unrealized Gains	713		765
Unrealized Losses	3,355		948
Fair Value	351,700		202,916
State and political subdivisions
Debt securities
Total	523,178		350,088
Unrealized Gains	1,141		310
Unrealized Losses	8,033		4,428
Fair Value	516,286		345,970
Residential mortgage-backed securities
Debt securities
Total	216,990		151,752
Unrealized Gains	261		5
Unrealized Losses	3,823		1,626
Fair Value	213,428		150,131
Collateralized mortgage obligations
Debt securities
Total	1,623,415		1,042,240
Unrealized Gains	2,903		89
Unrealized Losses	25,020		8,484
Fair Value	1,601,298		1,033,845
Corporate bonds
Debt securities
Total	304,243		193,230
Unrealized Gains	259		1,156
Unrealized Losses	11,439		1,592
Fair Value	293,063		192,794
Trust preferred securities
Debt securities
Total	47,477		34,848
Unrealized Gains	324		1,280
Unrealized Losses	1,744		62
Fair Value	$ 46,057		36,066
Preferred stock
Equity securities
Total			1,389
Unrealized Gains			435
Unrealized Losses			0
Fair Value		$ 1,800	$ 1,824

Investment Securities (Summar_2

Investment Securities (Summary of Amortized Cost and Fair Value of Held-to-Maturity Investment Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Investment Securities Held-to-Maturity
Amortized Cost	$ 624,099	$ 677,093
Unrealized Gains	2,548	3,856
Unrealized Losses	7,975	18,043
Fair Value	618,672	662,906
State and political subdivisions
Investment Securities Held-to-Maturity
Amortized Cost	623,599	676,593
Unrealized Gains	2,548	3,856
Unrealized Losses	7,915	17,933
Fair Value	618,232	662,516
Trust preferred securities
Investment Securities Held-to-Maturity
Amortized Cost	500	500
Unrealized Gains	0	0
Unrealized Losses	60	110
Fair Value	$ 440	$ 390

Investment Securities (Gains an

Investment Securities (Gains and (Losses) Recognized in Earnings) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Proceeds	$ 4,215	$ 409,220	$ 41,446
Gross gains	263	178	325
Gross losses	$ (39)	$ (7,566)	$ (196)

Investment Securities (Summar_3

Investment Securities (Summary of the Amortized Cost and Fair Value of Investment Securities by Maturity) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Amortized Cost
Due in one year or less	$ 51,523
Due after one year through five years	109,918
Due after five years through ten years	515,050
Due after ten years	2,393,154
Total	3,069,645	$ 1,975,257
Fair Value
Due in one year or less	51,244
Due after one year through five years	108,051
Due after five years through ten years	498,612
Due after ten years	2,363,925
Total	3,021,832	1,961,722
Amortized Cost
Due in one year or less	55,840
Due after one year through five years	230,154
Due after five years through ten years	164,325
Due after ten years	173,780
Total	624,099	677,093
Fair Value
Due in one year or less	55,728
Due after one year through five years	228,528
Due after five years through ten years	162,764
Due after ten years	171,652
Total	$ 618,672	$ 662,906

Investment Securities (Textual)

Investment Securities (Textual) (Details) $ in Thousands	Dec. 31, 2018USD ($)security	Jan. 01, 2018USD ($)	Dec. 31, 2017USD ($)
Investments, Debt and Equity Securities [Abstract]
Number of securities in portfolio (in security) | security	2,096
Number of securities in an unrealized loss position in portfolio (in security) | security	1,408
Fair Value			$ 1,824
Debt and Equity Securities, FV-NI [Line Items]
Retained earnings	$ 616,149		419,403
Collateral pledged
Debt and Equity Securities, FV-NI [Line Items]
Securities pledged as collateral	$ 1,050,000		937,200
Accounting Standards Update 2016-01
Debt and Equity Securities, FV-NI [Line Items]
Retained earnings		$ (344)	$ (300)

Investment Securities (Summar_4

Investment Securities (Summary of Investment Securities with Gross Unrealized Losses) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	$ 1,078,804	$ 1,379,705
Less Than 12 Months, Gross Unrealized Losses	16,485	21,534
12 Months or More, Fair Value	1,605,905	563,188
12 Months or More, Gross Unrealized Losses	44,904	13,649
Total, Fair Value	2,684,709	1,942,893
Total, Gross Unrealized Losses	61,389	35,183
Government and government-sponsored enterprises
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	167,164	63,818
Less Than 12 Months, Gross Unrealized Losses	1,672	510
12 Months or More, Fair Value	62,200	24,621
12 Months or More, Gross Unrealized Losses	1,683	438
Total, Fair Value	229,364	88,439
Total, Gross Unrealized Losses	3,355	948
State and political subdivisions
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	190,551	437,407
Less Than 12 Months, Gross Unrealized Losses	1,932	12,268
12 Months or More, Fair Value	657,327	349,242
12 Months or More, Gross Unrealized Losses	14,016	10,093
Total, Fair Value	847,878	786,649
Total, Gross Unrealized Losses	15,948	22,361
Residential mortgage-backed securities
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	20,679	93,508
Less Than 12 Months, Gross Unrealized Losses	85	383
12 Months or More, Fair Value	123,757	56,576
12 Months or More, Gross Unrealized Losses	3,738	1,243
Total, Fair Value	144,436	150,084
Total, Gross Unrealized Losses	3,823	1,626
Collateralized mortgage obligations
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	496,356	713,525
Less Than 12 Months, Gross Unrealized Losses	5,268	7,235
12 Months or More, Fair Value	656,208	73,707
12 Months or More, Gross Unrealized Losses	19,752	1,249
Total, Fair Value	1,152,564	787,232
Total, Gross Unrealized Losses	25,020	8,484
Corporate bonds
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	169,431	71,447
Less Than 12 Months, Gross Unrealized Losses	5,888	1,138
12 Months or More, Fair Value	103,688	47,878
12 Months or More, Gross Unrealized Losses	5,551	454
Total, Fair Value	273,119	119,325
Total, Gross Unrealized Losses	11,439	1,592
Trust preferred securities
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	34,623	0
Less Than 12 Months, Gross Unrealized Losses	1,640	0
12 Months or More, Fair Value	2,725	11,164
12 Months or More, Gross Unrealized Losses	164	172
Total, Fair Value	37,348	11,164
Total, Gross Unrealized Losses	$ 1,804	$ 172

Loans (Textual) (Details)

Loans (Textual) (Details)	12 Months Ended
	Dec. 31, 2018USD ($)loanSegmenttenantemployee	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of portfolio segment | Segment	2
Number of classes of loans | loan	6
Minimum number of tenants leased to for non-owner occupied real estate | tenant	1
Loans held-for-sale, at fair value	$ 85,030,000	$ 52,133,000
Minimum value of loan requires regional loan committee approval	3,000,000
Maximum value of loan requires regional loan committee approval	$ 7,000,000
Minimum due period of loans consider in a nonperforming status	90 days
Nonaccrual TDRs reported in nonaccrual loans	$ 28,100,000	29,100,000
Loans and Leases Receivable, Impaired, Interest Income Recognized on Nonaccrual Loans While In Accruing Status	2,100,000	1,300,000	$ 400,000
Interest lost on nonaccrual loans	4,800,000	3,100,000	2,900,000
Interest income recognized on TDRs	2,700,000	2,600,000	3,900,000
Real estate properties for which formal foreclosure proceedings are in process	4,500,000
Residential mortgage loans in process of foreclosure		4,200,000
Impaired loans	73,655,000	77,888,000
Commitments to lend additional funds to borrowers whose terms have been modified in TDRs	3,200,000	2,000,000
Proceeds from sales of loans	741,902,000	838,549,000	$ 723,521,000
Management
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to directors, executive officers and affiliates	3,600,000	3,800,000
Loans to directors, executive officers and affiliates, current year additions	3,800,000	44,100,000
Loans to directors, executive officers and affiliates, current year reductions	4,000,000	64,200,000
Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans	45,580,000	48,782,000
Commercial Loan Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans	56,851,000	58,842,000
Commercial Loan Portfolio | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans	$ 32,508,000	$ 34,484,000
Land Development Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Maximum period for payment of loan	12 months
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Period for loan secured under real estate residential security	15 years
Loan-to-value ratio at the time of origination	80.00%
Residential mortgage | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Lower limit of number of family residential properties | tenant	1
Residential mortgage | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Upper limit of number of family residential properties | tenant	4
Commercial | Commercial Loan Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum value of loan requires group loan authority approval	$ 3,000,000
Number of bank executives and senior officers with credit decision limits similar to group loan authorities | employee	6
Maximum value of loan requires executive and senior officer approval	$ 8,000,000
Minimum value of loan requires group loan authority approval	$ 7,000,000
Commercial Loan Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum due period of loans consider in a nonperforming status	90 days
Consumer Loan Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Original contractual terms	90 days
Minimum due period of loans consider in a nonperforming status	90 days
Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Impaired, Interest Income Recognized on Nonaccrual Loans While In Accruing Status	$ 0

Loans (Summary of Loans) (Detai

Loans (Summary of Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Summary of loans under portfolio
Loans	$ 15,269,779	$ 14,155,267
Deferred costs	19,700	26,100
Commercial Loan Portfolio
Summary of loans under portfolio
Loans	9,511,867	8,460,527
Commercial Loan Portfolio | Commercial
Summary of loans under portfolio
Loans	4,002,568	3,385,642
Commercial Loan Portfolio | Commercial real estate:
Summary of loans under portfolio
Loans	4,912,087	4,500,670
Commercial Loan Portfolio | Real estate construction and land development
Summary of loans under portfolio
Loans	597,212	574,215
Consumer Loan Portfolio
Summary of loans under portfolio
Loans	5,757,912	5,694,740
Consumer Loan Portfolio | Residential mortgage
Summary of loans under portfolio
Loans	3,458,666	3,252,487
Consumer Loan Portfolio | Consumer installment
Summary of loans under portfolio
Loans	1,521,074	1,613,008
Consumer Loan Portfolio | Home equity
Summary of loans under portfolio
Loans	778,172	829,245
Originated
Summary of loans under portfolio
Loans	11,844,756	9,747,429
Originated | Commercial
Summary of loans under portfolio
Loans	3,287,087	2,407,606
Originated | Commercial real estate:
Summary of loans under portfolio
Loans	3,520,157	2,751,425
Originated | Real estate construction and land development
Summary of loans under portfolio
Loans	566,726	498,155
Originated | Residential mortgage
Summary of loans under portfolio
Loans	2,407,305	1,967,857
Originated | Consumer installment
Summary of loans under portfolio
Loans	1,451,352	1,510,540
Originated | Home equity
Summary of loans under portfolio
Loans	612,129	611,846
Originated | Commercial Loan Portfolio
Summary of loans under portfolio
Loans	7,373,970	5,657,186
Originated | Commercial Loan Portfolio | Commercial
Summary of loans under portfolio
Loans	3,287,087	2,407,606
Originated | Commercial Loan Portfolio | Commercial real estate:
Summary of loans under portfolio
Loans	3,520,157	2,751,425
Originated | Commercial Loan Portfolio | Real estate construction and land development
Summary of loans under portfolio
Loans	566,726	498,155
Originated | Consumer Loan Portfolio
Summary of loans under portfolio
Loans	4,470,786	4,090,243
Originated | Consumer Loan Portfolio | Residential mortgage
Summary of loans under portfolio
Loans	2,407,305	1,967,857
Originated | Consumer Loan Portfolio | Consumer installment
Summary of loans under portfolio
Loans	1,451,352	1,510,540
Originated | Consumer Loan Portfolio | Home equity
Summary of loans under portfolio
Loans	612,129	611,846
Acquired
Summary of loans under portfolio
Loans	3,425,023	4,407,838
Acquired | Commercial Loan Portfolio
Summary of loans under portfolio
Loans	2,137,897	2,803,341
Acquired | Commercial Loan Portfolio | Commercial
Summary of loans under portfolio
Loans	715,481	978,036
Acquired | Commercial Loan Portfolio | Commercial real estate:
Summary of loans under portfolio
Loans	1,391,930	1,749,245
Acquired | Commercial Loan Portfolio | Real estate construction and land development
Summary of loans under portfolio
Loans	30,486	76,060
Acquired | Consumer Loan Portfolio
Summary of loans under portfolio
Loans	1,287,126	1,604,497
Acquired | Consumer Loan Portfolio | Residential mortgage
Summary of loans under portfolio
Loans	1,051,361	1,284,630
Acquired | Consumer Loan Portfolio | Consumer installment
Summary of loans under portfolio
Loans	69,722	102,468
Acquired | Consumer Loan Portfolio | Home equity
Summary of loans under portfolio
Loans	166,043	217,399
Owner-occupied | Commercial Loan Portfolio | Commercial
Summary of loans under portfolio
Loans	2,059,557	1,813,562
Owner-occupied | Originated | Commercial
Summary of loans under portfolio
Loans	1,513,532	1,185,614
Owner-occupied | Originated | Commercial Loan Portfolio | Commercial
Summary of loans under portfolio
Loans	1,513,532	1,185,614
Owner-occupied | Acquired | Commercial Loan Portfolio | Commercial
Summary of loans under portfolio
Loans	546,025	627,948
Non-owner occupied | Commercial Loan Portfolio | Commercial
Summary of loans under portfolio
Loans	2,785,020	2,606,761
Non-owner occupied | Originated | Commercial
Summary of loans under portfolio
Loans	1,966,330	1,518,787
Non-owner occupied | Originated | Commercial Loan Portfolio | Commercial
Summary of loans under portfolio
Loans	1,966,330	1,518,787
Non-owner occupied | Acquired | Commercial Loan Portfolio | Commercial
Summary of loans under portfolio
Loans	818,690	1,087,974
Vacant land | Commercial Loan Portfolio | Commercial
Summary of loans under portfolio
Loans	67,510	80,347
Vacant land | Originated | Commercial
Summary of loans under portfolio
Loans	40,295	47,024
Vacant land | Originated | Commercial Loan Portfolio | Commercial
Summary of loans under portfolio
Loans	40,295	47,024
Vacant land | Acquired | Commercial Loan Portfolio | Commercial
Summary of loans under portfolio
Loans	$ 27,215	$ 33,323

Loans (Activity for Accretable

Loans (Activity for Accretable Yield) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	$ 926,897	$ 1,039,971	$ 298,257
Addition attributable to acquisitions			862,127
Accretion recognized in interest income	(221,419)	(242,169)	(131,559)
Net reclassification (to) from nonaccretable difference	(58,153)	129,095	11,146
Balance at end of period	647,325	926,897	1,039,971
Talmer
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	731,353	798,210	0
Addition attributable to acquisitions			862,127
Accretion recognized in interest income	(164,614)	(175,678)	(63,917)
Net reclassification (to) from nonaccretable difference	(61,407)	108,821	0
Balance at end of period	505,332	731,353	798,210
Lake Michigan
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	95,124	121,416	152,999
Addition attributable to acquisitions			0
Accretion recognized in interest income	(24,722)	(29,077)	(33,031)
Net reclassification (to) from nonaccretable difference	2,730	2,785	1,448
Balance at end of period	73,132	95,124	121,416
Monarch
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	22,496	27,182	34,558
Addition attributable to acquisitions			0
Accretion recognized in interest income	(3,881)	(4,533)	(5,468)
Net reclassification (to) from nonaccretable difference	(783)	(153)	(1,908)
Balance at end of period	17,832	22,496	27,182
Northwestern
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	60,814	69,847	82,623
Addition attributable to acquisitions			0
Accretion recognized in interest income	(17,988)	(20,318)	(15,791)
Net reclassification (to) from nonaccretable difference	(1,371)	11,285	3,015
Balance at end of period	41,455	60,814	69,847
OAK
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at beginning of period	17,110	23,316	28,077
Addition attributable to acquisitions			0
Accretion recognized in interest income	(10,214)	(12,563)	(13,352)
Net reclassification (to) from nonaccretable difference	2,678	6,357	8,591
Balance at end of period	$ 9,574	$ 17,110	$ 23,316

Loans (Summary of Recorded Inve

Loans (Summary of Recorded Investment of Commercial Loans by Risk Rating Categories) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 15,269,779	$ 14,155,267
Originated Loan Portfolio [Member] | Originated Loan Portfolio [Member]
Financing Receivable, Recorded Investment [Line Items]
Minimum Value of Loan Requires Group Loan Authority Approval	1,300
Commercial Loan Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	9,511,867	8,460,527
Commercial Loan Portfolio | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	8,998,284	8,038,463
Commercial Loan Portfolio | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	283,400	204,706
Commercial Loan Portfolio | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	225,924	216,353
Commercial Loan Portfolio | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	4,259	1,005
Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Minimum Value of Loan Requires Group Loan Authority Approval	3,000
Loans	4,002,568	3,385,642
Commercial Loan Portfolio | Commercial real estate:
Financing Receivable, Recorded Investment [Line Items]
Loans	4,912,087	4,500,670
Commercial Loan Portfolio | Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans	597,212	574,215
Originated
Financing Receivable, Recorded Investment [Line Items]
Loans	11,844,756	9,747,429
Originated | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	3,287,087	2,407,606
Originated | Commercial real estate:
Financing Receivable, Recorded Investment [Line Items]
Loans	3,520,157	2,751,425
Originated | Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans	566,726	498,155
Originated | Commercial Loan Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	7,373,970	5,657,186
Originated | Commercial Loan Portfolio | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	7,045,203	5,488,571
Originated | Commercial Loan Portfolio | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	164,802	66,100
Originated | Commercial Loan Portfolio | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	159,733	102,515
Originated | Commercial Loan Portfolio | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	4,232	0
Originated | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	3,287,087	2,407,606
Originated | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	3,118,894	2,316,464
Originated | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	87,222	41,059
Originated | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	77,036	50,083
Originated | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	3,935	0
Originated | Commercial Loan Portfolio | Commercial real estate:
Financing Receivable, Recorded Investment [Line Items]
Loans	3,520,157	2,751,425
Originated | Commercial Loan Portfolio | Commercial real estate: | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	3,369,269	2,677,579
Originated | Commercial Loan Portfolio | Commercial real estate: | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	71,472	24,204
Originated | Commercial Loan Portfolio | Commercial real estate: | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	79,119	49,642
Originated | Commercial Loan Portfolio | Commercial real estate: | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	297	0
Originated | Commercial Loan Portfolio | Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans	566,726	498,155
Originated | Commercial Loan Portfolio | Real estate construction and land development | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	557,040	494,528
Originated | Commercial Loan Portfolio | Real estate construction and land development | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	6,108	837
Originated | Commercial Loan Portfolio | Real estate construction and land development | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	3,578	2,790
Originated | Commercial Loan Portfolio | Real estate construction and land development | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Acquired
Financing Receivable, Recorded Investment [Line Items]
Loans	3,425,023	4,407,838
Acquired | Commercial Loan Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	2,137,897	2,803,341
Acquired | Commercial Loan Portfolio | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,953,081	2,549,892
Acquired | Commercial Loan Portfolio | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	118,598	138,606
Acquired | Commercial Loan Portfolio | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	66,191	113,838
Acquired | Commercial Loan Portfolio | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	27	1,005
Acquired | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	715,481	978,036
Acquired | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	655,883	873,861
Acquired | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	36,809	68,418
Acquired | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	22,773	35,539
Acquired | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	16	218
Acquired | Commercial Loan Portfolio | Commercial real estate:
Financing Receivable, Recorded Investment [Line Items]
Loans	1,391,930	1,749,245
Acquired | Commercial Loan Portfolio | Commercial real estate: | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,267,950	1,603,685
Acquired | Commercial Loan Portfolio | Commercial real estate: | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	81,692	67,970
Acquired | Commercial Loan Portfolio | Commercial real estate: | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	42,277	76,803
Acquired | Commercial Loan Portfolio | Commercial real estate: | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	11	787
Acquired | Commercial Loan Portfolio | Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans	30,486	76,060
Acquired | Commercial Loan Portfolio | Real estate construction and land development | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	29,248	72,346
Acquired | Commercial Loan Portfolio | Real estate construction and land development | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	97	2,218
Acquired | Commercial Loan Portfolio | Real estate construction and land development | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	1,141	1,496
Acquired | Commercial Loan Portfolio | Real estate construction and land development | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Owner-occupied | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	2,059,557	1,813,562
Owner-occupied | Originated | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	1,513,532	1,185,614
Owner-occupied | Originated | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	1,513,532	1,185,614
Owner-occupied | Originated | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,430,948	1,133,609
Owner-occupied | Originated | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	32,056	19,438
Owner-occupied | Originated | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	50,286	32,567
Owner-occupied | Originated | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	242	0
Owner-occupied | Acquired | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	546,025	627,948
Owner-occupied | Acquired | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	500,072	580,127
Owner-occupied | Acquired | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	28,909	23,998
Owner-occupied | Acquired | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	17,033	23,036
Owner-occupied | Acquired | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	11	787
Non-owner occupied | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	2,785,020	2,606,761
Non-owner occupied | Originated | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	1,966,330	1,518,787
Non-owner occupied | Originated | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	1,966,330	1,518,787
Non-owner occupied | Originated | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,901,822	1,504,195
Non-owner occupied | Originated | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	39,416	4,728
Non-owner occupied | Originated | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	25,092	9,864
Non-owner occupied | Originated | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Non-owner occupied | Acquired | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	818,690	1,087,974
Non-owner occupied | Acquired | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	740,900	995,709
Non-owner occupied | Acquired | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	52,546	43,645
Non-owner occupied | Acquired | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	25,244	48,620
Non-owner occupied | Acquired | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Vacant land | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	67,510	80,347
Vacant land | Originated | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	40,295	47,024
Vacant land | Originated | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	40,295	47,024
Vacant land | Originated | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	36,499	39,775
Vacant land | Originated | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	0	38
Vacant land | Originated | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	3,741	7,211
Vacant land | Originated | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	55	0
Vacant land | Acquired | Commercial Loan Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	27,215	33,323
Vacant land | Acquired | Commercial Loan Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	26,978	27,849
Vacant land | Acquired | Commercial Loan Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	237	327
Vacant land | Acquired | Commercial Loan Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	0	5,147
Vacant land | Acquired | Commercial Loan Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 0	$ 0

Loans (Summary of Recorded In_2

Loans (Summary of Recorded Investment of Consumer Loans by Risk Rating Categories) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 15,269,779	$ 14,155,267
Consumer Loan Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	5,757,912	5,694,740
Consumer Loan Portfolio | Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans	3,458,666	3,252,487
Consumer Loan Portfolio | Consumer installment
Financing Receivable, Recorded Investment [Line Items]
Loans	1,521,074	1,613,008
Consumer Loan Portfolio | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	778,172	829,245
Originated
Financing Receivable, Recorded Investment [Line Items]
Loans	11,844,756	9,747,429
Originated | Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans	2,407,305	1,967,857
Originated | Consumer installment
Financing Receivable, Recorded Investment [Line Items]
Loans	1,451,352	1,510,540
Originated | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	612,129	611,846
Originated | Consumer Loan Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	4,470,786	4,090,243
Originated | Consumer Loan Portfolio | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	4,457,918	4,076,461
Originated | Consumer Loan Portfolio | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans	12,868	13,782
Originated | Consumer Loan Portfolio | Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans	2,407,305	1,967,857
Originated | Consumer Loan Portfolio | Residential mortgage | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	2,399,317	1,959,222
Originated | Consumer Loan Portfolio | Residential mortgage | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans	7,988	8,635
Originated | Consumer Loan Portfolio | Consumer installment
Financing Receivable, Recorded Investment [Line Items]
Loans	1,451,352	1,510,540
Originated | Consumer Loan Portfolio | Consumer installment | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	1,450,076	1,509,698
Originated | Consumer Loan Portfolio | Consumer installment | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans	1,276	842
Originated | Consumer Loan Portfolio | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	612,129	611,846
Originated | Consumer Loan Portfolio | Home equity | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	608,525	607,541
Originated | Consumer Loan Portfolio | Home equity | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans	3,604	4,305
Acquired
Financing Receivable, Recorded Investment [Line Items]
Loans	3,425,023	4,407,838
Acquired | Consumer Loan Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	1,287,126	1,604,497
Acquired | Consumer Loan Portfolio | Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans	1,051,361	1,284,630
Acquired | Consumer Loan Portfolio | Consumer installment
Financing Receivable, Recorded Investment [Line Items]
Loans	69,722	102,468
Acquired | Consumer Loan Portfolio | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 166,043	$ 217,399

Loans (Summary of Nonperforming

Loans (Summary of Nonperforming Loans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Impaired, Interest Income Recognized on Nonaccrual Loans While In Accruing Status	$ 2,100	$ 1,300	$ 400
Summary of nonperforming loans
Total nonaccrual loans	85,433	63,095
Other real estate owned and repossessed assets	6,256	8,807
Total nonperforming assets	91,689	71,902
Commercial
Summary of nonperforming loans
Total nonaccrual loans	30,139
Commercial real estate:
Summary of nonperforming loans
Total nonaccrual loans	42,414	$ 29,545
Real estate construction and land development
Summary of nonperforming loans
Total nonaccrual loans	12
Residential mortgage
Summary of nonperforming loans
Total nonaccrual loans	7,988
Consumer installment
Summary of nonperforming loans
Total nonaccrual loans	1,276
Home equity
Summary of nonperforming loans
Total nonaccrual loans	3,604
Owner-occupied | Commercial
Summary of nonperforming loans
Total nonaccrual loans	16,056
Non-owner occupied | Commercial
Summary of nonperforming loans
Total nonaccrual loans	23,021
Vacant land | Commercial
Summary of nonperforming loans
Total nonaccrual loans	$ 3,337

Loans (Summary of the Aging Sta

Loans (Summary of the Aging Status of the Recorded Investment in Loans by Portfolio Segment/Class) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	$ 85,433	$ 63,095
Total loans	15,269,779	14,155,267
Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	30,139
Commercial real estate:
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	42,414	29,545
Real estate construction and land development
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	12
Residential mortgage
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	7,988
Consumer installment
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	1,276
Home equity
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	3,604
Originated
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	35,381	32,281
Nonaccrual Loans	85,433	63,095
Current	11,723,942	9,652,053
Total loans	11,844,756	9,747,429
Originated | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	33,954	30,904
Originated | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	1,427	1,377
Originated | Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	16,835	16,269
Nonaccrual Loans	30,139	19,691
Current	3,240,113	2,371,646
Total loans	3,287,087	2,407,606
Originated | Commercial | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	16,835	16,269
Originated | Commercial | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	0
Financing receivable, recorded investment accruing loans past due 90 days or more		0
Originated | Commercial real estate:
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	7,549	5,769
Nonaccrual Loans	42,414	29,545
Current	3,470,194	2,716,111
Total loans	3,520,157	2,751,425
Originated | Commercial real estate: | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	6,610	5,756
Originated | Commercial real estate: | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	939	0
Financing receivable, recorded investment accruing loans past due 90 days or more		13
Originated | Real estate construction and land development
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	247	0
Nonaccrual Loans	12	77
Current	566,467	498,078
Total loans	566,726	498,155
Originated | Real estate construction and land development | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	247	0
Originated | Real estate construction and land development | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	0
Financing receivable, recorded investment accruing loans past due 90 days or more		0
Originated | Residential mortgage
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	1,688	2,325
Nonaccrual Loans	7,988	8,635
Current	2,397,629	1,956,897
Total loans	2,407,305	1,967,857
Originated | Residential mortgage | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	1,688	2,325
Originated | Residential mortgage | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	0
Financing receivable, recorded investment accruing loans past due 90 days or more		0
Originated | Consumer installment
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	4,731	3,663
Nonaccrual Loans	1,276	842
Current	1,445,345	1,506,035
Total loans	1,451,352	1,510,540
Originated | Consumer installment | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	4,731	3,663
Originated | Consumer installment | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	0
Financing receivable, recorded investment accruing loans past due 90 days or more		0
Originated | Home equity
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	4,331	4,255
Nonaccrual Loans	3,604	4,305
Current	604,194	603,286
Total loans	612,129	611,846
Originated | Home equity | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	3,843	2,891
Originated | Home equity | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	488
Financing receivable, recorded investment accruing loans past due 90 days or more		1,364
Non-owner occupied | Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	23,021
Non-owner occupied | Originated | Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	2,680	1,608
Nonaccrual Loans	23,021	5,270
Current	1,940,629	1,511,909
Total loans	1,966,330	1,518,787
Non-owner occupied | Originated | Commercial | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	1,793	1,595
Non-owner occupied | Originated | Commercial | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	887
Financing receivable, recorded investment accruing loans past due 90 days or more		13
Vacant land | Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	3,337
Vacant land | Originated | Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	160	83
Nonaccrual Loans	3,337	5,205
Current	36,798	41,736
Total loans	40,295	47,024
Vacant land | Originated | Commercial | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	160	83
Vacant land | Originated | Commercial | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	0
Financing receivable, recorded investment accruing loans past due 90 days or more		0
Owner-occupied | Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Nonaccrual Loans	16,056
Owner-occupied | Originated | Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	4,709	4,078
Nonaccrual Loans	16,056	19,070
Current	1,492,767	1,162,466
Total loans	1,513,532	1,185,614
Owner-occupied | Originated | Commercial | 30-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	4,657	4,078
Owner-occupied | Originated | Commercial | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	$ 52
Financing receivable, recorded investment accruing loans past due 90 days or more		$ 0

Loans (Summary of Impaired Loan

Loans (Summary of Impaired Loans by Classes of Loans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Impaired loans with a valuation allowance:
Average annual recorded investment	$ 60,156	$ 66,592	$ 39,582
Interest income recognized while on impaired status	1,457	2,250	2,120
Impaired loans with no related valuation allowance:
Average annual recorded investment	60,807	41,151	73,864
Interest income recognized while on impaired status	1,278	325	1,766
Total impaired loans:
Average annual recorded investment	120,963	107,743	113,446
Interest income recognized while on impaired status	2,735	2,575	3,886
Commercial
Impaired loans with a valuation allowance:
Recorded investment	20,957	28,897
Unpaid principal balance	23,781	31,655
Related valuation allowance	3,546	2,296
Average annual recorded investment	17,683	25,099	7,829
Interest income recognized while on impaired status	457	939	0
Impaired loans with no related valuation allowance:
Average annual recorded investment	21,954	10,196	29,559
Interest income recognized while on impaired status	577	28	1,343
Total impaired loans:
Related valuation allowance	3,546	2,296
Average annual recorded investment	39,637	35,295	37,388
Interest income recognized while on impaired status	1,034	967	1,343
Commercial real estate:
Impaired loans with a valuation allowance:
Average annual recorded investment	21,424	19,983	5,658
Interest income recognized while on impaired status	447	677	835
Impaired loans with no related valuation allowance:
Average annual recorded investment	27,218	24,658	41,646
Interest income recognized while on impaired status	559	245	401
Total impaired loans:
Average annual recorded investment	48,642	44,641	47,304
Interest income recognized while on impaired status	1,006	922	1,236
Real estate construction and land development
Impaired loans with a valuation allowance:
Average annual recorded investment	4,619	175	19
Interest income recognized while on impaired status	8	10	0
Impaired loans with no related valuation allowance:
Average annual recorded investment	1,520	78	585
Interest income recognized while on impaired status	7	0	22
Total impaired loans:
Average annual recorded investment	6,139	253	604
Interest income recognized while on impaired status	15	10	22
Residential mortgage
Impaired loans with a valuation allowance:
Average annual recorded investment	12,179	16,390	23,958
Interest income recognized while on impaired status	457	538	1,285
Impaired loans with no related valuation allowance:
Average annual recorded investment	7,594	4,622	1,519
Interest income recognized while on impaired status	110	38	0
Total impaired loans:
Average annual recorded investment	19,773	21,012	25,477
Interest income recognized while on impaired status	567	576	1,285
Consumer installment
Impaired loans with a valuation allowance:
Average annual recorded investment	989	744	359
Interest income recognized while on impaired status	8	4	0
Impaired loans with no related valuation allowance:
Average annual recorded investment	304	205	0
Interest income recognized while on impaired status	0	0	0
Total impaired loans:
Average annual recorded investment	1,293	949	359
Interest income recognized while on impaired status	8	4	0
Home equity
Impaired loans with a valuation allowance:
Average annual recorded investment	3,262	4,201	1,759
Interest income recognized while on impaired status	80	82	0
Impaired loans with no related valuation allowance:
Average annual recorded investment	2,217	1,392	555
Interest income recognized while on impaired status	25	14	0
Total impaired loans:
Average annual recorded investment	5,479	5,593	2,314
Interest income recognized while on impaired status	105	96	0
Non-owner occupied | Commercial real estate:
Impaired loans with a valuation allowance:
Average annual recorded investment	6,440	3,274	1,711
Interest income recognized while on impaired status	48	89	139
Impaired loans with no related valuation allowance:
Average annual recorded investment	10,681	9,143	14,306
Interest income recognized while on impaired status	263	241	339
Total impaired loans:
Average annual recorded investment	17,121	12,417	16,017
Interest income recognized while on impaired status	311	330	478
Vacant land | Commercial real estate:
Impaired loans with a valuation allowance:
Average annual recorded investment	1,881	2,566	253
Interest income recognized while on impaired status	47	57	113
Impaired loans with no related valuation allowance:
Average annual recorded investment	2,730	3,516	7,034
Interest income recognized while on impaired status	0	4	45
Total impaired loans:
Average annual recorded investment	4,611	6,082	7,287
Interest income recognized while on impaired status	47	61	158
Owner-occupied | Commercial real estate:
Impaired loans with a valuation allowance:
Average annual recorded investment	13,103	14,143	3,694
Interest income recognized while on impaired status	352	531	583
Impaired loans with no related valuation allowance:
Average annual recorded investment	13,807	11,999	20,306
Interest income recognized while on impaired status	296	0	17
Total impaired loans:
Average annual recorded investment	26,910	26,142	24,000
Interest income recognized while on impaired status	648	531	$ 600
Impaired Loans with No Valuation Allowance
Impaired loans with a valuation allowance:
Related valuation allowance	0	0
Total impaired loans:
Recorded investment	60,822	33,256
Unpaid principal balance	64,378	35,824
Related valuation allowance	0	0
Impaired Loans with No Valuation Allowance | Commercial
Impaired loans with a valuation allowance:
Related valuation allowance	0	0
Total impaired loans:
Recorded investment	25,093	8,504
Unpaid principal balance	25,934	9,291
Related valuation allowance	0	0
Impaired Loans with No Valuation Allowance | Commercial real estate:
Impaired loans with a valuation allowance:
Related valuation allowance	0	0
Total impaired loans:
Recorded investment	26,208	18,080
Unpaid principal balance	28,923	19,861
Related valuation allowance	0	0
Impaired Loans with No Valuation Allowance | Real estate construction and land development
Impaired loans with a valuation allowance:
Related valuation allowance	0
Total impaired loans:
Recorded investment	111
Unpaid principal balance	111
Related valuation allowance	0
Impaired Loans with No Valuation Allowance | Residential mortgage
Impaired loans with a valuation allowance:
Related valuation allowance	0	0
Total impaired loans:
Recorded investment	7,537	4,902
Unpaid principal balance	7,537	4,902
Related valuation allowance	0	0
Impaired Loans with No Valuation Allowance | Consumer installment
Impaired loans with a valuation allowance:
Related valuation allowance	0
Total impaired loans:
Recorded investment	377
Unpaid principal balance	377
Related valuation allowance	0
Impaired Loans with No Valuation Allowance | Home equity
Impaired loans with a valuation allowance:
Related valuation allowance	0	0
Total impaired loans:
Recorded investment	1,496	1,770
Unpaid principal balance	1,496	1,770
Related valuation allowance	0	0
Impaired Loans with No Valuation Allowance | Non-owner occupied | Commercial
Impaired loans with a valuation allowance:
Related valuation allowance	0	0
Total impaired loans:
Recorded investment	12,412	5,977
Unpaid principal balance	13,411	6,438
Related valuation allowance	0	0
Impaired Loans with No Valuation Allowance | Vacant land | Commercial
Impaired loans with a valuation allowance:
Related valuation allowance	0	0
Total impaired loans:
Recorded investment	2,825	752
Unpaid principal balance	3,911	792
Related valuation allowance	0	0
Impaired Loans with No Valuation Allowance | Owner-occupied | Commercial
Impaired loans with a valuation allowance:
Related valuation allowance	0	0
Total impaired loans:
Recorded investment	10,971	11,351
Unpaid principal balance	11,601	12,631
Related valuation allowance	0	0
Total Impaired Loans
Impaired loans with a valuation allowance:
Related valuation allowance	6,804	8,002
Total impaired loans:
Recorded investment	130,873	111,877
Unpaid principal balance	139,889	123,780
Related valuation allowance	6,804	8,002
Total Impaired Loans | Commercial
Impaired loans with a valuation allowance:
Related valuation allowance	3,546	2,296
Total impaired loans:
Recorded investment	46,050	37,401
Unpaid principal balance	49,715	40,946
Related valuation allowance	3,546	2,296
Total Impaired Loans | Commercial real estate:
Impaired loans with a valuation allowance:
Related valuation allowance	1,917	3,227
Total impaired loans:
Recorded investment	58,751	46,083
Unpaid principal balance	64,102	54,441
Related valuation allowance	1,917	3,227
Total Impaired Loans | Real estate construction and land development
Impaired loans with a valuation allowance:
Related valuation allowance	11	14
Total impaired loans:
Recorded investment	237	313
Unpaid principal balance	237	313
Related valuation allowance	11	14
Total Impaired Loans | Residential mortgage
Impaired loans with a valuation allowance:
Related valuation allowance	816	1,487
Total impaired loans:
Recorded investment	18,404	20,774
Unpaid principal balance	18,404	20,774
Related valuation allowance	816	1,487
Total Impaired Loans | Consumer installment
Impaired loans with a valuation allowance:
Related valuation allowance	186	120
Total impaired loans:
Recorded investment	1,503	966
Unpaid principal balance	1,503	966
Related valuation allowance	186	120
Total Impaired Loans | Home equity
Impaired loans with a valuation allowance:
Related valuation allowance	328	858
Total impaired loans:
Recorded investment	5,928	6,340
Unpaid principal balance	5,928	6,340
Related valuation allowance	328	858
Total Impaired Loans | Non-owner occupied | Commercial
Impaired loans with a valuation allowance:
Related valuation allowance	462	316
Total impaired loans:
Recorded investment	29,245	11,284
Unpaid principal balance	30,863	14,308
Related valuation allowance	462	316
Total Impaired Loans | Vacant land | Commercial
Impaired loans with a valuation allowance:
Related valuation allowance	96	594
Total impaired loans:
Recorded investment	3,833	5,674
Unpaid principal balance	5,119	5,914
Related valuation allowance	96	594
Total Impaired Loans | Owner-occupied | Commercial
Impaired loans with a valuation allowance:
Related valuation allowance	1,359	2,317
Total impaired loans:
Recorded investment	25,673	29,125
Unpaid principal balance	28,120	34,219
Related valuation allowance	1,359	2,317
Impaired Loans with Valuation Allowance
Impaired loans with a valuation allowance:
Related valuation allowance	6,804	8,002
Total impaired loans:
Recorded investment	70,051	78,621
Unpaid principal balance	75,511	87,956
Related valuation allowance	6,804	8,002
Impaired Loans with Valuation Allowance | Commercial real estate:
Impaired loans with a valuation allowance:
Related valuation allowance	1,917	3,227
Total impaired loans:
Recorded investment	32,543	28,003
Unpaid principal balance	35,179	34,580
Related valuation allowance	1,917	3,227
Impaired Loans with Valuation Allowance | Real estate construction and land development
Impaired loans with a valuation allowance:
Related valuation allowance	11	14
Total impaired loans:
Recorded investment	126	313
Unpaid principal balance	126	313
Related valuation allowance	11	14
Impaired Loans with Valuation Allowance | Residential mortgage
Impaired loans with a valuation allowance:
Related valuation allowance	816	1,487
Total impaired loans:
Recorded investment	10,867	15,872
Unpaid principal balance	10,867	15,872
Related valuation allowance	816	1,487
Impaired Loans with Valuation Allowance | Consumer installment
Impaired loans with a valuation allowance:
Related valuation allowance	186	120
Total impaired loans:
Recorded investment	1,126	966
Unpaid principal balance	1,126	966
Related valuation allowance	186	120
Impaired Loans with Valuation Allowance | Home equity
Impaired loans with a valuation allowance:
Related valuation allowance	328	858
Total impaired loans:
Recorded investment	4,432	4,570
Unpaid principal balance	4,432	4,570
Related valuation allowance	328	858
Impaired Loans with Valuation Allowance | Non-owner occupied | Commercial
Impaired loans with a valuation allowance:
Related valuation allowance	462	316
Total impaired loans:
Recorded investment	16,833	5,307
Unpaid principal balance	17,452	7,870
Related valuation allowance	462	316
Impaired Loans with Valuation Allowance | Vacant land | Commercial
Impaired loans with a valuation allowance:
Related valuation allowance	96	594
Total impaired loans:
Recorded investment	1,008	4,922
Unpaid principal balance	1,208	5,122
Related valuation allowance	96	594
Impaired Loans with Valuation Allowance | Owner-occupied | Commercial
Impaired loans with a valuation allowance:
Related valuation allowance	1,359	2,317
Total impaired loans:
Recorded investment	14,702	17,774
Unpaid principal balance	16,519	21,588
Related valuation allowance	$ 1,359	$ 2,317

Loans (Summary of Loan Modifica

Loans (Summary of Loan Modifications by Concession Type) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)loan	Dec. 31, 2017USD ($)loan	Dec. 31, 2016USD ($)loan
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	169	112	98
Pre- modification recorded investment	$ 17,872	$ 10,057	$ 20,819
Post- modification recorded investment	17,582	9,656	20,819
Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	6,946	3,853	15,269
Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	458	37	3,393
A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment			43
Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	7,787	2,637	364
Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 2,391	$ 3,129	$ 1,750
Commercial Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	88	53	70
Pre- modification recorded investment	$ 15,727	$ 8,549	$ 19,712
Post- modification recorded investment	15,547	8,343	19,712
Commercial Loan Portfolio | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	6,016	3,049	14,526
Commercial Loan Portfolio | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	66	0	3,393
Commercial Loan Portfolio | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment			43
Commercial Loan Portfolio | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	7,074	2,165	0
Commercial Loan Portfolio | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 2,391	$ 3,129	$ 1,750
Commercial Loan Portfolio | Commercial
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	67	36	54
Pre- modification recorded investment	$ 10,566	$ 6,416	$ 14,853
Post- modification recorded investment	10,534	6,311	14,853
Commercial Loan Portfolio | Commercial | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	4,967	2,308	11,533
Commercial Loan Portfolio | Commercial | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	0	1,527
Commercial Loan Portfolio | Commercial | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment			43
Commercial Loan Portfolio | Commercial | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	4,129	1,827	0
Commercial Loan Portfolio | Commercial | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 1,438	$ 2,176	$ 1,750
Commercial Loan Portfolio | Commercial real estate:
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	21	16	16
Pre- modification recorded investment	$ 5,161	$ 2,097	$ 4,859
Post- modification recorded investment	5,013	1,997	4,859
Commercial Loan Portfolio | Commercial real estate: | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	1,049	706	2,993
Commercial Loan Portfolio | Commercial real estate: | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	66	0	1,866
Commercial Loan Portfolio | Commercial real estate: | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment			0
Commercial Loan Portfolio | Commercial real estate: | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	2,945	338	0
Commercial Loan Portfolio | Commercial real estate: | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 953	$ 953	$ 0
Commercial Loan Portfolio | Real estate construction and land development
Financing Receivable, Modifications [Line Items]
Total number of loans | loan		1
Pre- modification recorded investment		$ 36
Post- modification recorded investment		35
Commercial Loan Portfolio | Real estate construction and land development | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment		35
Commercial Loan Portfolio | Real estate construction and land development | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment		0
Commercial Loan Portfolio | Real estate construction and land development | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment		0
Commercial Loan Portfolio | Real estate construction and land development | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment		$ 0
Consumer Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	81	59	28
Pre- modification recorded investment	$ 2,145	$ 1,508	$ 1,107
Post- modification recorded investment	2,035	1,313	1,107
Consumer Loan Portfolio | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	930	804	743
Consumer Loan Portfolio | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	392	37	0
Consumer Loan Portfolio | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment			0
Consumer Loan Portfolio | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	713	472	364
Consumer Loan Portfolio | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 0	$ 0	$ 0
Consumer Loan Portfolio | Residential mortgage
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	9	11	4
Pre- modification recorded investment	$ 577	$ 763	$ 477
Post- modification recorded investment	567	680	477
Consumer Loan Portfolio | Residential mortgage | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	269	297	477
Consumer Loan Portfolio | Residential mortgage | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	151	0	0
Consumer Loan Portfolio | Residential mortgage | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment			0
Consumer Loan Portfolio | Residential mortgage | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	147	383	0
Consumer Loan Portfolio | Residential mortgage | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 0	$ 0	$ 0
Consumer Loan Portfolio | Consumer installment
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	47	34	14
Pre- modification recorded investment	$ 492	$ 208	$ 87
Post- modification recorded investment	473	192	87
Consumer Loan Portfolio | Consumer installment | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	192	118	87
Consumer Loan Portfolio | Consumer installment | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	168	37	0
Consumer Loan Portfolio | Consumer installment | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment			0
Consumer Loan Portfolio | Consumer installment | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	113	37	0
Consumer Loan Portfolio | Consumer installment | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 0	$ 0	$ 0
Consumer Loan Portfolio | Home equity
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	25	14	10
Pre- modification recorded investment	$ 1,076	$ 537	$ 543
Post- modification recorded investment	995	441	543
Consumer Loan Portfolio | Home equity | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	469	389	179
Consumer Loan Portfolio | Home equity | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	73	0	0
Consumer Loan Portfolio | Home equity | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment			0
Consumer Loan Portfolio | Home equity | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	453	52	364
Consumer Loan Portfolio | Home equity | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 0	$ 0	$ 0
Non-owner occupied | Commercial Loan Portfolio | Commercial
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	2	3	3
Pre- modification recorded investment	$ 143	$ 629	$ 485
Post- modification recorded investment	134	592	485
Non-owner occupied | Commercial Loan Portfolio | Commercial | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	68	194	485
Non-owner occupied | Commercial Loan Portfolio | Commercial | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	66	0	0
Non-owner occupied | Commercial Loan Portfolio | Commercial | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment			0
Non-owner occupied | Commercial Loan Portfolio | Commercial | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	27	0
Non-owner occupied | Commercial Loan Portfolio | Commercial | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 0	$ 371	$ 0
Owner-occupied | Commercial Loan Portfolio | Commercial
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	19	13	13
Pre- modification recorded investment	$ 5,018	$ 1,468	$ 4,374
Post- modification recorded investment	4,879	1,405	4,374
Owner-occupied | Commercial Loan Portfolio | Commercial | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	981	512	2,508
Owner-occupied | Commercial Loan Portfolio | Commercial | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	0	1,866
Owner-occupied | Commercial Loan Portfolio | Commercial | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment			0
Owner-occupied | Commercial Loan Portfolio | Commercial | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	2,945	311	0
Owner-occupied | Commercial Loan Portfolio | Commercial | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 953	$ 582	$ 0

Loans (Summary of TDRs) (Detail

Loans (Summary of TDRs) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Modifications [Line Items]
Total TDRs	$ 73,655	$ 77,888
Commercial Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total TDRs	56,851	58,842
Consumer Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total TDRs	16,804	19,046
Accruing TDRs
Financing Receivable, Modifications [Line Items]
Total TDRs	45,580	48,782
Accruing TDRs | Commercial Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total TDRs	32,508	34,484
Accruing TDRs | Consumer Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total TDRs	13,072	14,298
Nonaccrual TDRs
Financing Receivable, Modifications [Line Items]
Total TDRs	28,075	29,106
Nonaccrual TDRs | Commercial Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total TDRs	24,343	24,358
Nonaccrual TDRs | Consumer Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total TDRs	$ 3,732	$ 4,748

Loans (Summary of TDRs with a P

Loans (Summary of TDRs with a Payment Default During the Period) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)loan	Dec. 31, 2017USD ($)loan	Dec. 31, 2016USD ($)loan
Troubled debt restructurings on financing receivables with defaults payment
Number of loans (in loan) | loan	27	22	16
Principal balance at year end | $	$ 1,621	$ 2,051	$ 1,980
Commercial Loan Portfolio
Troubled debt restructurings on financing receivables with defaults payment
Number of loans (in loan) | loan	9	5	2
Principal balance at year end | $	$ 1,208	$ 1,617	$ 1,721
Consumer Loan Portfolio
Troubled debt restructurings on financing receivables with defaults payment
Number of loans (in loan) | loan	18	17	14
Principal balance at year end | $	$ 413	$ 434	$ 259
Commercial | Commercial Loan Portfolio
Troubled debt restructurings on financing receivables with defaults payment
Number of loans (in loan) | loan	6	5	0
Principal balance at year end | $	$ 700	$ 1,617	$ 0
Commercial Real Estate | Commercial Loan Portfolio
Troubled debt restructurings on financing receivables with defaults payment
Number of loans (in loan) | loan	3	0	2
Principal balance at year end | $	$ 508	$ 0	$ 1,721

Loans (Schedule of the Allowanc

Loans (Schedule of the Allowance for Loan Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	$ 91,887
Ending balance	109,984	$ 91,887
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses				$ 6,804	$ 8,002
Loans collectively evaluated for impairment related to allowance for loan losses				102,760	83,885
Total	91,887	91,887		109,984	91,887
Loans individually evaluated for impairment related to recorded investment (loan balance)				130,873	111,877
Loans collectively evaluated for impairment related to recorded investment (loan balance)				11,713,883	9,635,552
Total loans				15,269,779	14,155,267
Commercial Loan Portfolio
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	66,133
Ending balance	83,179	66,133
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses				5,474	5,537
Loans collectively evaluated for impairment related to allowance for loan losses				77,285	60,596
Total	66,133	66,133		83,179	66,133
Loans individually evaluated for impairment related to recorded investment (loan balance)				105,038	83,797
Loans collectively evaluated for impairment related to recorded investment (loan balance)				7,268,932	5,573,389
Total loans				9,511,867	8,460,527
Consumer Loan Portfolio
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	25,754
Ending balance	26,805	25,754
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses				1,330	2,465
Loans collectively evaluated for impairment related to allowance for loan losses				25,475	23,289
Total	25,754	25,754		26,805	25,754
Loans individually evaluated for impairment related to recorded investment (loan balance)				25,835	28,080
Loans collectively evaluated for impairment related to recorded investment (loan balance)				4,444,951	4,062,163
Total loans				5,757,912	5,694,740
Receivables Acquired with Deteriorated Credit Quality
Allowance for loan losses
Allowance for loan losses related to loans acquired with deteriorated credit quality				420	0
Loans acquired with deteriorated credit quality related to recorded investment (loan balance)				3,425,023	4,407,838
Receivables Acquired with Deteriorated Credit Quality | Commercial Loan Portfolio
Allowance for loan losses
Allowance for loan losses related to loans acquired with deteriorated credit quality				420	0
Loans acquired with deteriorated credit quality related to recorded investment (loan balance)				2,137,897	2,803,341
Receivables Acquired with Deteriorated Credit Quality | Consumer Loan Portfolio
Allowance for loan losses
Allowance for loan losses related to loans acquired with deteriorated credit quality				0	0
Loans acquired with deteriorated credit quality related to recorded investment (loan balance)				1,287,126	1,604,497
Originated Loan Portfolio [Member]
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	91,887	78,268	$ 73,328
Provision for loan losses	30,330	23,300	14,875
Charge-offs	(18,464)	(16,867)	(15,302)
Recoveries	5,811	7,186	5,367
Ending balance	109,564	91,887	78,268
Allowance for loan losses
Total	91,887	78,268	73,328	109,564	91,887
Originated Loan Portfolio [Member] | Commercial Loan Portfolio
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	66,133	51,201	47,234
Provision for loan losses	22,656	19,007	9,788
Charge-offs	(9,563)	(8,570)	(8,906)
Recoveries	3,533	4,495	3,085
Ending balance	82,759	66,133	51,201
Allowance for loan losses
Total	66,133	51,201	47,234	82,759	66,133
Originated Loan Portfolio [Member] | Consumer Loan Portfolio
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	25,754	27,067	26,094
Provision for loan losses	7,674	4,293	5,087
Charge-offs	(8,901)	(8,297)	(6,396)
Recoveries	2,278	2,691	2,282
Ending balance	26,805	25,754	27,067
Allowance for loan losses
Total	25,754	27,067	$ 26,094	26,805	25,754
Acquired Loan Portfolio
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	0
Provision for loan losses	420
Charge-offs	0
Recoveries	0
Ending balance	420	0
Allowance for loan losses
Total	0	0		420	0
Acquired Loan Portfolio | Commercial Loan Portfolio
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	0
Provision for loan losses	420
Charge-offs	0
Recoveries	0
Ending balance	420	0
Allowance for loan losses
Total	0	0		420	0
Acquired Loan Portfolio | Consumer Loan Portfolio
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	0
Provision for loan losses	0
Charge-offs	0
Recoveries	0
Ending balance	0	0
Allowance for loan losses
Total	$ 0	$ 0		$ 0	$ 0

Premises and Equipment (Details

Premises and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 272,737	$ 262,387
Less accumulated depreciation	(149,295)	(135,491)
Premises and equipment, net	123,442	126,896
Net rent expense under operating leases	7,700	6,400	$ 3,300
Closed branch offices transferred to other assets	0	13,246	$ 4,846
Land and land improvements
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	31,357	31,427
Buildings
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	133,720	130,028
Furniture and equipment
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 107,660	$ 100,932

Other Real Estate Owned and R_3

Other Real Estate Owned and Repossessed Assets (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Changes in other real estate owned
Balance at the beginning of the period		$ 8,182	$ 16,812	$ 9,716
Additions due to acquisitions				13,227
Other additions		7,179	6,905	9,938
Net payments received		(249)	(1,064)	(1,560)
Disposals		(7,825)	(12,831)	(13,873)
Write-downs		(1,266)	(1,640)	(636)
Balance at the end of the period		5,832	8,182	16,812
Changes in repossessed assets
Balance at the beginning of the period		625	375	219
Additions due to acquisitions				313
Other additions		4,307	4,641	3,032
Net payments received		0	0	(763)
Disposals		(4,508)	(4,391)	(2,426)
Write-downs		0	0	0
Balance at the end of the period		424	625	375
Other Real Estate, Transfers Out (In)		(189)
Repossessed Assets, Transfers Out (In)		0
Cumulative effect adjustment of change in accounting policy, net of tax impact	[1]		1,339	3,659
Accounting Standards Update 2014-09
Changes in repossessed assets
Loans and Leases Receivable, Transferred In (Out)		$ 1,100
Retained Earnings
Changes in repossessed assets
Cumulative effect adjustment of change in accounting policy, net of tax impact	[1]		1,680	$ 3,659
Retained Earnings | Accounting Standards Update 2014-09
Changes in repossessed assets
Cumulative effect adjustment of change in accounting policy, net of tax impact			$ 900
[1]	Refer to Note 1, Summary of Significant Accounting Policies, Note 4, Investment Securities, Note 7, Other Real Estate Owned and Repossessed Assets and Note 9, Loan Servicing Rights, for further details on the changes in accounting policy.

Other Real Estate Owned and R_4

Other Real Estate Owned and Repossessed Assets (Textuals) (Details) $ in Millions	Dec. 31, 2018USD ($)
Other Real Estate [Abstract]
Other real estate owned and repossessed assets acquired in accordance with ASU 2014-04	$ 1.3
Real estate properties for which formal foreclosure proceedings are in process	$ 4.5

Other Real Estate Owned and R_5

Other Real Estate Owned and Repossessed Assets (Income and Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income and expenses related to other real estate owned
Net gain (loss) on sale	$ 1,372	$ 3,038	$ 5,325
Write-downs	(1,266)	(1,640)	(636)
Net operating expenses	(858)	(1,981)	(740)
Total	(752)	(583)	3,949
Income and expenses related to repossessed assets
Net gain (loss) on sale	(309)	(381)	523
Write-downs	0	0	0
Net operating expenses	(5)	(41)	(60)
Total	$ (314)	$ (422)	$ 463

Goodwill (Details)

Goodwill (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Aug. 31, 2016
Goodwill [Line Items]
Goodwill	$ 1,134,568,000	$ 1,134,568,000
Goodwill, Impairment Loss	0	$ 0
Talmer
Goodwill [Line Items]
Goodwill			$ 847,701,000
Goodwill acquired during period	$ 847,700,000

Loan Servicing Rights (Narrativ

Loan Servicing Rights (Narrative) (Details) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Retained Earnings Adjustments [Line Items]
Cumulative effect adjustment of change in accounting policy, net of tax impact	[1]	$ 1,339	$ 3,659
Retained Earnings [Member]
Retained Earnings Adjustments [Line Items]
Cumulative effect adjustment of change in accounting policy, net of tax impact	[1]	$ 1,680	$ 3,659
[1]	Refer to Note 1, Summary of Significant Accounting Policies, Note 4, Investment Securities, Note 7, Other Real Estate Owned and Repossessed Assets and Note 9, Loan Servicing Rights, for further details on the changes in accounting policy.

Loan Servicing Rights (LSRs Act

Loan Servicing Rights (LSRs Activity) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Activity for loan servicing rights and the related fair value changes
Fair value, beginning of period	$ 63,841	$ 48,085	$ 0
Acquired in Talmer Bancorp, Inc. merger			42,462
Transfers in based on new accounting election		15,891
Additions from loans sold with servicing retained	8,226	8,745	1,030
Changes in fair value due to:
Reductions from pay-offs, pay downs and run-off	(2,881)	(2,505)	(519)
Changes in estimates of fair value	1,827	(6,375)	5,112
Fair value, end of period	71,013	63,841	48,085
Principal balance of loans serviced	6,868,079	7,108,747	5,300,171
Commercial Real Estate
Activity for loan servicing rights and the related fair value changes
Fair value, beginning of period	427	344	0
Acquired in Talmer Bancorp, Inc. merger			365
Transfers in based on new accounting election		0
Additions from loans sold with servicing retained	139	188	0
Changes in fair value due to:
Reductions from pay-offs, pay downs and run-off	(115)	(105)	(17)
Changes in estimates of fair value	0	0	(4)
Fair value, end of period	451	427	344
Principal balance of loans serviced	41,127	40,316	64,756
Mortgage
Activity for loan servicing rights and the related fair value changes
Fair value, beginning of period	63,414	47,741	0
Acquired in Talmer Bancorp, Inc. merger			42,097
Transfers in based on new accounting election		15,891
Additions from loans sold with servicing retained	8,087	8,557	1,030
Changes in fair value due to:
Reductions from pay-offs, pay downs and run-off	(2,766)	(2,400)	(502)
Changes in estimates of fair value	1,827	(6,375)	5,116
Fair value, end of period	70,562	63,414	47,741
Principal balance of loans serviced	$ 6,826,952	$ 7,068,431	$ 5,235,415

Loan Servicing Rights (Carrying

Loan Servicing Rights (Carrying and Fair Value of LSRs) (Details) - Loan Servicing Rights $ in Thousands	Dec. 31, 2016USD ($)
Finite-Lived Intangible Assets [Line Items]
Net carrying value of LSRs	$ 10,230
Fair value of LSRs	15,891
Valuation allowance	8
Loans serviced for others that have servicing rights capitalized	$ 2,074,057

Loan Servicing Rights (Activity

Loan Servicing Rights (Activity for Capitalized LSRs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Activity for Capitalized LSRs
Balance at beginning of period	$ 34,271
Amortization	(5,716)	$ (6,090)	$ (10,046)
Balance at end of period	$ 28,556	34,271
Loan Servicing Rights
Activity for Capitalized LSRs
Balance at beginning of period		$ 10,230	11,122
Additions			3,303
Amortization			(4,187)
Change in valuation allowance			(8)
Balance at end of period			$ 10,230

Loan Servicing Rights (Assumpti

Loan Servicing Rights (Assumptions Used in Determining Fair Value) (Details)	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2018
Transfers and Servicing [Abstract]
Loan servicing fee income	$ 17,600,000	$ 18,200,000	$ 8,700,000
Mortgage
Loan servicing rights
WA Cost to service/per year	66	66
WA Ancillary income/per year	$ 31	$ 31
WA float range (as a percent)	2.50%	1.60%
Discount rate | Mortgage | Weighted Average
Loan servicing rights
Loan servicing rights, measurement input		0.101		0.101
Prepayment rate | Mortgage | Minimum
Loan servicing rights
Loan servicing rights, measurement input		0	0
Prepayment rate | Mortgage | Maximum
Loan servicing rights
Loan servicing rights, measurement input		0.264	0.388

Other Intangible Assets (Net Ca

Other Intangible Assets (Net Carrying Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other intangible assets:
Total other intangible assets	$ 28,556	$ 34,271
Core deposit intangible assets
Other intangible assets:
Total other intangible assets	28,556	34,259
Non-compete intangible assets
Other intangible assets:
Total other intangible assets	$ 0	$ 12

Other Intangible Assets (Textua

Other Intangible Assets (Textual) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 5,716	$ 6,090	$ 10,046
Core deposit intangible assets
Finite-Lived Intangible Assets [Line Items]
Remaining weighted-average useful life of intangible assets acquired	6 years 7 months 6 days
Amortization of intangible assets	$ 5,700	$ 6,000	$ 5,200

Other Intangible Assets (Amorti

Other Intangible Assets (Amortization Expense of Core Deposit Intangible Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Net carrying amount	$ 28,556	$ 34,271
Core deposit intangible assets
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Gross original amount	56,456	59,143
Accumulated amortization	27,900	24,884
Net carrying amount	$ 28,556	$ 34,259

Other Intangible Assets (Estima

Other Intangible Assets (Estimated Future Amortization Expense) (Details) - Core deposit intangible assets $ in Thousands	Dec. 31, 2018USD ($)
Estimated Future Amortization Expense
2,019	$ 5,441
2,020	4,851
2,021	4,471
2,022	4,218
2,023	$ 3,591

Derivative Instruments and Ba_3

Derivative Instruments and Balance Sheet Offsetting (Notional Amount and Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional Amount	$ 3,516,418	$ 2,210,925
Gross Derivative Assets	38,595	18,681
Gross Derivative Liabilities	32,379	12,357
Credit valuation adjustments for counterparty credit risk	900	800
Designated as hedging
Derivative [Line Items]
Notional Amount	820,000	620,000
Gross Derivative Assets	10,148	5,899
Gross Derivative Liabilities	3,278	0
Designated as hedging | Interest rate swaps
Derivative [Line Items]
Notional Amount	820,000	620,000
Gross Derivative Assets	10,148	5,899
Gross Derivative Liabilities	3,278	0
Not designated as hedging
Derivative [Line Items]
Notional Amount	2,696,418	1,590,925
Gross Derivative Assets	28,447	12,782
Gross Derivative Liabilities	29,101	12,357
Not designated as hedging | Customer-initiated derivatives
Derivative [Line Items]
Notional Amount	2,477,640	1,365,119
Gross Derivative Assets	26,680	9,376
Gross Derivative Liabilities	27,664	10,139
Not designated as hedging | Foreign exchange forwards
Derivative [Line Items]
Notional Amount	0	0
Gross Derivative Assets	0	0
Gross Derivative Liabilities	0	0
Not designated as hedging | Forward contracts related to mortgage loans to be delivered for sale
Derivative [Line Items]
Notional Amount	127,159	115,996
Gross Derivative Assets	0	0
Gross Derivative Liabilities	719	34
Not designated as hedging | Interest rate lock commitments
Derivative [Line Items]
Notional Amount	54,848	71,003
Gross Derivative Assets	1,049	1,222
Gross Derivative Liabilities	0	0
Not designated as hedging | Power Equity CD
Derivative [Line Items]
Notional Amount	36,771	38,807
Gross Derivative Assets	718	2,184
Gross Derivative Liabilities	$ 718	$ 2,184

Derivative Instruments and Ba_4

Derivative Instruments and Balance Sheet Offsetting (Net Gains (Losses) Related to Changes in Fair Value) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative instruments
Net gains (losses) relating to derivative instruments	$ (1,079)	$ (1,431)	$ (83)
Forward contracts related to mortgage loans to be delivered for sale | Net gain on sale of loans and other mortgage banking revenue
Derivative instruments
Net gains (losses) relating to derivative instruments	(685)	(669)	692
Interest rate lock commitments | Net gain on sale of loans and other mortgage banking revenue
Derivative instruments
Net gains (losses) relating to derivative instruments	(173)	266	(1,356)
Power Equity CD | Other noninterest income
Derivative instruments
Net gains (losses) relating to derivative instruments	0	0	0
Foreign exchange forwards | Other noninterest income
Derivative instruments
Net gains (losses) relating to derivative instruments	0	0	0
Customer-initiated derivatives | Other noninterest income
Derivative instruments
Net gains (losses) relating to derivative instruments	$ (221)	$ (1,028)	$ 581

Derivative Instruments and Ba_5

Derivative Instruments and Balance Sheet Offsetting (Balance Sheet Offsetting) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Offsetting derivative assets
Gross amounts recognized	$ 38,595	$ 18,681
Net amounts presented in the statements of financial position	38,595	18,681
Offsetting derivative liabilities
Gross amounts recognized	32,379	12,357
Net amounts presented in the statements of financial position	32,379	12,357
Interest rate swaps and customer-initiated derivatives
Offsetting derivative assets
Gross amounts recognized	36,791	15,228
Gross amounts offset in the statements of financial condition	0	0
Net amounts presented in the statements of financial position	36,791	15,228
Gross amounts of assets not offset in the statement of financial position
Financial instruments	0	0
Collateral (received)/posted	(16,120)	0
Net Amount	20,671	15,228
Offsetting derivative liabilities
Gross amounts recognized	30,822	10,139
Gross amounts offset in the statements of financial condition	0	0
Net amounts presented in the statements of financial position	30,822	10,139
Gross amounts of liabilities not offset in the statement of financial position
Financial instruments	0	0
Collateral (received)/posted	430	1,081
Net Amount	$ 30,392	$ 9,058

Derivative Instruments and Ba_6

Derivative Instruments and Balance Sheet Offsetting (Net Gains (Losses) Recorded in Other Comprehensive Income and the Income Statement) (Details) - Designated as hedging - Interest rate swaps - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Amount of gain recognized in other comprehensive income	$ 2,841	$ 4,263
Amount of gain (loss) reclassified from other comprehensive income to interest income or expense	$ 1,871	$ (1,633)

Derivative Instruments and Ba_7

Derivative Instruments and Balance Sheet Offsetting (Narrative) (Details) $ in Millions	Dec. 31, 2018USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Unrealized income on interest rate swaps expected to be reclassified during next twelve months	$ 4.5

Investments in Qualified Affo_2

Investments in Qualified Affordable Housing Projects, Federal Historic Projects and New Market Tax Credits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Expense related to qualified affordable housing projects	$ 4.2	$ 3.4	$ 2.6
Remaining investment in qualified affordable housing projects	84.9	51.4
Equity method investments	13.3	17.3
Remaining unfunded equity contributions	72	48.1
Impairment on tax credit projects	12.9	7.9	$ 0
Other noninterest expense
Variable Interest Entity [Line Items]
Impairment on tax credit projects	9.7
Operating expense
Variable Interest Entity [Line Items]
Impairment on tax credit projects	$ 12.3	9.3
Other Operating Expense
Variable Interest Entity [Line Items]
Impairment on tax credit projects		$ 6

Commitments, Contingencies an_3

Commitments, Contingencies and Guarantees (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Potential Losses From Standby Letters Of Credit	$ 0
Undisbursed loan commitments	493,300,000	$ 571,000,000
Allowance for credit losses on lending-related commitments	$ 1,700,000	1,200,000
Consumer Price Index increase	1.90%
Standby Letters of Credit
Loss Contingencies [Line Items]
Face amount of off-balance sheet liability	$ 119,000,000	187,600,000
Commitments to Extend Credit
Loss Contingencies [Line Items]
Face amount of off-balance sheet liability	3,550,000,000	3,030,000,000
Performance guarantee
Loss Contingencies [Line Items]
Outstanding balance of loans	11,600,000	13,300,000
Maximum potential amount of undiscounted future payments	11,400,000	12,800,000
Recourse liability	100,000	200,000
SBA Guaranteed Notes | Performance guarantee
Loss Contingencies [Line Items]
Maximum potential amount of undiscounted future payments	19,100,000	20,600,000
Recourse liability	$ 1,200,000	$ 1,200,000

Commitments, Contingencies an_4

Commitments, Contingencies and Guarantees (Warranties) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Changes in the activity related to liability recorded in connection with representations and warranties
Reserve balance at beginning of period	$ 5,349	$ 6,459	$ 4,048
Addition of fair value of representations and warranties due to mergers and acquisitions	0	0	3,100
Reserve reduction	(1,217)	(1,095)	(580)
Charge-offs	(48)	(15)	(109)
Ending reserve balance	4,084	5,349	6,459
Liability for specific claims				$ 398	$ 531	$ 730
General allowance				3,686	4,818	5,729
Total reserve balance	$ 5,349	$ 6,459	$ 4,048	$ 4,084	$ 5,349	$ 6,459

Commitments, Contingencies an_5

Commitments, Contingencies and Guarantees (Operating Leases and Other Noncancelable Contractual Obligations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Future Minimum Lease Payments
2,019	$ 7,251
2,020	6,239
2,021	5,135
2,022	4,775
2,023	4,375
Thereafter	12,107
Total	39,882
Other Noncancelable Contracts
2,019	46,225
2,020	37,566
2,021	31,330
2,022	30,124
2,023	27,849
Thereafter	46,771
Total	219,865
Total
2,019	53,476
2,020	43,805
2,021	36,465
2,022	34,899
2,023	32,224
Thereafter	58,878
Total	259,747
Future sublease income	632
Total expense recorded under operating leases and other noncancelable contractual obligations	$ 55,200	$ 30,800	$ 20,400

Deposits (Details)

Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Summary of Deposits
Noninterest-bearing demand	$ 3,809,252	$ 3,725,779
Savings and money market accounts	4,092,082	3,655,671
Interest-bearing demand	3,316,278	2,724,415
Brokered deposits	985,522	453,227
Other time deposits	3,390,148	3,083,711
Total deposits	15,593,282	13,642,803
Demand deposit overdrafts	7,900	5,900
Time Deposits, $250,000 or More	2,100,000	$ 1,600,000
Maturities of Time Deposits
2,019	2,776,097
2,020	1,032,314
2,021	148,995
2,022	82,076
2,023	33,900
Thereafter	866
Total	4,074,248
Executive officers, directors, principal shareholders and related interests
Summary of Deposits
Total deposits	$ 9,800

Borrowings and Other Short-te_3

Borrowings and Other Short-term Liabilities (Schedule of Short- and Long-term Borrowings) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Aug. 31, 2016
Short Term Borrowings and Long Term Debt [Line Items]
Long-term borrowings, Amount	$ 426,002	$ 372,882
Long-term borrowings, Weighted Average Rate	2.11%	1.47%
Total borrowings	$ 2,461,002	$ 2,372,882
Total short-term and long-term borrowings, Weighted Average Rate	2.41%	1.40%
FHLB advances: 2.46% - 2.59% fixed-rate notes | Minimum
Short Term Borrowings and Long Term Debt [Line Items]
Stated interest rate	2.46%
FHLB advances: 2.46% - 2.59% fixed-rate notes | Maximum
Short Term Borrowings and Long Term Debt [Line Items]
Stated interest rate	2.59%
Federal Home Loan Bank Advances | FHLB advances: 1.00% - 2.72% fixed-rate notes due 2019 to 2025(2)
Short Term Borrowings and Long Term Debt [Line Items]
Long-term borrowings, Amount	$ 410,102	$ 337,204
Long-term borrowings, Weighted Average Rate	2.00%	1.26%
Advances payable from Federal Home Loan Banks	$ 410,000	$ 337,000
Purchase accounting premiums	$ 100	200
Federal Home Loan Bank Advances | FHLB advances: 1.00% - 2.72% fixed-rate notes due 2019 to 2025(2) | Minimum
Short Term Borrowings and Long Term Debt [Line Items]
Stated interest rate	1.00%
Federal Home Loan Bank Advances | FHLB advances: 1.00% - 2.72% fixed-rate notes due 2019 to 2025(2) | Maximum
Short Term Borrowings and Long Term Debt [Line Items]
Stated interest rate	2.72%
Line of Credit
Short Term Borrowings and Long Term Debt [Line Items]
Long-term borrowings, Amount	$ 0	$ 19,963	$ 125,000
Long-term borrowings, Weighted Average Rate	0.00%	3.10%
Line of Credit | LIBOR
Short Term Borrowings and Long Term Debt [Line Items]
Basis spread on variable rate	1.75%
Subordinated Debt Obligations | Subordinated debt obligations: floating-rate based on three-month LIBOR plus 1.45% - 2.85% due 2034 to 2035
Short Term Borrowings and Long Term Debt [Line Items]
Long-term borrowings, Amount	$ 11,572	$ 11,425
Long-term borrowings, Weighted Average Rate	4.85%	3.69%
Purchase accounting discounts	$ 3,400	$ 3,600
Advances payable	$ 15,000	15,000
Subordinated Debt Obligations | Subordinated debt obligations: floating-rate based on three-month LIBOR plus 1.45% - 2.85% due 2034 to 2035 | Minimum | LIBOR
Short Term Borrowings and Long Term Debt [Line Items]
Basis spread on variable rate	1.45%
Subordinated Debt Obligations | Subordinated debt obligations: floating-rate based on three-month LIBOR plus 1.45% - 2.85% due 2034 to 2035 | Maximum | LIBOR
Short Term Borrowings and Long Term Debt [Line Items]
Basis spread on variable rate	2.85%
Subordinated Debt Obligations | Subordinated debt obligations: floating-rate based on three-month LIBOR plus 3.25% due in 2032
Short Term Borrowings and Long Term Debt [Line Items]
Long-term borrowings, Amount	$ 4,328	$ 4,290
Long-term borrowings, Weighted Average Rate	5.65%	4.59%
Purchase accounting discounts	$ 700	$ 700
Advances payable	$ 5,000	5,000
Subordinated Debt Obligations | Subordinated debt obligations: floating-rate based on three-month LIBOR plus 3.25% due in 2032 | LIBOR
Short Term Borrowings and Long Term Debt [Line Items]
Basis spread on variable rate	3.25%
Collateralized Customer Deposits
Short Term Borrowings and Long Term Debt [Line Items]
Short-term borrowings, Amount	$ 382,687	$ 415,236
Weighted average interest rate	0.75%	0.44%
Federal Home Loan Bank Advances | FHLB advances: 2.46% - 2.59% fixed-rate notes
Short Term Borrowings and Long Term Debt [Line Items]
Short-term borrowings, Amount	$ 2,035,000	$ 2,000,000
Weighted average interest rate	2.47%	1.39%

Borrowings and Other Short-te_4

Borrowings and Other Short-term Liabilities (Additional Information) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Aug. 31, 2016
Debt Disclosure [Abstract]
FHLB advances	$ 7,810,000
Additional borrowing availability through the FHLB	230,100
Debt Instrument [Line Items]
Long-term borrowings, Amount	426,002	$ 372,882
Line of Credit
Debt Instrument [Line Items]
Long-term borrowings, Amount	$ 0	$ 19,963	$ 125,000

Borrowings and Other Short-te_5

Borrowings and Other Short-term Liabilities (Long-term Debt by Maturity) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Long-term Debt by Maturity
2,019	$ 100,058
2,020	110,044
2,021	0
2,022	0
2,023	0
Thereafter	215,900
Long-term Debt	$ 426,002	$ 372,882

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Summary of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Noninterest income	$ 32,047	$ 37,917	$ 38,018	$ 40,554	$ 32,319	$ 32,122	$ 41,568	$ 38,010	$ 54,264	$ 27,770	$ 20,897	$ 19,419	$ 148,536	$ 144,019	$ 122,350
Noninterest expense	$ (108,366)	$ (109,661)	$ (104,561)	$ (101,610)	$ (100,022)	$ (119,539)	$ (98,237)	$ (104,196)	$ (114,302)	$ (106,144)	$ (59,085)	$ (58,887)	(424,198)	$ (421,994)	$ (338,418)
Noninterest income from contracts with customers within the scope of ASC 606
Disaggregation of Revenue [Line Items]
Noninterest income													33,513
Service charges and fees on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income													22,858
Wealth management revenue
Disaggregation of Revenue [Line Items]
Noninterest income													5,099
Other charges and fees for customer services
Disaggregation of Revenue [Line Items]
Noninterest income													5,556
Noninterest income within the scope of other GAAP topics
Disaggregation of Revenue [Line Items]
Noninterest income													115,023
Other
Disaggregation of Revenue [Line Items]
Noninterest expense													$ (1,063)

Income Taxes (Provision for Fed

Income Taxes (Provision for Federal Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current income tax expense (benefit)
Federal													$ (653)	$ 14,665	$ 19,144
State													321	20	(423)
Total current income tax expense													(332)	14,685	18,721
Deferred income tax expense
Federal													41,687	92,636	23,649
State													229	548	442
Total deferred income tax expense													41,916	93,184	24,091
Change in valuation allowance													317	(1,089)	(706)
Income tax provision	$ 5,200	$ 11,312	$ 12,434	$ 12,955	$ 61,234	$ 10,253	$ 23,036	$ 12,257	$ 18,969	$ 2,848	$ 10,532	$ 9,757	$ 41,901	$ 106,780	$ 42,106

Income Taxes (Effective Tax Rat

Income Taxes (Effective Tax Rate Reconciliation) (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Amount
Tax at statutory rate													$ 68,443	$ 89,706	$ 52,548
Tax-exempt interest income													(6,513)	(9,001)	(5,320)
State taxes, net of federal benefit													434	369	13
Change in valuation allowance													317	(1,089)	(706)
Bank-owned life insurance adjustments													(838)	(1,696)	(832)
Director plan change in control													0	0	(508)
Income tax credits, net													(16,148)	(11,449)	(2,454)
Nondeductible transaction expenses														156	2,100
Tax benefits in excess of compensation costs on share-based payments													(1,782)	(5,886)	(2,240)
Impact of Tax Cuts and Jobs Act													(2,939)	46,660	0
Other, net													(168)	(990)	(495)
Income tax provision	$ 5,200	$ 11,312	$ 12,434	$ 12,955	$ 61,234	$ 10,253	$ 23,036	$ 12,257	$ 18,969	$ 2,848	$ 10,532	$ 9,757	$ 41,901	$ 106,780	$ 42,106
Effective Income Tax Rate, Tax Rate Reconciliation, Percent
Tax at statutory rate													21.00%	35.00%	35.00%
Tax-exempt interest income													(2.00%)	(3.50%)	(3.50%)
State taxes, net of federal benefit													0.10%	0.10%	0.00%
Change in valuation allowance													0.10%	(0.40%)	(0.50%)
Bank-owned life insurance adjustments													(0.20%)	(0.70%)	(0.60%)
Director plan change in control													0.00%	0.00%	(0.30%)
Income tax credits, net													(4.90%)	(4.40%)	(1.60%)
Nondeductible transaction expenses													0.00%	0.10%	1.40%
Tax benefits in excess of compensation costs on share-based payments													(0.50%)	(2.30%)	(1.50%)
Impact of Tax Cuts and Jobs Act													(0.90%)	18.20%	0.00%
Other, net													(0.10%)	(0.40%)	(0.40%)
Income tax expense													12.90%	41.70%	28.00%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, FDIC Insurance Premiums, Amount													$ 1,095	$ 0	$ 0
Effective Income Tax Rate Reconciliation, Nondeductible Expense, FDIC Insurance Premiums, Percent													0.30%	0.00%	0.00%

Income Taxes (Deferred Tax Asse

Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Allowance for loan losses	$ 24,019	$ 20,446
Acquisition-related fair value adjustments	16,511	27,607
Unrealized loss on securities	10,040	2,751
Accrued stock-based compensation	3,239	4,082
Loss and tax credit carry forwards	30,169	57,969
Nonaccrual loan interest	10,830	6,155
Accrued expense	7,397	9,200
Other	4,888	9,330
Total deferred tax assets	107,093	137,540
Deferred tax liabilities:
Loan servicing rights	14,941	13,446
Core deposit intangible assets	4,966	6,022
Goodwill	4,281	4,076
Deferred loan fees	4,963	4,551
Prepaid expenses	5,625	7,390
Other	5,894	3,184
Total deferred tax liabilities	40,670	38,669
Net deferred tax asset before valuation allowance	66,423	98,871
Valuation allowance	(1,467)	(1,150)
Net deferred tax asset	$ 64,956	$ 97,721

Income Taxes (Textuals) (Detail

Income Taxes (Textuals) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Tax at statutory rate		21.00%	35.00%	35.00%
Impact of Tax Cuts and Jobs Act		$ (2,939,000)	$ 46,660,000	$ 0
Impact of Tax Cuts and Jobs Act, revaluation of deferred tax asset		46,000,000
Impact of Tax Cuts and Jobs Act, accelerated amortization		700,000
Realized Built-in Losses		70,253,000
Tax benefit from TCJA	$ 2,900,000
Valuation allowance for deferred tax assets	1,150,000	1,467,000	1,150,000
Bad debt reserve	91,887,000	109,984,000	91,887,000
Unrecognized tax benefits	0	0	0
Liabilities accrued for interest or penalties	0	0	0
Increase (Decrease) In Deferred Tax Assets Valuation Allowance		(317,000)	1,089,000	$ 706,000
Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses		55,231,000
Alternative Minimum Tax Credits - no expiration
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards		2,524,000
Talmer
Operating Loss Carryforwards [Line Items]
Valuation allowance for deferred tax assets	1,200,000	1,500,000	1,200,000
Valuation allowance for tax credit carryforward	$ 600,000		$ 600,000
Talmer | Subject to limitations under section 382
Operating Loss Carryforwards [Line Items]
Valuation allowance for deferred tax assets		600,000
First Place Holdings/First Place Bank | Subject to limitations under section 382
Operating Loss Carryforwards [Line Items]
Realized Built-in Losses		61,317,000
Bad debt reserve		36,000,000
Potential unrecognized tax expense that would impact effective tax rate		7,500,000
First Place Holdings/First Place Bank | Subject to limitations under section 382 | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses		0
First Place Holdings/First Place Bank | Alternative Minimum Tax Credits - no expiration | Subject to limitations under section 382
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards		2,115,000
Talmer West Bank | Subject to limitations under section 382
Operating Loss Carryforwards [Line Items]
Realized Built-in Losses		8,936,000
Talmer West Bank | Subject to limitations under section 382 | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses		41,039,000
Talmer West Bank | Alternative Minimum Tax Credits - no expiration | Subject to limitations under section 382
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards		$ 0

Income Taxes (Summary of Loss A

Income Taxes (Summary of Loss Attributes, Section 382 Limitations, and Tax Expiration Periods) (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Income Tax Expense (Benefit)	$ 5,200	$ 11,312	$ 12,434	$ 12,955	$ 61,234	$ 10,253	$ 23,036	$ 12,257	$ 18,969	$ 2,848	$ 10,532	$ 9,757	$ 41,901	$ 106,780	$ 42,106
Realized Built-in Losses	70,253												70,253
Less amounts not recorded due to Sec 382 Limitation	(2,023)												(2,023)
Valuation Allowance	(1,467)												(1,467)
Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	55,231												55,231
Gross Capital Losses
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	6,987												6,987
Business Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	2,432												2,432
Alternative Minimum Tax Credits - no expiration
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	2,524												2,524
Monarch
Operating Loss Carryforwards [Line Items]
Estimated recognized built in gain	1,600												1,600
Subject to limitations under section 382 | Monarch
Operating Loss Carryforwards [Line Items]
Annual Section 382 limitation-base	673												673
Realized Built-in Losses	0												0
Less amounts not recorded due to Sec 382 Limitation	(1,738)												(1,738)
Valuation Allowance	0												0
Subject to limitations under section 382 | Monarch | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	12,350												12,350
Subject to limitations under section 382 | Monarch | Gross Capital Losses
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0												0
Subject to limitations under section 382 | Monarch | Business Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	1,651												1,651
Subject to limitations under section 382 | Monarch | Alternative Minimum Tax Credits - no expiration
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	106												106
Subject to limitations under section 382 | First Place Holdings/First Place Bank
Operating Loss Carryforwards [Line Items]
Income Tax Expense (Benefit)													0
Annual Section 382 limitation-base	6,650												6,650
Realized Built-in Losses	61,317												61,317
Less amounts not recorded due to Sec 382 Limitation	(140)												(140)
Valuation Allowance	0												0
Subject to limitations under section 382 | First Place Holdings/First Place Bank | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	0												0
Subject to limitations under section 382 | First Place Holdings/First Place Bank | Gross Capital Losses
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0												0
Subject to limitations under section 382 | First Place Holdings/First Place Bank | Business Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	781												781
Subject to limitations under section 382 | First Place Holdings/First Place Bank | Alternative Minimum Tax Credits - no expiration
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	2,115												2,115
Subject to limitations under section 382 | Talmer West Bank
Operating Loss Carryforwards [Line Items]
Annual Section 382 limitation-base	3,028												3,028
Realized Built-in Losses	8,936												8,936
Less amounts not recorded due to Sec 382 Limitation	0												0
Valuation Allowance	0												0
Subject to limitations under section 382 | Talmer West Bank | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	41,039												41,039
Subject to limitations under section 382 | Talmer West Bank | Gross Capital Losses
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0												0
Subject to limitations under section 382 | Talmer West Bank | Business Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0												0
Subject to limitations under section 382 | Talmer West Bank | Alternative Minimum Tax Credits - no expiration
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0												0
Subject to limitations under section 382 | First of Huron Corp./Signature Bank
Operating Loss Carryforwards [Line Items]
Annual Section 382 limitation-base	365												365
Realized Built-in Losses	0												0
Less amounts not recorded due to Sec 382 Limitation	0												0
Valuation Allowance	0												0
Subject to limitations under section 382 | First of Huron Corp./Signature Bank | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	247												247
Subject to limitations under section 382 | First of Huron Corp./Signature Bank | Gross Capital Losses
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0												0
Subject to limitations under section 382 | First of Huron Corp./Signature Bank | Business Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0												0
Subject to limitations under section 382 | First of Huron Corp./Signature Bank | Alternative Minimum Tax Credits - no expiration
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	303												303
Subject to limitations under section 382 | From 2009 Ownership change
Operating Loss Carryforwards [Line Items]
Annual Section 382 limitation-base	145												145
Realized Built-in Losses	0												0
Less amounts not recorded due to Sec 382 Limitation	(145)												(145)
Valuation Allowance	0												0
Subject to limitations under section 382 | From 2009 Ownership change | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	1,595												1,595
Subject to limitations under section 382 | From 2009 Ownership change | Gross Capital Losses
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0												0
Subject to limitations under section 382 | From 2009 Ownership change | Business Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0												0
Subject to limitations under section 382 | From 2009 Ownership change | Alternative Minimum Tax Credits - no expiration
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0												0
Not subject to limitations under section 382
Operating Loss Carryforwards [Line Items]
Realized Built-in Losses	0												0
Less amounts not recorded due to Sec 382 Limitation	0												0
Valuation Allowance	(1,467)												(1,467)
Not subject to limitations under section 382 | Federal
Operating Loss Carryforwards [Line Items]
Annual Section 382 limitation-base	0												0
Gross Federal Net Operating Losses	0												0
Not subject to limitations under section 382 | Gross Capital Losses
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	6,987												6,987
Not subject to limitations under section 382 | Business Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0												0
Not subject to limitations under section 382 | Alternative Minimum Tax Credits - no expiration
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	$ 0												$ 0

Share-Based Compensation (Textu

Share-Based Compensation (Textual) (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares	Apr. 26, 2017shares
Share-Based Compensation Plans (Textual) [Abstract]
Share-based compensation expense	$ 8.6	$ 17.3	$ 14.7
Excess tax benefit from share-based compensation	$ 1.8	6.1	2.2
Common stock available for future grants under share-based compensation plans (in shares) | shares	1,301,285			1,750,000
Cash received from option exercises	$ 2.6	$ 3.2	$ 2.7
Shares issued from exercises (in shares) | shares	179,887	621,355	229,055
Granted after 2012
Share-Based Compensation Plans (Textual) [Abstract]
Stock option vesting period	5 years
Granted prior to 2013
Share-Based Compensation Plans (Textual) [Abstract]
Stock option vesting period	3 years
Stock Options
Share-Based Compensation Plans (Textual) [Abstract]
Stock option expiration period	10 years
Intrinsic value of outstanding in-the-money stock options	$ 5.8	$ 26.6	$ 80.4
Intrinsic value of exercisable in-the-money stock options	$ 5.2
Closing price of common stock (USD per share) | $ / shares	$ 36.61
Unrecognized compensation expense related to share-based compensation	$ 1.2
Unrecognized compensation expense related to share-based compensation, period for recognition	2 years 7 months
Stock Options | Non-vested stock options outstanding
Share-Based Compensation Plans (Textual) [Abstract]
Corporation granted options to purchase common stock (in shares) | shares		132,414	441,167
Restricted Stock Units
Share-Based Compensation Plans (Textual) [Abstract]
Corporation granted options to purchase restricted stock performance units (in shares) | shares	321,043
Shares issued from exercises (in shares) | shares	102,553
Unrecognized compensation expense related to share-based compensation	$ 16.4
Unrecognized compensation expense related to share-based compensation, period for recognition	3 years 1 month
Restricted Stock Units | Minimum
Share-Based Compensation Plans (Textual) [Abstract]
Restricted stock performance units eligible to vest as a multiple of number of units granted	0.5
Restricted Stock Units | Maximum
Share-Based Compensation Plans (Textual) [Abstract]
Restricted stock performance units eligible to vest as a multiple of number of units granted	1.5
Restricted Stock Awards
Share-Based Compensation Plans (Textual) [Abstract]
Unrecognized compensation expense related to share-based compensation	$ 0.3
Unrecognized compensation expense related to share-based compensation, period for recognition	2 months

Share-Based Compensation (Stock

Share-Based Compensation (Stock Options Outstanding Per Range of Exercise Prices) (Details) - Stock Options	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number Outstanding (in shares) | shares	777,443
Options Outstanding, Weighted Average Exercise Price Per Share (USD per share)	$ 31.42
Options Outstanding, Weighted Average Contractual Term	5 years 9 months 14 days
Options Exercisable, Weighted Average Exercise Price Per Share (USD per share)	$ 28.65
Options Exercisable, Weighted Average Contractual Term	5 years 1 month 17 days
Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, lower price range limit (USD per share)	$ 11.09
Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, upper price range limit (USD per share)	$ 53.72
$11.09 - 12.80
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number Outstanding (in shares) | shares	32,691
Options Outstanding, Weighted Average Exercise Price Per Share (USD per share)	$ 12.37
Options Outstanding, Weighted Average Contractual Term	1 year 11 months 6 days
Options Exercisable, Number Exercisable (in shares) | shares	32,691
Options Exercisable, Weighted Average Exercise Price Per Share (USD per share)	$ 12.37
Options Exercisable, Weighted Average Contractual Term	1 year 11 months 6 days
$11.09 - 12.80 | Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, lower price range limit (USD per share)	$ 11.09
$11.09 - 12.80 | Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, upper price range limit (USD per share)	$ 12.8
$13.20 - 16.24
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number Outstanding (in shares) | shares	26,669
Options Outstanding, Weighted Average Exercise Price Per Share (USD per share)	$ 15.73
Options Outstanding, Weighted Average Contractual Term	4 years
Options Exercisable, Number Exercisable (in shares) | shares	26,669
Options Exercisable, Weighted Average Exercise Price Per Share (USD per share)	$ 15.73
Options Exercisable, Weighted Average Contractual Term	4 years
$13.20 - 16.24 | Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, lower price range limit (USD per share)	$ 13.2
$13.20 - 16.24 | Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, upper price range limit (USD per share)	$ 16.24
$19.97 - 21.10
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number Outstanding (in shares) | shares	22,955
Options Outstanding, Weighted Average Exercise Price Per Share (USD per share)	$ 20.15
Options Outstanding, Weighted Average Contractual Term	1 year 11 months 28 days
Options Exercisable, Number Exercisable (in shares) | shares	22,955
Options Exercisable, Weighted Average Exercise Price Per Share (USD per share)	$ 20.15
Options Exercisable, Weighted Average Contractual Term	1 year 11 months 25 days
$19.97 - 21.10 | Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, lower price range limit (USD per share)	$ 19.97
$19.97 - 21.10 | Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, upper price range limit (USD per share)	$ 21.1
$23.78 - 25.14
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number Outstanding (in shares) | shares	162,561
Options Outstanding, Weighted Average Exercise Price Per Share (USD per share)	$ 24.59
Options Outstanding, Weighted Average Contractual Term	3 years 6 months 32 days
Options Exercisable, Number Exercisable (in shares) | shares	162,561
Options Exercisable, Weighted Average Exercise Price Per Share (USD per share)	$ 24.59
Options Exercisable, Weighted Average Contractual Term	3 years 6 months 32 days
$23.78 - 25.14 | Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, lower price range limit (USD per share)	$ 23.78
$23.78 - 25.14 | Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, upper price range limit (USD per share)	$ 25.14
$29.45 - 32.81
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number Outstanding (in shares) | shares	428,350
Options Outstanding, Weighted Average Exercise Price Per Share (USD per share)	$ 31.71
Options Outstanding, Weighted Average Contractual Term	6 years 7 months 20 days
Options Exercisable, Number Exercisable (in shares) | shares	267,067
Options Exercisable, Weighted Average Exercise Price Per Share (USD per share)	$ 31.05
Options Exercisable, Weighted Average Contractual Term	6 years 3 months 29 days
$29.45 - 32.81 | Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, lower price range limit (USD per share)	$ 29.45
$29.45 - 32.81 | Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, upper price range limit (USD per share)	$ 32.81
$46.95 - 53.72
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number Outstanding (in shares) | shares	104,217
Options Outstanding, Weighted Average Exercise Price Per Share (USD per share)	$ 53.35
Options Outstanding, Weighted Average Contractual Term	8 years 3 months 1 day
Options Exercisable, Number Exercisable (in shares) | shares	43,842
Options Exercisable, Weighted Average Exercise Price Per Share (USD per share)	$ 53.54
Options Exercisable, Weighted Average Contractual Term	8 years 2 months 27 days
$46.95 - 53.72 | Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, lower price range limit (USD per share)	$ 46.95
$46.95 - 53.72 | Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, upper price range limit (USD per share)	$ 53.72

Share-Based Compensation (Sto_2

Share-Based Compensation (Stock Option Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted- average grant date fair value per share
Granted, Weighted Average Grant Date Fair Value Per Share (USD per share)		$ 9.94	$ 6.15
Stock Options | Non-vested stock options outstanding
Number of options
Beginning balance, Number of Options	330,870	407,939	479,755
Granted, Number of Options		132,414	441,167
Acquired, Number of Options			0
Exercised, Number of Options	0	0	0
Vested, Number of Options	(78,533)	(161,751)	(454,360)
Forfeited/expired, Number of Options	(30,679)	(47,732)	(58,623)
Ending balance, Number of Options	221,658	330,870	407,939
Weighted- average exercise price per share
Beginning balance, Weighted Average Exercise Price Per Share (USD per share)	$ 37.97	$ 32.81	$ 28.75
Granted, Weighted Average Exercise Price Per Share (USD per share)		53.43	32.81
Acquired, Weighted Average Exercise Price Per Share (USD per share)			0
Exercised, Weighted Average Exercise Price Per Share (USD per share)	0	0	0
Vested, Weighted Average Exercise Price Per Share (USD per share)	37.16	37.73	28.74
Forfeited/expired, Weighted Average Exercise Price Per Share (USD per share)	37.20	37.55	31.10
Ending balance, Weighted Average Exercise Price Per Share (USD per share)	38.37	37.97	32.81
Weighted- average grant date fair value per share
Beginning balance, Weighted Average Grant Date Fair Value Per Share (USD per share)	7.09	6.15	8.49
Granted, Weighted Average Grant Date Fair Value Per Share (USD per share)		9.94	6.15
Acquired, Weighted Average Grant Date Fair Value Per Share (USD per share)			0
Exercised, Granted, Weighted Average Grant Date Fair Value Per Share (USD per share)	0	0	0
Vested, Granted, Weighted Average Grant Date Fair Value Per Share (USD per share)	6.94	7.07	8.49
Forfeited/expired, Granted, Weighted Average Grant Date Fair Value Per Share (USD per share)	6.97	7.03	7.17
Ending balance, Weighted Average Grant Date Fair Value Per Share (USD per share)	$ 7.16	$ 7.09	$ 6.15
Stock Options | Stock options outstanding
Number of options
Beginning balance, Number of Options	1,110,918	2,453,395	1,054,739
Granted, Number of Options		132,414	441,167
Acquired, Number of Options			1,466,408
Exercised, Number of Options	(302,796)	(1,427,159)	(450,296)
Vested, Number of Options	0	0	0
Forfeited/expired, Number of Options	(30,679)	(47,732)	(58,623)
Ending balance, Number of Options	777,443	1,110,918	2,453,395
Weighted- average exercise price per share
Beginning balance, Weighted Average Exercise Price Per Share (USD per share)	$ 29.56	$ 21.41	$ 25.38
Granted, Weighted Average Exercise Price Per Share (USD per share)		53.43	32.81
Acquired, Weighted Average Exercise Price Per Share (USD per share)			15.08
Exercised, Weighted Average Exercise Price Per Share (USD per share)	24	17.50	20.02
Vested, Weighted Average Exercise Price Per Share (USD per share)	0	0	0
Forfeited/expired, Weighted Average Exercise Price Per Share (USD per share)	37.20	37.55	31.10
Ending balance, Weighted Average Exercise Price Per Share (USD per share)	$ 31.42	$ 29.56	$ 21.41
Weighted- average grant date fair value per share
Options Exercisable, Number Exercisable (in shares)	555,785
Exercisable/vested, Weighted Average Exercise Price Per Share (USD per share)	$ 28.65

Share-Based Compensation (Black

Share-Based Compensation (Black-Scholes Pricing Model Assumptions) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Assumptions of Black-Scholes option pricing model
Expected dividend yield	3.31%	3.30%
Risk-free interest rate	2.05%	1.39%
Expected stock price volatility	26.70%	27.90%
Expected life of options — in years	6 years	6 years 6 months
Weighted average fair value of options granted (USD per share)	$ 9.94	$ 6.15

Share-Based Compensation (Restr

Share-Based Compensation (Restricted Stock Unit Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of units
Converted into shares of common stock, Number of Units	(179,887)	(621,355)	(229,055)
Restricted Stock Units
Number of units
Beginning balance, Number of Units	380,940
Granted, Number of Units	321,043
Converted into shares of common stock, Number of Units	(102,553)
Forfeited/expired, Number of Units	(22,940)
Ending balance, Number of Units	576,490	380,940
Weighted-average grant date fair value per unit
Beginning balance, Weighted Average Grant Date Fair Value Per Share (USD per share)	$ 41.29
Granted, Weighted Average Grant Date Fair Value Per Unit (USD per Unit)	54.15
Converted into shares of common stock, Weighted Average Grant Date Fair Value Per Unit (USD per Unit)	34.77
Forfeited/expired, Weighted Average Grant Date Fair Value Per Unit (USD per Unit)	47.87
Ending balance, Weighted Average Grant Date Fair Value Per Share (USD per share)	$ 49.35	$ 41.29

Share-Based Compensation (Res_2

Share-Based Compensation (Restricted Stock Awards Activity) (Details) - Restricted Stock Awards	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Number of awards
Beginning balance, Number of Units | shares	83,228,000
Vested, Number of Units | shares	(41,784,000)
Forfeited, Number of Units | shares	(592,000)
Ending balance, Number of Units | shares	40,852,000
Weighted-average acquisition-date fair value
Beginning balance, Weighted Average Grant Date Fair Value Per Share (USD per share) | $ / shares	$ 46.23
Vested (USD per share) | $ / shares	46.23
Forfeited (USD per share) | $ / shares	46.23
Ending balance, Weighted Average Grant Date Fair Value Per Share (USD per share) | $ / shares	$ 46.23

Retirement Plans (401(k) Saving

Retirement Plans (401(k) Savings Plan) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer discretionary contribution percent	4.00%
Maximum annual contribution per employee percent	50.00%
Employer matching contribution percent	4.00%
Employer total contribution amount	$ 8.4	$ 9.1	$ 6.5
Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer discretionary contribution percent	6.00%

Retirement Plans (Textual) (Det

Retirement Plans (Textual) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)employeeshares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)
Defined Benefit Plan Disclosure [Line Items]
Common Stock, Shares Held by Plan | shares	71,460,119	71,207,114
Dividends paid (in dollars per share)	$ 88,954	$ 78,498	$ 49,389
Multiemployer Plan, Contributions by Employer	0
Multiemployer Plan, Participating Company, Allocation of Plan Liabilities	$ 3,800	3,700
Multiemployer Plan, Company's Asset Participation Level	0.10%
Employer discretionary contribution percent	4.00%
Employer total contribution amount	$ 8,400	$ 9,100	$ 6,500
Maximum annual contribution per employee percent	50.00%
Employer matching contribution percent	4.00%
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate used in determining benefit obligation	4.32%	3.68%	4.22%
Number of Employees Covered (in employee) | employee	80
Pension Plan expense	$ (3,813)	$ (1,495)	$ 73
Employer contributions	$ 0	$ 0
Discount rate used in determining expense	3.68%	4.22%	4.55%
Curtailment	$ 0	$ 11,911
Pension plan actual asset allocations	100.00%	100.00%
Projected benefit obligation	$ 111,432	$ 121,361	$ 123,968
Accumulated benefit obligation	111,432	121,361
Settlement	$ 0	$ 0	$ 0
Pension Plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan actual asset allocations	67.00%	68.00%
Pension Plan | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan actual asset allocations	26.00%	28.00%
Pension Plan | Other
Defined Benefit Plan Disclosure [Line Items]
Pension plan actual asset allocations	7.00%	4.00%
Pension Plan | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Common Stock, Shares Held by Plan | shares		0
SERP
Defined Benefit Plan Disclosure [Line Items]
Discount rate used in determining benefit obligation	4.32%	3.38%	3.63%
Pension Plan expense	$ 5	$ 529	$ 367
Employer contributions	$ 0	$ 0
Discount rate used in determining expense	0.00%	0.00%	4.51%
Curtailment	$ 0	$ 0
Number of employees covered by the pension plan | employee	1
Projected benefit obligation	$ 337	2,423	$ 2,567
Accumulated benefit obligation	337	2,423
Settlement	$ 0	$ (322)	$ (120)
Postretirement Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate used in determining benefit obligation	4.11%	3.41%	3.79%
Pension Plan expense	$ (58)	$ (63)	$ 158
Employer contributions	$ 0	$ 198
Discount rate used in determining expense	3.41%	3.79%	4.23%
Curtailment	$ 0	$ 0
Expected health care cost trend rate assumed for 2014	7.50%
Expected ultimate health care cost trend rate in 2020	5.00%
Projected benefit obligation	$ 2,200	2,512	$ 2,601
Accumulated benefit obligation	2,200	2,512
Settlement	$ 0	0	$ 0
Minimum retirement age (years)	50 years
Maximum benefit age of spouse (years)	65 years
Minimum retirement age with twenty-five years of service to be eligible for postretirement benefits (years)	60 years
Minimum years of service for retirees at age sixty to be eligible for postretirement benefits (years)	25 years
Chemical Financial Corporation | Pension Plan | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Dividends paid (in dollars per share)		$ 200
Minimum | Pension Plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range	40.00%
Minimum | Pension Plan | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range	20.00%
Minimum | Pension Plan | Other
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range	0.00%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Employer discretionary contribution percent	6.00%
Maximum | Pension Plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range	70.00%
Maximum | Pension Plan | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range	60.00%
Maximum | Pension Plan | Other
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range	10.00%
Nonqualified Plan | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined benefits owed related to change in control	$ 300

Retirement Plans (Changes in th

Retirement Plans (Changes in the Projected Benefit Obligation and Plan Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plan
Projected benefit obligation:
Benefit obligation at beginning of year	$ 121,361	$ 123,968
Service cost	0	639	$ 1,041
Interest cost	4,356	4,966	5,335
Net actuarial loss (gain)	(7,048)	10,131
Benefits paid	(7,237)	(6,432)
Curtailment	0	(11,911)
Benefit obligation at end of year	111,432	121,361	123,968
Fair value of plan assets:
Fair value of plan assets at beginning of year	145,901	132,751
Actual return on plan assets	(10,312)	19,582
Employer contributions	0	0
Benefits paid	(7,237)	(6,432)
Fair value of plan assets at end of year	128,352	145,901	132,751
Funded (unfunded) status at December 31	16,920	24,540
Accumulated benefit obligation	111,432	121,361
Postretirement Plan
Projected benefit obligation:
Benefit obligation at beginning of year	2,512	2,601
Service cost	3	5	9
Interest cost	82	94	132
Net actuarial loss (gain)	(208)	10
Benefits paid	(189)	(198)
Curtailment	0	0
Benefit obligation at end of year	2,200	2,512	2,601
Fair value of plan assets:
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	0	198
Benefits paid	0	(198)
Fair value of plan assets at end of year	0	0	0
Funded (unfunded) status at December 31	(2,200)	(2,512)
Accumulated benefit obligation	2,200	2,512
SERP
Projected benefit obligation:
Benefit obligation at beginning of year	2,423	2,567
Service cost	0	61	77
Interest cost	12	69	92
Net actuarial loss (gain)	(36)	(274)
Benefits paid	(2,062)	0
Curtailment	0	0
Benefit obligation at end of year	337	2,423	2,567
Fair value of plan assets:
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	0	0
Benefits paid	0	0
Fair value of plan assets at end of year	0	0	$ 0
Funded (unfunded) status at December 31	(337)	(2,423)
Accumulated benefit obligation	$ 337	$ 2,423

Retirement Plans (Weighted-aver

Retirement Plans (Weighted-average rate assumptions of the Pension and Postretirement Plans) (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate used in determining benefit obligation — December 31	4.32%	3.68%	4.22%
Discount rate used in determining expense	3.68%	4.22%	4.55%
Discount rate used in determining expense — prior to remeasurement	0.00%	3.81%	0.00%
Expected long-term return on Pension Plan assets	6.50%	6.75%	6.75%
Rate of compensation increase used in determining benefit obligation — December 31	0.00%	0.00%	3.50%
Rate of compensation increase used in determining pension expense	0.00%	3.50%	3.50%
Year 1 increase in cost of postretirement benefits	0.00%	0.00%	0.00%
Postretirement Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate used in determining benefit obligation — December 31	4.11%	3.41%	3.79%
Discount rate used in determining expense	3.41%	3.79%	4.23%
Discount rate used in determining expense — prior to remeasurement	0.00%	0.00%	0.00%
Expected long-term return on Pension Plan assets	0.00%	0.00%	0.00%
Rate of compensation increase used in determining benefit obligation — December 31	0.00%	0.00%	0.00%
Rate of compensation increase used in determining pension expense	0.00%	0.00%	0.00%
Year 1 increase in cost of postretirement benefits	7.50%	6.50%	7.00%
SERP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate used in determining benefit obligation — December 31	4.32%	3.38%	3.63%
Discount rate used in determining expense	0.00%	0.00%	4.51%
Discount rate used in determining expense — prior to remeasurement	3.38%	3.63%	2.87%
Expected long-term return on Pension Plan assets	0.00%	0.00%	0.00%
Rate of compensation increase used in determining benefit obligation — December 31	0.00%	0.00%	3.50%
Rate of compensation increase used in determining pension expense	0.00%	3.50%	3.50%
Year 1 increase in cost of postretirement benefits	0.00%	0.00%	0.00%

Retirement Plans (Net Periodic

Retirement Plans (Net Periodic Pension Cost (Income)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plan
Components of net periodic benefit cost (income) for the Corporation's qualified and nonqualified pension plans and nonqualified postretirement benefits plan
Service cost	$ 0	$ 639	$ 1,041
Interest cost	4,356	4,966	5,335
Expected return on plan assets	(8,879)	(8,938)	(8,562)
Amortization of prior service credit	0	0	0
Amortization of net actuarial loss (gain)	710	1,837	2,259
Curtailment	0	1	0
Settlement	0	0	0
Net cost (income)	(3,813)	(1,495)	73
Postretirement Plan
Components of net periodic benefit cost (income) for the Corporation's qualified and nonqualified pension plans and nonqualified postretirement benefits plan
Service cost	3	5	9
Interest cost	82	94	132
Expected return on plan assets	0	0	0
Amortization of prior service credit	0	0	117
Amortization of net actuarial loss (gain)	(143)	(162)	(100)
Curtailment	0	0	0
Settlement	0	0	0
Net cost (income)	(58)	(63)	158
SERP
Components of net periodic benefit cost (income) for the Corporation's qualified and nonqualified pension plans and nonqualified postretirement benefits plan
Service cost	0	61	77
Interest cost	12	69	92
Expected return on plan assets	0	0	0
Amortization of prior service credit	0	0	0
Amortization of net actuarial loss (gain)	(7)	77	78
Curtailment	0	0	0
Settlement	0	322	120
Net cost (income)	$ 5	$ 529	$ 367

Retirement Plans (Schedule of E

Retirement Plans (Schedule of Estimated Future Benefit Payments) (Details) $ in Thousands	Dec. 31, 2018USD ($)
Pension Plan
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	$ 6,387
2,020	6,522
2,021	6,680
2,022	6,795
2,023	6,895
2024 - 2028	35,908
Total	69,187
Postretirement Plan
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	241
2,020	237
2,021	231
2,022	221
2,023	209
2024 - 2028	853
Total	1,992
SERP
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	22
2,020	22
2,021	22
2,022	22
2,023	22
2024 - 2028	106
Total	$ 216

Retirement Plans (Impact of One

Retirement Plans (Impact of One Percentage Point Change in Assumed Health Care and Dental Cost Trend Rates) (Details) - Postretirement Plan $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Effect of one percentage point increase on service and interest cost components	$ 7
Effect of one percentage point decrease on service and interest cost components	(6)
Effect of one percentage point increase on postretirement benefit obligation	157
Effect of one percentage point decrease on postretirement benefit obligation	$ (143)

Retirement Plans (Pension Plan

Retirement Plans (Pension Plan Asset Allocations) (Details) - Pension Plan	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension plan actual asset allocations	100.00%	100.00%
Equity securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension plan actual asset allocations	67.00%	68.00%
Debt securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension plan actual asset allocations	26.00%	28.00%
Other
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension plan actual asset allocations	7.00%	4.00%

Retirement Plans (Fair Value of

Retirement Plans (Fair Value of Plan Assets by Fair Value Level) (Details) - Pension Plan - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 128,352,000	$ 145,901,000	$ 132,751,000
Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	128,352,000	145,901,000
Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	127,805,000	145,353,000
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	547,000	548,000
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8,770,000	5,238,000
Cash | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8,770,000	5,238,000
Cash | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. large- and mid-cap stocks
Defined Benefit Plan Disclosure [Line Items]
Minimum market capitalization for investments	3,000,000,000
U.S. large- and mid-cap stocks | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	63,823,000	68,909,000
U.S. large- and mid-cap stocks | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	63,823,000	68,909,000
U.S. large- and mid-cap stocks | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. large- and mid-cap stocks | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. small-cap mutual funds | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,713,000	5,377,000
U.S. small-cap mutual funds | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,713,000	5,377,000
U.S. small-cap mutual funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. small-cap mutual funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International large-cap mutual funds | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11,091,000	18,341,000
International large-cap mutual funds | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11,091,000	18,341,000
International large-cap mutual funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International large-cap mutual funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Emerging markets mutual funds | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,439,000	7,363,000
Emerging markets mutual funds | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6,439,000	7,363,000
Emerging markets mutual funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Emerging markets mutual funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. Treasury and government sponsored agency bonds and notes | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	547,000	548,000
U.S. Treasury and government sponsored agency bonds and notes | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. Treasury and government sponsored agency bonds and notes | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	547,000	548,000
U.S. Treasury and government sponsored agency bonds and notes | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mutual funds | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	32,969,000	40,046,000
Mutual funds | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	32,969,000	40,046,000
Mutual funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mutual funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	0
Other | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		79,000
Other | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		79,000
Other | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Other | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 0

Retirement Plans (Changes in Ac

Retirement Plans (Changes in Accumulated Other Comprehensive Income (Loss) Related to Retirement Plans) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Pension Plan
Accumulated Other Comprehensive Income (Loss), Net of Tax
Accumulated other comprehensive income (loss) at beginning of year	$ (20,483)
Net actuarial income (loss)	(9,032)
Comprehensive income (loss) adjustment	(9,032)
Accumulated other comprehensive income (loss) at end of year	(29,515)
Postretirement Plan
Accumulated Other Comprehensive Income (Loss), Net of Tax
Accumulated other comprehensive income (loss) at beginning of year	744
Net actuarial income (loss)	51
Comprehensive income (loss) adjustment	51
Accumulated other comprehensive income (loss) at end of year	795
SERP
Accumulated Other Comprehensive Income (Loss), Net of Tax
Accumulated other comprehensive income (loss) at beginning of year	(69)
Net actuarial income (loss)	23
Comprehensive income (loss) adjustment	23
Accumulated other comprehensive income (loss) at end of year	(46)
Defined Benefit Pension Plans
Accumulated Other Comprehensive Income (Loss), Net of Tax
Accumulated other comprehensive income (loss) at beginning of year	(19,808)
Net actuarial income (loss)	(8,958)
Comprehensive income (loss) adjustment	(8,958)
Accumulated other comprehensive income (loss) at end of year	$ (28,766)

Retirement Plans (Income (Loss)

Retirement Plans (Income (Loss) Estimated to be Amortized from Accumulated Other Comprehensive Income (Loss) into Net Periodic Cost) (Details) $ in Thousands	Dec. 31, 2018USD ($)
Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Twelve Months
Net gain (loss)	$ (302)
Pension Plan
Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Twelve Months
Net gain (loss)	(444)
Postretirement Plan
Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Twelve Months
Net gain (loss)	143
SERP
Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Twelve Months
Net gain (loss)	$ (1)

Equity (Details)

Equity (Details) - shares	Dec. 31, 2018	Dec. 31, 2017	Apr. 26, 2017	Apr. 25, 2017	Jul. 19, 2016	Jul. 18, 2016	Apr. 20, 2015	Apr. 20, 2009
Equity [Abstract]
Preferred stock, shares authorized	2,000,000	2,000,000					2,000,000	200,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0
Common sock, shares authorized	135,000,000	135,000,000	135,000,000	100,000,000	100,000,000	60,000,000

Regulatory Capital and Reserv_3

Regulatory Capital and Reserve Requirements (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 22, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Minimum average regulatory cash reserve balance		$ 57,000				$ 71,700								$ 57,000	$ 71,700
Leverage Ratio:
Cash dividends declared per share (in dollars per share)		$ 0.34	$ 0.34	$ 0.28	$ 0.28	$ 0.28	$ 0.28	$ 0.27	$ 0.27	$ 0.27	$ 0.27	$ 0.26	$ 0.26	$ 1.24	$ 1.10	$ 1.06
Subsequent Event
Leverage Ratio:
Cash dividends declared per share (in dollars per share)	$ 0.34
Chemical Financial Corporation
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Risk weighted assets		$ 16,100,000				$ 14,740,000								$ 16,100,000	$ 14,740,000
Total Capital to Risk-Weighted Assets:
Actual, Capital Amount		$ 1,855,922				$ 1,614,046								$ 1,855,922	$ 1,614,046
Actual, Ratio		11.50%				11.00%								11.50%	11.00%
Minimum Required for Capital Adequacy Purposes, Capital Amount		$ 1,288,363				$ 1,179,076								$ 1,288,363	$ 1,179,076
Minimum Required for Capital Adequacy Purposes, Ratio		8.00%				8.00%								8.00%	8.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 1,590,323				$ 1,363,307								$ 1,590,323	$ 1,363,307
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		9.90%				9.30%								9.90%	9.30%
Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount		$ 1,723,004				$ 1,498,463								$ 1,723,004	$ 1,498,463
Actual, Ratio		10.70%				10.20%								10.70%	10.20%
Minimum Required for Capital Adequacy Purposes, Capital Amount		$ 966,272				$ 884,307								$ 966,272	$ 884,307
Minimum Required for Capital Adequacy Purposes, Ratio		6.00%				6.00%								6.00%	6.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 1,268,232				$ 1,068,538								$ 1,268,232	$ 1,068,538
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		7.90%				7.30%								7.90%	7.30%
Common Equity Tier 1 Capital to Risk-Weighted Assets
Actual, Capital Amount		$ 1,723,004				$ 1,498,463								$ 1,723,004	$ 1,498,463
Minimum Required for Capital Adequacy Purposes, Capital Amount		10.70%				10.20%								10.70%	10.20%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount		$ 724,704				$ 663,230								$ 724,704	$ 663,230
Actual, Ratio		4.50%				4.50%								4.50%	4.50%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 1,026,664				$ 847,461								$ 1,026,664	$ 847,461
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		6.40%				5.80%								6.40%	5.80%
Leverage Ratio:
Actual, Capital Amount		$ 1,723,004				$ 1,498,463								$ 1,723,004	$ 1,498,463
Actual, Ratio		8.70%				8.30%								8.70%	8.30%
Minimum Required for Capital Adequacy Purposes, Capital Amount		$ 793,669				$ 720,890								$ 793,669	$ 720,890
Minimum Required for Capital Adequacy Purposes, Ratio		4.00%				4.00%								4.00%	4.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 793,669				$ 720,890								$ 793,669	$ 720,890
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		4.00%				4.00%								4.00%	4.00%
Cash dividends from subsidiaries														$ 114,300	$ 165,000	$ 110,450
Chemical Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Risk weighted assets		$ 16,070,000				$ 14,700,000								16,070,000	14,700,000
Total Capital to Risk-Weighted Assets:
Actual, Capital Amount		$ 1,825,742				$ 1,613,087								$ 1,825,742	$ 1,613,087
Actual, Ratio		11.40%				11.00%								11.40%	11.00%
Minimum Required for Capital Adequacy Purposes, Capital Amount		$ 1,285,444				$ 1,176,361								$ 1,285,444	$ 1,176,361
Minimum Required for Capital Adequacy Purposes, Ratio		8.00%				8.00%								8.00%	8.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 1,586,719				$ 1,360,167								$ 1,586,719	$ 1,360,167
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		9.90%				9.30%								9.90%	9.30%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount		$ 1,606,804				$ 1,470,451								$ 1,606,804	$ 1,470,451
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio		10.00%				10.00%								10.00%	10.00%
Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount		$ 1,708,724				$ 1,513,219								$ 1,708,724	$ 1,513,219
Actual, Ratio		10.60%				10.30%								10.60%	10.30%
Minimum Required for Capital Adequacy Purposes, Capital Amount		$ 964,083				$ 882,271								$ 964,083	$ 882,271
Minimum Required for Capital Adequacy Purposes, Ratio		6.00%				6.00%								6.00%	6.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 1,265,358				$ 1,066,077								$ 1,265,358	$ 1,066,077
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		7.90%				7.30%								7.90%	7.30%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount		$ 1,285,444				$ 1,176,361								$ 1,285,444	$ 1,176,361
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio		8.00%				8.00%								8.00%	8.00%
Common Equity Tier 1 Capital to Risk-Weighted Assets
Actual, Capital Amount		$ 1,708,724				$ 1,513,219								$ 1,708,724	$ 1,513,219
Minimum Required for Capital Adequacy Purposes, Capital Amount		10.60%				10.30%								10.60%	10.30%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount		$ 723,062				$ 661,703								$ 723,062	$ 661,703
Actual, Ratio		4.50%				4.50%								4.50%	4.50%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 1,024,338				$ 845,509								$ 1,024,338	$ 845,509
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		6.40%				5.80%								6.40%	5.80%
Minimum Required for Capital Adequacy Purposes, Ratio		$ 1,044,423				$ 955,793								$ 1,044,423	$ 955,793
Required to be Well Capital Under Prompt Corrective Action Regulations, Ratio		6.50%				6.50%								6.50%	6.50%
Leverage Ratio:
Actual, Capital Amount		$ 1,708,724				$ 1,513,219								$ 1,708,724	$ 1,513,219
Actual, Ratio		8.60%				8.40%								8.60%	8.40%
Minimum Required for Capital Adequacy Purposes, Capital Amount		$ 792,184				$ 720,043								$ 792,184	$ 720,043
Minimum Required for Capital Adequacy Purposes, Ratio		4.00%				4.00%								4.00%	4.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 792,184				$ 720,043								$ 792,184	$ 720,043
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		4.00%				4.00%								4.00%	4.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount		$ 990,230				$ 900,053								$ 990,230	$ 900,053
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio		5.00%				5.00%								5.00%	5.00%

Parent Company Only Financial_3

Parent Company Only Financial Statements (Financial Position) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Premises and equipment	$ 123,442	$ 126,896
Goodwill	1,134,568	1,134,568
Other assets	754,167	709,154
Total assets	21,498,341	19,280,873
Liabilities and Equity [Abstract]
Other liabilities	225,110	181,203
Total liabilities	18,662,081	16,612,124
Shareholders' equity	2,836,260	2,668,749	$ 2,581,526	$ 1,015,974
Total liabilities and shareholders' equity	21,498,341	19,280,873
Chemical Financial Corporation
Assets
Cash at subsidiary bank	11,477	5,761
Investment in subsidiaries	2,820,866	2,673,858
Premises and equipment	3,595	3,931
Goodwill	1,092	1,092
Deferred tax asset	5,865	7,203
Other assets	27,157	31,459
Total assets	2,870,052	2,723,304
Liabilities and Equity [Abstract]
Other liabilities	17,892	18,877
Non-revolving line-of-credit	0	19,963
Subordinated debentures	15,900	15,715
Total liabilities	33,792	54,555
Shareholders' equity	2,836,260	2,668,749
Total liabilities and shareholders' equity	$ 2,870,052	$ 2,723,304

Parent Company Only Financial_4

Parent Company Only Financial Statements (Statements of Income) (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Other (loss) income													$ 28,589	$ 25,918	$ 11,988
Interest expense	$ 46,651	$ 38,896	$ 32,045	$ 26,071	$ 23,257	$ 21,316	$ 17,185	$ 12,799	$ 11,969	$ 6,753	$ 5,442	$ 5,134	143,663	74,557	29,298
Operating expenses	108,366	109,661	104,561	101,610	100,022	119,539	98,237	104,196	114,302	106,144	59,085	58,887	424,198	421,994	338,418
Income tax benefit	(5,200)	(11,312)	(12,434)	(12,955)	(61,234)	(10,253)	(23,036)	(12,257)	(18,969)	(2,848)	(10,532)	(9,757)	(41,901)	(106,780)	(42,106)
Net income	$ 73,039	$ 70,397	$ 68,988	$ 71,596	$ 9,446	$ 40,459	$ 52,014	$ 47,604	$ 47,168	$ 11,484	$ 25,775	$ 23,605	284,020	149,523	108,032
Chemical Financial Corporation
Condensed Financial Statements, Captions [Line Items]
Cash dividends from subsidiaries													114,300	165,000	110,450
Other (loss) income													(269)	921	151
Total income													114,031	165,921	110,601
Interest expense													1,601	3,076	1,816
Operating expenses													13,784	23,298	30,589
Total expenses													15,385	26,374	32,405
Income before income taxes and equity in undistributed net income of subsidiaries													98,646	139,547	78,196
Income tax benefit													4,472	12,670	11,378
Equity in undistributed net income (loss) of subsidiaries													180,902	(2,694)	18,458
Net income													$ 284,020	$ 149,523	$ 108,032

Parent Company Only Financial_5

Parent Company Only Financial Statements (Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows From Operating Activities
Net income	$ 73,039	$ 70,397	$ 68,988	$ 71,596	$ 9,446	$ 40,459	$ 52,014	$ 47,604	$ 47,168	$ 11,484	$ 25,775	$ 23,605	$ 284,020	$ 149,523	$ 108,032
Share-based compensation expense													8,578	17,346	13,452
Depreciation of premises and equipment													17,026	17,722	13,270
Net cash provided by operating activities													324,401	274,866	280,501
Cash Flows From Investing Activities
Purchases of premises and equipment, net													(13,572)	(12,852)	(18,098)
Net cash used in investing activities													(2,199,328)	(1,982,936)	(542,869)
Cash Flows From Financing Activities
Cash dividends paid													(88,954)	(78,498)	(49,389)
Repayments of other borrowings													(147,000)	(224,850)	(351,018)
Proceeds from issuance of other borrowings													200,000	0	375,000
Proceeds from directors' stock purchase plan and exercise of stock options													3,115	3,991	1,572
Cash paid for payroll taxes upon conversion of restricted stock units													(5,316)	(27,854)	(1,065)
Net cash provided by financing activities													1,914,775	1,689,659	497,981
Net increase (decrease) in cash and cash equivalents													39,848	(18,411)	235,613
Cash and cash equivalents at beginning of year				455,991				474,402				238,789	455,991	474,402	238,789
Cash and cash equivalents at end of year	495,839				455,991				474,402				495,839	455,991	474,402
Business combinations:
Fair value of tangible assets acquired (noncash)													0	420	6,371,781
Liabilities assumed													0	1,454	6,100,901
Common stock and stock options issued													0	0	1,504,811
Chemical Financial Corporation
Cash Flows From Operating Activities
Net income													284,020	149,523	108,032
Share-based compensation expense													8,578	17,346	13,452
Depreciation of premises and equipment													435	408	355
Equity in undistributed net (income) loss of subsidiaries													(180,902)	2,694	(18,458)
Net decrease in other assets													4,302	1,410	9,752
Net increase (decrease) in other liabilities													537	25,178	(11,830)
Net cash provided by operating activities													116,970	196,559	101,303
Cash Flows From Investing Activities
Cash acquired, net of cash paid, in business combinations													0	0	(107,622)
Purchases of premises and equipment, net													(99)	(288)	(774)
Net cash used in investing activities													(99)	(288)	(108,396)
Cash Flows From Financing Activities
Cash dividends paid													(88,954)	(78,498)	(49,389)
Proceeds from issuance of common stock, net of issuance costs													0	0	0
Repayment of subordinated debt obligations													0	0	(18,558)
Repayments of other borrowings													(20,000)	(105,000)	(62,500)
Proceeds from issuance of other borrowings													0	0	125,000
Proceeds from directors' stock purchase plan and exercise of stock options													3,115	3,991	1,572
Cash paid for payroll taxes upon conversion of restricted stock units													(5,316)	(27,854)	(1,065)
Net cash provided by financing activities													(111,155)	(207,361)	(4,940)
Net increase (decrease) in cash and cash equivalents													5,716	(11,090)	(12,033)
Cash and cash equivalents at beginning of year				$ 5,761				$ 16,851				$ 28,884	5,761	16,851	28,884
Cash and cash equivalents at end of year	$ 11,477				$ 5,761				$ 16,851				11,477	5,761	16,851
Business combinations:
Fair value of tangible assets acquired (noncash)													0	0	46,898
Liabilities assumed													0	0	58,309
Common stock and stock options issued													$ 0	$ 0	$ 1,504,811

Earnings Per Common Share (Deta

Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income	$ 73,039	$ 70,397	$ 68,988	$ 71,596	$ 9,446	$ 40,459	$ 52,014	$ 47,604	$ 47,168	$ 11,484	$ 25,775	$ 23,605	$ 284,020	$ 149,523	$ 108,032
Net income allocated to participating securities													186	495	166
Net income allocated to common shareholders													$ 283,834	$ 149,028	$ 107,866
Weighted average common shares - issued (in shares)													71,385,000	71,103,000	49,091,000
Average unvested restricted share awards (in shares)													(47,000)	(238,000)	(139,000)
Weighted average common shares outstanding - basic (in shares)													71,338,000	70,865,000	48,952,000
Effect of dilutive securities
Weighted average common stock equivalents (in shares)													687,000	648,000	651,000
Weighted average common shares outstanding - diluted (in shares)													72,025,000	71,513,000	49,603,000
EPS available to common shareholders
Basic earnings per common share (usd per share)	$ 1.02	$ 0.99	$ 0.97	$ 1.01	$ 0.13	$ 0.57	$ 0.73	$ 0.67	$ 0.67	$ 0.23	$ 0.67	$ 0.61	$ 3.98	$ 2.11	$ 2.21
Diluted earnings per common share (usd per share)	$ 1.01	$ 0.98	$ 0.96	$ 0.99	$ 0.13	$ 0.56	$ 0.73	$ 0.67	$ 0.66	$ 0.23	$ 0.67	$ 0.60	3.94	2.08	2.17
Schedule Of Earnings Per Share By Common Class [Line Items]
Average stock valuation (usd per share)													$ 53.70	$ 50.26	$ 40.58
Stock Option
Schedule Of Earnings Per Share By Common Class [Line Items]
Average number of exercisable employee stock option awards that were not included in the computation of diluted earnings per common share (in shares)													61,298	107,272	0

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss (Changes in Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of accumulated other comprehensive income (loss), net of related tax benefit/expense
Beginning balance		$ 2,668,749	$ 2,581,526	$ 1,015,974
Cumulative effect adjustment of change in accounting policy, net of tax impact	[1]		1,339	3,659
Other comprehensive income (loss) before reclassifications		(24,658)	12,054	(12,399)
Amounts reclassified from accumulated other comprehensive income (loss)		(10,613)	7,002	1,395
Net current period other comprehensive income (loss)		(35,271)	19,056	(11,004)
Reclassification of certain income tax effects	[2]		0
Ending balance		2,836,260	2,668,749	2,581,526
Total
Components of accumulated other comprehensive income (loss), net of related tax benefit/expense
Beginning balance		(25,498)	(40,036)	(29,032)
Adjusted beginning balance			(25,839)
Cumulative effect adjustment of change in accounting policy, net of tax impact	[1]		(341)
Reclassification of certain income tax effects	[2]		(4,518)
Ending balance		(61,110)	(25,498)	(40,036)
Unrealized gains (losses) on securities carried at fair value, net of tax
Components of accumulated other comprehensive income (loss), net of related tax benefit/expense
Beginning balance		(10,348)	(14,142)	(1,888)
Adjusted beginning balance			(10,692)
Cumulative effect adjustment of change in accounting policy, net of tax impact			(344)
Other comprehensive income (loss) before reclassifications		(26,903)	826	(12,170)
Amounts reclassified from accumulated other comprehensive income (loss)		(177)	4,802	(84)
Net current period other comprehensive income (loss)		(27,080)	5,628	(12,254)
Reclassification of certain income tax effects			(1,834)
Ending balance		(37,772)	(10,348)	(14,142)
Defined Benefit Pension Plans
Components of accumulated other comprehensive income (loss), net of related tax benefit/expense
Beginning balance		(19,808)	(25,894)	(27,144)
Adjusted beginning balance			(19,808)
Cumulative effect adjustment of change in accounting policy, net of tax impact			0
Other comprehensive income (loss) before reclassifications		0	8,457	(229)
Amounts reclassified from accumulated other comprehensive income (loss)		(8,958)	1,139	1,479
Net current period other comprehensive income (loss)		(8,958)	9,596	1,250
Reclassification of certain income tax effects			(3,510)
Ending balance		(28,766)	(19,808)	(25,894)
Unrealized gains (losses) on cash flow hedges, net of tax
Components of accumulated other comprehensive income (loss), net of related tax benefit/expense
Beginning balance		4,658	0	0
Adjusted beginning balance			4,661
Cumulative effect adjustment of change in accounting policy, net of tax impact			3
Other comprehensive income (loss) before reclassifications		2,245	2,771	0
Amounts reclassified from accumulated other comprehensive income (loss)		(1,478)	1,061	0
Net current period other comprehensive income (loss)		767	3,832	0
Reclassification of certain income tax effects			826
Ending balance		$ 5,428	$ 4,658	$ 0
[1]	Refer to Note 1, Summary of Significant Accounting Policies, Note 4, Investment Securities, Note 7, Other Real Estate Owned and Repossessed Assets and Note 9, Loan Servicing Rights, for further details on the changes in accounting policy.
[2]	The reclassification from accumulated other comprehensive income (loss) to retained earnings was due to the early adoption of ASU 2018-02, refer to Note 1 for further details on the adoption.

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Loss (Reclassifications Out of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax (expense)/benefit	$ (5,200)	$ (11,312)	$ (12,434)	$ (12,955)	$ (61,234)	$ (10,253)	$ (23,036)	$ (12,257)	$ (18,969)	$ (2,848)	$ (10,532)	$ (9,757)	$ (41,901)	$ (106,780)	$ (42,106)
Net (income) loss													10,613	(7,002)	(1,395)
Interest on short-term borrowings													37,510	19,052	1,357
Net income	$ 73,039	$ 70,397	$ 68,988	$ 71,596	$ 9,446	$ 40,459	$ 52,014	$ 47,604	$ 47,168	$ 11,484	$ 25,775	$ 23,605	284,020	149,523	108,032
Unrealized gains (losses) on securities carried at fair value, net of tax
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net (income) loss													177	(4,802)	84
Unrealized gains (losses) on securities carried at fair value, net of tax | Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gains and losses on available-for-sale securities													224	(7,388)	129
Income tax (expense)/benefit													(47)	2,586	(45)
Net income													177	(4,802)	84
Amortization of defined benefit pension plan items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Salaries, wages and employee benefits (operating expenses)													11,339	(1,752)	(2,276)
Income tax expense/(benefit)													(2,381)	613	797
Net (income) loss													8,958	(1,139)	(1,479)
Unrealized gains (losses) on cash flow hedges, net of tax
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net (income) loss													1,478	(1,061)	0
Unrealized gains (losses) on cash flow hedges, net of tax | Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense/(benefit)													393	(572)	0
Interest on short-term borrowings													(1,871)	1,633	0
Net income													$ (1,478)	$ 1,061	$ 0

Subsequent Events (Details)

Subsequent Events (Details) $ / shares in Units, $ in Thousands	Jan. 28, 2019$ / shares	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Subsequent Event [Line Items]
Assets		$ 21,498,341	$ 19,280,873
Subsequent Event
Subsequent Event [Line Items]
Share price (in dollars per share) | $ / shares	$ 21.58
Ownership percentage	46.00%
TCF | Subsequent Event
Subsequent Event [Line Items]
Conversion ratio	0.5081
Ownership percentage	54.00%
TCF
Subsequent Event [Line Items]
Assets		$ 23,700,000
TCF | Subsequent Event
Subsequent Event [Line Items]
Preferred stock, dividend rate	5.70%

Summary of Quarterly Statemen_3

Summary of Quarterly Statements of Income (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Selected Quarterly Financial Information [Abstract]
Interest income	$ 210,103	$ 198,377	$ 189,582	$ 177,934	$ 169,162	$ 164,944	$ 155,133	$ 142,896	$ 144,416	$ 103,562	$ 82,937	$ 79,464	$ 775,996	$ 632,135	$ 410,379
Interest expense	46,651	38,896	32,045	26,071	23,257	21,316	17,185	12,799	11,969	6,753	5,442	5,134	143,663	74,557	29,298
Net interest income	163,452	159,481	157,537	151,863	145,905	143,628	137,948	130,097	132,447	96,809	77,495	74,330	632,333	557,578	381,081
Provision for loan losses	8,894	6,028	9,572	6,256	7,522	5,499	6,229	4,050	6,272	4,103	3,000	1,500	30,750	23,300	14,875
Noninterest income	32,047	37,917	38,018	40,554	32,319	32,122	41,568	38,010	54,264	27,770	20,897	19,419	148,536	144,019	122,350
Operating expenses	108,366	109,661	104,561	101,610	100,022	119,539	98,237	104,196	114,302	106,144	59,085	58,887	424,198	421,994	338,418
Income before income taxes	78,239	81,709	81,422	84,551	70,680	50,712	75,050	59,861	66,137	14,332	36,307	33,362	325,921	256,303	150,138
Income tax expense	5,200	11,312	12,434	12,955	61,234	10,253	23,036	12,257	18,969	2,848	10,532	9,757	41,901	106,780	42,106
Net income	$ 73,039	$ 70,397	$ 68,988	$ 71,596	$ 9,446	$ 40,459	$ 52,014	$ 47,604	$ 47,168	$ 11,484	$ 25,775	$ 23,605	$ 284,020	$ 149,523	$ 108,032
Basic earnings per common share (usd per share)	$ 1.02	$ 0.99	$ 0.97	$ 1.01	$ 0.13	$ 0.57	$ 0.73	$ 0.67	$ 0.67	$ 0.23	$ 0.67	$ 0.61	$ 3.98	$ 2.11	$ 2.21
Diluted earnings per common share (usd per share)	1.01	0.98	0.96	0.99	0.13	0.56	0.73	0.67	0.66	0.23	0.67	0.60	3.94	2.08	2.17
Cash dividends declared per share (in dollars per share)	$ 0.34	$ 0.34	$ 0.28	$ 0.28	$ 0.28	$ 0.28	$ 0.27	$ 0.27	$ 0.27	$ 0.27	$ 0.26	$ 0.26	$ 1.24	$ 1.10	$ 1.06