TCF Financial 10-Q 27 Apr 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2016	Apr. 15, 2016
Entity Information [Line Items]
Entity Registrant Name	CHEMICAL FINANCIAL CORP
Entity Central Index Key	19,612
Document Type	10-Q
Document Period End Date	Mar. 31, 2016
Amendment Flag	false
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		38,248,768

Consolidated Statements of Fina

Consolidated Statements of Financial Position - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Cash and cash equivalents:
Cash and cash due from banks	$ 168,739	$ 194,136	$ 121,796
Interest-bearing deposits with the Federal Reserve Bank and other banks	122,635	44,653	272,142
Total cash and cash equivalents	291,374	238,789	393,938
Investment securities:
Available-for-sale, at fair value	514,015	553,731	680,644
Held-to-maturity (fair value - $525,593 at March 31, 2016, $512,705 at December 31, 2015 and $380,176 at March 31, 2015)	518,300	509,971	381,450
Total investment securities	1,032,315	1,063,702	1,062,094
Loans held-for-sale, at fair value	9,667	10,327	9,675
Loans	7,366,885	7,271,147	5,702,874
Allowance for loan losses	(70,318)	(73,328)	(75,256)
Net loans	7,296,567	7,197,819	5,627,618
Premises and equipment (net of accumulated depreciation of $121,762 at March 31, 2016, $120,382 at December 31, 2015 and $111,270 at March 31, 2015)	105,868	106,317	96,486
Goodwill	286,867	287,393	180,128
Other intangible assets	36,266	38,104	31,655
Interest receivable and other assets	244,708	246,346	150,041
Total Assets	9,303,632	9,188,797	7,551,635
Deposits:
Noninterest-bearing	1,951,193	1,934,583	1,614,319
Interest-bearing	5,698,923	5,522,184	4,706,034
Total deposits	7,650,116	7,456,767	6,320,353
Interest payable and other liabilities	64,120	76,466	48,545
Securities Sold under Agreements to Repurchase	283,383	297,199	372,236
Short-term Borrowings	0	100,000	0
Other Borrowings	273,722	242,391	0
Total liabilities	8,271,341	8,172,823	6,741,134
Shareholders’ equity:
Preferred stock, no par value: Authorized - 2,000,000 shares at both March 31, 2016 and December 31, 2015 and 200,000 shares at March 31, 2015, none issued	0	0	0
Common stock, $1 par value per share, Authorized - 60,000,000 shares at both March 31, 2016 and December 31, 2015 and 45,000,000 shares at March 31, 2015, Issued and outstanding — 38,248,489 shares at March 31, 2016, 38,167,861 shares at December 31, 2015 and 32,487,063 shares at March 31, 2015	38,248	38,168	32,847
Additional paid-in capital	725,874	725,280	565,851
Retained earnings	294,859	281,558	241,582
Accumulated other comprehensive loss	(26,690)	(29,032)	(29,779)
Total shareholders’ equity	1,032,291	1,015,974	810,501
Total Liabilities and Shareholders’ Equity	$ 9,303,632	$ 9,188,797	$ 7,551,635

Consolidated Statements of Fin3

Consolidated Statements of Financial Position (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Held-to-maturity, fair value	$ 525,593	$ 512,705	$ 380,176
Accumulated depreciation of premises and equipment	$ 121,762	$ 120,382	$ 111,270
Preferred stock, no par value
Preferred stock, shares authorized	2,000,000	2,000,000	200,000
Preferred stock, shares issued	0	0	0
Common stock, par value	$ 1	$ 1	$ 1
Common stock, shares authorized	60,000,000	60,000,000	45,000,000
Common stock, shares issued	38,248,489	38,167,861	32,847,063
Common stock, shares outstanding	38,248,489	38,167,861	32,847,063

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Interest Income
Interest and fees on loans	$ 74,401	$ 58,097
Interest on investment securities:
Taxable	1,929	2,307
Tax-exempt	2,665	1,906
Dividends on nonmarketable equity securities	256	198
Interest on deposits with the Federal Reserve Bank and other banks	213	122
Total interest income	79,464	62,630
Interest Expense
Interest on deposits	4,059	3,352
Interest on short-term borrowings	100	98
Interest Expense, Other	975	0
Total interest expense	5,134	3,450
Net Interest Income	74,330	59,180
Provision for loan losses	1,500	1,500
Net interest income after provision for loan losses	72,830	57,680
Noninterest Income
Service charges and fees on deposit accounts	5,720	5,916
Wealth management revenue	5,201	5,071
Other charges and fees for customer services	6,392	5,990
Mortgage banking revenue	1,405	1,403
Gain on sale of investment securities	19	579
Other	682	316
Total noninterest income	19,419	19,275
Operating Expenses
Salaries, wages and employee benefits	33,890	29,253
Occupancy	4,905	4,426
Equipment and software	4,404	4,398
Acquisition-related expenses	2,594	1,362
Other	13,094	11,581
Total operating expenses	58,887	51,020
Income before income taxes	33,362	25,935
Federal income tax expense	10,100	8,100
Net Income	$ 23,262	$ 17,835
Net Income Per Common Share:
Basic (in dollars per share)	$ 0.61	$ 0.54
Diluted (in dollars per share)	0.60	0.54
Cash Dividends Declared Per Common Share (dollars per share)	$ 0.26	$ 0.24

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Net income	$ 23,262	$ 17,835
Other comprehensive income (loss), net of tax:
Net unrealized gains on investment securities available-for-sale, net of tax expense of $1,470 and $1,262 for the three months ended March 31, 2016 and 2015, respectively	2,729	2,344
Reclassification adjustment for realized gain on sale of investment securities available-for-sale included in net income, net of tax expense of $7 and $203 for the three months ended March 31, 2016 and 2015, respectively.	(12)	(376)
Adjustment for pension and other postretirement benefits, net of tax expense (benefit) of $(202) and $381 for the three months ended March 31, 2016 and 2015, respectively	(375)	706
Total other comprehensive income (loss), net of tax	2,342	2,674
Comprehensive income	$ 25,604	$ 20,509

Consolidated Statements of Com6

Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Tax expense (benefit) on net unrealized gains (losses) on investment securities available-for-sale	$ 1,470	$ 1,262
Tax expense (benefit) on reclassification adjustment for realized gains on sale of investment securities available-for-sale	(7)	(203)
Tax expense (benefit) on adjustment for pension and other postretirement benefits	$ (202)	$ 381

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance at Dec. 31, 2014	$ 797,133	$ 32,774	$ 565,166	$ 231,646	$ (32,453)
Changes in Stockholders' Equity [Roll Forward]
Comprehensive income	20,509			17,835	2,674
Cash dividends declared and paid, $0.26 and $0.24 per share at March 31, 2016 and March 31, 2015, respectively.	7,899			7,899
Stock issued - stock options	131	13	118
Shares issued – directors’ stock plans	316	11	305
Shares issued – restricted stock units	(444)	48	(492)
Share-based compensation	755	1	754
Ending Balance at Mar. 31, 2015	810,501	32,847	565,851	241,582	(29,779)
Beginning Balance at Dec. 31, 2015	1,015,974	38,168	725,280	281,558	(29,032)
Changes in Stockholders' Equity [Roll Forward]
Comprehensive income	25,604			23,262	2,342
Cash dividends declared and paid, $0.26 and $0.24 per share at March 31, 2016 and March 31, 2015, respectively.	9,961			9,961
Stock issued - stock options	382	36	346
Shares issued – restricted stock units	(457)	43	(500)
Share-based compensation	749	1	748
Ending Balance at Mar. 31, 2016	$ 1,032,291	$ 38,248	$ 725,874	$ 294,859	$ (26,690)

Consolidated Statements of Cha8

Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash dividends declared per share	$ 0.26	$ 0.24

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating Activities
Net income	$ 23,262	$ 17,835
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	1,500	1,500
Gains on sales of loans	(1,296)	(1,589)
Proceeds from sales of loans	45,928	54,280
Loans originated for sale	(43,972)	(53,238)
Net gains from sales/writedowns of other real estate and repossessed assets	(547)	(570)
Depreciation of premises and equipment	2,775	2,479
Amortization of intangible assets	2,169	1,825
Net gains on sale of investment securities	(19)	(579)
Net amortization of premiums and discounts on investment securities	1,493	1,373
Share-based compensation expense	749	755
Net increase in interest receivable and other assets	(921)	(9,562)
Net decrease in interest payable and other liabilities	(11,875)	(7,038)
Net cash provided by operating activities	19,246	7,471
Investment securities – available-for-sale:
Proceeds from sales	0	13,172
Proceeds from maturities, calls and principal reductions	42,925	57,449
Investment securities – held-to-maturity:
Proceeds from maturities, calls and principal reductions	8,133	7,542
Purchases	(16,965)	(72,748)
Net increase in loans	(101,915)	(20,233)
Proceeds from sales of other real estate and repossessed assets	2,901	3,693
Purchases of premises and equipment, net of disposals	(2,406)	(1,469)
Net cash used in investing activities	(67,327)	(12,594)
Financing Activities
Net increase in interest- and noninterest-bearing demand deposits and savings accounts	234,102	247,244
Net decrease in time deposits	(40,753)	(5,862)
Net decrease in securities sold under agreements to repurchase with customers and other short-term borrowings	(113,816)	(17,231)
Proceeds from long-term borrowings	50,000	0
Repayment of long-term borrowings	(18,558)	0
Cash dividends paid	(9,961)	(7,899)
Proceeds from directors’ stock plans and exercise of stock options, net of shares withheld	382	447
Cash paid for payroll taxes upon conversion of share-based awards	(730)	(658)
Net cash provided by financing activities	100,666	216,041
Net increase in cash and cash equivalents	52,585	210,918
Cash and cash equivalents at beginning of period	238,789	183,020
Cash and cash equivalents at end of period	291,374	393,938
Supplemental Disclosure of Cash Flow Information:
Interest paid	5,080	3,426
Loans transferred to other real estate and repossessed assets	1,667	3,662
Income Taxes Paid	$ 0	$ 9,800

Significant Accounting Policies

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2016
Accounting Policies [Abstract]
Significant Accounting Policies	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 Midland, Michigan, that operates through one commercial bank, Chemical Bank. Chemical Bank operates within the State of Michigan as a state-chartered commercial bank. Chemical Bank operates through an internal organizational structure of four regional banking units and offers a full range of traditional banking and fiduciary products and services to the residents and business customers in the bank’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 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 and wealth management revenue. Basis of Presentation The accompanying unaudited consolidated financial statements of the Corporation and its subsidiaries have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") for interim financial information and the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, the interim consolidated financial statements do not include all of the information and footnotes required by GAAP for complete financial statements and should be read in conjunction with the Corporation’s consolidated financial statements and footnotes thereto included in the Corporation’s Annual Report on Form 10-K for the year ended December 31, 2015. In the opinion of management, the accompanying unaudited interim consolidated financial statements contain all adjustments believed necessary to present fairly the financial condition and results of operations of the Corporation for the periods presented. Operating results for the three months ended March 31, 2016 are not necessarily indicative of the results that may be expected for the year ending December 31, 2016 . 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, fair value amounts related to business combinations, pension expense, income taxes, goodwill impairment and those assets that require fair value measurement. Actual results could differ from these estimates. Business Combinations Pursuant to the guidance of 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. ASC 805 affords a measurement period beyond the acquisition date that allows the Corporation the opportunity to finalize the acquisition accounting in the event that new information is identified that existed as of the acquisition date but was not known by the Corporation at that time. The Corporation anticipates that measurement period adjustments may arise from adjustments to the fair values of assets and liabilities recognized at the acquisition date for its May 31, 2015 acquisition of Lake Michigan Financial Corporation ("Lake Michigan"), as additional information is obtained, such as appraisals of collateral securing loans and other borrower information. In the event that a measurement period adjustment is identified, the Corporation will recognize the adjustment as part of its acquisition accounting, which may result in an adjustment to goodwill being recorded in the period the adjustment was identified. See Note 2 for further information regarding the Corporation's mergers and acquisitions, including its pending merger with Talmer Bancorp, Inc. ("Talmer"). Originated Loans Originated loans include all of the Corporation's portfolio loans, 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. 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 more (except for a loan that is secured by residential real estate, which is transferred to nonaccrual status at 120 days past due), 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, 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 May 31, 2015 in the acquisition of 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, through a fair value discount that was, in part, attributable to deterioration in credit quality. 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 fair value discount was recorded as a reduction of the acquired loans’ outstanding principal balances in the consolidated statement of financial position at the acquisition date. The Corporation accounts for acquired loans, which are recorded at fair value at acquisition, in accordance with ASC Topic 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality ("ASC 310-30"). 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 2 pools in the acquisition of Lake Michigan, 2 pools in the acquisition of Monarch, 4 pools in the acquisition of Northwestern and 14 pools in the acquisition of OAK 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. If an individual loan is removed from a pool of loans, the difference between its relative carrying amount and the cash, fair value of the collateral, or other assets received would not affect the effective yield used to recognize the accretable difference on the remaining pool. 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 in each loan pool in subsequent periods will require the Corporation to record a provision for loan losses. Improvements in expected cash flows in each loan pool in subsequent periods will 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 ("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 or interest rate, which generally would not otherwise be considered. The Corporation’s TDRs include performing and nonperforming TDRs, which consist of originated loans that continue to accrue interest at the loan's original interest rate 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. In accordance with ASC Topic 310-30, acquired loans are excluded from TDRs as these loans are accounted for in pools at net realizable value based on the principal and interest the Corporation expects to collect on such loans. At the time of modification (except for loans on nonaccrual status), a TDR is reported as a nonperforming TDR until a six -month payment history of principal and interest payments, in accordance with the terms of the loan modification, is sustained, at which time the Corporation moves the loan to a performing status ("performing TDR"). If the Corporation does not expect to collect all principal and interest on the loan, the modified loan is classified as a nonaccrual TDR. 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. 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. 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 classified as a nonperforming TDR until a six-month payment history is sustained, at which time the loan is classified as a performing TDR. Since no loss is expected to be incurred on these loans, no additional provision for loan losses has been recognized related to these loans, and these loans accrue interest at their contractual interest rate. These loans are individually evaluated for impairment and 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. Loans in the Corporation’s consumer loan portfolio (comprised of residential mortgage, consumer installment and home equity loans) that meet the definition of a performing or nonperforming TDR generally consist of residential mortgage loans that 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. These loans are moved to nonaccrual status if they become 90 days past due as to principal or interest payments, or sooner if conditions warrant. Impaired Loans A loan is defined to be impaired when it is probable that payment of principal and interest will not be paid in accordance with the original contractual terms of the loan agreement. Impaired loans include nonaccrual loans (including nonaccrual TDRs), performing and nonperforming TDRs and acquired loans that were not performing in accordance with original contractual terms. 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 an allocation of the 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), accruing originated loans contractually past due 90 days or more as to interest or principal payments and nonperforming 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. Allowance for Loan Losses The allowance for loan losses ("allowance") is presented as a reserve against loans. The allowance represents management’s assessment of probable loan losses inherent in the Corporation’s loan portfolio. Management’s evaluation of the adequacy of the allowance is based on a continuing review of the loan portfolio, actual loan loss experience, the underlying value of the collateral, risk characteristics of the loan portfolio, the level and composition of nonperforming loans, the financial condition of the borrowers, the balance of the loan portfolio, loan growth, economic conditions, employment levels in the Corporation’s local markets, and special factors affecting specific business sectors. The Corporation maintains formal policies and procedures to monitor and control credit risk. Management evaluates the allowance on a quarterly basis in an effort to ensure the level is appropriate to absorb probable losses inherent in the loan portfolio. The allowance provides for probable losses that have been identified with specific customer relationships and for probable losses believed to be incurred in the remainder of the originated loan portfolio, but that have not been specifically identified. The Corporation utilizes its own loss experience to estimate inherent losses on loans. Internal risk ratings are assigned to each loan in the commercial loan portfolio (commercial, commercial real estate, real estate construction and land development loans) at the time of origination and are subject to subsequent periodic reviews by senior management. The Corporation performs a detailed credit quality review quarterly on all loans greater than $0.25 million that have deteriorated below certain levels of credit risk, and may allocate a specific portion of the allowance to such loans based upon this review. A portion of the allowance is allocated to the remaining loans by applying projected loss ratios, based on numerous factors. Projected loss ratios incorporate factors such as charge-off experience, trends with respect to adversely risk-rated loans in the commercial loan portfolio, trends with respect to past due and nonaccrual loans, changes in economic conditions and trends, changes in the value of underlying collateral and other credit risk factors. This evaluation involves a high degree of uncertainty. In determining the allowance and the related provision for loan losses, the Corporation considers four principal elements: (i) valuation allowances based upon probable losses identified during the review of impaired loans in the commercial loan portfolio, (ii) reserves established for adversely-rated loans in the commercial loan portfolio and nonaccrual residential mortgage, consumer installment and home equity loans based on loan loss experience of other adversely-rated loans, (iii) reserves, by loan classes, on all other loans based principally on a five -year historical loan loss experience, with equal weighting placed on all of the years, loan loss trends giving consideration to estimated loss emergence periods and (iv) a reserve for qualitative factors that take into consideration risks inherent in the originated loan portfolio that differ from historical loan loss experience. 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 process, 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. 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. The fair value option (i) may be applied instrument by instrument, with certain exceptions, allowing the Corporation to record identical financial assets and liabilities at fair value or by another measurement basis permitted under GAAP, (ii) is irrevocable (unless a new election date occurs) and (iii) is applied only to entire instruments and not to portions of instruments. At March 31, 2016 , December 31, 2015 and March 31, 2015 , the Corporation had elected the fair value option on all of its residential mortgage loans held-for-sale. The Corporation has not elected the fair value option for any other financial assets or liabilities. Share-Based Compensation The Corporation grants stock options, stock awards, restricted stock performance units and restricted stock service-based units 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 of the award. The fair values of both stock options and stock awards are recognized as compensation expense on a straight-line basis over the requisite service period. The Corporation accounts for restricted stock performance units 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 restricted stock performance units 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 restricted stock service-based units 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 restricted stock service-based units. The fair value of the restricted stock service-based units is recognized as compensation expense over the requisite service period. Cash flows realized from the tax benefits of exercised stock option awards that result from actual tax deductions that are in excess of the recorded tax benefits related to the compensation expense recognized for those options (excess tax benefits) are classified as financing activities on the consolidated statements of cash flows. 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. Bank-owned life insurance is recorded at the cash surrender value, net of surrender charges, and is included within other assets on the consolidated statements of financial position and changes in the cash surrender values are recorded as other noninterest income on the consolidated statements of income. Income and Other Taxes The Corporation is subject to the income and other tax laws of the United States, the State of Michigan and any 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. 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. If a tax position is more-likely-than-not to be sustained, a tax benefit is recognized for the amount that is greater than 50% likely to be realized. Reserves for contingent income tax liabilities attributable to unrecognized tax benefits associated with 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 contingent income tax liabilities recorded at March 31, 2016 , December 31, 2015 or March 31, 2015 . 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 are reflected in 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 allocated. The Corporation recognized additional income tax expense attributable to the amortization of investments in qualified affordable housing projects of $0.6 million and $0.1 million during the three months ended March 31, 2016 , and 2015, respectively. The Corporation's remaining investment in qualified affordable housing projects accounted for under the proportional amortization method totaled $21.1 million at March 31, 2016 , $21.7 million at December 31, 2015 and $4.8 million at March 31, 2015 . The increase in qualified affordable housing project investments at March 31, 2016 , compared to March 31, 2015 , was attributable to investments acquired as part of the Lake Michigan transaction. Under the equity method, the Corporation's share of the earnings or losses are 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 $1.5 million and $1.7 million at March 31, 2016 and December 31, 2015 , respectively. There were no investments in such projects accounted for under the equity method as of March 31, 2015 . 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 other liabilities on the consolidated statements of financial position. The Corporation's remaining unfunded equity contributions totaled $4.2 million and $8.0 million at March 31, 2016 and December 31, 2015 . 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. There were no impairment losses recognized as of March 31, 2016 , December 31, 2015 or March 31, 2015 . 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 interests 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 Corporation's consolidated financial statements. Shareholders’ Equity Common Stock Repurchase Programs From time to time, the board of directors of the Corporation approves common stock rep

Acquisitions

Acquisitions	3 Months Ended
	Mar. 31, 2016
Business Combinations [Abstract]
Acquisitions	Mergers and Acquisitions Pending Merger with Talmer Bancorp, Inc. On January 25, 2016, the Corporation entered into an Agreement and Plan of Merger with Talmer. Under the terms of the merger agreement, each Talmer shareholder will receive $1.61 in cash and 0.4725 shares of the Corporation's common stock for each share of Talmer common stock, subject to adjustment in limited circumstances. Based on the 30-day volume weighted price per share of the Corporation's common stock as of January 25, 2016, the merger had a transaction value of approximately $1.1 billion . Following the completion of the merger, the Corporation intends to consolidate Talmer's wholly-owned subsidiary bank, Talmer Bank and Trust, with and into Chemical Bank. At December 31, 2015, Talmer had total assets of $6.6 billion , total loans of $4.8 billion and total deposits of $ 5.0 billion , including brokered deposits of $229 million . Talmer Bank and Trust is a full service community bank offering a full suite of commercial banking, retail banking, mortgage banking, wealth management and trust services to small and medium-sized businesses and individuals through 80 full service banking offices located primarily within southeast Michigan and northeast Ohio, as well as in west Michigan, northeast Michigan, Chicago, Illinois, northern Indiana, and Las Vegas, Nevada. Completion of the merger is subject to regulatory approval and the approval of the Corporation's and Talmer's shareholders, in addition to satisfaction of other customary closing conditions. Acquisition of Lake Michigan Financial Corporation On May 31, 2015, the Corporation acquired all the outstanding stock of Lake Michigan for total consideration of $187.4 million , which included stock consideration of $132.9 million and cash consideration of $54.5 million . As a result of the acquisition, the Corporation issued approximately 4.3 million shares of its common stock, based on an exchange ratio of 1.326 shares of its common stock, and paid $16.64 in cash, for each share of Lake Michigan common stock outstanding. Lake Michigan, a bank holding company which owned The Bank of Holland and The Bank of Northern Michigan, provided traditional banking services and products with five banking offices in Holland, Grand Haven, Grand Rapids, Petoskey and Traverse City, Michigan. The Bank of Holland and The Bank of Northern Michigan were consolidated with and into Chemical Bank on November 13, 2015. At the acquisition date, Lake Michigan added total assets of $1.24 billion , including total loans of $986 million , and total deposits of $925 million to the Corporation's consolidated statement of financial position. The Corporation recorded $ 101 million of goodwill, which was primarily attributable to the synergies and economies of scale expected from combining the operations of the Corporation and Lake Michigan. In addition, the Corporation recorded $8.6 million of core deposit and other intangible assets in conjunction with the acquisition. During the first quarter 2016, the Corporation obtained additional information regarding the valuation of deferred tax assets, which resulted in a decrease to goodwill recognized in the transaction of $0.5 million . In accordance with ASU 2015-16, no amounts were recorded in the consolidated statements of income during 2016 for these adjustments that would have been recorded in a previous reporting period had these adjustments been recognized as of the acquisition date. Upon acquisition, the Lake Michigan loan portfolio had contractually required principal and interest payments receivable of $1.01 billion and $190.2 million , respectively, expected principal and interest cash flows of $986.1 million and $189.6 million , respectively, and a fair value of $985.5 million . The difference between the contractually required payments receivable and the expected cash flows represents the nonaccretable difference, which totaled $22.6 million at the acquisition date, with $22.0 million attributable to expected credit losses. The difference between the expected cash flows and fair value represents the accretable yield, which totaled $190.2 million at the date of acquisition. The outstanding contractual principal balance and the carrying amount of the Lake Michigan acquired loan portfolio were $804 million and $782 million , respectively, at March 31, 2016, compared to $ 864 million and $842 million , respectively, at December 31, 2015 and there was no related allowance for loan losses at those dates. Acquisition of Monarch Community Bancorp, Inc. On April 1, 2015, the Corporation acquired all of the outstanding stock of Monarch in an all-stock transaction valued at $27.2 million . As a result of the acquisition, the Corporation issued 860,575 shares of its common stock based on an exchange ratio of 0.0982 shares of its common stock for each share of Monarch common stock outstanding. Monarch, a bank holding company, owned Monarch Community Bank, which operated five full service branch offices in Coldwater, Marshall, Hillsdale and Union City, Michigan. Monarch Community Bank was consolidated with and into Chemical Bank on May 8, 2015. As of the April 1, 2015 acquisition date, Monarch added total assets of $183 million , including total loans of $122 million , and total deposits of $144 million to the Corporation's consolidated statement of financial position. In connection with the acquisition of Monarch, the Corporation recorded $5.3 million of goodwill, which was primarily attributable to the synergies and economies of scale expected from combining the operations of the Corporation and Monarch. In addition, the Corporation recorded $1.9 million of core deposit intangible assets in conjunction with the acquisition. Upon acquisition, the Monarch loan portfolio had contractually required principal and interest payments receivable of $128.9 million and $37.8 million , respectively, expected principal and interest cash flows of $122.6 million and $37.1 million , respectively, and a fair value of $121.8 million . The difference between the contractually required payments receivable and the expected cash flows represents the nonaccretable difference, which totaled $7.1 million at the acquisition date, with $6.3 million attributable to expected credit losses. The difference between the expected cash flows and fair value represents the accretable yield, which totaled $37.9 million at the date of acquisition. The outstanding contractual principal balance and the carrying amount of the Monarch acquired loan portfolio were $107 million and $101 million , respectively, at March 31, 2016, compared to $115 million and $108 million , respectively as of December 31, 2015 and there was no related allowance for loan losses at those dates. Acquisition of Northwestern Bancorp, Inc. On October 31, 2014, the Corporation acquired all of the outstanding stock of Northwestern Bancorp, Inc. (Northwestern) for total cash consideration of $121 million . Northwestern, a bank holding company which owned Northwestern Bank, provided traditional banking services and products through 25 banking offices serving communities in the northwestern lower peninsula of Michigan. At the acquisition date, Northwestern added total assets of $815 million , including total loans of $475 million , and total deposits of $794 million to the Corporation. Northwestern Bank was consolidated with and into Chemical Bank as of the acquisition date. In connection with the acquisition of Northwestern, the Corporation recorded $60.3 million of goodwill, which was primarily attributable to the synergies and economies of scale expected from combining the operations of the Corporation and Northwestern. In addition, the Corporation recorded $12.9 million of core deposit intangible assets in conjunction with the acquisition. Upon acquisition, the Northwestern loan portfolio had contractually required principal and interest payments receivable of $507 million and $112 million , respectively, expected principal and interest cash flows of $481 million and $104 million , respectively, and a fair value of $475 million . The difference between the contractually required payments receivable and the expected cash flows represents the nonaccretable difference, which totaled $34 million at the acquisition date, with $26 million attributable to expected credit losses. The difference between the expected cash flows and fair value represents the accretable yield, which totaled $110 million at the acquisition date. The outstanding contractual principal balance and the carrying amount of the Northwestern acquired loan portfolio were $336 million and $305 million , respectively, at March 31, 2016 , compared to $361 million and $330 million , respectively, at December 31, 2015 and $453 million and $421 million , respectively, at March 31, 2015 . Acquisition of 21 Branches On December 7, 2012, Chemical Bank acquired 21 branches from Independent Bank, a subsidiary of Independent Bank Corporation, located in the Northeast and Battle Creek regions of Michigan, including $404 million in deposits and $44 million in loans (branch acquisition transaction). The purchase price of the branch offices, including equipment, was $8.1 million and the Corporation paid a premium on deposits of $11.5 million , or approximately 2.85% of total deposits. The loans were purchased at a discount of 1.75% . In connection with the branch acquisition transaction, the Corporation recorded goodwill of $6.8 million and other intangible assets attributable to customer core deposits of $5.6 million . Acquisition of O.A.K. Financial Corporation On April 30, 2010, the Corporation acquired OAK in an all-stock transaction for total consideration of $83.7 million . OAK provided traditional banking services and products through 14 banking offices serving communities in Ottawa, Allegan and Kent counties in west Michigan. At the acquisition date, OAK added total assets of $820 million , including total loans of $627 million , and total deposits of $693 million , including brokered deposits of $193 million . Upon acquisition, the OAK loan portfolio had contractually required principal payments receivable of $683 million and a fair value of $627 million . The outstanding contractual principal balance and the carrying amount of the OAK acquired loan portfolio were $196 million and $178 million , respectively, at March 31, 2016 , compared to $204 million and $183 million , respectively, at December 31, 2015 and $255 million and $234 million , respectively, at March 31, 2015 . Accretable Yield Activity for the accretable yield, which includes contractually due interest 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: Lake Michigan Monarch North-western OAK Total Three Months Ended March 31, 2016 (In thousands) Balance at beginning of period $ 152,999 $ 34,558 $ 82,623 $ 28,077 $ 298,257 Additions (reductions)* (6,071 ) 128 (2,254 ) 1,516 (6,681 ) Accretion recognized in interest income (8,953 ) (1,451 ) (4,001 ) (2,557 ) (16,962 ) Balance at end of period $ 137,975 $ 33,235 $ 76,368 $ 27,036 $ 274,614 Three Months Ended March 31, 2015 Balance at beginning of period $ 104,675 $ 33,286 $ 137,961 Additions (reductions)* (1,410 ) 714 (696 ) Accretion recognized in interest income (4,998 ) (3,207 ) (8,205 ) Balance at end of period $ 98,267 $ 30,793 $ 129,060 *Represents additions of estimated contractual interest expected to be collected from acquired loans being renewed or extended, less reductions in contractual interest resulting from the early payoff of acquired loans.

Investment Securities

Investment Securities	3 Months Ended
	Mar. 31, 2016
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 available-for-sale and investment securities held-to-maturity at March 31, 2016 , December 31, 2015 and March 31, 2015 : Investment Securities Available-for-Sale Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) March 31, 2016 U.S. Treasury securities $ 5,777 $ 20 $ — $ 5,797 Government sponsored agencies 177,537 591 491 177,637 State and political subdivisions 14,707 356 2 15,061 Residential mortgage-backed securities 178,498 899 248 179,149 Collateralized mortgage obligations 118,501 338 441 118,398 Corporate bonds 14,832 — 124 14,708 Preferred stock and trust preferred securities 2,888 377 — 3,265 Total $ 512,740 $ 2,581 $ 1,306 $ 514,015 December 31, 2015 U.S. Treasury securities $ 5,773 $ — $ 8 $ 5,765 Government sponsored agencies 195,711 78 800 194,989 State and political subdivisions 14,731 395 6 15,120 Residential mortgage-backed securities 189,452 538 2,222 187,768 Collateralized mortgage obligations 133,256 111 1,137 132,230 Corporate bonds 14,825 2 200 14,627 Preferred stock and trust preferred securities 2,888 344 — 3,232 Total $ 556,636 $ 1,468 $ 4,373 $ 553,731 March 31, 2015 U.S. Treasury securities $ 8,271 $ 31 $ — $ 8,302 Government sponsored agencies 249,642 889 101 250,430 State and political subdivisions 31,701 624 3 32,322 Residential mortgage-backed securities 218,299 1,358 56 219,601 Collateralized mortgage obligations 133,713 305 718 133,300 Corporate bonds 34,925 136 64 34,997 Preferred stock 1,389 303 — 1,692 Total $ 677,940 $ 3,646 $ 942 $ 680,644 Investment Securities Held-to-Maturity Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) March 31, 2016 State and political subdivisions $ 517,800 $ 9,493 $ 1,985 $ 525,308 Trust preferred securities 500 — 215 285 Total $ 518,300 $ 9,493 $ 2,200 $ 525,593 December 31, 2015 State and political subdivisions $ 509,471 $ 7,446 $ 4,512 $ 512,405 Trust preferred securities 500 — 200 300 Total $ 509,971 $ 7,446 $ 4,712 $ 512,705 March 31, 2015 State and political subdivisions $ 370,950 $ 6,852 $ 4,926 $ 372,876 Trust preferred securities 10,500 — 3,200 7,300 Total $ 381,450 $ 6,852 $ 8,126 $ 380,176 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). As of March 31, 2015, the Corporation held a $10.0 million trust preferred investment security of Lake Michigan. With the acquisition of Lake Michigan, this investment was settled as of the acquisition date at par. The following is a summary of the amortized cost and fair value of investment securities at March 31, 2016 , by maturity, for both available-for-sale and held-to-maturity investment securities. 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. March 31, 2016 Amortized Cost Fair Value (In thousands) Investment Securities Available-for-Sale: Due in one year or less $ 167,082 $ 167,114 Due after one year through five years 293,731 294,443 Due after five years through ten years 45,820 45,935 Due after ten years 4,719 4,757 Preferred stock 1,388 1,766 Total $ 512,740 $ 514,015 Investment Securities Held-to-Maturity: Due in one year or less $ 57,074 $ 57,148 Due after one year through five years 239,496 241,445 Due after five years through ten years 142,968 145,988 Due after ten years 78,762 81,012 Total $ 518,300 $ 525,593 The following schedule summarizes information for both available-for-sale and held-to-maturity investment securities with gross unrealized losses at March 31, 2016 , December 31, 2015 and March 31, 2015 , aggregated by category and length of time that individual securities have been in a continuous unrealized loss position. Less Than 12 Months 12 Months or More Total Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses (In thousands) March 31, 2016 Government sponsored agencies $ 2,501 $ 1 $ 20,275 $ 490 $ 22,776 $ 491 State and political subdivisions 83,997 1,067 96,143 920 180,140 1,987 Residential mortgage-backed securities 54,163 63 63,869 185 118,032 248 Collateralized mortgage obligations 29,973 34 35,489 407 65,462 441 Corporate bonds 4,666 73 4,950 51 9,616 124 Trust preferred securities — — 285 215 285 215 Total $ 175,300 $ 1,238 $ 221,011 $ 2,268 $ 396,311 $ 3,506 December 31, 2015 U.S. Treasury securities $ 5,765 $ 8 $ — $ — $ 5,765 $ 8 Government sponsored agencies 114,640 292 21,681 508 136,321 800 State and political subdivisions 195,285 2,891 68,361 1,627 263,646 4,518 Residential mortgage-backed securities 169,226 2,146 3,435 76 172,661 2,222 Collateralized mortgage obligations 60,459 408 39,382 729 99,841 1,137 Corporate bonds 9,532 200 — — 9,532 200 Trust preferred securities — — 300 200 300 200 Total $ 554,907 $ 5,945 $ 133,159 $ 3,140 $ 688,066 $ 9,085 March 31, 2015 Government sponsored agencies $ 27,889 $ 64 $ 18,896 $ 37 $ 46,785 $ 101 State and political subdivisions 156,010 1,989 49,839 2,940 205,849 4,929 Residential mortgage-backed securities 82,303 28 3,847 28 86,150 56 Collateralized mortgage obligations 22,694 22 41,061 696 63,755 718 Corporate bonds 4,989 11 14,946 53 19,935 64 Trust preferred securities — — 7,300 3,200 7,300 3,200 Total $ 293,885 $ 2,114 $ 135,889 $ 6,954 $ 429,774 $ 9,068 An assessment is performed quarterly by the Corporation to determine whether unrealized losses in its investment securities portfolio are temporary or other-than-temporary by carefully considering all 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 investment security, as of March 31, 2016 , represented an other-than-temporary impairment (OTTI). Management believed that the unrealized losses on investment securities at March 31, 2016 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 March 31, 2016 , the Corporation did not have the intent to sell any of its impaired investment securities and believed that it was more-likely-than-not that the Corporation will not have to sell any such investment securities before a full recovery of amortized cost. Accordingly, at March 31, 2016 , the Corporation believed the impairments in its investment securities portfolio were temporary in nature. However, there is no assurance that OTTI may not occur in the future.

Loans

Loans	3 Months Ended
	Mar. 31, 2016
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, non-owner occupied real estate leased to one or more tenants and vacant land that has been acquired for investment or future land development. 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 March 31, 2016 , December 31, 2015 and March 31, 2015 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 personal watercraft and comprised primarily of indirect loans purchased from dealers. These loans 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. 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 loans follows: March 31, December 31, March 31, (In thousands) Commercial loan portfolio: Commercial $ 1,922,259 $ 1,905,879 $ 1,356,169 Commercial real estate 2,143,051 2,112,162 1,616,923 Real estate construction and land development 242,899 232,076 108,839 Subtotal 4,308,209 4,250,117 3,081,931 Consumer loan portfolio: Residential mortgage 1,461,120 1,429,636 1,117,445 Consumer installment 897,078 877,457 844,066 Home equity 700,478 713,937 659,432 Subtotal 3,058,676 3,021,030 2,620,943 Total loans $ 7,366,885 $ 7,271,147 $ 5,702,874 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 across the lower peninsula of Michigan, except for the southeastern portion of Michigan. The Corporation has no foreign loans. 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 $1.0 million requiring group loan authority approval, except for six executive and senior officers who have varying loan limits exceeding $1.5 million and up to $3.5 million . With respect to the group loan authorities, Chemical Bank has a loan committee, consisting of certain executive and senior officers, that meets weekly to consider loans ranging in amounts from $1.0 million to $10.0 million , depending on risk rating and credit action required. A directors’ loan committee of Chemical Bank, consisting of eight independent members of the board of directors of Chemical Bank, the chief executive officer of Chemical Bank and the senior credit officer of Chemical Bank, meets bi-weekly to consider loans in amounts over $10.0 million , and certain loans under $10.0 million depending on a loan’s risk rating and credit action required. Loans over $15.0 million 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 The Corporation uses a nine grade risk rating system to monitor the ongoing credit quality of its commercial loan portfolio. These loan grades rank the credit quality of a borrower by measuring liquidity, debt capacity, coverage and payment behavior as shown in the borrower’s financial statements. The loan grades also measure the quality of the borrower’s management and the repayment support offered by any guarantors. A summary of the Corporation’s loan grades (or characteristics of the loans within each grade) follows: Risk Grades 1-5 (Acceptable Credit Quality) — All loans in risk grades 1 through 5 are considered to be acceptable credit risks by the Corporation and are grouped for purposes of allowance for loan loss considerations and financial reporting. The five grades essentially represent a ranking of loans that are all viewed to be of acceptable credit quality, taking into consideration the various factors mentioned above, but with varying degrees of financial strength, debt coverage, management and factors that could impact credit quality. Business credits within risk grades 1 through 5 range from Risk Grade 1: Prime Quality (factors include: excellent business credit; excellent debt capacity and coverage; outstanding management; strong guarantors; superior liquidity and net worth; favorable loan-to-value ratios; debt secured by cash or equivalents, or backed by the full faith and credit of the U.S. Government) to Risk Grade 5: Acceptable Quality With Care (factors include: acceptable business credit, but with added risk due to specific industry or internal situations). Risk Grade 6 (Watch) — A business credit that is not acceptable within the Corporation’s loan origination criteria; cash flow may not be adequate or is continually inconsistent to service current debt; financial condition has deteriorated as company trends/management have become inconsistent; the company is slow in furnishing quality financial information; working capital needs of the company are reliant on short-term borrowings; personal guarantees are weak and/or with little or no liquidity; the net worth of the company has deteriorated after recent or continued losses; the loan requires constant monitoring and attention from the Corporation; payment delinquencies becoming more serious; if left uncorrected, these potential weaknesses may, at some future date, result in deterioration of repayment prospects. Risk Grade 7 (Substandard — Accrual) — A business credit that is inadequately protected by the current financial net worth and paying capacity of the obligor or of the collateral pledged, if any; management has deteriorated or has become non-existent; quality financial information is not available; a high level of maintenance is required by the Corporation; cash flow can no longer support debt requirements; loan payments are continually and/or severely delinquent; negative net worth; personal guaranty has become insignificant; a credit that has a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. The Corporation still expects a full recovery of all contractual principal and interest payments; however, a possibility exists that the Corporation will sustain some loss if deficiencies are not corrected. Risk Grade 8 (Substandard — Nonaccrual ) — A business credit accounted for on a nonaccrual basis that has all the weaknesses inherent in a loan classified as risk grade 7 with the added characteristic that the weaknesses are so pronounced that, on the basis of current financial information, conditions and values, collection in full is highly questionable; a partial loss is possible and interest is no longer being accrued. This loan meets the definition of an impaired loan. The risk of loss requires analysis to determine whether a valuation allowance needs to be established. Risk Grade 9 (Substandard — Doubtful) — A business credit that has all the weaknesses inherent in a loan classified as risk grade 8 and interest is no longer being accrued, but additional deficiencies make it highly probable that liquidation will not satisfy the majority of the obligation; the primary source of repayment is nonexistent and there is doubt as to the value of the secondary source of repayment; the possibility of loss is likely, but current pending factors could strengthen the credit. This loan meets the definition of an impaired loan. A loan charge-off is recorded when management deems an amount uncollectible; however, the Corporation will establish a valuation allowance for probable losses, if required. The Corporation considers all loans graded 1 through 5 as acceptable credit risks and structures and manages such relationships accordingly. Periodic financial and operating data combined with regular loan officer interactions are deemed adequate to monitor borrower performance. Loans graded 6 and 7 are considered higher-risk credits than loans graded 1 through 5 and the frequency of loan officer contact and receipt of financial data is increased to stay abreast of borrower performance. Loans graded 8 and 9 are considered problematic and require special care. Further, loans graded 6 through 9 are managed and monitored regularly through a number of processes, procedures and committees, including oversight by a loan administration committee comprised of executive and senior management of the Corporation, and include highly structured reporting of financial and operating data, intensive loan officer intervention and strategies to exit, as well as potential management by the Corporation’s special assets group. The following schedule presents the recorded investment of loans in the commercial loan portfolio by risk rating categories at March 31, 2016 , December 31, 2015 and March 31, 2015 : Commercial Commercial Real Estate Real Estate Construction and Land Development Total (In thousands) March 31, 2016 Originated Portfolio: Risk Grades 1-5 $ 1,466,094 $ 1,409,991 $ 196,982 $ 3,073,067 Risk Grade 6 43,129 44,210 1,163 88,502 Risk Grade 7 35,437 20,250 977 56,664 Risk Grade 8 17,595 25,858 546 43,999 Risk Grade 9 1,669 1 — 1,670 Subtotal 1,563,924 1,500,310 199,668 3,263,902 Acquired Portfolio: Risk Grades 1-5 319,672 590,151 39,260 949,083 Risk Grade 6 25,978 17,692 1,539 45,209 Risk Grade 7 11,103 30,679 1,273 43,055 Risk Grade 8 1,582 4,219 1,159 6,960 Risk Grade 9 — — — — Subtotal 358,335 642,741 43,231 1,044,307 Total $ 1,922,259 $ 2,143,051 $ 242,899 $ 4,308,209 December 31, 2015 Originated Portfolio: Risk Grades 1-5 $ 1,418,301 $ 1,341,202 $ 183,323 $ 2,942,826 Risk Grade 6 34,727 31,036 180 65,943 Risk Grade 7 39,933 26,658 1,123 67,714 Risk Grade 8 26,459 25,163 521 52,143 Risk Grade 9 2,095 — — 2,095 Subtotal 1,521,515 1,424,059 185,147 3,130,721 Acquired Portfolio: Risk Grades 1-5 340,782 629,430 41,683 1,011,895 Risk Grade 6 28,321 23,926 2,556 54,803 Risk Grade 7 11,607 29,975 1,537 43,119 Risk Grade 8 3,654 4,772 1,153 9,579 Risk Grade 9 — — — — Subtotal 384,364 688,103 46,929 1,119,396 Total $ 1,905,879 $ 2,112,162 $ 232,076 $ 4,250,117 March 31, 2015 Originated Portfolio: Risk Grades 1-5 $ 1,176,021 $ 1,175,373 $ 96,497 $ 2,447,891 Risk Grade 6 40,999 44,248 738 85,985 Risk Grade 7 28,983 27,961 1,997 58,941 Risk Grade 8 18,904 24,760 953 44,617 Risk Grade 9 — 6 — 6 Subtotal 1,264,907 1,272,348 100,185 2,637,440 Acquired Portfolio: Risk Grades 1-5 71,422 318,113 6,724 396,259 Risk Grade 6 11,299 7,786 253 19,338 Risk Grade 7 6,509 12,735 140 19,384 Risk Grade 8 2,032 5,941 1,537 9,510 Risk Grade 9 — — — — Subtotal 91,262 344,575 8,654 444,491 Total $ 1,356,169 $ 1,616,923 $ 108,839 $ 3,081,931 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 or classified as a nonperforming TDR are considered to be in a nonperforming status. Nonaccrual TDRs in the consumer loan portfolio are included with nonaccrual loans, while other TDRs in the consumer loan portfolio are considered to be in a nonperforming status until they meet the Corporation’s definition of a performing TDR, at which time they are considered to be in a performing 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 March 31, 2016 , December 31, 2015 and March 31, 2015 : Residential Mortgage Consumer Installment Home Equity Total Consumer (In thousands) March 31, 2016 Originated Loans: Performing $ 1,253,670 $ 889,792 $ 582,485 $ 2,725,947 Nonperforming 8,498 360 3,007 11,865 Subtotal 1,262,168 890,152 585,492 2,737,812 Acquired Loans: Performing 197,075 6,881 113,989 317,945 Nonperforming 1,877 45 997 2,919 Subtotal 198,952 6,926 114,986 320,864 Total $ 1,461,120 $ 897,078 $ 700,478 $ 3,058,676 December 31, 2015 Originated Loans: Performing $ 1,207,945 $ 868,975 $ 587,566 $ 2,664,486 Nonperforming 9,030 451 3,246 12,727 Subtotal 1,216,975 869,426 590,812 2,677,213 Acquired Loans: Performing 210,580 7,984 122,118 340,682 Nonperforming 2,081 47 1,007 3,135 Subtotal 212,661 8,031 123,125 343,817 Total $ 1,429,636 $ 877,457 $ 713,937 $ 3,021,030 March 31, 2015 Originated Loans: Performing $ 998,196 $ 834,926 $ 565,992 $ 2,399,114 Nonperforming 9,376 433 2,299 12,108 Subtotal 1,007,572 835,359 568,291 2,411,222 Acquired Loans: Performing 109,005 8,696 90,686 208,387 Nonperforming 868 11 455 1,334 Subtotal 109,873 8,707 91,141 209,721 Total $ 1,117,445 $ 844,066 $ 659,432 $ 2,620,943 Nonperforming Loans A summary of nonperforming loans follows: March 31, December 31, March 31, (In thousands) Nonaccrual loans: Commercial $ 19,264 $ 28,554 $ 18,904 Commercial real estate 25,859 25,163 24,766 Real estate construction and land development 546 521 953 Residential mortgage 5,062 5,557 6,514 Consumer installment 360 451 433 Home equity 2,328 1,979 1,870 Total nonaccrual loans 53,419 62,225 53,440 Accruing loans contractually past due 90 days or more as to interest or principal payments: Commercial 370 364 52 Commercial real estate — 254 148 Residential mortgage 423 402 172 Home equity 679 1,267 429 Total accruing loans contractually past due 90 days or more as to interest or principal payments 1,472 2,287 801 Nonperforming TDRs: Commercial loan portfolio 15,351 16,297 15,810 Consumer loan portfolio 3,013 3,071 2,690 Total nonperforming TDRs 18,364 19,368 18,500 Total nonperforming loans $ 73,255 $ 83,880 $ 72,741 The Corporation’s nonaccrual loans at March 31, 2016 , December 31, 2015 and March 31, 2015 included $32.5 million , $35.9 million and $37.3 million , respectively, of nonaccrual TDRs. The Corporation had $2.3 million of residential mortgage loans that were in the process of foreclosure at March 31, 2016 , compared to $2.9 million and $2.2 million at December 31, 2015 and March 31, 2015 , respectively. Impaired Loans The following schedule presents impaired loans by classes of loans at March 31, 2016 , December 31, 2015 and March 31, 2015 : Recorded Investment Unpaid Principal Balance Related Valuation Allowance (In thousands) March 31, 2016 Impaired loans with a valuation allowance: Commercial $ 4,944 $ 4,949 $ 1,926 Commercial real estate 3,558 4,016 810 Residential mortgage 21,003 21,003 180 Subtotal 29,505 29,968 2,916 Impaired loans with no related valuation allowance: Commercial 35,353 45,042 — Commercial real estate 54,097 67,744 — Real estate construction and land development 2,164 3,104 — Residential mortgage 6,939 7,793 — Consumer installment 405 418 — Home equity 3,325 3,617 — Subtotal 102,283 127,718 — Total impaired loans: Commercial 40,297 49,991 1,926 Commercial real estate 57,655 71,760 810 Real estate construction and land development 2,164 3,104 — Residential mortgage 27,942 28,796 180 Consumer installment 405 418 — Home equity 3,325 3,617 — Total $ 131,788 $ 157,686 $ 2,916 December 31, 2015 Impaired loans with a valuation allowance: Commercial $ 18,898 $ 19,426 $ 5,700 Commercial real estate 4,448 4,688 497 Residential mortgage 21,037 21,037 192 Subtotal 44,383 45,151 6,389 Impaired loans with no related valuation allowance: Commercial 31,039 37,703 — Commercial real estate 53,518 69,130 — Real estate construction and land development 2,136 3,108 — Residential mortgage 7,638 8,644 — Consumer installment 498 512 — Home equity 2,986 3,270 — Subtotal 97,815 122,367 — Total impaired loans: Commercial 49,937 57,129 5,700 Commercial real estate 57,966 73,818 497 Real estate construction and land development 2,136 3,108 — Residential mortgage 28,675 29,681 192 Consumer installment 498 512 — Home equity 2,986 3,270 — Total $ 142,198 $ 167,518 $ 6,389 Recorded Investment Unpaid Principal Balance Related Valuation Allowance (In thousands) March 31, 2015 Impaired loans with a valuation allowance: Commercial $ 3,433 $ 3,527 $ 1,119 Commercial real estate 1,780 1,961 496 Residential mortgage 19,887 19,887 297 Subtotal 25,100 25,375 1,912 Impaired loans with no related valuation allowance: Commercial 33,733 39,382 — Commercial real estate 57,628 79,696 — Real estate construction and land development 2,540 4,264 — Residential mortgage 7,382 7,382 — Consumer installment 444 444 — Home equity 2,325 2,325 — Subtotal 104,052 133,493 — Total impaired loans: Commercial 37,166 42,909 1,119 Commercial real estate 59,408 81,657 496 Real estate construction and land development 2,540 4,264 — Residential mortgage 27,269 27,269 297 Consumer installment 444 444 — Home equity 2,325 2,325 — Total $ 129,152 $ 158,868 $ 1,912 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, and for acquired loans that meet the definition of an impaired loan represents fair value adjustments recognized at the acquisition date attributable to expected credit losses and the discounting of expected cash flows at market interest rates. The difference between the recorded investment and the unpaid principal balance of $25.9 million , $25.3 million and $29.7 million at March 31, 2016 , December 31, 2015 and March 31, 2015 , respectively, includes confirmed losses (partial charge-offs) of $19.9 million , $17.1 million and $14.8 million , respectively, and fair value discount adjustments of $6.0 million , $8.2 million and $14.9 million , respectively. Impaired loans included $10.1 million , $12.8 million and $11.2 million at March 31, 2016 , December 31, 2015 and March 31, 2015 , respectively, of acquired loans that were not performing in accordance with original contractual terms. Acquired loans that are not performing in accordance with contractual terms are not reported as nonperforming loans 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. Impaired loans also included $49.9 million , $47.8 million and $46.0 million at March 31, 2016 , December 31, 2015 and March 31, 2015 , respectively, of performing TDRs. The following schedule presents information related to impaired loans for the three months ended March 31, 2016 and 2015 : Average Recorded Investment Interest Income Recognized While on Impaired Status (In thousands) Three Months Ended March 31, 2016 Commercial $ 45,017 $ 329 Commercial real estate 57,956 458 Real estate construction and land development 2,068 25 Residential mortgage 28,092 366 Consumer installment 387 1 Home equity 3,252 15 Total $ 136,772 $ 1,194 Three Months Ended March 31, 2015 Commercial $ 38,576 $ 289 Commercial real estate 60,240 525 Real estate construction and land development 2,515 27 Residential mortgage 27,352 331 Consumer installment 499 — Home equity 2,352 8 Total $ 131,534 $ 1,180 The following schedule presents the aging status of the recorded investment in loans by classes of loans at March 31, 2016 , December 31, 2015 and March 31, 2015 : 31-60 Days Past Due 61-89 Days Past Due Accruing Loans Past Due 90 Days or More Non-accrual Loans Total Past Due Current Total Loans (In thousands) March 31, 2016 Originated Portfolio: Commercial $ 4,069 $ 7,359 $ 370 $ 19,264 $ 31,062 $ 1,532,862 $ 1,563,924 Commercial real estate 3,096 376 — 25,859 29,331 1,470,979 1,500,310 Real estate construction and land development 216 — — 546 762 198,906 199,668 Residential mortgage 757 23 423 5,062 6,265 1,255,903 1,262,168 Consumer installment 2,158 336 — 360 2,854 887,298 890,152 Home equity 1,632 323 679 2,328 4,962 580,530 585,492 Total $ 11,928 $ 8,417 $ 1,472 $ 53,419 $ 75,236 $ 5,926,478 $ 6,001,714 Acquired Portfolio: Commercial $ 55 $ 70 $ 1,582 $ — $ 1,707 $ 356,628 $ 358,335 Commercial real estate 249 557 4,459 — 5,265 637,476 642,741 Real estate construction and land development — — 1,159 — 1,159 42,072 43,231 Residential mortgage 301 — 1,877 — 2,178 196,774 198,952 Consumer installment 59 — 45 — 104 6,822 6,926 Home equity 543 511 997 — 2,051 112,935 114,986 Total $ 1,207 $ 1,138 $ 10,119 $ — $ 12,464 $ 1,352,707 $ 1,365,171 31-60 Days Past Due 61-89 Days Past Due Accruing Loans Past Due 90 Days or More Non-accrual Loans Total Past Due Current Total Loans (In thousands) December 31, 2015 Originated Portfolio: Commercial $ 3,685 $ 1,230 $ 364 $ 28,554 $ 33,833 $ 1,487,682 $ 1,521,515 Commercial real estate 4,168 1,603 254 25,163 31,188 1,392,871 1,424,059 Real estate construction and land development — — — 521 521 184,626 185,147 Residential mortgage 1,737 — 402 5,557 7,696 1,209,279 1,216,975 Consumer installment 3,145 644 — 451 4,240 865,186 869,426 Home equity 1,767 788 1,267 1,979 5,801 585,011 590,812 Total $ 14,502 $ 4,265 $ 2,287 $ 62,225 $ 83,279 $ 5,724,655 $ 5,807,934 Acquired Portfolio: Commercial $ 490 $ 532 $ 3,735 $ — $ 4,757 $ 379,607 $ 384,364 Commercial real estate 3,557 691 4,771 — 9,019 679,084 688,103 Real estate construction and land development — — 1,154 — 1,154 45,775 46,929 Residential mortgage 1,370 — 2,081 — 3,451 209,210 212,661 Consumer installment 55 — 47 — 102 7,929 8,031 Home equity 847 78 1,007 — 1,932 121,193 123,125 Total $ 6,319 $ 1,301 $ 12,795 $ — $ 20,415 $ 1,442,798 $ 1,463,213 March 31, 2015 Originated Portfolio: Commercial $ 10,121 $ 729 $ 52 $ 18,904 $ 29,806 $ 1,235,101 $ 1,264,907 Commercial real estate 7,238 2,267 148 24,766 34,419 1,237,929 1,272,348 Real estate construction and land development 340 — — 953 1,293 98,892 100,185 Residential mortgage 1,246 88 172 6,514 8,020 999,552 1,007,572 Consumer installment 2,143 344 — 433 2,920 832,439 835,359 Home equity 1,728 197 429 1,870 4,224 564,067 568,291 Total $ 22,816 $ 3,625 $ 801 $ 53,440 $ 80,682 $ 4,967,980 $ 5,048,662 Acquired Portfolio: Commercial $ 59 $ 5 $ 2,089 $ — $ 2,153 $ 89,109 $ 91,262 Commercial real estate 1,784 138 6,271 — 8,193 336,382 344,575 Real estate construction and land development — — 1,537 — 1,537 7,117 8,654 Residential mortgage 104 — 868 — 972 108,901 109,873 Consumer installment 3 1 11 — 15 8,692 8,707 Home equity 349 234 455 — 1,038 90,103 91,141 Total $ 2,299 $ 378 $ 11,231 $ — $ 13,908 $ 640,304 $ 654,212 Loans Modified Under Troubled Debt Restructurings (TDRs) The following schedule presents the Corporation’s TDRs at March 31, 2016 , December 31, 2015 and March 31, 2015 : Performing TDRs Non-Performing TDRs Nonaccrual TDRs Total (In thousands) March 31, 2016 Commercial loan portfolio $ 31,896 $ 15,351 $ 29,368 $ 76,615 Consumer loan portfolio 17,990 3,013 3,146 24,149 Total $ 49,886 $ 18,364 $ 32,514 $ 100,764 December 31, 2015 Commercial loan portfolio $ 29,844 $ 16,297 $ 32,682 $ 78,823 Consumer loan portfolio 17,966 3,071 3,251 24,288 Total $ 47,810 $ 19,368 $ 35,933 $ 103,111 March 31, 2015 Commercial loan portfolio $ 28,784 $ 15,810 $ 32,917 $ 77,511 Consumer loan portfolio 17,197 2,690 4,426 24,313 Total $ 45,981 $ 18,500 $ 37,343 $ 101,824 The following schedule provides information on the Corporation's TDRs that were modified during the three months ended March 31, 2016 and 2015 : Number of Loans Pre- Modification Recorded Investment Post- Modification Recorded Investment (Dollars in thousands) Three Months Ended March 31, 2016 Commercial loan portfolio: Commercial 7 $ 3,832 $ 3,832 Commercial real estate 4 987 987 Subtotal – commercial loan portfolio 11 4,819 4,819 Consumer loan portfolio 7 204 204 Total 18 $ 5,023 $ 5,023 Three Months Ended March 31, 2015 Commercial loan portfolio: Commercial 5 $ 1,932 $ 1,932 Commercial real estate 5 2,534 2,534 Subtotal – commercial loan portfolio 10 4,466 4,466 Consumer loan portfolio 10 336 336 Total 20 $ 4,802 $ 4,802 The pre-modification and post-modification recorded investment represents amounts as of the date of loan modification. The difference between the pre-modification and post-modification recorded investment of residential mortgage TDRs represents impairment recognized by the Corporation through the provision for loan losses computed based on a loan's post-modification present value of expected future cash flows discounted at the loan's original effective interest rate. The following schedule includes TDRs for which there was a payment default during the three months ended March 31, 2016 and 2015 , 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: Number of Loans Principal Balance at End of Period (Dollars in thousands) Three Months Ended March 31, 2016 Commercial loan portfolio: Commercial — $ — Commercial real estate 1 933 Subtotal – commercial loan portfolio 1 933 Consumer loan portfolio 1 — Total 2 $ 933 Three Months Ended March 31, 2015 Commercial loan portfolio: Commercial — $ — Commercial real estate 3 759 Subtotal – commercial loan portfolio 3 759 Consumer loan portfolio 1 33 Total 4 $ 792 Allowance for Loan Losses The following schedule presents, by loan portfolio segment, the changes in the allowance for the three months ended March 31, 2016 and details regarding the balance in the allowance and the recorded investment in loans at March 31, 2016 by impairment evaluation method. Commercial Loan Portfolio Consumer Loan Portfolio Unallocated Total (In thousands) Changes in allowance for loan losses for the three months ended March 31, 2016: Beginning balance $ 47,234 $ 26,094 $ — $ 73,328 Provision for loan losses 1,000 500 — 1,500 Charge-offs (3,896 ) (1,562 ) — (5,458 ) Recoveries 330 618 — 948 Ending balance $ 44,668 $ 25,650 $ — $ 70,318 Allowance for loan losses balance at March 31, 2016 attributable to: Loans individually evaluated for impairment $ 2,736 $ 180 $ — $ 2,916 Loans collectively evaluated for impairment 41,932 25,470 — 67,402 Loans acquired with deteriorated credit quality — — — — Total $ 44,668 $ 25,650 $ — $ 70,318 Recorded investment (loan balance) at March 31, 2016: Loans individually evaluated for impairment $ 92,916 $ 21,003 $ — $ 113,919 Loans collectively evaluated for impairment 3,170,986 2,716,809 — 5,887,795 Loans acquired with deteriorated credit quality 1,044,307 320,864 — 1,365,171 Total $ 4,308,209 $ 3,058,676 $ — $ 7,366,885 The following schedule presents, by loan portfolio segment, details regarding the balance in the allowance and the recorded investment in loans at December 31, 2015 by impairment evaluation method. Commercial Loan Portfolio Consumer Loan Portfolio Unallocated Total (In thousands) Allowance for loan losses balance at December 31, 2015 attributable to: Loans individually evaluated for impairment $ 6,197 $ 192 $ — $ 6,389 Loans collectively evaluated for impairment 41,037 25,902 — 66,939 Loans acquired with deteriorated credit quality — — — — Total $ 47,234 $ 26,094 $ — $ 73,328 Recorded investment (loan balance) at December 31, 2015: Loans individually evaluated for impairment $ 100,379 $ 21,037 $ — $ 121,416 Loans collectively evaluated for impairment 3,030,342 2,656,176 — 5,686,518 Loans acquired with deteriorated credit quality 1,119,396 343,817 — 1,463,213 Total $ 4,250,117 $ 3,021,030 $ — $ 7,271,147 The following schedule presents, by loan portfolio segment, the changes in the allowance for the three months ended March 31, 2015 and details regarding the balance in the allowance and the recorded investment in loans at March 31, 2015 by impairment evaluation method. Commercial Loan Portfolio Consumer Loan Portfolio Unallocated Total (In thousands) Changes in allowance for

Intangible Assets

Intangible Assets	3 Months Ended
	Mar. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	Intangible Assets The Corporation has the following types of intangible assets: goodwill, core deposit intangible assets, non-compete intangible assets and mortgage servicing rights (MSRs). Goodwill, core deposit intangible assets, and non-compete intangible assets arose as a result of business combinations or other acquisitions. MSRs arose as a result of selling residential mortgage 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 MSRs. Amortization is recorded on the core deposit intangible assets, non-compete intangible assets and MSRs. Goodwill recorded is primarily attributable to the synergies and economies of scale expected from combining the operations of the Corporation and other acquisitions. The Corporation recorded additional goodwill in the first quarter of 2016 of $0.5 million related to the 2015 acquisition of Lake Michigan resulting from adjustments to the original acquisition date valuation of acquired assets and liabilities. Goodwill is not amortized but is evaluated at least annually for impairment. The Corporation’s most recent annual goodwill impairment test performed as of October 31, 2015 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 March 31, 2016 and that the Corporation's goodwill was not impaired at March 31, 2016 . The following table shows the net carrying value of the Corporation’s intangible assets: March 31, December 31, March 31, (In thousands) Goodwill $ 286,867 $ 287,393 $ 180,128 Other intangible assets: Core deposit intangible assets $ 25,542 $ 26,654 $ 20,072 Non-compete intangible assets 246 328 — Mortgage servicing rights 10,478 11,122 11,583 Total other intangible assets $ 36,266 $ 38,104 $ 31,655 The following table sets forth the carrying amount, accumulated amortization and amortization expense of core deposit intangible assets that are amortizable and arose from business combinations or other acquisitions: March 31, December 31, March 31, (In thousands) Gross original amount $ 40,055 $ 40,055 $ 30,122 Accumulated amortization 14,513 13,401 10,050 Carrying amount $ 25,542 $ 26,654 $ 20,072 Amortization expense for the three months ended March 31 $ 1,112 $ 791 The estimated future amortization expense on core deposit intangible assets for periods ending after March 31, 2016 is as follows: 2016 — $3.2 million ; 2017 — $3.8 million ; 2018 — $3.6 million ; 2019 — $3.4 million ; 2020 — $2.9 million ; 2021 and thereafter — $8.6 million . The non-compete intangible assets will be fully amortized during 2016. The following shows the net carrying value and fair value of MSRs and the total loans that the Corporation is servicing for others: March 31, December 31, March 31, (In thousands) Net carrying value of MSRs $ 10,478 $ 11,122 $ 11,583 Fair value of MSRs $ 13,909 $ 15,542 $ 14,378 Loans serviced for others that have servicing rights capitalized $ 2,047,435 $ 2,082,899 $ 2,062,544 The following table shows the activity for capitalized MSRs: Three Months Ended March 31, 2016 2015 (In thousands) Balance at beginning of period $ 11,122 $ 12,217 Additions 331 400 Amortization (975 ) (1,034 ) Balance at end of period $ 10,478 $ 11,583 MSRs are stratified into servicing assets originated by the Corporation and those acquired in acquisitions of other institutions and further stratified into relatively homogeneous pools based on products with similar characteristics. There was no impairment valuation allowance recorded on the Corporation's MSRs at March 31, 2016 and December 31, 2015. There was a valuation allowance of $0.2 million as of March 31, 2015 related to impairment within certain pools attributable to the Corporation's servicing portfolio that was acquired in the Northwestern portfolio.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	3 Months Ended
	Mar. 31, 2016
Equity [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss The components of accumulated other comprehensive loss, net of related tax benefit/expense, were as follows: March 31, December 31, March 31, (In thousands) Net unrealized gains (losses) on investment securities – available-for-sale, net of related tax expense (benefit) of $446 at March 31, 2016, $(1,017) at December 31, 2015 and $946 at March 31, 2015 $ 829 $ (1,888 ) $ 1,758 Pension and other postretirement benefits adjustment, net of related tax benefit of $14,818 at March 31, 2016, $14,616 at December 31, 2015 and $16,981 at March 31, 2015 (27,519 ) (27,144 ) (31,537 ) Accumulated other comprehensive loss $ (26,690 ) $ (29,032 ) $ (29,779 )

Borrowings Borrowings (Notes)

Borrowings Borrowings (Notes)	3 Months Ended
	Mar. 31, 2016
Borrowings [Abstract]
Borrowings [Text Block]	Borrowings Short-term Borrowings The Corporation had short-term borrowings, which generally have an original term to maturity of 30 days or less. Short-term borrowings consisted of short-term FHLB advances outstanding of $100 million at December 31, 2015 . There were no short-term borrowings outstanding at March 31, 2016 or March 31, 2015 . Long-term Borrowings A summary of the Corporation's long-term borrowings follows: March 31, December 31, March 31, (In thousands) Long-term borrowings: Long-term FHLB advances $ 231,357 $ 181,394 $ — Securities sold under agreements to repurchase 17,365 17,453 — Non-revolving line-of-credit 25,000 25,000 — Subordinated debt obligations — 18,544 — Total long-term borrowings $ 273,722 $ 242,391 $ — During the first quarter of 2016, the Corporation borrowed an additional $50 million of long-term FHLB advances, which has a five-year term fixed-rate advance with a weighted-average interest rate of 1.30% . Long-term FHLB advances have a combined weighted-average interest rate of 1.39% . The Corporation's FHLB advances, including both short-term and long-term, require monthly interest payments and are collateralized by eligible loans totaling $2.92 billion as of March 31, 2016 . The scheduled reductions of long-term FHLB advances as of March 31, 2016 were as follows: 2016 - $7.1 million ; 2017 - $47.1 million ; 2018 - $67.1 million ; 2019; - $0.1 million ; and 2020 - $110.0 million . Securities sold under agreements to repurchase are with an unaffiliated financial institution and are secured by available for-sale-securities. As of March 31, 2016 , these agreements had scheduled maturities of $8.3 million in 2016 and $9.1 million in 2017. The Corporation has a $25 million secured non-revolving line-of-credit with an unaffiliated third-party financial institution that matures in May 2016. The Corporation drew on the entire amount of the line-of-credit. This line-of-credit bears a variable rate of interest which is based on the one-, two- or three-month LIBOR, as periodically selected by the Corporation, plus a fixed stated rate (effective interest rate of 2.39% at March 31, 2016 ). The line-of-credit agreement contains certain restrictive covenants. The Corporation was in compliance with all of the covenants at March 31, 2016 . As a result of the Lake Michigan transaction on May 31, 2015, the Corporation acquired subordinated debt obligations in the amount of $18.6 million . The Corporation fully repaid these debt obligations during the first quarter of 2016.

Regulatory Capital

Regulatory Capital	3 Months Ended
	Mar. 31, 2016
Banking and Thrift [Abstract]
Regulatory Capital	Regulatory Capital 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 March 31, 2016 , 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. 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 Corporation’s consolidated financial statements. 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 of the Corporation totaled $7.22 billion , $7.14 billion and $5.58 billion at March 31, 2016 , December 31, 2015 and March 31, 2015 , respectively. In July 2013, the Board of Governors of the Federal Reserve System ("Reserve Board") and FDIC approved final rules implementing the Basel Committee on Banking Supervision's ("BCBS") capital guidelines for U.S. banks (commonly referred to as "Basel III"). Beginning January 1, 2015, the Basel III capital rules include a new minimum common equity Tier 1 capital to risk-weighted assets ("CET Tier 1") ratio of 4.5%, in addition to raising the minimum ratio of Tier 1 capital to risk-weighted assets from 4.0% to 6.0% and requiring a minimum leverage ratio of 4.0%. The Basel III capital rules also establish 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. At March 31, 2016 , December 31, 2015 and March 31, 2015 , 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. 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 Required to be Well Capitalized Under Prompt Corrective Action Regulations Capital Amount Ratio Capital Amount Ratio Capital Amount Ratio (Dollars in thousands) March 31, 2016 Total Capital to Risk-Weighted Assets: Corporation $ 832,457 11.5 % $ 577,668 8.0 % N/A N/A Chemical Bank 840,372 11.7 576,068 8.0 $ 720,086 10.0 % Tier 1 Capital to Risk-Weighted Assets: Corporation 762,139 10.6 433,251 6.0 N/A N/A Chemical Bank 770,054 10.7 432,051 6.0 576,068 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets: Corporation 762,139 10.6 324,938 4.5 N/A N/A Chemical Bank 770,054 10.7 324,038 4.5 468,056 6.5 Leverage Ratio: Corporation 762,139 8.5 357,773 4.0 N/A N/A Chemical Bank 770,054 8.6 357,190 4.0 446,488 5.0 December 31, 2015 Total Capital to Risk-Weighted Assets: Corporation $ 841,257 11.8 % $ 571,509 8.0 % N/A N/A Chemical Bank 830,294 11.7 570,073 8.0 $ 712,591 10.0 % Tier 1 Capital to Risk-Weighted Assets: Corporation 767,929 10.7 428,631 6.0 N/A N/A Chemical Bank 756,966 10.6 427,555 6.0 570,073 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets: Corporation 753,815 10.6 321,474 4.5 N/A N/A Chemical Bank 756,966 10.6 320,666 4.5 463,184 6.5 Leverage Ratio: Corporation 767,929 8.6 356,396 4.0 N/A N/A Chemical Bank 756,966 8.5 355,911 4.0 444,888 5.0 March 31, 2015 Total Capital to Risk-Weighted Assets: Corporation $ 727,090 13.0 % $ 446,173 8.0 % N/A N/A Chemical Bank 676,488 12.1 445,471 8.0 $ 556,838 10.0 % Tier 1 Capital to Risk-Weighted Assets: Corporation 657,307 11.8 334,630 6.0 N/A N/A Chemical Bank 606,813 10.9 334,103 6.0 445,471 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets: Corporation 657,307 11.8 250,972 4.5 N/A N/A Chemical Bank 606,813 10.9 250,577 4.5 361,945 6.5 Leverage Ratio: Corporation 657,307 9.1 289,948 4.0 N/A N/A Chemical Bank 606,813 8.4 289,840 4.0 362,300 5.0

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2016
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 to determine fair value disclosures. Investment securities — available-for-sale and loans held-for-sale 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 1 valuations for the Corporation would include U.S. Treasury securities that are traded by dealers or brokers in active over-the-counter markets. Valuations are obtained from a third-party pricing service for these investment securities. 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 sponsored agency securities, including securities issued by the Federal Home Loan Bank, 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. 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 securities issued by certain state and political subdivisions, held-to-maturity trust preferred investment securities, impaired loans, goodwill, core deposit intangible assets, non-compete intangible assets, MSRs 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. 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 — available-for-sale are recorded at fair value on a recurring basis. 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. The Corporation elected the fair value option for all residential mortgage loans held-for-sale originated on or after July 1, 2012. 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. Disclosure of Recurring Basis Fair Value Measurements For assets measured at fair value on a recurring basis, quantitative disclosures about the fair value measurements for each major category of assets were as follows: Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (In thousands) March 31, 2016 Investment securities – available-for-sale: U.S. Treasury securities $ 5,797 $ — $ — $ 5,797 Government sponsored agencies — 177,637 — 177,637 State and political subdivisions — 15,061 — 15,061 Residential mortgage-backed securities — 179,149 — 179,149 Collateralized mortgage obligations — 118,398 — 118,398 Corporate bonds — 14,708 — 14,708 Preferred stock and trust preferred securities — 3,265 — 3,265 Total investment securities – available-for-sale 5,797 508,218 — 514,015 Loans held-for-sale — 9,667 — 9,667 Total assets measured at fair value on a recurring basis $ 5,797 $ 517,885 $ — $ 523,682 December 31, 2015 Investment securities – available-for-sale: U.S. Treasury securities $ 5,765 $ — $ — $ 5,765 Government sponsored agencies — 194,989 — 194,989 State and political subdivisions — 15,120 — 15,120 Residential mortgage-backed securities — 187,768 — 187,768 Collateralized mortgage obligations — 132,230 — 132,230 Corporate bonds — 14,627 — 14,627 Preferred stock and trust preferred securities — 3,232 — 3,232 Total investment securities – available-for-sale 5,765 547,966 — 553,731 Loans held-for-sale — 10,327 — 10,327 Total assets measured at fair value on a recurring basis $ 5,765 $ 558,293 $ — $ 564,058 March 31, 2015 Investment securities – available-for-sale: U.S. Treasury securities $ 8,302 $ — $ — $ 8,302 Government sponsored agencies — 250,430 — 250,430 State and political subdivisions — 32,322 — 32,322 Residential mortgage-backed securities — 219,601 — 219,601 Collateralized mortgage obligations — 133,300 — 133,300 Corporate bonds — 34,997 — 34,997 Preferred stock — 1,692 — 1,692 Total investment securities – available-for-sale 8,302 672,342 — 680,644 Loans held-for-sale — 9,675 — 9,675 Total assets measured at fair value on a recurring basis $ 8,302 $ 682,017 $ — $ 690,319 There were no liabilities recorded at fair value on a recurring basis at March 31, 2016 , December 31, 2015 or March 31, 2015 . Assets and Liabilities Recorded at Fair Value on a Nonrecurring Basis 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 independent appraised value, or management determines the fair value of the collateral is further impaired below the appraised value. When management determines the fair value of the collateral is further impaired below appraised value, discount factors ranging between 70% and 80% of the appraised value are used depending on the nature of the collateral and the age of the most recent appraisal. 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 March 31, 2016 , December 31, 2015 and March 31, 2015 , no goodwill was impaired, and therefore, goodwill was not recorded at fair value on a nonrecurring basis. Other intangible assets consist of core deposit intangible assets, non-compete intangible assets, and MSRs. 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 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 March 31, 2016 , December 31, 2015 and March 31, 2015 , there was no impairment identified for core deposit intangible assets or non-compete intangible assets. The fair value of MSRs is initially estimated using a model that calculates the net present value of estimated future cash flows using various assumptions, including prepayment speeds, the discount rate and servicing costs. If the valuation model reflects a value less than the carrying value, MSRs are adjusted to fair value, as determined by the model, through a valuation allowance. The Corporation classifies MSRs subject to nonrecurring fair value measurements as Level 3 valuations. At March 31, 2015 , the Corporation recognized a valuation allowance of $0.2 million related to impairment within certain pools attributable to the Corporation's servicing portfolio that was acquired in the Northwestern transaction. As a result, the MSRs related to this servicing portfolio were considered to be recorded at fair value on a nonrecurring basis. At March 31, 2016 and December 31, 2015 , there was no impairment identified for MSRs and, therefore, no other intangible assets were recorded at fair value on a nonrecurring basis. The carrying amounts for other real estate (ORE) and repossessed assets (RA) are reported in the consolidated statements of financial position under “Interest receivable and other assets.” ORE and RA include real estate and other types of assets repossessed by the Corporation. ORE and RA are recorded at the lower of cost or fair value upon the transfer of a loan to ORE or RA and, subsequently, ORE and RA 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 ORE and RA 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, discount factors ranging between 70% and 75% 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 For assets measured at fair value on a nonrecurring basis, quantitative disclosures about fair value measurements for each major category of assets were as follows: Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (In thousands) March 31, 2016 Impaired originated loans $ — $ — $ 30,925 $ 30,925 Other real estate/repossessed assets — — 9,248 9,248 Total $ — $ — $ 40,173 $ 40,173 December 31, 2015 Impaired originated loans $ — $ — $ 42,065 $ 42,065 Other real estate/repossessed assets — — 9,935 9,935 Total $ — $ — $ 52,000 $ 52,000 March 31, 2015 Impaired originated loans $ — $ — $ 23,730 $ 23,730 Other real estate/repossessed assets — — 14,744 14,744 Mortgage servicing rights — — 8,115 8,115 Total $ — $ — $ 46,589 $ 46,589 There were no liabilities recorded at fair value on a nonrecurring basis at March 31, 2016 , December 31, 2015 and March 31, 2015 . 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. However, the method of estimating fair value for certain financial instruments, such as loans, that are not required to be measured on a recurring or nonrecurring basis, as prescribed by ASC 820, Fair Value Measurements and Disclosures, does not incorporate the exit-price concept of fair value. 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 present value methods 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, do not necessarily indicate amounts that could 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. The methodologies for estimating the fair value of financial assets and financial liabilities on a recurring or nonrecurring basis are discussed above. At March 31, 2016 , December 31, 2015 and March 31, 2015 , the estimated fair values of cash and cash equivalents, interest receivable and interest payable approximated their carrying values at those dates. The methodologies for other financial assets and financial liabilities follow. Fair value measurement for investment securities — held-to-maturity is based upon quoted prices, if available. If quoted prices are not available, fair values are 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. Fair value measurements using Level 2 valuations of investment securities — held-to-maturity include the majority of the Corporation's investment securities issued by state and political subdivisions. Level 3 valuations include certain securities issued by state and political subdivisions and trust preferred investment securities. Fair value measurements of nonmarketable equity securities, which consisted of Federal Home Loan Bank (FHLB) and Federal Reserve Bank (FRB) stock, are based on their redeemable value, which is cost. The market for these securities is restricted to the issuer of the stock and subject to impairment evaluation. It is not practicable to determine the fair value of these securities within the fair value hierarchy due to the restrictions placed on their transferability. Loans held-for-sale are carried at fair value, as the Corporation elected the fair value option on these loans. 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. The fair value of variable interest rate loans that reprice regularly with changes in market interest rates are based on carrying values. The fair values for fixed interest rate loans are estimated using discounted cash flow analyses, using the Corporation’s interest rates currently being offered for loans with similar terms to borrowers of similar credit quality. The resulting fair value amounts are adjusted to estimate the impact of changes in the credit quality of borrowers after the loans were originated. The fair value measurements for loans are Level 3 valuations. The fair values of deposit accounts without defined maturities, such as interest- and noninterest-bearing checking, savings and money market accounts, are equal to the amounts payable on demand. The fair values for variable-interest rate time deposits with defined maturities approximate their carrying amounts. Fair value measurements for fixed-interest rate time deposits with defined maturities are based on the discounted value of contractual cash flows, using the Corporation’s interest rates currently being offered for deposits of similar maturities, and are Level 3 valuations. However, if the estimated fair value is less than the carrying value, the carrying value is reported as the fair value. Short-term borrowings consist of securities sold under agreements to repurchase with customers, short-term FHLB advances and federal funds purchased. Fair value measurements for short-term borrowings are based on the present value of future estimated cash flows using current interest rates offered to the Corporation for debt with similar terms and are Level 2 valuations. Long-term borrowings consist of long-term FHLB advances, securities sold under agreements to repurchase with an unaffiliated financial institution, a non-revolving line-of-credit and subordinated debt obligations. Fair value measurements for long-term borrowings are based on the present value of future estimated cash flows using current interest rates offered to the Corporation for debt with similar terms. Long-term FHLB advances and the non-revolving line-of-credit included in long-term borrowings are Level 2 valuations, while securities sold under agreements to repurchase with an unaffiliated financial institution and subordinated debt obligations are Level 3 valuations. The Corporation’s unused commitments to extend credit, standby letters of credit and loan commitments have no carrying amount and have been estimated to have no realizable fair value. Historically, a majority of the unused commitments to extend credit have not been drawn upon and, generally, the Corporation does not receive fees in connection with these commitments other than standby letter of credit fees, which are not significant. Fair value measurements have not been made for items that are not defined by GAAP as financial instruments, including such items as the value of the Corporation’s Wealth Management department and the value of the Corporation’s core deposit base. The Corporation believes it is impractical to estimate a representative fair value for these types of assets, even though management believes they add significant value to the Corporation. A summary of carrying amounts and estimated fair values of the Corporation’s financial instruments included in the consolidated statements of financial position was as follows: Level in Fair Value Measurement Hierarchy March 31, 2016 December 31, 2015 March 31, 2015 Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value (In thousands) Assets: Cash and cash equivalents Level 1 $ 291,374 $ 291,374 $ 238,789 $ 238,789 $ 393,938 $ 393,938 Investment securities: Available-for-sale Level 1 5,797 5,797 5,765 5,765 8,302 8,302 Available-for-sale Level 2 508,218 508,218 547,966 547,966 672,342 672,342 Held-to-maturity Level 2 517,800 525,308 509,471 512,405 370,950 372,876 Held-to-maturity Level 3 500 285 500 300 10,500 7,300 Nonmarketable equity securities NA 43,267 43,267 36,907 36,907 31,249 31,249 Loans held-for-sale Level 2 9,667 9,667 10,327 10,327 9,675 9,675 Net loans Level 3 7,296,567 7,297,375 7,197,819 7,201,994 5,627,618 5,633,217 Interest receivable Level 2 26,010 26,010 21,953 21,953 19,816 19,816 Liabilities: Deposits without defined maturities Level 2 $ 6,043,457 $ 6,043,457 $ 5,809,355 $ 5,809,355 $ 4,988,268 $ 4,988,268 Time deposits Level 3 1,606,659 1,609,073 1,647,412 1,647,412 1,332,085 1,335,605 Interest payable Level 2 1,632 1,632 1,578 1,578 779 779 Short-term borrowings Level 2 283,383 283,383 397,199 397,199 372,236 372,236 Long-term borrowings Level 2 256,357 257,993 206,394 206,394 — — Long-term borrowings Level 3 17,365 17,317 35,997 35,997 — —

Earnings Per Common Share

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
Earnings Per Common Share	Earnings Per Common Share Basic earnings per common share for the Corporation is computed by dividing net income by the weighted average number of common shares outstanding during the period. Basic earnings per common share excludes any dilutive effect of common stock equivalents. Diluted earnings per common share for the Corporation is computed by dividing net income by the sum of the weighted average number of common shares outstanding and the dilutive effect of common stock equivalents using the treasury stock method. 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 and stock to be issued under the deferred stock compensation plan for non-employee directors. For any period in which a net loss is recorded, the assumed exercise of stock options, restricted stock units that may be converted to stock and stock to be issued under the deferred stock compensation plan would have an anti-dilutive impact on the net loss per common share and thus are excluded in the diluted earnings per common share calculation. The following summarizes the numerator and denominator of the basic and diluted earnings per common share computations: Three Months Ended March 31, 2016 2015 (In thousands, except per share data) Numerator for both basic and diluted earnings per common share, net income $ 23,262 $ 17,835 Denominator for basic earnings per common share, weighted average common shares outstanding 38,198 32,809 Weighted average common stock equivalents 323 235 Denominator for diluted earnings per common share 38,521 33,044 Basic earnings per common share $ 0.61 $ 0.54 Diluted earnings per common share $ 0.60 $ 0.54 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 zero and 121,050 for the three months ended March 31, 2016 and 2015 , respectively.

Share-Based Compensation

Share-Based Compensation	3 Months Ended
	Mar. 31, 2016
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 both the three-month periods ended March 31, 2016 and 2015 , share-based compensation expense related to stock options, restricted stock units and other share-based awards totaled $0.8 million . During the three-month period ended March 31, 2016 , the Corporation granted options to purchase 441,167 shares of common stock, 98,425 restricted stock units and 940 shares of common stock to certain officers of the Corporation. On April 20, 2015, the shareholders of the Corporation approved the Stock Incentive Plan of 2015, which provides for 1,300,000 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 March 31, 2016 , there were 704,273 shares of common stock available for future grants under the Stock Incentive Plan of 2015. Stock Options The Corporation issues stock options to certain officers. Stock options are issued at the current market price of the Corporation's common stock on the date of grant and 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. A summary of activity for the Corporation’s stock options as of and for the three months ended March 31, 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 Exercised — — — (70,885 ) 20.69 Vested (118,273 ) 28.30 8.40 — — Forfeited/expired (8,783 ) 32.21 6.66 (8,783 ) 32.21 Outstanding at March 31, 2016 793,866 $ 31.03 $ 7.22 1,416,238 $ 27.89 Exercisable/vested at March 31, 2016 622,372 $ 23.88 The weighted-average remaining contractual terms were 7.4 years for all outstanding stock options and 5.1 years for exercisable stock options at March 31, 2016 . The intrinsic value of all outstanding in-the-money stock options and exercisable in-the-money stock options was $11.0 million and $7.3 million , respectively, at March 31, 2016 . The aggregate intrinsic values of outstanding and exercisable options at March 31, 2016 were calculated based on the closing market price of the Corporation’s common stock on March 31, 2016 of $35.69 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. At March 31, 2016 , unrecognized compensation expense related to stock options totaled $5.7 million and is expected to be recognized over a remaining weighted average period of 4.0 years . The fair value of the stock options granted during the three months ended March 31, 2016 was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions. Expected dividend yield 3.30 % Risk-free interest rate 1.39 % Expected stock price volatility 27.9 % Expected life of options – in years 6.5 Weighted average fair value of options granted $ 6.15 Restricted Stock Units In addition to stock options, the Corporation grants restricted stock performance units and restricted stock service-based units (collectively referred to as restricted stock units) to certain officers. The restricted stock performance units vest based on the Corporation achieving certain performance target levels and the grantee completing the requisite service period. The restricted stock performance units 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 restricted stock performance units. The restricted stock service-based units vest upon satisfaction of a service condition. Upon achievement of the performance target level and/or satisfaction of a service condition, if applicable, the restricted stock units are converted into shares of the Corporation’s common stock on a one-to-one basis. Compensation expense related to restricted stock units is recognized over the expected requisite performance or service period, as applicable. A summary of the activity for restricted stock units as of and for the three months ended March 31, 2016 is presented below: Number of Units Weighted- Average Grant Date Fair Value Per Unit Outstanding at December 31, 2015 207,989 $ 26.41 Granted 98,425 30.40 Converted into shares of common stock (42,812 ) 22.47 Forfeited/expired (1,116 ) 30.29 Outstanding at March 31, 2016 262,486 $ 28.53 At March 31, 2016 , unrecognized compensation expense related to restricted stock units totaled $5.6 million and is expected to be recognized over a remaining weighted average period of 2.9 years .

Pension and Other Postretiremen

Pension and Other Postretirement Benefit Plans	3 Months Ended
	Mar. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Pension and Other Postretirement Benefit Plans	Pension and Other Postretirement Benefit Plans The Corporation's retirement plans include a qualified pension plan, a nonqualified pension plan, a nonqualified postretirement benefit plan, a 401(k) savings plan, and a multi-employer defined benefit plan. Qualified and Nonqualified Pension Plans and Nonqualified Postretirement Benefit Plans The components of net periodic benefit cost for the Corporation’s qualified and nonqualified pension plans and nonqualified postretirement benefit plan are as follows: Three Months Ended March 31, 2016 2015 (In thousands) Defined Benefit Pension Plans Service cost $ 277 $ 273 Interest cost 1,358 1,332 Expected return on plan assets (2,141 ) (2,161 ) Amortization of prior service credit — (1 ) Amortization of unrecognized net loss 572 1,056 Net periodic benefit cost $ 66 $ 499 Postretirement Benefit Plan Service cost $ 2 $ 4 Interest cost 33 33 Amortization of prior service cost 29 32 Amortization of unrecognized net gain (24 ) — Net periodic benefit cost $ 40 $ 69 The Corporation’s pension plan does not have a contribution requirement in 2016 . The Corporation did no t make a contribution to the pension plan during 2015 . The discount rate used to compute the Corporation's pension plan expense for 2016 is 4.55% . 401(k) Savings Plan 401(k) Savings Plan expense for the Corporation’s match of participants’ base compensation contributions and a 4% of eligible pay contribution to certain employees who are not grandfathered under the pension plan was $1.3 million and $1.1 million for the three months ended March 31, 2016 and 2015 , respectively. 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 pension plan. Employee benefits for Monarch employees under the 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 of 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 by the Corporation to the Pentegra DB Plan for the three months ended March 31, 2016 .

Financial Guarantees

Financial Guarantees	3 Months Ended
	Mar. 31, 2016
Guarantees [Abstract]
Financial Guarantees	Financial Guarantees In the normal course of business, the Corporation is a party to financial instruments containing credit risk that are not required to be reflected in the consolidated statements of financial position. For the Corporation, these financial instruments are financial and performance 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 March 31, 2016 , December 31, 2015 and March 31, 2015 , the Corporation had $43 million , $39 million and $38 million , respectively, of outstanding financial and performance standby letters of credit that expire in five years or less. 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 March 31, 2016 , December 31, 2015 and March 31, 2015 .

Significant Accounting Polici23

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2016
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 Midland, Michigan, that operates through one commercial bank, Chemical Bank. Chemical Bank operates within the State of Michigan as a state-chartered commercial bank. Chemical Bank operates through an internal organizational structure of four regional banking units and offers a full range of traditional banking and fiduciary products and services to the residents and business customers in the bank’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 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 and wealth management revenue.
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated financial statements of the Corporation and its subsidiaries have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") for interim financial information and the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, the interim consolidated financial statements do not include all of the information and footnotes required by GAAP for complete financial statements and should be read in conjunction with the Corporation’s consolidated financial statements and footnotes thereto included in the Corporation’s Annual Report on Form 10-K for the year ended December 31, 2015. In the opinion of management, the accompanying unaudited interim consolidated financial statements contain all adjustments believed necessary to present fairly the financial condition and results of operations of the Corporation for the periods presented. Operating results for the three months ended March 31, 2016 are not necessarily indicative of the results that may be expected for the year ending December 31, 2016 .
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, fair value amounts related to business combinations, pension expense, income taxes, goodwill impairment and those assets that require fair value measurement. Actual results could differ from these estimates.
Business Combinations Policy [Policy Text Block]	Business Combinations Pursuant to the guidance of 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. ASC 805 affords a measurement period beyond the acquisition date that allows the Corporation the opportunity to finalize the acquisition accounting in the event that new information is identified that existed as of the acquisition date but was not known by the Corporation at that time. The Corporation anticipates that measurement period adjustments may arise from adjustments to the fair values of assets and liabilities recognized at the acquisition date for its May 31, 2015 acquisition of Lake Michigan Financial Corporation ("Lake Michigan"), as additional information is obtained, such as appraisals of collateral securing loans and other borrower information. In the event that a measurement period adjustment is identified, the Corporation will recognize the adjustment as part of its acquisition accounting, which may result in an adjustment to goodwill being recorded in the period the adjustment was identified. See Note 2 for further information regarding the Corporation's mergers and acquisitions, including its pending merger with Talmer Bancorp, Inc. ("Talmer").
Originated Loans	Originated Loans Originated loans include all of the Corporation's portfolio loans, 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. 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 more (except for a loan that is secured by residential real estate, which is transferred to nonaccrual status at 120 days past due), 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, 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 May 31, 2015 in the acquisition of 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, through a fair value discount that was, in part, attributable to deterioration in credit quality. 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 fair value discount was recorded as a reduction of the acquired loans’ outstanding principal balances in the consolidated statement of financial position at the acquisition date. The Corporation accounts for acquired loans, which are recorded at fair value at acquisition, in accordance with ASC Topic 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality ("ASC 310-30"). 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 2 pools in the acquisition of Lake Michigan, 2 pools in the acquisition of Monarch, 4 pools in the acquisition of Northwestern and 14 pools in the acquisition of OAK 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. If an individual loan is removed from a pool of loans, the difference between its relative carrying amount and the cash, fair value of the collateral, or other assets received would not affect the effective yield used to recognize the accretable difference on the remaining pool. 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 in each loan pool in subsequent periods will require the Corporation to record a provision for loan losses. Improvements in expected cash flows in each loan pool in subsequent periods will 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 troubled debt restructurings ("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 or interest rate, which generally would not otherwise be considered. The Corporation’s TDRs include performing and nonperforming TDRs, which consist of originated loans that continue to accrue interest at the loan's original interest rate 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. In accordance with ASC Topic 310-30, acquired loans are excluded from TDRs as these loans are accounted for in pools at net realizable value based on the principal and interest the Corporation expects to collect on such loans. At the time of modification (except for loans on nonaccrual status), a TDR is reported as a nonperforming TDR until a six -month payment history of principal and interest payments, in accordance with the terms of the loan modification, is sustained, at which time the Corporation moves the loan to a performing status ("performing TDR"). If the Corporation does not expect to collect all principal and interest on the loan, the modified loan is classified as a nonaccrual TDR. 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. 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. 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 classified as a nonperforming TDR until a six-month payment history is sustained, at which time the loan is classified as a performing TDR. Since no loss is expected to be incurred on these loans, no additional provision for loan losses has been recognized related to these loans, and these loans accrue interest at their contractual interest rate. These loans are individually evaluated for impairment and 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. Loans in the Corporation’s consumer loan portfolio (comprised of residential mortgage, consumer installment and home equity loans) that meet the definition of a performing or nonperforming TDR generally consist of residential mortgage loans that 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. These loans are moved to nonaccrual status if they become 90 days past due as to principal or interest payments, or sooner if conditions warrant.
Impaired Loans	Impaired Loans A loan is defined to be impaired when it is probable that payment of principal and interest will not be paid in accordance with the original contractual terms of the loan agreement. Impaired loans include nonaccrual loans (including nonaccrual TDRs), performing and nonperforming TDRs and acquired loans that were not performing in accordance with original contractual terms. 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 an allocation of the 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), accruing originated loans contractually past due 90 days or more as to interest or principal payments and nonperforming 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.
Allowance for Loan Losses	Allowance for Loan Losses The allowance for loan losses ("allowance") is presented as a reserve against loans. The allowance represents management’s assessment of probable loan losses inherent in the Corporation’s loan portfolio. Management’s evaluation of the adequacy of the allowance is based on a continuing review of the loan portfolio, actual loan loss experience, the underlying value of the collateral, risk characteristics of the loan portfolio, the level and composition of nonperforming loans, the financial condition of the borrowers, the balance of the loan portfolio, loan growth, economic conditions, employment levels in the Corporation’s local markets, and special factors affecting specific business sectors. The Corporation maintains formal policies and procedures to monitor and control credit risk. Management evaluates the allowance on a quarterly basis in an effort to ensure the level is appropriate to absorb probable losses inherent in the loan portfolio. The allowance provides for probable losses that have been identified with specific customer relationships and for probable losses believed to be incurred in the remainder of the originated loan portfolio, but that have not been specifically identified. The Corporation utilizes its own loss experience to estimate inherent losses on loans. Internal risk ratings are assigned to each loan in the commercial loan portfolio (commercial, commercial real estate, real estate construction and land development loans) at the time of origination and are subject to subsequent periodic reviews by senior management. The Corporation performs a detailed credit quality review quarterly on all loans greater than $0.25 million that have deteriorated below certain levels of credit risk, and may allocate a specific portion of the allowance to such loans based upon this review. A portion of the allowance is allocated to the remaining loans by applying projected loss ratios, based on numerous factors. Projected loss ratios incorporate factors such as charge-off experience, trends with respect to adversely risk-rated loans in the commercial loan portfolio, trends with respect to past due and nonaccrual loans, changes in economic conditions and trends, changes in the value of underlying collateral and other credit risk factors. This evaluation involves a high degree of uncertainty. In determining the allowance and the related provision for loan losses, the Corporation considers four principal elements: (i) valuation allowances based upon probable losses identified during the review of impaired loans in the commercial loan portfolio, (ii) reserves established for adversely-rated loans in the commercial loan portfolio and nonaccrual residential mortgage, consumer installment and home equity loans based on loan loss experience of other adversely-rated loans, (iii) reserves, by loan classes, on all other loans based principally on a five -year historical loan loss experience, with equal weighting placed on all of the years, loan loss trends giving consideration to estimated loss emergence periods and (iv) a reserve for qualitative factors that take into consideration risks inherent in the originated loan portfolio that differ from historical loan loss experience. 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 process, 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.
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. The fair value option (i) may be applied instrument by instrument, with certain exceptions, allowing the Corporation to record identical financial assets and liabilities at fair value or by another measurement basis permitted under GAAP, (ii) is irrevocable (unless a new election date occurs) and (iii) is applied only to entire instruments and not to portions of instruments. At March 31, 2016 , December 31, 2015 and March 31, 2015 , the Corporation had elected the fair value option on all of its residential mortgage loans held-for-sale. The Corporation has not elected the fair value option for any other financial assets or liabilities.
Share-Based Compensation	Share-Based Compensation The Corporation grants stock options, stock awards, restricted stock performance units and restricted stock service-based units 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 of the award. The fair values of both stock options and stock awards are recognized as compensation expense on a straight-line basis over the requisite service period. The Corporation accounts for restricted stock performance units 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 restricted stock performance units 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 restricted stock service-based units 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 restricted stock service-based units. The fair value of the restricted stock service-based units is recognized as compensation expense over the requisite service period. Cash flows realized from the tax benefits of exercised stock option awards that result from actual tax deductions that are in excess of the recorded tax benefits related to the compensation expense recognized for those options (excess tax benefits) are classified as financing activities on the consolidated statements of cash flows.
Life Insurance, Corporate or Bank Owned [Text Block]	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. Bank-owned life insurance is recorded at the cash surrender value, net of surrender charges, and is included within other assets on the consolidated statements of financial position and changes in the cash surrender values are recorded as other noninterest income on the consolidated statements of income.
Income and Other Taxes	Income and Other Taxes The Corporation is subject to the income and other tax laws of the United States, the State of Michigan and any 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. 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. If a tax position is more-likely-than-not to be sustained, a tax benefit is recognized for the amount that is greater than 50% likely to be realized. Reserves for contingent income tax liabilities attributable to unrecognized tax benefits associated with 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 contingent income tax liabilities recorded at March 31, 2016 , December 31, 2015 or March 31, 2015 .
Investments in Tax Credit Projects [Policy Text Block]	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 are reflected in 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 allocated. The Corporation recognized additional income tax expense attributable to the amortization of investments in qualified affordable housing projects of $0.6 million and $0.1 million during the three months ended March 31, 2016 , and 2015, respectively. The Corporation's remaining investment in qualified affordable housing projects accounted for under the proportional amortization method totaled $21.1 million at March 31, 2016 , $21.7 million at December 31, 2015 and $4.8 million at March 31, 2015 . The increase in qualified affordable housing project investments at March 31, 2016 , compared to March 31, 2015 , was attributable to investments acquired as part of the Lake Michigan transaction. Under the equity method, the Corporation's share of the earnings or losses are 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 $1.5 million and $1.7 million at March 31, 2016 and December 31, 2015 , respectively. There were no investments in such projects accounted for under the equity method as of March 31, 2015 . 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 other liabilities on the consolidated statements of financial position. The Corporation's remaining unfunded equity contributions totaled $4.2 million and $8.0 million at March 31, 2016 and December 31, 2015 . 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. There were no impairment losses recognized as of March 31, 2016 , December 31, 2015 or March 31, 2015 . 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 interests 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 Corporation's consolidated financial statements.
Shareholders' Equity	Shareholders’ Equity Common Stock Repurchase Programs From time to time, the board of directors of the Corporation approves common stock repurchase programs allowing management to repurchase shares of the Corporation’s common stock in the open market. The repurchased shares are available for later reissuance in connection with potential future stock dividends, the Corporation’s dividend reinvestment plan, employee benefit plans and other general corporate purposes. Under these programs, the timing and actual number of shares subject to repurchase are at the discretion of management and are contingent on a number of factors, including the projected parent company cash flow requirements and the Corporation’s market price per share. In January 2008, the board of directors of the Corporation authorized the repurchase of up to 500,000 shares of the Corporation’s common stock under a stock repurchase program. In November 2011, the board of directors of the Corporation reaffirmed the stock buy-back authorization with the qualification that the shares may only be repurchased if the share price is below the tangible book value per share of the Corporation’s common stock at the time of the repurchase. Since the January 2008 authorization, no shares have been repurchased. At March 31, 2016 , there were 500,000 remaining shares available for repurchase under the Corporation’s stock repurchase program. Shelf Registration On June 12, 2014, the Corporation filed an automatic shelf registration statement on Form S-3 with the Securities and Exchange Commission ("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, that had been approved by shareholders on April 20, 2009, with a new class of 2,000,000 shares of preferred stock. At March 31, 2016 , no shares of preferred stock were issued and outstanding. Common Stock On April 20, 2015, 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 45,000,000 to 60,000,000 .
Legal Matters	Legal Matters On February 22, 2016, two putative class action and derivative complaints were filed in the Circuit Court for Oakland County, Michigan by individuals purporting to be a shareholder of Talmer. The actions are styled Regina Gertel Lee v. Chemical Financial Corporation, et. al. , Case No. 2016-151642-CB and City of Livonia Employees’ Retirement System v. Chemical Financial Corporation et. al., Case No. 2016-151641-CB. These complaints purport to be brought derivatively on behalf of Talmer against the individual defendants, and individually and on behalf of all others similarly situated against Talmer and Chemical. The complaints allege, among other things, that the directors of Talmer breached their fiduciary duties to Talmer’s shareholders in connection with the merger by approving a transaction pursuant to an allegedly inadequate process that undervalues Talmer and includes preclusive deal protection provisions, and that Chemical allegedly aided and abetted the Talmer directors in breaching their duties to Talmer’s shareholders. The complaints also allege that the individual defendants have been unjustly enriched. Both complaints seek various remedies on behalf of the putative class (consisting of all shareholders of Talmer who are not related to or affiliated with any defendant). They request, among other things, that the Court enjoin the merger from being consummated in accordance with its agreed-upon terms, direct the Talmer directors to exercise their fiduciary duties, rescind the merger agreement to the extent that it is already implemented, award the plaintiff all costs and disbursements in each respective action (including reasonable attorneys’ and experts’ fees), and grant such further relief as the court deems just and proper. The City of Livonia plaintiff amended its complaint on April 21, 2016 to add additional factual allegations, including but not limited to allegations that Keefe Bruyette & Woods, Inc. served as a financial advisor for the proposed merger despite an alleged conflict of interest, that Talmer’s board acted under actual or potential conflicts of interest, and that the defendants omitted and/or misrepresented material information about the proposed merger in the Form S-4 Registration Statement relating to the proposed merger. Talmer, Chemical and the individual defendants all believe that the claims asserted against each of them in the above-described lawsuits are without merit and intend to vigorously defend against these lawsuits. On March 22, 2016, an additional putative class action and derivative complaint was filed in the Circuit Court for Oakland County, Michigan, by an individual purporting to be a shareholder of Talmer, styled Stephen Bushansky v . Gary Torgow et. al . Case No. 2016-152112-CB. This action contained similar allegations, claims, and requests for relief as the complaints filed in the Lee and City of Livonia lawsuits discussed above. The Bushansky lawsuit was voluntarily dismissed by the plaintiff as to all defendants, without prejudice, on April 18, 2016. On April 6, 2016, a complaint was filed in the United States District Court for the Eastern District of Michigan by another purported shareholder of Talmer, styled Matthew Sciabacucchi v. Chemical Financial Corporation et. al ., Docket No. 1:16-cv-11261. Mr. Sciabacucchi purports to bring this action “on behalf of himself and all others similarly situated.” This lawsuit alleges violations of Sections 14(a) and 20(a) of the Securities Exchange Act of 1934, naming Talmer, Chemical, and several individuals as defendants. The complaint alleges, among other things, that the Defendants issued materially incomplete and misleading disclosures in the Form S-4 Registration Statement relating to the proposed merger. The Complaint contains requests for relief that include, among other things, that the Court enjoin the proposed transaction, rescind the transaction if it is consummated or award rescissory damages, order the Talmer directors to file a revised Registration Statement, declare that the Defendants violated Sections 14(a) and/or Section 20(a) of the Securities Exchange Act, as well as Rule 14a-9 promulgated thereunder, award the plaintiff all costs associated with bringing the action (including reasonable attorneys’ and experts’ fees), and grant such further relief as the court deems just and proper. Talmer, Chemical and the individual defendants all believe that the claims asserted against each of them in this lawsuit are without merit and intend to vigorously defend against this lawsuit. On April 25, 2016, a complaint was filed in the United States District Court for the Eastern District of Michigan by another purported shareholder of Talmer, styled Kevin Nicholl v. Chemical Financial Corporation et. al ., Docket No. 1:16-cv-11482. The plaintiff names Talmer, Chemical, and several individuals as defendants. This lawsuit is styled as a class action and derivative action, and alleges breach of fiduciary duties as well as violations of Sections 14(a) and 20(a) of the Securities Exchange Act of 1934. The complaint alleges, among other things, that the individual defendants breached their fiduciary duties as directors of Talmer by, among other things, entering into the proposed merger under various alleged conflicts of interest without regard to the fairness of the transaction to Talmer’s shareholders, using a flawed process in entering into the proposed merger that failed to maximize value for Talmer shareholders, and knowingly or recklessly attempting to unfairly deprive the Talmer shareholders of the true value of their investment in Talmer. The Complaint further alleges that the individual defendants issued materially incomplete and misleading disclosures in the Form S-4 Registration Statement relating to the proposed merger, in violation of Section 14(a) of the Securities Exchange Act, and/or were control persons liable for these alleged violations under Section 20(a) of the Securities Exchange Act. The Complaint alleges that Chemical aided and abetted the alleged wrongdoing of the individual defendants, as described in the Complaint. The Complaint contains requests for relief that include, among other things, that the Court certify the action as a class and derivative action, declare that the individual defendants breached their fiduciary duties in entering into the transaction, direct the individual defendants to comply with their fiduciary duties to obtain a transaction in the best interest of Talmer’s shareholders, enjoin the proposed transaction unless an appropriate procedure or process is implemented to provide the best terms to Talmer’s shareholders, rescind the transaction if it is consummated, award the plaintiff the costs and disbursements of the action (including reasonable attorneys’ and experts’ fees), and grant such further equitable relief as the court deems just and proper. Talmer, Chemical and the individual defendants all believe that the claims asserted against each of them in this lawsuit are without merit and intend to vigorously defend against this lawsuit. In addition, the Corporation and Chemical Bank are subject to certain legal actions arising in the ordinary course of business. In the opinion of management, after consultation with legal counsel, the ultimate disposition of these matters is not expected to have a material adverse effect on the consolidated financial condition or results of operations of the Corporation.
Reclassifications [Text Block]	Reclassifications Certain amounts appearing in the consolidated financial statements and notes thereto for prior periods have been reclassified to conform with the current presentation. The reclassification had no effect on net income or shareholders’ equity as previously reported.
Adopted Accounting Pronouncements	Adopted Accounting Pronouncements Consolidation of Variable Interest Entities In February 2015, the FASB issued ASU No. 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis ("ASU 2015-02"). ASU 2015-02 is applicable to reporting entities that are required to evaluate whether they should consolidate certain legal entities. Specifically, ASU 2015-02 (i) modifies the evaluation of whether limited partnerships and similar legal entities are VIEs, (ii) eliminates the presumption that a general partner should consolidate a limited partnership, (iii) affects the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships and (iv) provides a scope exception from consolidation guidance for reporting entities with interests in legal entities that are required to comply with or operate in accordance with requirements that are similar to those in Rule 2a-7 of the Investment Company Act of 1940 for registered money market funds. The adoption of ASU 2015-02 effective January 1, 2016 did not have a material impact on the Corporation's consolidated financial condition or results of operations. Customer's Accounting for Cloud Computing Fees In April 2015, the FASB issued ASU No. 2015-05, Intangibles - Goodwill and Other - Internal Use Software (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement ("ASU 2015-05"). ASU 2015-05 provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. ASU 2015-05 does not change the accounting for a customer’s accounting for service contracts. The purpose of ASU 2015-05 is to clarify which fees paid in a cloud computing arrangement should be capitalized and which fees should be expensed as incurred. The adoption of ASU 2015-05 prospectively effective January 1, 2016 did not have a material impact on the Corporation's consolidated financial condition or results of operations.
Pending Accounting Pronouncements	Pending Accounting Pronouncements Recognition and Measurement In January 2016, the FASB issued 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 amends 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, if any, plus or minus changes in observable prices, with changes in measurement recognized in net income, (iii) simplifying the 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 significant assumptions used to estimate the fair value for financial instruments measured at amortized cost on the balance sheet; (v) requiring use the of exit price notion when measuring the fair value of financial instruments for disclosure purposes; (vi) requiring recognition of changes in the fair value related to instrument-specific credit risk in other comprehensive income if the fair value option for financial liabilities is elected, (vii) requiring separate presentation in the financial statements of financial assets and financial liabilities by measurement category, and (8) clarifying that an entity should evaluate the need for a valuation allowance on deferred tax assets related to available-for-sale securities in combination with the entity’s other deferred tax assets. ASU 2016-01 is effective for interim and annual reporting periods beginning after December 15, 2017. Early application is permitted as of the beginning of the fiscal year of adoption only for items (iv) and (vi) above. Early adoption of the other items mentioned above is not permitted. The adoption of ASU 2016-01 is not expected to have a material impact on the Corporation's consolidated financial condition or results of operations. Leases In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) ("ASU 2016-02"). Under ASU 2016-02, the Corporation will be required to recognize the following for all leases (with the exception of short-term leases): (i) a right to use asset, which is an asset that represents the lessee's right to use, or control the use of, a specified asset for the lease term and (ii) a lease liability, which is a liability that represents lessee's obligation to make lease payments arising from a lease, measured on a discounted basis. ASU 2016-02 requires a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. ASU 2016-02 is effective for public companies for interim and annual periods beginning after December 15, 2018. The adoption of ASU 2016-02 is not expected to have a material impact on the Corporation's consolidated financial condition or results of operations. Stock Compensation In March 2016, the FASB issued ASU No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting ("ASU 2016-09"). ASU 2016-09 allows for simplification of several aspects of the accounting for share-based payment transactions including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. Under ASU 2016-09, all excess tax benefits and tax deficiencies (including tax benefits of dividends on share-based payment awards) should be recognized as income tax expense or benefit in the income statement. ASU 2016-09 also requires recognition of excess tax benefits regardless of whether the benefit reduces taxes payable in the current period. ASU 2016-09 further permits the withholding of an amount up to employees' maximum individual tax rate in the relevant jurisdiction without resulting in a liability classification. ASU 2016-09 also requires any excess tax benefits be classified along with other income tax cash flows as an operating activity and cash paid by an employer when directly withholding shares for tax-withholding purposes to be classified as a financing activity. ASU 2016-09 is effective for public companies for interim and annual periods beginning after December 15, 2016. The Corporation is currently evaluating the impact of ASU 2016-09 on the Corporation's consolidated financial condition and results of operations.

Acquisitions (Tables)

Acquisitions (Tables)	3 Months Ended
	Mar. 31, 2016
Business Acquisition [Line Items]
Activity for accretable yield includes contractually due interest of acquired loans	Activity for the accretable yield, which includes contractually due interest 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: Lake Michigan Monarch North-western OAK Total Three Months Ended March 31, 2016 (In thousands) Balance at beginning of period $ 152,999 $ 34,558 $ 82,623 $ 28,077 $ 298,257 Additions (reductions)* (6,071 ) 128 (2,254 ) 1,516 (6,681 ) Accretion recognized in interest income (8,953 ) (1,451 ) (4,001 ) (2,557 ) (16,962 ) Balance at end of period $ 137,975 $ 33,235 $ 76,368 $ 27,036 $ 274,614 Three Months Ended March 31, 2015 Balance at beginning of period $ 104,675 $ 33,286 $ 137,961 Additions (reductions)* (1,410 ) 714 (696 ) Accretion recognized in interest income (4,998 ) (3,207 ) (8,205 ) Balance at end of period $ 98,267 $ 30,793 $ 129,060 *Represents additions of estimated contractual interest expected to be collected from acquired loans being renewed or extended, less reductions in contractual interest resulting from the early payoff of acquired loans.

Investment Securities (Tables)

Investment Securities (Tables)	3 Months Ended
	Mar. 31, 2016
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 available-for-sale and investment securities held-to-maturity at March 31, 2016 , December 31, 2015 and March 31, 2015 : Investment Securities Available-for-Sale Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) March 31, 2016 U.S. Treasury securities $ 5,777 $ 20 $ — $ 5,797 Government sponsored agencies 177,537 591 491 177,637 State and political subdivisions 14,707 356 2 15,061 Residential mortgage-backed securities 178,498 899 248 179,149 Collateralized mortgage obligations 118,501 338 441 118,398 Corporate bonds 14,832 — 124 14,708 Preferred stock and trust preferred securities 2,888 377 — 3,265 Total $ 512,740 $ 2,581 $ 1,306 $ 514,015 December 31, 2015 U.S. Treasury securities $ 5,773 $ — $ 8 $ 5,765 Government sponsored agencies 195,711 78 800 194,989 State and political subdivisions 14,731 395 6 15,120 Residential mortgage-backed securities 189,452 538 2,222 187,768 Collateralized mortgage obligations 133,256 111 1,137 132,230 Corporate bonds 14,825 2 200 14,627 Preferred stock and trust preferred securities 2,888 344 — 3,232 Total $ 556,636 $ 1,468 $ 4,373 $ 553,731 March 31, 2015 U.S. Treasury securities $ 8,271 $ 31 $ — $ 8,302 Government sponsored agencies 249,642 889 101 250,430 State and political subdivisions 31,701 624 3 32,322 Residential mortgage-backed securities 218,299 1,358 56 219,601 Collateralized mortgage obligations 133,713 305 718 133,300 Corporate bonds 34,925 136 64 34,997 Preferred stock 1,389 303 — 1,692 Total $ 677,940 $ 3,646 $ 942 $ 680,644
Held-to-maturity Securities	Investment Securities Held-to-Maturity Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) March 31, 2016 State and political subdivisions $ 517,800 $ 9,493 $ 1,985 $ 525,308 Trust preferred securities 500 — 215 285 Total $ 518,300 $ 9,493 $ 2,200 $ 525,593 December 31, 2015 State and political subdivisions $ 509,471 $ 7,446 $ 4,512 $ 512,405 Trust preferred securities 500 — 200 300 Total $ 509,971 $ 7,446 $ 4,712 $ 512,705 March 31, 2015 State and political subdivisions $ 370,950 $ 6,852 $ 4,926 $ 372,876 Trust preferred securities 10,500 — 3,200 7,300 Total $ 381,450 $ 6,852 $ 8,126 $ 380,176
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 March 31, 2016 , by maturity, for both available-for-sale and held-to-maturity investment securities. 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. March 31, 2016 Amortized Cost Fair Value (In thousands) Investment Securities Available-for-Sale: Due in one year or less $ 167,082 $ 167,114 Due after one year through five years 293,731 294,443 Due after five years through ten years 45,820 45,935 Due after ten years 4,719 4,757 Preferred stock 1,388 1,766 Total $ 512,740 $ 514,015 Investment Securities Held-to-Maturity: Due in one year or less $ 57,074 $ 57,148 Due after one year through five years 239,496 241,445 Due after five years through ten years 142,968 145,988 Due after ten years 78,762 81,012 Total $ 518,300 $ 525,593
Summary of continuous unrealized loss position of securities	The following schedule summarizes information for both available-for-sale and held-to-maturity investment securities with gross unrealized losses at March 31, 2016 , December 31, 2015 and March 31, 2015 , aggregated by category and length of time that individual securities have been in a continuous unrealized loss position. Less Than 12 Months 12 Months or More Total Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses (In thousands) March 31, 2016 Government sponsored agencies $ 2,501 $ 1 $ 20,275 $ 490 $ 22,776 $ 491 State and political subdivisions 83,997 1,067 96,143 920 180,140 1,987 Residential mortgage-backed securities 54,163 63 63,869 185 118,032 248 Collateralized mortgage obligations 29,973 34 35,489 407 65,462 441 Corporate bonds 4,666 73 4,950 51 9,616 124 Trust preferred securities — — 285 215 285 215 Total $ 175,300 $ 1,238 $ 221,011 $ 2,268 $ 396,311 $ 3,506 December 31, 2015 U.S. Treasury securities $ 5,765 $ 8 $ — $ — $ 5,765 $ 8 Government sponsored agencies 114,640 292 21,681 508 136,321 800 State and political subdivisions 195,285 2,891 68,361 1,627 263,646 4,518 Residential mortgage-backed securities 169,226 2,146 3,435 76 172,661 2,222 Collateralized mortgage obligations 60,459 408 39,382 729 99,841 1,137 Corporate bonds 9,532 200 — — 9,532 200 Trust preferred securities — — 300 200 300 200 Total $ 554,907 $ 5,945 $ 133,159 $ 3,140 $ 688,066 $ 9,085 March 31, 2015 Government sponsored agencies $ 27,889 $ 64 $ 18,896 $ 37 $ 46,785 $ 101 State and political subdivisions 156,010 1,989 49,839 2,940 205,849 4,929 Residential mortgage-backed securities 82,303 28 3,847 28 86,150 56 Collateralized mortgage obligations 22,694 22 41,061 696 63,755 718 Corporate bonds 4,989 11 14,946 53 19,935 64 Trust preferred securities — — 7,300 3,200 7,300 3,200 Total $ 293,885 $ 2,114 $ 135,889 $ 6,954 $ 429,774 $ 9,068

Loans (Tables)

Loans (Tables)	3 Months Ended
	Mar. 31, 2016
Receivables [Abstract]
Summary of loans under portfolio	A summary of loans follows: March 31, December 31, March 31, (In thousands) Commercial loan portfolio: Commercial $ 1,922,259 $ 1,905,879 $ 1,356,169 Commercial real estate 2,143,051 2,112,162 1,616,923 Real estate construction and land development 242,899 232,076 108,839 Subtotal 4,308,209 4,250,117 3,081,931 Consumer loan portfolio: Residential mortgage 1,461,120 1,429,636 1,117,445 Consumer installment 897,078 877,457 844,066 Home equity 700,478 713,937 659,432 Subtotal 3,058,676 3,021,030 2,620,943 Total loans $ 7,366,885 $ 7,271,147 $ 5,702,874
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 risk rating categories at March 31, 2016 , December 31, 2015 and March 31, 2015 : Commercial Commercial Real Estate Real Estate Construction and Land Development Total (In thousands) March 31, 2016 Originated Portfolio: Risk Grades 1-5 $ 1,466,094 $ 1,409,991 $ 196,982 $ 3,073,067 Risk Grade 6 43,129 44,210 1,163 88,502 Risk Grade 7 35,437 20,250 977 56,664 Risk Grade 8 17,595 25,858 546 43,999 Risk Grade 9 1,669 1 — 1,670 Subtotal 1,563,924 1,500,310 199,668 3,263,902 Acquired Portfolio: Risk Grades 1-5 319,672 590,151 39,260 949,083 Risk Grade 6 25,978 17,692 1,539 45,209 Risk Grade 7 11,103 30,679 1,273 43,055 Risk Grade 8 1,582 4,219 1,159 6,960 Risk Grade 9 — — — — Subtotal 358,335 642,741 43,231 1,044,307 Total $ 1,922,259 $ 2,143,051 $ 242,899 $ 4,308,209 December 31, 2015 Originated Portfolio: Risk Grades 1-5 $ 1,418,301 $ 1,341,202 $ 183,323 $ 2,942,826 Risk Grade 6 34,727 31,036 180 65,943 Risk Grade 7 39,933 26,658 1,123 67,714 Risk Grade 8 26,459 25,163 521 52,143 Risk Grade 9 2,095 — — 2,095 Subtotal 1,521,515 1,424,059 185,147 3,130,721 Acquired Portfolio: Risk Grades 1-5 340,782 629,430 41,683 1,011,895 Risk Grade 6 28,321 23,926 2,556 54,803 Risk Grade 7 11,607 29,975 1,537 43,119 Risk Grade 8 3,654 4,772 1,153 9,579 Risk Grade 9 — — — — Subtotal 384,364 688,103 46,929 1,119,396 Total $ 1,905,879 $ 2,112,162 $ 232,076 $ 4,250,117 March 31, 2015 Originated Portfolio: Risk Grades 1-5 $ 1,176,021 $ 1,175,373 $ 96,497 $ 2,447,891 Risk Grade 6 40,999 44,248 738 85,985 Risk Grade 7 28,983 27,961 1,997 58,941 Risk Grade 8 18,904 24,760 953 44,617 Risk Grade 9 — 6 — 6 Subtotal 1,264,907 1,272,348 100,185 2,637,440 Acquired Portfolio: Risk Grades 1-5 71,422 318,113 6,724 396,259 Risk Grade 6 11,299 7,786 253 19,338 Risk Grade 7 6,509 12,735 140 19,384 Risk Grade 8 2,032 5,941 1,537 9,510 Risk Grade 9 — — — — Subtotal 91,262 344,575 8,654 444,491 Total $ 1,356,169 $ 1,616,923 $ 108,839 $ 3,081,931
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 March 31, 2016 , December 31, 2015 and March 31, 2015 : Residential Mortgage Consumer Installment Home Equity Total Consumer (In thousands) March 31, 2016 Originated Loans: Performing $ 1,253,670 $ 889,792 $ 582,485 $ 2,725,947 Nonperforming 8,498 360 3,007 11,865 Subtotal 1,262,168 890,152 585,492 2,737,812 Acquired Loans: Performing 197,075 6,881 113,989 317,945 Nonperforming 1,877 45 997 2,919 Subtotal 198,952 6,926 114,986 320,864 Total $ 1,461,120 $ 897,078 $ 700,478 $ 3,058,676 December 31, 2015 Originated Loans: Performing $ 1,207,945 $ 868,975 $ 587,566 $ 2,664,486 Nonperforming 9,030 451 3,246 12,727 Subtotal 1,216,975 869,426 590,812 2,677,213 Acquired Loans: Performing 210,580 7,984 122,118 340,682 Nonperforming 2,081 47 1,007 3,135 Subtotal 212,661 8,031 123,125 343,817 Total $ 1,429,636 $ 877,457 $ 713,937 $ 3,021,030 March 31, 2015 Originated Loans: Performing $ 998,196 $ 834,926 $ 565,992 $ 2,399,114 Nonperforming 9,376 433 2,299 12,108 Subtotal 1,007,572 835,359 568,291 2,411,222 Acquired Loans: Performing 109,005 8,696 90,686 208,387 Nonperforming 868 11 455 1,334 Subtotal 109,873 8,707 91,141 209,721 Total $ 1,117,445 $ 844,066 $ 659,432 $ 2,620,943
Summary of nonperforming loans	A summary of nonperforming loans follows: March 31, December 31, March 31, (In thousands) Nonaccrual loans: Commercial $ 19,264 $ 28,554 $ 18,904 Commercial real estate 25,859 25,163 24,766 Real estate construction and land development 546 521 953 Residential mortgage 5,062 5,557 6,514 Consumer installment 360 451 433 Home equity 2,328 1,979 1,870 Total nonaccrual loans 53,419 62,225 53,440 Accruing loans contractually past due 90 days or more as to interest or principal payments: Commercial 370 364 52 Commercial real estate — 254 148 Residential mortgage 423 402 172 Home equity 679 1,267 429 Total accruing loans contractually past due 90 days or more as to interest or principal payments 1,472 2,287 801 Nonperforming TDRs: Commercial loan portfolio 15,351 16,297 15,810 Consumer loan portfolio 3,013 3,071 2,690 Total nonperforming TDRs 18,364 19,368 18,500 Total nonperforming loans $ 73,255 $ 83,880 $ 72,741
Schedule of Impaired loans by classes	The following schedule presents impaired loans by classes of loans at March 31, 2016 , December 31, 2015 and March 31, 2015 : Recorded Investment Unpaid Principal Balance Related Valuation Allowance (In thousands) March 31, 2016 Impaired loans with a valuation allowance: Commercial $ 4,944 $ 4,949 $ 1,926 Commercial real estate 3,558 4,016 810 Residential mortgage 21,003 21,003 180 Subtotal 29,505 29,968 2,916 Impaired loans with no related valuation allowance: Commercial 35,353 45,042 — Commercial real estate 54,097 67,744 — Real estate construction and land development 2,164 3,104 — Residential mortgage 6,939 7,793 — Consumer installment 405 418 — Home equity 3,325 3,617 — Subtotal 102,283 127,718 — Total impaired loans: Commercial 40,297 49,991 1,926 Commercial real estate 57,655 71,760 810 Real estate construction and land development 2,164 3,104 — Residential mortgage 27,942 28,796 180 Consumer installment 405 418 — Home equity 3,325 3,617 — Total $ 131,788 $ 157,686 $ 2,916 December 31, 2015 Impaired loans with a valuation allowance: Commercial $ 18,898 $ 19,426 $ 5,700 Commercial real estate 4,448 4,688 497 Residential mortgage 21,037 21,037 192 Subtotal 44,383 45,151 6,389 Impaired loans with no related valuation allowance: Commercial 31,039 37,703 — Commercial real estate 53,518 69,130 — Real estate construction and land development 2,136 3,108 — Residential mortgage 7,638 8,644 — Consumer installment 498 512 — Home equity 2,986 3,270 — Subtotal 97,815 122,367 — Total impaired loans: Commercial 49,937 57,129 5,700 Commercial real estate 57,966 73,818 497 Real estate construction and land development 2,136 3,108 — Residential mortgage 28,675 29,681 192 Consumer installment 498 512 — Home equity 2,986 3,270 — Total $ 142,198 $ 167,518 $ 6,389 Recorded Investment Unpaid Principal Balance Related Valuation Allowance (In thousands) March 31, 2015 Impaired loans with a valuation allowance: Commercial $ 3,433 $ 3,527 $ 1,119 Commercial real estate 1,780 1,961 496 Residential mortgage 19,887 19,887 297 Subtotal 25,100 25,375 1,912 Impaired loans with no related valuation allowance: Commercial 33,733 39,382 — Commercial real estate 57,628 79,696 — Real estate construction and land development 2,540 4,264 — Residential mortgage 7,382 7,382 — Consumer installment 444 444 — Home equity 2,325 2,325 — Subtotal 104,052 133,493 — Total impaired loans: Commercial 37,166 42,909 1,119 Commercial real estate 59,408 81,657 496 Real estate construction and land development 2,540 4,264 — Residential mortgage 27,269 27,269 297 Consumer installment 444 444 — Home equity 2,325 2,325 — Total $ 129,152 $ 158,868 $ 1,912
Schedule presents information related to impaired loans	The following schedule presents information related to impaired loans for the three months ended March 31, 2016 and 2015 : Average Recorded Investment Interest Income Recognized While on Impaired Status (In thousands) Three Months Ended March 31, 2016 Commercial $ 45,017 $ 329 Commercial real estate 57,956 458 Real estate construction and land development 2,068 25 Residential mortgage 28,092 366 Consumer installment 387 1 Home equity 3,252 15 Total $ 136,772 $ 1,194 Three Months Ended March 31, 2015 Commercial $ 38,576 $ 289 Commercial real estate 60,240 525 Real estate construction and land development 2,515 27 Residential mortgage 27,352 331 Consumer installment 499 — Home equity 2,352 8 Total $ 131,534 $ 1,180
Schedule representing the aging status of the recorded investment in loans by classes	The following schedule presents the aging status of the recorded investment in loans by classes of loans at March 31, 2016 , December 31, 2015 and March 31, 2015 : 31-60 Days Past Due 61-89 Days Past Due Accruing Loans Past Due 90 Days or More Non-accrual Loans Total Past Due Current Total Loans (In thousands) March 31, 2016 Originated Portfolio: Commercial $ 4,069 $ 7,359 $ 370 $ 19,264 $ 31,062 $ 1,532,862 $ 1,563,924 Commercial real estate 3,096 376 — 25,859 29,331 1,470,979 1,500,310 Real estate construction and land development 216 — — 546 762 198,906 199,668 Residential mortgage 757 23 423 5,062 6,265 1,255,903 1,262,168 Consumer installment 2,158 336 — 360 2,854 887,298 890,152 Home equity 1,632 323 679 2,328 4,962 580,530 585,492 Total $ 11,928 $ 8,417 $ 1,472 $ 53,419 $ 75,236 $ 5,926,478 $ 6,001,714 Acquired Portfolio: Commercial $ 55 $ 70 $ 1,582 $ — $ 1,707 $ 356,628 $ 358,335 Commercial real estate 249 557 4,459 — 5,265 637,476 642,741 Real estate construction and land development — — 1,159 — 1,159 42,072 43,231 Residential mortgage 301 — 1,877 — 2,178 196,774 198,952 Consumer installment 59 — 45 — 104 6,822 6,926 Home equity 543 511 997 — 2,051 112,935 114,986 Total $ 1,207 $ 1,138 $ 10,119 $ — $ 12,464 $ 1,352,707 $ 1,365,171 31-60 Days Past Due 61-89 Days Past Due Accruing Loans Past Due 90 Days or More Non-accrual Loans Total Past Due Current Total Loans (In thousands) December 31, 2015 Originated Portfolio: Commercial $ 3,685 $ 1,230 $ 364 $ 28,554 $ 33,833 $ 1,487,682 $ 1,521,515 Commercial real estate 4,168 1,603 254 25,163 31,188 1,392,871 1,424,059 Real estate construction and land development — — — 521 521 184,626 185,147 Residential mortgage 1,737 — 402 5,557 7,696 1,209,279 1,216,975 Consumer installment 3,145 644 — 451 4,240 865,186 869,426 Home equity 1,767 788 1,267 1,979 5,801 585,011 590,812 Total $ 14,502 $ 4,265 $ 2,287 $ 62,225 $ 83,279 $ 5,724,655 $ 5,807,934 Acquired Portfolio: Commercial $ 490 $ 532 $ 3,735 $ — $ 4,757 $ 379,607 $ 384,364 Commercial real estate 3,557 691 4,771 — 9,019 679,084 688,103 Real estate construction and land development — — 1,154 — 1,154 45,775 46,929 Residential mortgage 1,370 — 2,081 — 3,451 209,210 212,661 Consumer installment 55 — 47 — 102 7,929 8,031 Home equity 847 78 1,007 — 1,932 121,193 123,125 Total $ 6,319 $ 1,301 $ 12,795 $ — $ 20,415 $ 1,442,798 $ 1,463,213 March 31, 2015 Originated Portfolio: Commercial $ 10,121 $ 729 $ 52 $ 18,904 $ 29,806 $ 1,235,101 $ 1,264,907 Commercial real estate 7,238 2,267 148 24,766 34,419 1,237,929 1,272,348 Real estate construction and land development 340 — — 953 1,293 98,892 100,185 Residential mortgage 1,246 88 172 6,514 8,020 999,552 1,007,572 Consumer installment 2,143 344 — 433 2,920 832,439 835,359 Home equity 1,728 197 429 1,870 4,224 564,067 568,291 Total $ 22,816 $ 3,625 $ 801 $ 53,440 $ 80,682 $ 4,967,980 $ 5,048,662 Acquired Portfolio: Commercial $ 59 $ 5 $ 2,089 $ — $ 2,153 $ 89,109 $ 91,262 Commercial real estate 1,784 138 6,271 — 8,193 336,382 344,575 Real estate construction and land development — — 1,537 — 1,537 7,117 8,654 Residential mortgage 104 — 868 — 972 108,901 109,873 Consumer installment 3 1 11 — 15 8,692 8,707 Home equity 349 234 455 — 1,038 90,103 91,141 Total $ 2,299 $ 378 $ 11,231 $ — $ 13,908 $ 640,304 $ 654,212
Schedule of Corporation's TDRs	The following schedule presents the Corporation’s TDRs at March 31, 2016 , December 31, 2015 and March 31, 2015 : Performing TDRs Non-Performing TDRs Nonaccrual TDRs Total (In thousands) March 31, 2016 Commercial loan portfolio $ 31,896 $ 15,351 $ 29,368 $ 76,615 Consumer loan portfolio 17,990 3,013 3,146 24,149 Total $ 49,886 $ 18,364 $ 32,514 $ 100,764 December 31, 2015 Commercial loan portfolio $ 29,844 $ 16,297 $ 32,682 $ 78,823 Consumer loan portfolio 17,966 3,071 3,251 24,288 Total $ 47,810 $ 19,368 $ 35,933 $ 103,111 March 31, 2015 Commercial loan portfolio $ 28,784 $ 15,810 $ 32,917 $ 77,511 Consumer loan portfolio 17,197 2,690 4,426 24,313 Total $ 45,981 $ 18,500 $ 37,343 $ 101,824
Schedule providing information on TDRs	The following schedule provides information on the Corporation's TDRs that were modified during the three months ended March 31, 2016 and 2015 : Number of Loans Pre- Modification Recorded Investment Post- Modification Recorded Investment (Dollars in thousands) Three Months Ended March 31, 2016 Commercial loan portfolio: Commercial 7 $ 3,832 $ 3,832 Commercial real estate 4 987 987 Subtotal – commercial loan portfolio 11 4,819 4,819 Consumer loan portfolio 7 204 204 Total 18 $ 5,023 $ 5,023 Three Months Ended March 31, 2015 Commercial loan portfolio: Commercial 5 $ 1,932 $ 1,932 Commercial real estate 5 2,534 2,534 Subtotal – commercial loan portfolio 10 4,466 4,466 Consumer loan portfolio 10 336 336 Total 20 $ 4,802 $ 4,802
Troubled debt restructurings on financing receivables with defaults payment	The following schedule includes TDRs for which there was a payment default during the three months ended March 31, 2016 and 2015 , 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: Number of Loans Principal Balance at End of Period (Dollars in thousands) Three Months Ended March 31, 2016 Commercial loan portfolio: Commercial — $ — Commercial real estate 1 933 Subtotal – commercial loan portfolio 1 933 Consumer loan portfolio 1 — Total 2 $ 933 Three Months Ended March 31, 2015 Commercial loan portfolio: Commercial — $ — Commercial real estate 3 759 Subtotal – commercial loan portfolio 3 759 Consumer loan portfolio 1 33 Total 4 $ 792
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 three months ended March 31, 2016 and details regarding the balance in the allowance and the recorded investment in loans at March 31, 2016 by impairment evaluation method. Commercial Loan Portfolio Consumer Loan Portfolio Unallocated Total (In thousands) Changes in allowance for loan losses for the three months ended March 31, 2016: Beginning balance $ 47,234 $ 26,094 $ — $ 73,328 Provision for loan losses 1,000 500 — 1,500 Charge-offs (3,896 ) (1,562 ) — (5,458 ) Recoveries 330 618 — 948 Ending balance $ 44,668 $ 25,650 $ — $ 70,318 Allowance for loan losses balance at March 31, 2016 attributable to: Loans individually evaluated for impairment $ 2,736 $ 180 $ — $ 2,916 Loans collectively evaluated for impairment 41,932 25,470 — 67,402 Loans acquired with deteriorated credit quality — — — — Total $ 44,668 $ 25,650 $ — $ 70,318 Recorded investment (loan balance) at March 31, 2016: Loans individually evaluated for impairment $ 92,916 $ 21,003 $ — $ 113,919 Loans collectively evaluated for impairment 3,170,986 2,716,809 — 5,887,795 Loans acquired with deteriorated credit quality 1,044,307 320,864 — 1,365,171 Total $ 4,308,209 $ 3,058,676 $ — $ 7,366,885 The following schedule presents, by loan portfolio segment, details regarding the balance in the allowance and the recorded investment in loans at December 31, 2015 by impairment evaluation method. Commercial Loan Portfolio Consumer Loan Portfolio Unallocated Total (In thousands) Allowance for loan losses balance at December 31, 2015 attributable to: Loans individually evaluated for impairment $ 6,197 $ 192 $ — $ 6,389 Loans collectively evaluated for impairment 41,037 25,902 — 66,939 Loans acquired with deteriorated credit quality — — — — Total $ 47,234 $ 26,094 $ — $ 73,328 Recorded investment (loan balance) at December 31, 2015: Loans individually evaluated for impairment $ 100,379 $ 21,037 $ — $ 121,416 Loans collectively evaluated for impairment 3,030,342 2,656,176 — 5,686,518 Loans acquired with deteriorated credit quality 1,119,396 343,817 — 1,463,213 Total $ 4,250,117 $ 3,021,030 $ — $ 7,271,147 The following schedule presents, by loan portfolio segment, the changes in the allowance for the three months ended March 31, 2015 and details regarding the balance in the allowance and the recorded investment in loans at March 31, 2015 by impairment evaluation method. Commercial Loan Portfolio Consumer Loan Portfolio Unallocated Total (In thousands) Changes in allowance for loan losses for the three months ended March 31, 2015: Beginning balance $ 44,156 $ 28,803 $ 2,724 $ 75,683 Provision for loan losses 3,593 (3,227 ) 1,134 1,500 Charge-offs (1,504 ) (1,639 ) — (3,143 ) Recoveries 574 642 — 1,216 Ending balance $ 46,819 $ 24,579 $ 3,858 $ 75,256 Allowance for loan losses balance at March 31, 2015 attributable to: Loans individually evaluated for impairment $ 1,615 $ 297 $ — $ 1,912 Loans collectively evaluated for impairment 45,204 24,282 3,858 73,344 Loans acquired with deteriorated credit quality — — — — Total $ 46,819 $ 24,579 $ 3,858 $ 75,256 Recorded investment (loan balance) at March 31, 2015: Loans individually evaluated for impairment $ 89,217 $ 19,887 $ — $ 109,104 Loans collectively evaluated for impairment 2,548,223 2,391,335 — 4,939,558 Loans acquired with deteriorated credit quality 444,491 209,721 — 654,212 Total $ 3,081,931 $ 2,620,943 $ — $ 5,702,874

Intangible Assets (Tables)

Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Net carrying value of intangible assets	The following table shows the net carrying value of the Corporation’s intangible assets: March 31, December 31, March 31, (In thousands) Goodwill $ 286,867 $ 287,393 $ 180,128 Other intangible assets: Core deposit intangible assets $ 25,542 $ 26,654 $ 20,072 Non-compete intangible assets 246 328 — Mortgage servicing rights 10,478 11,122 11,583 Total other intangible assets $ 36,266 $ 38,104 $ 31,655
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets	The following table sets forth the carrying amount, accumulated amortization and amortization expense of core deposit intangible assets that are amortizable and arose from business combinations or other acquisitions: March 31, December 31, March 31, (In thousands) Gross original amount $ 40,055 $ 40,055 $ 30,122 Accumulated amortization 14,513 13,401 10,050 Carrying amount $ 25,542 $ 26,654 $ 20,072 Amortization expense for the three months ended March 31 $ 1,112 $ 791
Net carrying value, fair value of MSRs and loans Corporation servicing for others	The following shows the net carrying value and fair value of MSRs and the total loans that the Corporation is servicing for others: March 31, December 31, March 31, (In thousands) Net carrying value of MSRs $ 10,478 $ 11,122 $ 11,583 Fair value of MSRs $ 13,909 $ 15,542 $ 14,378 Loans serviced for others that have servicing rights capitalized $ 2,047,435 $ 2,082,899 $ 2,062,544
Activity for capitalized MSRs	The following table shows the activity for capitalized MSRs: Three Months Ended March 31, 2016 2015 (In thousands) Balance at beginning of period $ 11,122 $ 12,217 Additions 331 400 Amortization (975 ) (1,034 ) Balance at end of period $ 10,478 $ 11,583

Accumulated Other Comprehensi28

Accumulated Other Comprehensive Loss (Tables)	3 Months Ended
	Mar. 31, 2016
Equity [Abstract]
Components of accumulated other comprehensive loss, net of related tax benefit/expense	The components of accumulated other comprehensive loss, net of related tax benefit/expense, were as follows: March 31, December 31, March 31, (In thousands) Net unrealized gains (losses) on investment securities – available-for-sale, net of related tax expense (benefit) of $446 at March 31, 2016, $(1,017) at December 31, 2015 and $946 at March 31, 2015 $ 829 $ (1,888 ) $ 1,758 Pension and other postretirement benefits adjustment, net of related tax benefit of $14,818 at March 31, 2016, $14,616 at December 31, 2015 and $16,981 at March 31, 2015 (27,519 ) (27,144 ) (31,537 ) Accumulated other comprehensive loss $ (26,690 ) $ (29,032 ) $ (29,779 )

Borrowings Borrowings (Tables)

Borrowings Borrowings (Tables)	3 Months Ended
	Mar. 31, 2016
Borrowings [Abstract]
Schedule of Other Borrowings [Table Text Block]	A summary of the Corporation's long-term borrowings follows: March 31, December 31, March 31, (In thousands) Long-term borrowings: Long-term FHLB advances $ 231,357 $ 181,394 $ — Securities sold under agreements to repurchase 17,365 17,453 — Non-revolving line-of-credit 25,000 25,000 — Subordinated debt obligations — 18,544 — Total long-term borrowings $ 273,722 $ 242,391 $ —

Regulatory Capital (Tables)

Regulatory Capital (Tables)	3 Months Ended
	Mar. 31, 2016
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 Required to be Well Capitalized Under Prompt Corrective Action Regulations Capital Amount Ratio Capital Amount Ratio Capital Amount Ratio (Dollars in thousands) March 31, 2016 Total Capital to Risk-Weighted Assets: Corporation $ 832,457 11.5 % $ 577,668 8.0 % N/A N/A Chemical Bank 840,372 11.7 576,068 8.0 $ 720,086 10.0 % Tier 1 Capital to Risk-Weighted Assets: Corporation 762,139 10.6 433,251 6.0 N/A N/A Chemical Bank 770,054 10.7 432,051 6.0 576,068 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets: Corporation 762,139 10.6 324,938 4.5 N/A N/A Chemical Bank 770,054 10.7 324,038 4.5 468,056 6.5 Leverage Ratio: Corporation 762,139 8.5 357,773 4.0 N/A N/A Chemical Bank 770,054 8.6 357,190 4.0 446,488 5.0 December 31, 2015 Total Capital to Risk-Weighted Assets: Corporation $ 841,257 11.8 % $ 571,509 8.0 % N/A N/A Chemical Bank 830,294 11.7 570,073 8.0 $ 712,591 10.0 % Tier 1 Capital to Risk-Weighted Assets: Corporation 767,929 10.7 428,631 6.0 N/A N/A Chemical Bank 756,966 10.6 427,555 6.0 570,073 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets: Corporation 753,815 10.6 321,474 4.5 N/A N/A Chemical Bank 756,966 10.6 320,666 4.5 463,184 6.5 Leverage Ratio: Corporation 767,929 8.6 356,396 4.0 N/A N/A Chemical Bank 756,966 8.5 355,911 4.0 444,888 5.0 March 31, 2015 Total Capital to Risk-Weighted Assets: Corporation $ 727,090 13.0 % $ 446,173 8.0 % N/A N/A Chemical Bank 676,488 12.1 445,471 8.0 $ 556,838 10.0 % Tier 1 Capital to Risk-Weighted Assets: Corporation 657,307 11.8 334,630 6.0 N/A N/A Chemical Bank 606,813 10.9 334,103 6.0 445,471 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets: Corporation 657,307 11.8 250,972 4.5 N/A N/A Chemical Bank 606,813 10.9 250,577 4.5 361,945 6.5 Leverage Ratio: Corporation 657,307 9.1 289,948 4.0 N/A N/A Chemical Bank 606,813 8.4 289,840 4.0 362,300 5.0

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2016
Fair Value Disclosures [Abstract]
Summary of assets measured at fair value on a recurring basis	For assets measured at fair value on a recurring basis, quantitative disclosures about the fair value measurements for each major category of assets were as follows: Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (In thousands) March 31, 2016 Investment securities – available-for-sale: U.S. Treasury securities $ 5,797 $ — $ — $ 5,797 Government sponsored agencies — 177,637 — 177,637 State and political subdivisions — 15,061 — 15,061 Residential mortgage-backed securities — 179,149 — 179,149 Collateralized mortgage obligations — 118,398 — 118,398 Corporate bonds — 14,708 — 14,708 Preferred stock and trust preferred securities — 3,265 — 3,265 Total investment securities – available-for-sale 5,797 508,218 — 514,015 Loans held-for-sale — 9,667 — 9,667 Total assets measured at fair value on a recurring basis $ 5,797 $ 517,885 $ — $ 523,682 December 31, 2015 Investment securities – available-for-sale: U.S. Treasury securities $ 5,765 $ — $ — $ 5,765 Government sponsored agencies — 194,989 — 194,989 State and political subdivisions — 15,120 — 15,120 Residential mortgage-backed securities — 187,768 — 187,768 Collateralized mortgage obligations — 132,230 — 132,230 Corporate bonds — 14,627 — 14,627 Preferred stock and trust preferred securities — 3,232 — 3,232 Total investment securities – available-for-sale 5,765 547,966 — 553,731 Loans held-for-sale — 10,327 — 10,327 Total assets measured at fair value on a recurring basis $ 5,765 $ 558,293 $ — $ 564,058 March 31, 2015 Investment securities – available-for-sale: U.S. Treasury securities $ 8,302 $ — $ — $ 8,302 Government sponsored agencies — 250,430 — 250,430 State and political subdivisions — 32,322 — 32,322 Residential mortgage-backed securities — 219,601 — 219,601 Collateralized mortgage obligations — 133,300 — 133,300 Corporate bonds — 34,997 — 34,997 Preferred stock — 1,692 — 1,692 Total investment securities – available-for-sale 8,302 672,342 — 680,644 Loans held-for-sale — 9,675 — 9,675 Total assets measured at fair value on a recurring basis $ 8,302 $ 682,017 $ — $ 690,319
Summary of assets measured at fair value on a nonrecurring basis	For assets measured at fair value on a nonrecurring basis, quantitative disclosures about fair value measurements for each major category of assets were as follows: Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (In thousands) March 31, 2016 Impaired originated loans $ — $ — $ 30,925 $ 30,925 Other real estate/repossessed assets — — 9,248 9,248 Total $ — $ — $ 40,173 $ 40,173 December 31, 2015 Impaired originated loans $ — $ — $ 42,065 $ 42,065 Other real estate/repossessed assets — — 9,935 9,935 Total $ — $ — $ 52,000 $ 52,000 March 31, 2015 Impaired originated loans $ — $ — $ 23,730 $ 23,730 Other real estate/repossessed assets — — 14,744 14,744 Mortgage servicing rights — — 8,115 8,115 Total $ — $ — $ 46,589 $ 46,589
Summary of carrying amounts and estimated fair values of the financial instruments	A summary of carrying amounts and estimated fair values of the Corporation’s financial instruments included in the consolidated statements of financial position was as follows: Level in Fair Value Measurement Hierarchy March 31, 2016 December 31, 2015 March 31, 2015 Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value (In thousands) Assets: Cash and cash equivalents Level 1 $ 291,374 $ 291,374 $ 238,789 $ 238,789 $ 393,938 $ 393,938 Investment securities: Available-for-sale Level 1 5,797 5,797 5,765 5,765 8,302 8,302 Available-for-sale Level 2 508,218 508,218 547,966 547,966 672,342 672,342 Held-to-maturity Level 2 517,800 525,308 509,471 512,405 370,950 372,876 Held-to-maturity Level 3 500 285 500 300 10,500 7,300 Nonmarketable equity securities NA 43,267 43,267 36,907 36,907 31,249 31,249 Loans held-for-sale Level 2 9,667 9,667 10,327 10,327 9,675 9,675 Net loans Level 3 7,296,567 7,297,375 7,197,819 7,201,994 5,627,618 5,633,217 Interest receivable Level 2 26,010 26,010 21,953 21,953 19,816 19,816 Liabilities: Deposits without defined maturities Level 2 $ 6,043,457 $ 6,043,457 $ 5,809,355 $ 5,809,355 $ 4,988,268 $ 4,988,268 Time deposits Level 3 1,606,659 1,609,073 1,647,412 1,647,412 1,332,085 1,335,605 Interest payable Level 2 1,632 1,632 1,578 1,578 779 779 Short-term borrowings Level 2 283,383 283,383 397,199 397,199 372,236 372,236 Long-term borrowings Level 2 256,357 257,993 206,394 206,394 — — Long-term borrowings Level 3 17,365 17,317 35,997 35,997 — —

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
Numerator and denominator of the basic and diluted earnings per common share computations	The following summarizes the numerator and denominator of the basic and diluted earnings per common share computations: Three Months Ended March 31, 2016 2015 (In thousands, except per share data) Numerator for both basic and diluted earnings per common share, net income $ 23,262 $ 17,835 Denominator for basic earnings per common share, weighted average common shares outstanding 38,198 32,809 Weighted average common stock equivalents 323 235 Denominator for diluted earnings per common share 38,521 33,044 Basic earnings per common share $ 0.61 $ 0.54 Diluted earnings per common share $ 0.60 $ 0.54

Share-Based Compensation (Table

Share-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of activity for Corporation's stock options	A summary of activity for the Corporation’s stock options as of and for the three months ended March 31, 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 Exercised — — — (70,885 ) 20.69 Vested (118,273 ) 28.30 8.40 — — Forfeited/expired (8,783 ) 32.21 6.66 (8,783 ) 32.21 Outstanding at March 31, 2016 793,866 $ 31.03 $ 7.22 1,416,238 $ 27.89 Exercisable/vested at March 31, 2016 622,372 $ 23.88
Assumptions of Black-Scholes option pricing model	The fair value of the stock options granted during the three months ended March 31, 2016 was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions. Expected dividend yield 3.30 % Risk-free interest rate 1.39 % Expected stock price volatility 27.9 % Expected life of options – in years 6.5 Weighted average fair value of options granted $ 6.15
Summary of activity for restricted stock performance units	A summary of the activity for restricted stock units as of and for the three months ended March 31, 2016 is presented below: Number of Units Weighted- Average Grant Date Fair Value Per Unit Outstanding at December 31, 2015 207,989 $ 26.41 Granted 98,425 30.40 Converted into shares of common stock (42,812 ) 22.47 Forfeited/expired (1,116 ) 30.29 Outstanding at March 31, 2016 262,486 $ 28.53

Pension and Other Postretirem34

Pension and Other Postretirement Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Components of net periodic benefit cost (income) for the Corporation's qualified and nonqualified pension plans and nonqualified postretirement benefits plan	The components of net periodic benefit cost for the Corporation’s qualified and nonqualified pension plans and nonqualified postretirement benefit plan are as follows: Three Months Ended March 31, 2016 2015 (In thousands) Defined Benefit Pension Plans Service cost $ 277 $ 273 Interest cost 1,358 1,332 Expected return on plan assets (2,141 ) (2,161 ) Amortization of prior service credit — (1 ) Amortization of unrecognized net loss 572 1,056 Net periodic benefit cost $ 66 $ 499 Postretirement Benefit Plan Service cost $ 2 $ 4 Interest cost 33 33 Amortization of prior service cost 29 32 Amortization of unrecognized net gain (24 ) — Net periodic benefit cost $ 40 $ 69

Significant Accounting Polici35

Significant Accounting Policies (Details)	May. 31, 2015USD ($)	Apr. 01, 2015USD ($)	Mar. 31, 2016USD ($)BankPoolsshares	Mar. 31, 2015USD ($)shares	Dec. 31, 2015USD ($)shares	Apr. 20, 2015shares	Apr. 20, 2009shares	Jan. 31, 2008shares
Business Acquisition [Line Items]
Number of banks through which company operates | Bank			1
Number of regional banking units Chemical Bank operates through | Bank			4
Number of minimum days when principal or interest is past due is placed in nonaccrual category			90 days
Number of minimum days in real estate residential loan when principal or interest is past due is placed in nonaccrual category			120 days
Time period in which payments receive consistently and loans are returned to accrual status			6 months
Time period sustained for payment history of principal and interest payments to move them to performing status			6 months
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
Minimum number of days past due as to interest or principal payments in accruing loans moves to nonperforming loans			90 days
Minimum amount of loan reviewed for detailed credit quality			$ 250,000
Time period for historical loan loss experience			5 years
Minimum percentage of tax benefit is recognized for the amount likely to be realized			50.00%
Reserve for contingent income tax liabilities recorded			$ 0	$ 0	$ 0
Expense related to qualified affordable housing projects			600,000	100,000
Remaining investment in qualified affordable housing projects			21,100,000	4,800,000	21,700,000
Equity Method Investments			1,500,000	0	1,700,000
Variable Interest Entity, Reporting Entity Involvement, Unfunded Obligation, Amount			4,200,000		8,000,000
Impairment on tax credit projects			$ 0	$ 0	$ 0
Number of shares authorized to be repurchased | shares								500,000
Stock repurchased (shares) | shares			0
Number of remaining shares authorized to be repurchased (shares) | shares			500,000
Preferred stock, shares authorized | shares			2,000,000	200,000	2,000,000	2,000,000	200,000
Preferred stock, shares issued | shares			0	0	0
Preferred stock, shares outstanding | shares			0
Common Stock, Shares, Issued | shares			38,248,489	32,847,063	38,167,861
Common Stock, Shares Authorized | shares			60,000,000	45,000,000	60,000,000	60,000,000
Goodwill			$ 286,867,000	$ 180,128,000	$ 287,393,000
Lake Michigan Financial Corp [Member]
Business Acquisition [Line Items]
Number of pools of aggregate acquired loans based upon common risk characteristics | Pools			2
Monarch Community Bancorp [Member]
Business Acquisition [Line Items]
Number of pools of aggregate acquired loans based upon common risk characteristics | Pools			2
Northwestern Bancorp [Member]
Business Acquisition [Line Items]
Number of pools of aggregate acquired loans based upon common risk characteristics | Pools			4
OAK [Member]
Business Acquisition [Line Items]
Number of pools of aggregate acquired loans based upon common risk characteristics | Pools			14
Monarch Community Bancorp [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred		$ 27,200,000
Goodwill		$ 5,300,000
Lake Michigan Financial Corp [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 187,400,000
Business Combination, Consideration Transferred, Value of Stock and Options Issued	132,900,000
Business Combination, Consideration Transferred, Cash Paid for Outstanding Stock	54,500,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	8,600,000
Goodwill	$ 101,000,000

Acquisitions (Activity for Acqu

Acquisitions (Activity for Acquired Loans) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period		$ 298,257	$ 137,961
Accretable Yield Additions, Net of Reductions	[1]	(6,681)	(696)
Accretion recognized in interest income		(16,962)	(8,205)
Balance at end of period		274,614	129,060
Northwestern Bancorp [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period		82,623	104,675
Accretable Yield Additions, Net of Reductions	[1]	(2,254)	(1,410)
Accretion recognized in interest income		(4,001)	(4,998)
Balance at end of period		76,368	98,267
OAK [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period		28,077	33,286
Accretable Yield Additions, Net of Reductions	[1]	1,516	714
Accretion recognized in interest income		(2,557)	(3,207)
Balance at end of period		27,036	$ 30,793
Lake Michigan Financial Corp [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period		152,999
Accretable Yield Additions, Net of Reductions	[1]	(6,071)
Accretion recognized in interest income		(8,953)
Balance at end of period		137,975
Monarch Community Bancorp [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period		34,558
Accretable Yield Additions, Net of Reductions	[1]	128
Accretion recognized in interest income		(1,451)
Balance at end of period		$ 33,235
[1]	Represents additions of estimated contractual interest expected to be collected from acquired loans being renewed or extended, less reductions in contractual interest resulting from the early payoff of acquired loans.

Acquisitions (Textual) (Details

Acquisitions (Textual) (Details)	Jan. 25, 2016USD ($)Offices$ / shares	May. 31, 2015USD ($)Offices$ / sharesshares	Apr. 01, 2015USD ($)shares	Oct. 31, 2014USD ($)Offices	Dec. 07, 2012USD ($)Branches	Apr. 30, 2010USD ($)Offices	Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Mar. 31, 2015USD ($)
Business Acquisition [Line Items]
Goodwill							$ 286,867,000	$ 287,393,000	$ 180,128,000
Talmer Bancorp, Inc. [Member]
Business Acquisition [Line Items]
Business Acquisition, Share Price | $ / shares	$ 1.61
Exchange Ratio of Common Stock Issued, Business Combinations	0.4725
Acquisition purchase price	$ 1,100,000,000
Assets of acquiree company	6,600,000,000
Brokered deposits of acquiree company	229,000,000
Business Combination, Acquired Receivables, Fair Value	$ 4,800,000,000
Service provided by acquiree bank through number of branches | Offices	80
Deposits of acquiree company	$ 5,000,000,000
Lake Michigan Financial Corp [Member]
Business Acquisition [Line Items]
Business Acquisition, Share Price | $ / shares		$ 16.64
Exchange Ratio of Common Stock Issued, Business Combinations		1.326
Acquisition purchase price		$ 187,400,000
Assets of acquiree company		1,240,000,000
Business Combination, Acquired Receivables, Gross Contractual Amount		1,010,000,000
Expected Principal Cash Flows of Contractually Required Acquired Loan Portfolio		986,100,000
Expected Interest Cash Flows of Contractually Required Acquired Loan Portfolio		189,600,000
Business Combination, Acquired Receivables, Fair Value		985,500,000
Certain Loans Acquired in Transfer, Nonaccretable Difference		$ 22,600,000
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares		4,322,101
Goodwill		$ 101,000,000
Service provided by acquiree bank through number of branches | Offices		5
Deposits of acquiree company		$ 925,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		8,600,000
Business Combination, Provision Information, Initial Accounting Incomplete, Goodwill							500,000
Outstanding contractual principal balance of acquired loan portfolio							804,000,000	864,000,000
Carrying amount of acquired loan portfolio							782,000,000	842,000,000
Interest Payments Receivable of Acquired Loan Portfolio		190,200,000
Business Combination, Acquired Receivables, Estimated Uncollectible		22,000,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Disposals of Loans		190,200,000
Business Combination, Consideration Transferred, Value of Stock and Options Issued		132,900,000
Business Combination, Consideration Transferred, Cash Paid for Outstanding Stock		$ 54,500,000
Monarch Community Bancorp [Member]
Business Acquisition [Line Items]
Exchange Ratio of Common Stock Issued, Business Combinations			0.0982
Acquisition purchase price			$ 27,200,000
Assets of acquiree company			183,000,000
Purchase Accounting Fair Value Adjustment, Core Deposit Intangible Asset			1,900,000
Business Combination, Acquired Receivables, Gross Contractual Amount			128,900,000
Expected Principal Cash Flows of Contractually Required Acquired Loan Portfolio			122,600,000
Expected Interest Cash Flows of Contractually Required Acquired Loan Portfolio			37,100,000
Business Combination, Acquired Receivables, Fair Value			121,800,000
Certain Loans Acquired in Transfer, Nonaccretable Difference			$ 7,100,000
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares			860,575
Goodwill			$ 5,300,000
Deposits of acquiree company			144,000,000
Outstanding contractual principal balance of acquired loan portfolio							107,000,000	115,000,000
Carrying amount of acquired loan portfolio							101,000,000	108,000,000
Interest Payments Receivable of Acquired Loan Portfolio			37,800,000
Business Combination, Acquired Receivables, Estimated Uncollectible			6,300,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Disposals of Loans			$ 37,900,000
Northwestern Bancorp [Member]
Business Acquisition [Line Items]
Acquisition purchase price				$ 121,000,000
Assets of acquiree company				815,000,000
Business Combination, Acquired Receivables, Gross Contractual Amount				507,000,000
Expected Principal Cash Flows of Contractually Required Acquired Loan Portfolio				481,000,000
Expected Interest Cash Flows of Contractually Required Acquired Loan Portfolio				104,000,000
Business Combination, Acquired Receivables, Fair Value				475,000,000
Certain Loans Acquired in Transfer, Nonaccretable Difference				34,000,000
Goodwill				60,300,000
Intangibles acquired				$ 12,900,000
Service provided by acquiree bank through number of branches | Offices				25
Deposits of acquiree company				$ 794,000,000
Outstanding contractual principal balance of acquired loan portfolio							336,000,000	361,000,000	453,000,000
Carrying amount of acquired loan portfolio							305,000,000	330,000,000	421,000,000
Interest Payments Receivable of Acquired Loan Portfolio				112,000,000
Business Combination, Acquired Receivables, Estimated Uncollectible				26,000,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Disposals of Loans				$ 110,000,000
Independent Bank [Member]
Business Acquisition [Line Items]
Acquisition purchase price					$ 8,100,000
Loans acquired					44,000,000
Deposits acquired					$ 404,000,000
Number of branches acquired (branches) | Branches					21
Premium paid on deposits purchased					$ 11,500,000
Premium paid as a percentage of deposits purchased (percent)					2.85%
Discount on loans purchased (percent)					1.75%
Goodwill					$ 6,800,000
Independent Bank [Member] | Core Deposits [Member]
Business Acquisition [Line Items]
Intangibles acquired					$ 5,600,000
OAK [Member]
Business Acquisition [Line Items]
Acquisition purchase price						$ 83,700,000
Assets of acquiree company						820,000,000
Loans acquired						627,000,000
Brokered deposits of acquiree company						$ 193,000,000
Service provided by acquiree bank through number of branches | Offices						14
Deposits of acquiree company						$ 693,000,000
Contractually required principal payments of loan portfolio, acquisition date						683,000,000
Acquired loan portfolio acquisition date fair value						$ 627,000,000
Outstanding contractual principal balance of acquired loan portfolio							196,000,000	204,000,000	255,000,000
Carrying amount of acquired loan portfolio							$ 178,000,000	$ 183,000,000	$ 234,000,000

Investment Securities (Summary

Investment Securities (Summary of Amortized Cost and Fair Value of Available-For-Sale Investment Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	$ 512,740	$ 556,636	$ 677,940
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	2,581	1,468	3,646
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	1,306	4,373	942
Available-for-sale Securities, Total	514,015	553,731	680,644
US Treasury Securities [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	5,777	5,773	8,271
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	20	0	31
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	8	0
Available-for-sale Securities, Total	5,797	5,765	8,302
Government sponsored agencies [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	177,537	195,711	249,642
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	591	78	889
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	491	800	101
Available-for-sale Securities, Total	177,637	194,989	250,430
State and political subdivisions [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	14,707	14,731	31,701
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	356	395	624
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	2	6	3
Available-for-sale Securities, Total	15,061	15,120	32,322
Residential mortgage-backed securities [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	178,498	189,452	218,299
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	899	538	1,358
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	248	2,222	56
Available-for-sale Securities, Total	179,149	187,768	219,601
Collateralized Mortgage Obligations [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	118,501	133,256	133,713
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	338	111	305
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	441	1,137	718
Available-for-sale Securities, Total	118,398	132,230	133,300
Corporate bonds [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	14,832	14,825	34,925
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0	2	136
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	124	200	64
Available-for-sale Securities, Total	14,708	14,627	34,997
Preferred stock [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	2,888	2,888	1,389
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	377	344	303
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	0	0
Available-for-sale Securities, Total	$ 3,265	$ 3,232	$ 1,692

Investment Securities (Summar39

Investment Securities (Summary of Amortized Cost and Fair Value of Held-To-Maturity Investment Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Held-to-maturity Securities
Investment securities held-to-maturity, Amortized Cost	$ 518,300	$ 509,971	$ 381,450
Investment securities held-to-maturity, Unrealized Gains	9,493	7,446	6,852
Investment securities held-to-maturity, Unrealized Losses	2,200	4,712	8,126
Total Held-to-maturity securities, Debt maturities, Fair Value	525,593	512,705	380,176
State and political subdivisions [Member]
Held-to-maturity Securities
Investment securities held-to-maturity, Amortized Cost	517,800	509,471	370,950
Investment securities held-to-maturity, Unrealized Gains	9,493	7,446	6,852
Investment securities held-to-maturity, Unrealized Losses	1,985	4,512	4,926
Total Held-to-maturity securities, Debt maturities, Fair Value	525,308	512,405	372,876
Trust Preferred Securities [Member]
Held-to-maturity Securities
Investment securities held-to-maturity, Amortized Cost	500	500	10,500
Investment securities held-to-maturity, Unrealized Gains	0	0	0
Investment securities held-to-maturity, Unrealized Losses	215	200	3,200
Total Held-to-maturity securities, Debt maturities, Fair Value	$ 285	$ 300	$ 7,300

Investment Securities (Maturiti

Investment Securities (Maturities of Debt Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Investment Securities Available-for-Sale:
Due in one year or less, Amortized Cost	$ 167,082
Due after one year through five years, Amortized Cost	293,731
Due after five years through ten years, Amortized Cost	45,820
Due after ten years, Amortized Cost	4,719
Preferred stock, Amortized Cost	1,388
Total Available-for-sale Securities, Debt Maturities, Amortized Cost	512,740
Due in one year or less , Fair Value	167,114
Due after one year through five years, Fair Value	294,443
Due after five years through ten years, Fair Value	45,935
Due after ten years, Fair Value	4,757
Preferred stock, Fair Value	1,766
Total Available-for-sale securities, Debt maturities, Fair Value	514,015
Investment Securities Held-to-Maturity:
Due in one year or less, Amortized Cost	57,074
Due after one year through five years, Amortized Cost	239,496
Due after five years through ten years, Amortized Cost	142,968
Due after ten years, Amortized Cost	78,762
Total Held-to-maturity securities, Debt maturities, Amortized Cost	518,300	$ 509,971	$ 381,450
Due in one year or less , Fair Value	57,148
Due after one year through five years, Fair Value	241,445
Due after five years through ten years, Fair Value	145,988
Due after ten years, Fair Value	81,012
Total Held-to-maturity securities, Debt maturities, Fair Value	$ 525,593	$ 512,705	$ 380,176

Investment Securities (Summar41

Investment Securities (Summary of Investment Securities with Gross Unrealized Losses) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	$ 175,300	$ 554,907	$ 293,885
Less Than 12 Months, Gross Unrealized Losses	1,238	5,945	2,114
12 Months or More, Fair Value	221,011	133,159	135,889
12 Months or More, Gross Unrealized Losses	2,268	3,140	6,954
Total, Fair Value	396,311	688,066	429,774
Total, Gross Unrealized Losses	3,506	9,085	9,068
Government sponsored agencies [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	2,501	114,640	27,889
Less Than 12 Months, Gross Unrealized Losses	1	292	64
12 Months or More, Fair Value	20,275	21,681	18,896
12 Months or More, Gross Unrealized Losses	490	508	37
Total, Fair Value	22,776	136,321	46,785
Total, Gross Unrealized Losses	491	800	101
State and political subdivisions [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	83,997	195,285	156,010
Less Than 12 Months, Gross Unrealized Losses	1,067	2,891	1,989
12 Months or More, Fair Value	96,143	68,361	49,839
12 Months or More, Gross Unrealized Losses	920	1,627	2,940
Total, Fair Value	180,140	263,646	205,849
Total, Gross Unrealized Losses	1,987	4,518	4,929
Residential mortgage-backed securities [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	54,163	169,226	82,303
Less Than 12 Months, Gross Unrealized Losses	63	2,146	28
12 Months or More, Fair Value	63,869	3,435	3,847
12 Months or More, Gross Unrealized Losses	185	76	28
Total, Fair Value	118,032	172,661	86,150
Total, Gross Unrealized Losses	248	2,222	56
Collateralized Mortgage Obligations [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	29,973	60,459	22,694
Less Than 12 Months, Gross Unrealized Losses	34	408	22
12 Months or More, Fair Value	35,489	39,382	41,061
12 Months or More, Gross Unrealized Losses	407	729	696
Total, Fair Value	65,462	99,841	63,755
Total, Gross Unrealized Losses	441	1,137	718
Corporate bonds [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	4,666	9,532	4,989
Less Than 12 Months, Gross Unrealized Losses	73	200	11
12 Months or More, Fair Value	4,950	0	14,946
12 Months or More, Gross Unrealized Losses	51	0	53
Total, Fair Value	9,616	9,532	19,935
Total, Gross Unrealized Losses	124	200	64
Trust Preferred Securities [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	0	0	0
Less Than 12 Months, Gross Unrealized Losses	0	0	0
12 Months or More, Fair Value	285	300	7,300
12 Months or More, Gross Unrealized Losses	215	200	3,200
Total, Fair Value	285	300	7,300
Total, Gross Unrealized Losses	$ 215	200	$ 3,200
US Treasury Securities [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value		5,765
Less Than 12 Months, Gross Unrealized Losses		8
12 Months or More, Fair Value		0
12 Months or More, Gross Unrealized Losses		0
Total, Fair Value		5,765
Total, Gross Unrealized Losses		$ 8

Investment Securities (Textual)

Investment Securities (Textual) (Details) $ in Millions	Dec. 31, 2015USD ($)
Schedule of Investments [Line Items]
Trust preferred investment security of Non Public bank company	$ 10

Loans (Summary of Loans) (Detai

Loans (Summary of Loans) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Summary of loans under portfolio
Commercial loan	$ 4,308,209	$ 4,250,117	$ 3,081,931
Consumer loan	3,058,676	3,021,030	2,620,943
Total loans	7,366,885	7,271,147	5,702,874
Commercial [Member]
Summary of loans under portfolio
Commercial loan	1,922,259	1,905,879	1,356,169
Real estate commercial [Member]
Summary of loans under portfolio
Commercial loan	2,143,051	2,112,162	1,616,923
Real estate construction [Member]
Summary of loans under portfolio
Commercial loan	242,899	232,076	108,839
Real estate residential [Member]
Summary of loans under portfolio
Consumer loan	1,461,120	1,429,636	1,117,445
Consumer installment [Member]
Summary of loans under portfolio
Consumer loan	897,078	877,457	844,066
Home equity [Member]
Summary of loans under portfolio
Consumer loan	$ 700,478	$ 713,937	$ 659,432

Loans (Summary of Recorded Inve

Loans (Summary of Recorded Investment of Commercial Loans by Risk Rating Categories) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	$ 4,308,209	$ 4,250,117	$ 3,081,931
Commercial [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,922,259	1,905,879	1,356,169
Real estate commercial [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	2,143,051	2,112,162	1,616,923
Real estate construction [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	242,899	232,076	108,839
Originated Portfolio [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	3,263,902	3,130,721	2,637,440
Originated Portfolio [Member] | Risk Grades 1-5 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	3,073,067	2,942,826	2,447,891
Originated Portfolio [Member] | Risk Grade 6 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	88,502	65,943	85,985
Originated Portfolio [Member] | Risk Grade 7 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	56,664	67,714	58,941
Originated Portfolio [Member] | Risk Grade 8 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	43,999	52,143	44,617
Originated Portfolio [Member] | Risk Grade 9 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,670	2,095	6
Originated Portfolio [Member] | Commercial [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,563,924	1,521,515	1,264,907
Originated Portfolio [Member] | Commercial [Member] | Risk Grades 1-5 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,466,094	1,418,301	1,176,021
Originated Portfolio [Member] | Commercial [Member] | Risk Grade 6 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	43,129	34,727	40,999
Originated Portfolio [Member] | Commercial [Member] | Risk Grade 7 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	35,437	39,933	28,983
Originated Portfolio [Member] | Commercial [Member] | Risk Grade 8 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	17,595	26,459	18,904
Originated Portfolio [Member] | Commercial [Member] | Risk Grade 9 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,669	2,095	0
Originated Portfolio [Member] | Real estate commercial [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,500,310	1,424,059	1,272,348
Originated Portfolio [Member] | Real estate commercial [Member] | Risk Grades 1-5 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,409,991	1,341,202	1,175,373
Originated Portfolio [Member] | Real estate commercial [Member] | Risk Grade 6 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	44,210	31,036	44,248
Originated Portfolio [Member] | Real estate commercial [Member] | Risk Grade 7 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	20,250	26,658	27,961
Originated Portfolio [Member] | Real estate commercial [Member] | Risk Grade 8 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	25,858	25,163	24,760
Originated Portfolio [Member] | Real estate commercial [Member] | Risk Grade 9 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1	0	6
Originated Portfolio [Member] | Real estate construction [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	199,668	185,147	100,185
Originated Portfolio [Member] | Real estate construction [Member] | Risk Grades 1-5 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	196,982	183,323	96,497
Originated Portfolio [Member] | Real estate construction [Member] | Risk Grade 6 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,163	180	738
Originated Portfolio [Member] | Real estate construction [Member] | Risk Grade 7 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	977	1,123	1,997
Originated Portfolio [Member] | Real estate construction [Member] | Risk Grade 8 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	546	521	953
Originated Portfolio [Member] | Real estate construction [Member] | Risk Grade 9 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	0	0	0
Acquired Portfolio [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,044,307	1,119,396	444,491
Acquired Portfolio [Member] | Risk Grades 1-5 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	949,083	1,011,895	396,259
Acquired Portfolio [Member] | Risk Grade 6 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	45,209	54,803	19,338
Acquired Portfolio [Member] | Risk Grade 7 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	43,055	43,119	19,384
Acquired Portfolio [Member] | Risk Grade 8 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	6,960	9,579	9,510
Acquired Portfolio [Member] | Risk Grade 9 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	0	0	0
Acquired Portfolio [Member] | Commercial [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	358,335	384,364	91,262
Acquired Portfolio [Member] | Commercial [Member] | Risk Grades 1-5 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	319,672	340,782	71,422
Acquired Portfolio [Member] | Commercial [Member] | Risk Grade 6 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	25,978	28,321	11,299
Acquired Portfolio [Member] | Commercial [Member] | Risk Grade 7 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	11,103	11,607	6,509
Acquired Portfolio [Member] | Commercial [Member] | Risk Grade 8 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,582	3,654	2,032
Acquired Portfolio [Member] | Commercial [Member] | Risk Grade 9 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	0	0	0
Acquired Portfolio [Member] | Real estate commercial [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	642,741	688,103	344,575
Acquired Portfolio [Member] | Real estate commercial [Member] | Risk Grades 1-5 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	590,151	629,430	318,113
Acquired Portfolio [Member] | Real estate commercial [Member] | Risk Grade 6 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	17,692	23,926	7,786
Acquired Portfolio [Member] | Real estate commercial [Member] | Risk Grade 7 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	30,679	29,975	12,735
Acquired Portfolio [Member] | Real estate commercial [Member] | Risk Grade 8 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	4,219	4,772	5,941
Acquired Portfolio [Member] | Real estate commercial [Member] | Risk Grade 9 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	0	0	0
Acquired Portfolio [Member] | Real estate construction [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	43,231	46,929	8,654
Acquired Portfolio [Member] | Real estate construction [Member] | Risk Grades 1-5 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	39,260	41,683	6,724
Acquired Portfolio [Member] | Real estate construction [Member] | Risk Grade 6 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,539	2,556	253
Acquired Portfolio [Member] | Real estate construction [Member] | Risk Grade 7 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,273	1,537	140
Acquired Portfolio [Member] | Real estate construction [Member] | Risk Grade 8 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,159	1,153	1,537
Acquired Portfolio [Member] | Real estate construction [Member] | Risk Grade 9 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	$ 0	$ 0	$ 0

Loans (Summary of Recorded In45

Loans (Summary of Recorded Investment of Consumer Loans by Risk Rating Categories) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	$ 3,058,676	$ 3,021,030	$ 2,620,943
Real estate residential [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	1,461,120	1,429,636	1,117,445
Consumer installment [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	897,078	877,457	844,066
Home equity [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	700,478	713,937	659,432
Originated Loans [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	2,737,812	2,677,213	2,411,222
Originated Loans [Member] | Real estate residential [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	1,262,168	1,216,975	1,007,572
Originated Loans [Member] | Consumer installment [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	890,152	869,426	835,359
Originated Loans [Member] | Home equity [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	585,492	590,812	568,291
Originated Loans [Member] | Performing [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	2,725,947	2,664,486	2,399,114
Originated Loans [Member] | Performing [Member] | Real estate residential [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	1,253,670	1,207,945	998,196
Originated Loans [Member] | Performing [Member] | Consumer installment [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	889,792	868,975	834,926
Originated Loans [Member] | Performing [Member] | Home equity [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	582,485	587,566	565,992
Originated Loans [Member] | Nonperforming [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	11,865	12,727	12,108
Originated Loans [Member] | Nonperforming [Member] | Real estate residential [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	8,498	9,030	9,376
Originated Loans [Member] | Nonperforming [Member] | Consumer installment [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	360	451	433
Originated Loans [Member] | Nonperforming [Member] | Home equity [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	3,007	3,246	2,299
Acquired Loans [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	320,864	343,817	209,721
Acquired Loans [Member] | Real estate residential [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	198,952	212,661	109,873
Acquired Loans [Member] | Consumer installment [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	6,926	8,031	8,707
Acquired Loans [Member] | Home equity [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	114,986	123,125	91,141
Acquired Loans [Member] | Performing [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	317,945	340,682	208,387
Acquired Loans [Member] | Performing [Member] | Real estate residential [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	197,075	210,580	109,005
Acquired Loans [Member] | Performing [Member] | Consumer installment [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	6,881	7,984	8,696
Acquired Loans [Member] | Performing [Member] | Home equity [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	113,989	122,118	90,686
Acquired Loans [Member] | Nonperforming [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	2,919	3,135	1,334
Acquired Loans [Member] | Nonperforming [Member] | Real estate residential [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	1,877	2,081	868
Acquired Loans [Member] | Nonperforming [Member] | Consumer installment [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	45	47	11
Acquired Loans [Member] | Nonperforming [Member] | Home equity [Member]
Recorded investment of loans in consumer loan portfolio based on credit risk profile of loans in performing and nonperforming status
Recorded investment (loan balance), Consumer, Total	$ 997	$ 1,007	$ 455

Loans (Summary of Nonperforming

Loans (Summary of Nonperforming Loans) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Summary of nonperforming loans
Total TDRs	$ 100,764	$ 103,111	$ 101,824
Total loans	$ 7,366,885	7,271,147	5,702,874
Minimum number of days accruing loans past due move to nonaccrual status	90 days
Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	$ 76,615	78,823	77,511
Total loans	4,308,209	4,250,117	3,081,931
Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	24,149	24,288	24,313
Total loans	3,058,676	3,021,030	2,620,943
Nonperforming [Member]
Summary of nonperforming loans
Total nonaccrual loans	53,419	62,225	53,440
Total accruing loans contractually past due 90 days or more as to interest or principal payments	1,472	2,287	801
Total TDRs	18,364	19,368	18,500
Total loans	73,255	83,880	72,741
Nonperforming [Member] | Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	15,351	16,297	15,810
Nonperforming [Member] | Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	3,013	3,071	2,690
Nonperforming [Member] | Commercial [Member]
Summary of nonperforming loans
Total nonaccrual loans	19,264	28,554	18,904
Total accruing loans contractually past due 90 days or more as to interest or principal payments	370	364	52
Nonperforming [Member] | Real estate commercial [Member]
Summary of nonperforming loans
Total nonaccrual loans	25,859	25,163	24,766
Total accruing loans contractually past due 90 days or more as to interest or principal payments	0	254	148
Nonperforming [Member] | Real Estate Construction Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	546	521	953
Nonperforming [Member] | Real estate residential [Member]
Summary of nonperforming loans
Total nonaccrual loans	5,062	5,557	6,514
Total accruing loans contractually past due 90 days or more as to interest or principal payments	423	402	172
Nonperforming [Member] | Consumer Installment Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	360	451	433
Nonperforming [Member] | Home Equity Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	2,328	1,979	1,870
Total accruing loans contractually past due 90 days or more as to interest or principal payments	$ 679	$ 1,267	$ 429

Loans (Summary of Impaired Loan

Loans (Summary of Impaired Loans by Classes of Loans) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Impaired loans with a valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	$ 29,505	$ 44,383	$ 25,100
Unpaid Principal Balance	29,968	45,151	25,375
Related Valuation Allowance	2,916	6,389	1,912
Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	102,283	97,815	104,052
Unpaid Principal Balance	127,718	122,367	133,493
Related Valuation Allowance	0	0	0
Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	131,788	142,198	129,152
Unpaid Principal Balance	157,686	167,518	158,868
Related Valuation Allowance	2,916	6,389	1,912
Commercial [Member] | Impaired loans with a valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	4,944	18,898	3,433
Unpaid Principal Balance	4,949	19,426	3,527
Related Valuation Allowance	1,926	5,700	1,119
Commercial [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	35,353	31,039	33,733
Unpaid Principal Balance	45,042	37,703	39,382
Related Valuation Allowance	0	0	0
Commercial [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	40,297	49,937	37,166
Unpaid Principal Balance	49,991	57,129	42,909
Related Valuation Allowance	1,926	5,700	1,119
Real estate commercial [Member] | Impaired loans with a valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	3,558	4,448	1,780
Unpaid Principal Balance	4,016	4,688	1,961
Related Valuation Allowance	810	497	496
Real estate commercial [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	54,097	53,518	57,628
Unpaid Principal Balance	67,744	69,130	79,696
Related Valuation Allowance	0	0	0
Real estate commercial [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	57,655	57,966	59,408
Unpaid Principal Balance	71,760	73,818	81,657
Related Valuation Allowance	810	497	496
Real estate construction [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	2,164	2,136	2,540
Unpaid Principal Balance	3,104	3,108	4,264
Related Valuation Allowance	0	0	0
Real estate construction [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	2,164	2,136	2,540
Unpaid Principal Balance	3,104	3,108	4,264
Related Valuation Allowance	0	0	0
Real estate residential [Member] | Impaired loans with a valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	21,003	21,037	19,887
Unpaid Principal Balance	21,003	21,037	19,887
Related Valuation Allowance	180	192	297
Real estate residential [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	6,939	7,638	7,382
Unpaid Principal Balance	7,793	8,644	7,382
Related Valuation Allowance	0	0	0
Real estate residential [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	27,942	28,675	27,269
Unpaid Principal Balance	28,796	29,681	27,269
Related Valuation Allowance	180	192	297
Consumer installment [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	405	498	444
Unpaid Principal Balance	418	512	444
Related Valuation Allowance	0	0	0
Consumer installment [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	405	498	444
Unpaid Principal Balance	418	512	444
Related Valuation Allowance	0	0	0
Home equity [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	3,325	2,986	2,325
Unpaid Principal Balance	3,617	3,270	2,325
Related Valuation Allowance	0	0	0
Home equity [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	3,325	2,986	2,325
Unpaid Principal Balance	3,617	3,270	2,325
Related Valuation Allowance	$ 0	$ 0	$ 0

Loans (Summary of Information R

Loans (Summary of Information Related to Impaired Loans) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	$ 136,772	$ 131,534
Interest income recognized related to loans with impaired status	1,194	1,180
Commercial [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	45,017	38,576
Interest income recognized related to loans with impaired status	329	289
Real estate commercial [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	57,956	60,240
Interest income recognized related to loans with impaired status	458	525
Real estate construction [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	2,068	2,515
Interest income recognized related to loans with impaired status	25	27
Real estate residential [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	28,092	27,352
Interest income recognized related to loans with impaired status	366	331
Consumer installment [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	387	499
Interest income recognized related to loans with impaired status	1	0
Home equity [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	3,252	2,352
Interest income recognized related to loans with impaired status	$ 15	$ 8

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	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Originated Portfolio [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	$ 11,928	$ 14,502	$ 22,816
Financing receivable, recorded investment 61 to 89 days past due	8,417	4,265	3,625
Financing receivable, recorded investment accruing loans past due 90 days or more	1,472	2,287	801
Financing receivable, recorded investment, Nonaccrual loans	53,419	62,225	53,440
Financing receivable recorded investment, Total past due	75,236	83,279	80,682
Financing receivable, recorded investment, current	5,926,478	5,724,655	4,967,980
Financing receivable, recorded investment, Total loans	6,001,714	5,807,934	5,048,662
Originated Portfolio [Member] | Commercial [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	4,069	3,685	10,121
Financing receivable, recorded investment 61 to 89 days past due	7,359	1,230	729
Financing receivable, recorded investment accruing loans past due 90 days or more	370	364	52
Financing receivable, recorded investment, Nonaccrual loans	19,264	28,554	18,904
Financing receivable recorded investment, Total past due	31,062	33,833	29,806
Financing receivable, recorded investment, current	1,532,862	1,487,682	1,235,101
Financing receivable, recorded investment, Total loans	1,563,924	1,521,515	1,264,907
Originated Portfolio [Member] | Real estate commercial [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	3,096	4,168	7,238
Financing receivable, recorded investment 61 to 89 days past due	376	1,603	2,267
Financing receivable, recorded investment accruing loans past due 90 days or more	0	254	148
Financing receivable, recorded investment, Nonaccrual loans	25,859	25,163	24,766
Financing receivable recorded investment, Total past due	29,331	31,188	34,419
Financing receivable, recorded investment, current	1,470,979	1,392,871	1,237,929
Financing receivable, recorded investment, Total loans	1,500,310	1,424,059	1,272,348
Originated Portfolio [Member] | Real estate construction [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	216	0	340
Financing receivable, recorded investment 61 to 89 days past due	0	0	0
Financing receivable, recorded investment accruing loans past due 90 days or more	0	0	0
Financing receivable, recorded investment, Nonaccrual loans	546	521	953
Financing receivable recorded investment, Total past due	762	521	1,293
Financing receivable, recorded investment, current	198,906	184,626	98,892
Financing receivable, recorded investment, Total loans	199,668	185,147	100,185
Originated Portfolio [Member] | Real estate residential [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	757	1,737	1,246
Financing receivable, recorded investment 61 to 89 days past due	23	0	88
Financing receivable, recorded investment accruing loans past due 90 days or more	423	402	172
Financing receivable, recorded investment, Nonaccrual loans	5,062	5,557	6,514
Financing receivable recorded investment, Total past due	6,265	7,696	8,020
Financing receivable, recorded investment, current	1,255,903	1,209,279	999,552
Financing receivable, recorded investment, Total loans	1,262,168	1,216,975	1,007,572
Originated Portfolio [Member] | Consumer installment [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	2,158	3,145	2,143
Financing receivable, recorded investment 61 to 89 days past due	336	644	344
Financing receivable, recorded investment accruing loans past due 90 days or more	0	0	0
Financing receivable, recorded investment, Nonaccrual loans	360	451	433
Financing receivable recorded investment, Total past due	2,854	4,240	2,920
Financing receivable, recorded investment, current	887,298	865,186	832,439
Financing receivable, recorded investment, Total loans	890,152	869,426	835,359
Originated Portfolio [Member] | Home equity [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	1,632	1,767	1,728
Financing receivable, recorded investment 61 to 89 days past due	323	788	197
Financing receivable, recorded investment accruing loans past due 90 days or more	679	1,267	429
Financing receivable, recorded investment, Nonaccrual loans	2,328	1,979	1,870
Financing receivable recorded investment, Total past due	4,962	5,801	4,224
Financing receivable, recorded investment, current	580,530	585,011	564,067
Financing receivable, recorded investment, Total loans	585,492	590,812	568,291
Acquired Portfolio [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	1,207	6,319	2,299
Financing receivable, recorded investment 61 to 89 days past due	1,138	1,301	378
Financing receivable, recorded investment accruing loans past due 90 days or more	10,119	12,795	11,231
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	12,464	20,415	13,908
Financing receivable, recorded investment, current	1,352,707	1,442,798	640,304
Financing receivable, recorded investment, Total loans	1,365,171	1,463,213	654,212
Acquired Portfolio [Member] | Commercial [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	55	490	59
Financing receivable, recorded investment 61 to 89 days past due	70	532	5
Financing receivable, recorded investment accruing loans past due 90 days or more	1,582	3,735	2,089
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	1,707	4,757	2,153
Financing receivable, recorded investment, current	356,628	379,607	89,109
Financing receivable, recorded investment, Total loans	358,335	384,364	91,262
Acquired Portfolio [Member] | Real estate commercial [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	249	3,557	1,784
Financing receivable, recorded investment 61 to 89 days past due	557	691	138
Financing receivable, recorded investment accruing loans past due 90 days or more	4,459	4,771	6,271
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	5,265	9,019	8,193
Financing receivable, recorded investment, current	637,476	679,084	336,382
Financing receivable, recorded investment, Total loans	642,741	688,103	344,575
Acquired Portfolio [Member] | Real estate construction [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	0	0	0
Financing receivable, recorded investment 61 to 89 days past due	0	0	0
Financing receivable, recorded investment accruing loans past due 90 days or more	1,159	1,154	1,537
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	1,159	1,154	1,537
Financing receivable, recorded investment, current	42,072	45,775	7,117
Financing receivable, recorded investment, Total loans	43,231	46,929	8,654
Acquired Portfolio [Member] | Real estate residential [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	301	1,370	104
Financing receivable, recorded investment 61 to 89 days past due	0	0	0
Financing receivable, recorded investment accruing loans past due 90 days or more	1,877	2,081	868
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	2,178	3,451	972
Financing receivable, recorded investment, current	196,774	209,210	108,901
Financing receivable, recorded investment, Total loans	198,952	212,661	109,873
Acquired Portfolio [Member] | Consumer installment [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	59	55	3
Financing receivable, recorded investment 61 to 89 days past due	0	0	1
Financing receivable, recorded investment accruing loans past due 90 days or more	45	47	11
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	104	102	15
Financing receivable, recorded investment, current	6,822	7,929	8,692
Financing receivable, recorded investment, Total loans	6,926	8,031	8,707
Acquired Portfolio [Member] | Home equity [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	543	847	349
Financing receivable, recorded investment 61 to 89 days past due	511	78	234
Financing receivable, recorded investment accruing loans past due 90 days or more	997	1,007	455
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	2,051	1,932	1,038
Financing receivable, recorded investment, current	112,935	121,193	90,103
Financing receivable, recorded investment, Total loans	$ 114,986	$ 123,125	$ 91,141

Loans (Summary of TDRs) (Detail

Loans (Summary of TDRs) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Schedule of corporation's TDRs
Total TDRs	$ 100,764	$ 103,111	$ 101,824
Commercial Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	76,615	78,823	77,511
Consumer Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	24,149	24,288	24,313
Substandard Nonaccrual [Member]
Schedule of corporation's TDRs
Total TDRs	32,514	35,933	37,343
Substandard Nonaccrual [Member] | Commercial Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	29,368	32,682	32,917
Substandard Nonaccrual [Member] | Consumer Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	3,146	3,251	4,426
Nonperforming Financial Instruments [Member]
Schedule of corporation's TDRs
Total TDRs	18,364	19,368	18,500
Nonperforming Financial Instruments [Member] | Commercial Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	15,351	16,297	15,810
Nonperforming Financial Instruments [Member] | Consumer Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	3,013	3,071	2,690
Performing Financial Instruments [Member]
Schedule of corporation's TDRs
Total TDRs	49,886	47,810	45,981
Performing Financial Instruments [Member] | Commercial Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	31,896	29,844	28,784
Performing Financial Instruments [Member] | Consumer Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	$ 17,990	$ 17,966	$ 17,197

Loans (Summary of TDRs Modified

Loans (Summary of TDRs Modified During the Period) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016USD ($)Loans	Mar. 31, 2015USD ($)Loans
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	18	20
Modified TDRs, Pre-modification recorded investment	$ 5,023	$ 4,802
Modified TDRs, Post-modification recorded investment	$ 5,023	$ 4,802
Subtotal-commercial loan portfolio [Member] | Commercial Loan Portfolio [Member]
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	11	10
Modified TDRs, Pre-modification recorded investment	$ 4,819	$ 4,466
Modified TDRs, Post-modification recorded investment	$ 4,819	$ 4,466
Consumer loan portfolio [Member] | Consumer Portfolio Segment [Member]
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	7	10
Modified TDRs, Pre-modification recorded investment	$ 204	$ 336
Modified TDRs, Post-modification recorded investment	$ 204	$ 336
Commercial [Member] | Commercial Loan Portfolio [Member]
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	7	5
Modified TDRs, Pre-modification recorded investment	$ 3,832	$ 1,932
Modified TDRs, Post-modification recorded investment	$ 3,832	$ 1,932
Real estate commercial [Member] | Commercial Loan Portfolio [Member]
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	4	5
Modified TDRs, Pre-modification recorded investment	$ 987	$ 2,534
Modified TDRs, Post-modification recorded investment	$ 987	$ 2,534

Loans (Summary of TDRs with a P

Loans (Summary of TDRs with a Payment Default During the Period) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016USD ($)Loans	Mar. 31, 2015USD ($)Loans
Troubled debt restructurings on financing receivables with defaults payment
Financing receivable modifications subsequent default number of contract | Loans	2	4
Financing receivable modification subsequent default recorded investment | $	$ 933	$ 792
Consumer Portfolio Segment [Member]
Troubled debt restructurings on financing receivables with defaults payment
Financing receivable modifications subsequent default number of contract | Loans	1	1
Financing receivable modification subsequent default recorded investment | $	$ 0	$ 33
Commercial [Member] | Commercial Loan Portfolio [Member]
Troubled debt restructurings on financing receivables with defaults payment
Financing receivable modifications subsequent default number of contract | Loans	0	0
Financing receivable modification subsequent default recorded investment | $	$ 0	$ 0
Real estate commercial [Member] | Commercial Loan Portfolio [Member]
Troubled debt restructurings on financing receivables with defaults payment
Financing receivable modifications subsequent default number of contract | Loans	1	3
Financing receivable modification subsequent default recorded investment | $	$ 933	$ 759
Subtotal-commercial loan portfolio [Member] | Commercial Loan Portfolio [Member]
Troubled debt restructurings on financing receivables with defaults payment
Financing receivable modifications subsequent default number of contract | Loans	1	3
Financing receivable modification subsequent default recorded investment | $	$ 933	$ 759

Loans (Schedule of the Allowanc

Loans (Schedule of the Allowance for Loan Losses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	$ 73,328	$ 75,683
Provision for loan losses	1,500	1,500
Charge-offs	(5,458)	(3,143)
Recoveries	948	1,216
Ending balance	70,318	75,256
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses			$ 2,916	$ 6,389	$ 1,912
Loans collectively evaluated for impairment related to allowance for loan losses			67,402	66,939	73,344
Total	73,328	75,683	70,318	73,328	75,256
Loans individually evaluated for impairment related to recorded investment (loan balance)			113,919	121,416	109,104
Loans collectively evaluated for impairment related to recorded investment (loan balance)			5,887,795	5,686,518	4,939,558
Total loans			7,366,885	7,271,147	5,702,874
Commercial Loan Portfolio [Member]
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	47,234	44,156
Provision for loan losses	1,000	3,593
Charge-offs	(3,896)	(1,504)
Recoveries	330	574
Ending balance	44,668	46,819
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses			2,736	6,197	1,615
Loans collectively evaluated for impairment related to allowance for loan losses			41,932	41,037	45,204
Total	47,234	44,156	44,668	47,234	46,819
Loans individually evaluated for impairment related to recorded investment (loan balance)			92,916	100,379	89,217
Loans collectively evaluated for impairment related to recorded investment (loan balance)			3,170,986	3,030,342	2,548,223
Total loans			4,308,209	4,250,117	3,081,931
Consumer Loan Portfolio [Member]
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	26,094	28,803
Provision for loan losses	500	(3,227)
Charge-offs	(1,562)	(1,639)
Recoveries	618	642
Ending balance	25,650	24,579
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses			180	192	297
Loans collectively evaluated for impairment related to allowance for loan losses			25,470	25,902	24,282
Total	26,094	28,803	25,650	26,094	24,579
Loans individually evaluated for impairment related to recorded investment (loan balance)			21,003	21,037	19,887
Loans collectively evaluated for impairment related to recorded investment (loan balance)			2,716,809	2,656,176	2,391,335
Total loans			3,058,676	3,021,030	2,620,943
Unallocated [Member]
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	0	2,724
Provision for loan losses	0	1,134
Charge-offs	0	0
Recoveries	0	0
Ending balance	0	3,858
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses			0	0	0
Loans collectively evaluated for impairment related to allowance for loan losses			0	0	3,858
Total	$ 0	$ 2,724	0	0	3,858
Loans individually evaluated for impairment related to recorded investment (loan balance)			0	0	0
Loans collectively evaluated for impairment related to recorded investment (loan balance)			0	0	0
Total loans			0	0	0
Receivables Acquired with Deteriorated Credit Quality [Member]
Allowance for loan losses
Financing Receivable, Allowance for Credit Losses			0	0	0
Loans acquired with deteriorated credit quality			1,365,171	1,463,213	654,212
Receivables Acquired with Deteriorated Credit Quality [Member] | Commercial Loan Portfolio [Member]
Allowance for loan losses
Financing Receivable, Allowance for Credit Losses			0	0	0
Loans acquired with deteriorated credit quality			1,044,307	1,119,396	444,491
Receivables Acquired with Deteriorated Credit Quality [Member] | Consumer Loan Portfolio [Member]
Allowance for loan losses
Financing Receivable, Allowance for Credit Losses			0	0	0
Loans acquired with deteriorated credit quality			320,864	343,817	209,721
Receivables Acquired with Deteriorated Credit Quality [Member] | Unallocated [Member]
Allowance for loan losses
Financing Receivable, Allowance for Credit Losses			0	0	0
Loans acquired with deteriorated credit quality			$ 0	$ 0	$ 0

Loans (Textual) (Details)

Loans (Textual) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)SegmentLoansBaordOfDirectorsTenants	Dec. 31, 2015USD ($)	Mar. 31, 2015USD ($)
Loans (Textual) [Abstract]
Number of portfolio segment | Segment	2
Number of classes of loans | Loans	6
Number of minimum tenants under lease of non-owner occupied commercial real estate | Tenants	1
Number of members of the board of directors in loan committee | BaordOfDirectors	8
Minimum due period of loans consider in a nonperforming status	90 days
Total nonaccrual TDR loans	$ 32.5	$ 35.9	$ 37.3
Residential Mortgage Loans in Process of Foreclosure	2.3	2.9	2.2
Difference between recorded investment and unpaid principal balance of loan	25.9	25.3	29.7
Confirmed losses (partial charge-offs)	19.9	17.1	14.8
Fair value of discount adjustment	6	8.2	14.9
Acquired impaired loans	10.1	12.8	11.2
Performing trouble debt restructuring under impaired loans	49.9	$ 47.8	$ 46
Commercial Loan Portfolio [Member]
Loans (Textual) [Abstract]
Minimum value of loan requires executive and senior officer approval	$ 1.5
Consumer Portfolio Segment [Member]
Loans (Textual) [Abstract]
Maximum due period of loans consider in performing status	90 days
Minimum due period of loans consider in a nonperforming status	90 days
Commercial [Member]
Loans (Textual) [Abstract]
Minimum value of loan requires group loan authority approval	$ 1
Maximum value of loan requires executive and senior officer approval	$ 3.5
Real Estate Residential Loans [Member]
Loans (Textual) [Abstract]
Period for loan secured under real estate residential security	15 years
Loan-to-value ratio at the time of origination	80.00%
Land Development Loans [Member]
Loans (Textual) [Abstract]
Maximum period for payment of loan	12 months
Maximum [Member] | Commercial Loan Portfolio [Member]
Loans (Textual) [Abstract]
Maximum value of loan requires group loan authority approval	$ 10
Other loans requiring director loan committee approval depending on risk rating and credit action required	$ 10
Maximum [Member] | Real Estate Residential Loans [Member]
Loans (Textual) [Abstract]
Upper limit of number of family residential properties | Tenants	4
Minimum [Member] | Commercial Loan Portfolio [Member]
Loans (Textual) [Abstract]
Minimum value of loan requires group loan authority approval	$ 1
Minimum value of loans depending on risk rating and requires credit action from board of directors	15
Minimum [Member] | Commercial [Member]
Loans (Textual) [Abstract]
Minimum value of loans requiring only director loan committee approval	$ 10
Minimum [Member] | Real Estate Residential Loans [Member]
Loans (Textual) [Abstract]
Lower limit of number of family residential properties | Tenants	1

Intangible Assets (Net Carrying

Intangible Assets (Net Carrying Value) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	May. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Net carrying value of intangible assets
Goodwill	$ 286,867	$ 287,393		$ 180,128
Other intangible assets:
Total other intangible assets	36,266	38,104		31,655
Core deposit intangible assets [Member]
Other intangible assets:
Finite-Lived Core Deposits, Gross	25,542	26,654		20,072
Total other intangible assets	25,542	26,654		20,072
Noncompete Agreements [Member]
Other intangible assets:
Finite-Lived Noncompete Agreements, Gross	246	328		0
Mortgage servicing rights [Member]
Other intangible assets:
Servicing Asset at Amortized Cost	10,478	11,122		11,583
Total other intangible assets	$ 10,478	$ 11,122		$ 11,583	$ 12,217
Lake Michigan Financial Corp [Member]
Net carrying value of intangible assets
Goodwill			$ 101,000

Intangible Assets (Amortization

Intangible Assets (Amortization Expense of Core Deposit Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Carrying amount	$ 36,266	$ 31,655	$ 38,104
Amortization of intangible assets	2,169	1,825
Core deposit intangible assets [Member]
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Gross original amount	40,055	30,122	40,055
Accumulated amortization	14,513	10,050	13,401
Carrying amount	25,542	20,072	$ 26,654
Amortization of intangible assets	$ 1,112	$ 791

Intangible Assets (Carrying and

Intangible Assets (Carrying and Fair Value of MSRs) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Net carrying value, fair value of MSRs and loans Corporation servicing for others
Loans serviced for others that have servicing rights capitalized	$ 2,047,435	$ 2,082,899	$ 2,062,544
Mortgage servicing rights [Member]
Net carrying value, fair value of MSRs and loans Corporation servicing for others
Net carrying value of MSRs	10,478	11,122	11,583
Fair value of MSRs	$ 13,909	$ 15,542	$ 14,378

Intangible Assets (Activity for

Intangible Assets (Activity for Capitalized MSRs) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Capitalized MSRs [Roll Forward]
Balance at beginning of period	$ 38,104
Amortization	(2,169)	$ (1,825)
Balance at end of period	36,266	31,655
Mortgage servicing rights [Member]
Capitalized MSRs [Roll Forward]
Balance at beginning of period	11,122	12,217
Additions	331	400
Amortization	(975)	(1,034)
Balance at end of period	$ 10,478	$ 11,583

Intangible Assets (Textual) (De

Intangible Assets (Textual) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Goodwill and Identifiable Intangible Assets Acquired	$ (500)
Goodwill	286,867	$ 287,393	$ 180,128
Intangible Assets (Textual) [Abstract]
Impairment valuation allowance			200
Core deposit intangible assets [Member]
Intangible Assets (Textual) [Abstract]
Impairment valuation allowance	0
Estimated Future Amortization Expense, Fiscal Year Maturity [Abstract]
2,016	3,200
2,017	3,800
2,018	3,600
2,019	3,400
2,020	2,900
2021 and thereafter	8,600
Mortgage servicing rights [Member]
Intangible Assets (Textual) [Abstract]
Impairment valuation allowance	$ 0	$ 0	$ 0

Accumulated Other Comprehensi60

Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Components of accumulated other comprehensive loss, net of related tax benefit/expense
Net unrealized gains (losses) on investment securities – available-for-sale, net of related tax expense (benefit) of $446 at March 31, 2016, $(1,017) at December 31, 2015 and $946 at March 31, 2015	$ 829	$ (1,888)	$ 1,758
Pension and other postretirement benefits adjustment, net of related tax benefit of $14,818 at March 31, 2016, $14,616 at December 31, 2015 and $16,981 at March 31, 2015	(27,519)	(27,144)	(31,537)
Accumulated other comprehensive loss	$ (26,690)	$ (29,032)	$ (29,779)

Accumulated Other Comprehensi61

Accumulated Other Comprehensive Loss (Textual) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Accumulated Other Comprehensive Loss (Textual) [Abstract]
Net unrealized gains (losses) on investment securities-available-for-sale, tax expense (benefit)	$ 446	$ (1,017)	$ 946
Pension and other postretirement benefits adjustment, tax benefit	$ 14,818	$ 14,616	$ 16,981

Borrowings Schedule of Short-te

Borrowings Schedule of Short-term Borrowings (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Schedule of Short-Term Borrowings [Abstract]
Federal Home Loan Bank Advances, Short Term		$ 100,000
Short-term borrowings	$ 0	$ 100,000	$ 0

Borrowings Schedule of Other Bo

Borrowings Schedule of Other Borrowings (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	May. 31, 2015	Mar. 31, 2015
Schedule of Other Borrowings [Abstract]
Long-term Federal Home Loan Bank Advances	$ 231,357	$ 181,394		$ 0
nonrevolving line of credit	25,000	25,000		0
Other Securities Sold under Agreements to Repurchase	17,365	17,453		0
Subordinated Debt	0	18,544	$ 18,600	0
Other Borrowings	$ 273,722	$ 242,391		$ 0

Borrowings Textuals (Details)

Borrowings Textuals (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	May. 31, 2015	Mar. 31, 2015
Borrowings [Line Items]
Proceeds from Federal Home Loan Bank Advances	$ 50,000
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Weighted Average Interest Rate	1.30%
Federal Home Loan Bank, Advances, Weighted Average Interest Rate	1.39%
Maximum original maturity term of short-term borrowings	30 days
Long-term Federal Home Loan Bank Advances	$ 231,357	$ 181,394		$ 0
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	2,920,000
Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Two	7,100
Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Three	47,100
Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Four	67,100
Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Five	100
Federal Home Loan Bank, Advances, Maturities Summary, Floating Rate, after Five Years	110,000
Securities Sold under Agreements to Repurchase	283,383	297,199		372,236
Securities Sold Under Agreements to Repurchase, Maturities Summary, Due Remainder of Current Year	8,300
Securities Sold Under Agreements to Repurchase, Maturities, Due in Year Two	9,100
nonrevolving line of credit	$ 25,000	25,000		0
Line of Credit Facility, Interest Rate at Period End	2.39%
Subordinated Debt	$ 0	$ 18,544	$ 18,600	$ 0

Regulatory Capital (Details)

Regulatory Capital (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Risk weighted assets	$ 7,220,000	$ 7,140,000	$ 5,580,000
Chemical Financial Corporation [Member]
Total Capital to Risk-Weighted Assets:
Actual, Capital Amount	832,457	841,257	727,090
Minimum Required for Capital Adequacy Purposes, Capital Amount	$ 577,668	$ 571,509	$ 446,173
Actual, Ratio	11.50%	11.80%	13.00%
Minimum Required for Capital Adequacy Purposes, Ratio	8.00%	8.00%	8.00%
Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount	$ 762,139	$ 767,929	$ 657,307
Minimum Required for Capital Adequacy Purposes, Capital Amount	$ 433,251	$ 428,631	$ 334,630
Actual, Ratio	10.60%	10.70%	11.80%
Minimum Required for Capital Adequacy Purposes, Ratio	6.00%	6.00%	6.00%
Common Equity Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount	$ 762,139	$ 753,815	$ 657,307
Minimum Required for Capital Adequacy Purposes, Capital Amount	$ 324,938	$ 321,474	$ 250,972
Actual, Ratio	10.60%	10.60%	11.80%
Minimum Required for Capital Adequacy Purposes, Ratio	4.50%	4.50%	4.50%
Leverage Ratio:
Actual, Capital Amount	$ 762,139	$ 767,929	$ 657,307
Minimum Required for Capital Adequacy Purposes, Capital Amount	$ 357,773	$ 356,396	$ 289,948
Actual, Ratio	8.50%	8.60%	9.10%
Minimum Required for Capital Adequacy Purposes, Ratio	4.00%	4.00%	4.00%
Chemical Bank [Member]
Total Capital to Risk-Weighted Assets:
Actual, Capital Amount	$ 840,372	$ 830,294	$ 676,488
Minimum Required for Capital Adequacy Purposes, Capital Amount	576,068	570,073	445,471
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 720,086	$ 712,591	$ 556,838
Actual, Ratio	11.70%	11.70%	12.10%
Minimum Required for Capital Adequacy Purposes, Ratio	8.00%	8.00%	8.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio	10.00%	10.00%	10.00%
Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount	$ 770,054	$ 756,966	$ 606,813
Minimum Required for Capital Adequacy Purposes, Capital Amount	432,051	427,555	334,103
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 576,068	$ 570,073	$ 445,471
Actual, Ratio	10.70%	10.60%	10.90%
Minimum Required for Capital Adequacy Purposes, Ratio	6.00%	6.00%	6.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio	8.00%	8.00%	8.00%
Common Equity Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount	$ 770,054	$ 756,966	$ 606,813
Minimum Required for Capital Adequacy Purposes, Capital Amount	324,038	320,666	250,577
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 468,056	$ 463,184	$ 361,945
Actual, Ratio	10.70%	10.60%	10.90%
Minimum Required for Capital Adequacy Purposes, Ratio	4.50%	4.50%	4.50%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio	6.50%	6.50%	6.50%
Leverage Ratio:
Actual, Capital Amount	$ 770,054	$ 756,966	$ 606,813
Minimum Required for Capital Adequacy Purposes, Capital Amount	357,190	355,911	289,840
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 446,488	$ 444,888	$ 362,300
Actual, Ratio	8.60%	8.50%	8.40%
Minimum Required for Capital Adequacy Purposes, Ratio	4.00%	4.00%	4.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio	5.00%	5.00%	5.00%

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value of Assets on a Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	$ 514,015	$ 553,731	$ 680,644
Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	514,015	553,731	680,644
Loans Held-for-sale	9,667	10,327	9,675
Total assets measured at fair value on a recurring basis	523,682	564,058	690,319
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	5,797	5,765	8,302
Loans Held-for-sale	0	0	0
Total assets measured at fair value on a recurring basis	5,797	5,765	8,302
Significant Other Observable Inputs (Level 2) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	508,218	547,966	672,342
Loans Held-for-sale	9,667	10,327	9,675
Total assets measured at fair value on a recurring basis	517,885	558,293	682,017
Significant Unobservable Inputs (Level 3) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0	0
Loans Held-for-sale	0	0	0
Total assets measured at fair value on a recurring basis	0	0	0
US Treasury Securities [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	5,797	5,765	8,302
US Treasury Securities [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	5,797	5,765	8,302
US Treasury Securities [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	5,797	5,765	8,302
US Treasury Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0	0
US Treasury Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0	0
Government sponsored agencies [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	177,637	194,989	250,430
Government sponsored agencies [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	177,637	194,989	250,430
Government sponsored agencies [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0	0
Government sponsored agencies [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	177,637	194,989	250,430
Government sponsored agencies [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0	0
State and political subdivisions [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	15,061	15,120	32,322
State and political subdivisions [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	15,061	15,120	32,322
State and political subdivisions [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0	0
State and political subdivisions [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	15,061	15,120	32,322
State and political subdivisions [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0	0
Residential mortgage-backed securities [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	179,149	187,768	219,601
Residential mortgage-backed securities [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	179,149	187,768	219,601
Residential mortgage-backed securities [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0	0
Residential mortgage-backed securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	179,149	187,768	219,601
Residential mortgage-backed securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0	0
Collateralized mortgage obligations [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	118,398	132,230	133,300
Collateralized mortgage obligations [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	118,398	132,230	133,300
Collateralized mortgage obligations [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0	0
Collateralized mortgage obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	118,398	132,230	133,300
Collateralized mortgage obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0	0
Corporate bonds [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	14,708	14,627	34,997
Corporate bonds [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	14,708	14,627	34,997
Corporate bonds [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0	0
Corporate bonds [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	14,708	14,627	34,997
Corporate bonds [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0	0
Preferred stock [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	3,265	3,232	1,692
Preferred stock [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	3,265	3,232	1,692
Preferred stock [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0	0
Preferred stock [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	3,265	3,232	1,692
Preferred stock [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	$ 0	$ 0	$ 0

Fair Value Measurements (Fair67

Fair Value Measurements (Fair Value of Assets on a Nonrecurring Basis) (Details) - Fair Value Measurements Nonrecurring [Member] - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	$ 40,173	$ 52,000	$ 46,589
Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	0	0	0
Significant Other Observable Inputs (Level 2) [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	0	0	0
Significant Unobservable Inputs (Level 3) [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	40,173	52,000	46,589
Impaired originated loans [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	30,925	42,065	23,730
Impaired originated loans [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	0	0	0
Impaired originated loans [Member] | Significant Other Observable Inputs (Level 2) [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	0	0	0
Impaired originated loans [Member] | Significant Unobservable Inputs (Level 3) [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	30,925	42,065	23,730
Other real estate/repossessed assets [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	9,248	9,935	14,744
Other real estate/repossessed assets [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	0	0	0
Other real estate/repossessed assets [Member] | Significant Other Observable Inputs (Level 2) [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	0	0	0
Other real estate/repossessed assets [Member] | Significant Unobservable Inputs (Level 3) [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	$ 9,248	$ 9,935	14,744
Mortgage Servicing Rights [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis			8,115
Mortgage Servicing Rights [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis			0
Mortgage Servicing Rights [Member] | Significant Other Observable Inputs (Level 2) [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis			0
Mortgage Servicing Rights [Member] | Significant Unobservable Inputs (Level 3) [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis			$ 8,115

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule of Carrying Amounts and Estimated Fair Value of Financial Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Investment securities:
Available-for-sale	$ 514,015	$ 553,731	$ 680,644
Held-to-maturity	525,593	512,705	380,176
Carrying Amount [Member]
Investment securities:
Nonmarketable equity securities	43,267	36,907	31,249
Carrying Amount [Member] | Level 1[Member]
Assets:
Cash and cash equivalents	291,374	238,789	393,938
Investment securities:
Available-for-sale	5,797	5,765	8,302
Carrying Amount [Member] | Level 2 [Member]
Investment securities:
Available-for-sale	508,218	547,966	672,342
Held-to-maturity	517,800	509,471	370,950
Loans Held-for-sale	9,667	10,327	9,675
Interest receivable	26,010	21,953	19,816
Liabilities:
Deposits without defined maturities	6,043,457	5,809,355	4,988,268
Interest payable	1,632	1,578	779
Short-term borrowings	283,383	397,199	372,236
Other borrowings	256,357	206,394	0
Carrying Amount [Member] | Level 3 [Member]
Investment securities:
Held-to-maturity	500	500	10,500
Net loans	7,296,567	7,197,819	5,627,618
Liabilities:
Time deposits	1,606,659	1,647,412	1,332,085
Other borrowings	17,365	35,997	0
Fair Value [Member]
Investment securities:
Nonmarketable equity securities	43,267	36,907	31,249
Fair Value [Member] | Level 1[Member]
Assets:
Cash and cash equivalents	291,374	238,789	393,938
Investment securities:
Available-for-sale	5,797	5,765	8,302
Fair Value [Member] | Level 2 [Member]
Investment securities:
Available-for-sale	508,218	547,966	672,342
Held-to-maturity	525,308	512,405	372,876
Loans Held-for-sale	9,667	10,327	9,675
Interest receivable	26,010	21,953	19,816
Liabilities:
Deposits without defined maturities	6,043,457	5,809,355	4,988,268
Interest payable	1,632	1,578	779
Short-term borrowings	283,383	397,199	372,236
Other borrowings	257,993	206,394	0
Fair Value [Member] | Level 3 [Member]
Investment securities:
Held-to-maturity	285	300	7,300
Net loans	7,297,375	7,201,994	5,633,217
Liabilities:
Time deposits	1,609,073	1,647,412	1,335,605
Other borrowings	$ 17,317	$ 35,997	$ 0

Fair Value Measurements (Textua

Fair Value Measurements (Textual) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Fair Value Measurements (Textual) [Abstract]
Impairment of goodwill	$ 0	$ 0	$ 0
Valuation Allowance on Mortgage Servicing Rights			200
Impairment identified for intangible assets	0
Core deposit intangible assets [Member]
Fair Value Measurements (Textual) [Abstract]
Valuation Allowance on Mortgage Servicing Rights	$ 0
Impairment identified for intangible assets		0	0
Maximum [Member]
Fair Value Measurements (Textual) [Abstract]
Expected life of intangible assets	15 years
Minimum [Member]
Fair Value Measurements (Textual) [Abstract]
Expected life of intangible assets	10 years
Total Impaired Loans [Member] | Maximum [Member]
Fair Value Measurements (Textual) [Abstract]
Percentage of discount factors used to determine fair value	80.00%
Total Impaired Loans [Member] | Minimum [Member]
Fair Value Measurements (Textual) [Abstract]
Percentage of discount factors used to determine fair value	70.00%
Other Real Estate and Repossessed Assets [Member] | Maximum [Member]
Fair Value Measurements (Textual) [Abstract]
Percentage of discount factors used to determine fair value	75.00%
Other Real Estate and Repossessed Assets [Member] | Minimum [Member]
Fair Value Measurements (Textual) [Abstract]
Percentage of discount factors used to determine fair value	70.00%
Fair Value Measurements Recurring [Member]
Fair Value Measurements (Textual) [Abstract]
Liabilities recorded at fair value	$ 0	0	0
Fair Value Measurements Nonrecurring [Member]
Fair Value Measurements (Textual) [Abstract]
Liabilities recorded at fair value	$ 0	$ 0	$ 0

Earnings Per Common Share (Deta

Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Numerator and denominator of the basic and diluted earnings per common share computations
Numerator for both basic and diluted earnings per common share, net income	$ 23,262	$ 17,835
Denominator for basic earnings per common share, weighted average common shares outstanding	38,198,000	32,809,000
Weighted average common stock equivalents	323,000	235,000
Denominator for diluted earnings per common share	38,521,000	33,044,000
Basic earnings per common share (dollars per share)	$ 0.61	$ 0.54
Diluted earnings per common share (dollars per share)	$ 0.60	$ 0.54
Stock Option [Member]
Earnings Per Common Share (Textual) [Abstract]
Average number of exercisable employee stock option awards that were not included in the computation of diluted earnings per common share	0	121,050

Share-Based Compensation (Stock

Share-Based Compensation (Stock Option Activity) (Details)	3 Months Ended
	Mar. 31, 2016$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted average fair value of options granted	$ 6.15
Stock Options [Member] | Non Vested [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance, Number of Options | shares	479,755
Granted, Number of Options | shares	441,167
Exercised, Number of Options | shares	0
Vested, Number of Options | shares	(118,273)
Forfeited/expired, Number of Options | shares	(8,783)
Ending balance, Number of Options | shares	793,866
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Beginning balance, Weighted Average Exercise Price	$ 28.75
Granted, Weighted Average Exercise Price	32.81
Exercised, Weighted Average Exercise Price	0
Vested, Weighted Average Exercise Price	28.30
Forfeited/expired, Weighted Average Exercise Price	32.21
Ending balance, Weighted Average Exercise Price	31.03
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Grant Date Fair Value [Roll Forward]
Beginning balance, Weighted average grant date fair value	8.49
Weighted average fair value of options granted	6.15
Exercised, Weighted Average Grant Date Fair Value	0
Vested, Weighted Average Grant Date Fair Value	8.40
Forfeited/expired, Weighted Average Grant Date Fair Value	6.66
Ending balance, Weighted average grant date fair value	$ 7.22
Stock Options [Member] | Vested & Nonvested [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance, Number of Options | shares	1,054,739
Granted, Number of Options | shares	441,167
Exercised, Number of Options | shares	(70,885)
Vested, Number of Options | shares	0
Forfeited/expired, Number of Options | shares	(8,783)
Ending balance, Number of Options | shares	1,416,238
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Beginning balance, Weighted Average Exercise Price	$ 25.38
Granted, Weighted Average Exercise Price	32.81
Exercised, Weighted Average Exercise Price	20.69
Vested, Weighted Average Exercise Price	0
Forfeited/expired, Weighted Average Exercise Price	32.21
Ending balance, Weighted Average Exercise Price	$ 27.89
Stock Options [Member] | Vested [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Grant Date Fair Value [Roll Forward]
Exercisable/vested, Number of Options | shares	622,372
Exercisable/vested, Weighted Average Exercise Price	$ 23.88

Share-Based Compensation (Black

Share-Based Compensation (Black-Scholes Pricing Model Assumptions) (Details)	3 Months Ended
	Mar. 31, 2016$ / shares
Assumptions of Black-Scholes option pricing model
Expected dividend yield	3.30%
Risk-free interest rate	1.39%
Expected stock price volatility	27.90%
Expected life of options - in years	6 years 6 months
Weighted average fair value of options granted	$ 6.15

Share-Based Compensation (Restr

Share-Based Compensation (Restricted Stock Unit Activity) (Details) - Restricted Stock Units (RSUs) [Member]	3 Months Ended
	Mar. 31, 2016$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Number of Shares [Roll Forward]
Beginning balance, Number of shares | shares	207,989
Granted, Number of shares | shares	98,425
Converted into shares of common stock, Number of shares | shares	(42,812)
Forfeited/expired, Number of shares | shares	(1,116)
Ending balance, Number of shares | shares	262,486
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Weighted Average Grant Date Fair Value [Abstract]
Beginning balance, Weighted average grant date fair value | $ / shares	$ 26.41
Granted, Weighted Average grant date fair value | $ / shares	30.40
Converted into shares of common stock, Weighted average grant date fair value | $ / shares	22.47
Forfeited/expired, Weighted average grant date fair value | $ / shares	30.29
Ending balance, Weighted average grant date fair value | $ / shares	$ 28.53

(Textual) (Details)

(Textual) (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)$ / sharesshares	Apr. 20, 2015shares
Share-Based Compensation Plans (Textual) [Abstract]
Share-based compensation expense | $	$ 0.8
Corporation granted shares of common stock | shares	940
Common stock available for future grants under share-based compensation plans | shares		1,300,000
Stock Option Vesting Period, Post 2012 Grants	5 years
Stock Option Vesting Period Pre 2013 Grants	3 years
Restricted Stock Units (RSUs) [Member]
Share-Based Compensation Plans (Textual) [Abstract]
Corporation granted options to purchase restricted stock performance units | shares	98,425
Unrecognized compensation expense | $	$ 5.6
Unrecognized compensation expense, period for recognition	2 years 10 months 24 days
Restricted Stock Units (RSUs) [Member] | Maximum [Member]
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 Units (RSUs) [Member] | Minimum [Member]
Share-Based Compensation Plans (Textual) [Abstract]
Restricted stock performance units eligible to vest as a multiple of number of units granted	0.5
Equity Option [Member]
Share-Based Compensation Plans (Textual) [Abstract]
Common stock available for future grants under share-based compensation plans | shares	704,273
Weighted-average remaining contractual terms for outstanding stock options	7 years 4 months 24 days
Weighted-average remaining contractual terms for exercisable stock options	5 years 1 month 6 days
Outstanding in-the-money stock options, intrinsic value | $	$ 11
Exercisable in-the-money stock options, intrinsic value | $	$ 7.3
Closing price of common stock | $ / shares	$ 35.69
Unrecognized compensation expense | $	$ 5.7
Unrecognized compensation expense, period for recognition	4 years
Employee Stock Option [Member]
Share-Based Compensation Plans (Textual) [Abstract]
Stock Option Award Vesting Period	10 years
Vested & Nonvested [Member] | Employee Stock Option [Member]
Share-Based Compensation Plans (Textual) [Abstract]
Corporation granted options to purchase common stock | shares	441,167

Pension and Other Postretirem75

Pension and Other Postretirement Benefit Plans (Components of Net Periodic Benefit Cost (Income)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Pension Plans [Member]
Components of net periodic benefit cost (income) for the Corporation's qualified and nonqualified pension plans and nonqualified postretirement benefits plan
Service cost	$ 277	$ 273
Interest cost	1,358	1,332
Expected return on plan assets	(2,141)	(2,161)
Amortization of prior service cost	0	(1)
Amortization of unrecognized net loss (gain)	572	1,056
Net periodic benefit cost	66	499
Postretirement Benefit Plan [Member]
Components of net periodic benefit cost (income) for the Corporation's qualified and nonqualified pension plans and nonqualified postretirement benefits plan
Service cost	2	4
Interest cost	33	33
Amortization of prior service cost	29	32
Amortization of unrecognized net loss (gain)	(24)	0
Net periodic benefit cost	$ 40	$ 69

Pension and Other Postretirem76

Pension and Other Postretirement Benefit Plans (Textual) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Multiemployer Plan, Period Contributions	$ 0
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to defined benefit pension plan	$ 0		$ 0
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	4.55%
Chemical Financial Corporation [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of eligible pay contribution to certain employees	4.00%
Defined Contribution Plan, Employer Total Contribution Amount	$ 1.3	$ 1.1

Financial Guarantees (Textual)

Financial Guarantees (Textual) (Details) - Financial Standby Letter of Credit [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Financial Guarantees (Textual) [Abstract]
Letters of credit outstanding	$ 43	$ 39	$ 38
Expiration period for letters of credit, maximum	5 years