TCF Financial 10-Q 28 Jul 16 2016 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2016	Jul. 21, 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	Jun. 30, 2016
Amendment Flag	false
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		38,268,487

Consolidated Statements of Fina

Consolidated Statements of Financial Position - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Cash and cash equivalents:
Cash and cash due from banks	$ 179,310	$ 194,136	$ 167,054
Interest-bearing deposits with the Federal Reserve Bank and other banks	53,650	44,653	47,980
Total cash and cash equivalents	232,960	238,789	215,034
Investment securities:
Available-for-sale, at fair value	458,552	553,731	685,706
Held-to-maturity (fair value - $568,415 at June 30, 2016, $512,705 at December 31, 2015 and $466,578 at June 30, 2015)	552,828	509,971	469,837
Total investment securities	1,011,380	1,063,702	1,155,543
Loans held-for-sale, at fair value	13,990	10,327	7,798
Loans	7,647,269	7,271,147	7,034,743
Allowance for loan losses	(71,506)	(73,328)	(74,941)
Net loans	7,575,763	7,197,819	6,959,802
Premises and equipment (net of accumulated depreciation of $121,890 at June 30, 2016, $120,382 at December 31, 2015 and $112,530 at June 30, 2015)	102,709	106,317	111,968
Goodwill	286,867	287,393	285,512
Other intangible assets	34,270	38,104	41,201
Interest receivable and other assets	256,233	246,346	243,867
Total Assets	9,514,172	9,188,797	9,020,725
Deposits:
Noninterest-bearing	2,007,629	1,934,583	1,860,863
Interest-bearing	5,457,017	5,522,184	5,432,116
Total deposits	7,464,646	7,456,767	7,292,979
Interest payable and other liabilities	71,417	76,466	66,174
Securities Sold under Agreements to Repurchase	256,213	297,199	305,291
Short-term Borrowings	300,000	100,000	227,000
Other Borrowings	371,597	242,391	148,490
Total liabilities	8,463,873	8,172,823	8,039,934
Shareholders’ equity:
Preferred stock, no par value: Authorized - 2,000,000 shares, none issued	0	0	0
Common stock, $1 par value per share, Authorized - 60,000,000 shares, Issued and outstanding — 38,267,118 shares at June 30, 2016, 38,167,861 shares at December 31, 2015 and 38,110,136 shares at June 30, 2015	38,267	38,168	38,110
Additional paid-in capital	727,145	725,280	722,329
Retained earnings	310,585	281,558	251,456
Accumulated other comprehensive loss	(25,698)	(29,032)	(31,104)
Total shareholders’ equity	1,050,299	1,015,974	980,791
Total Liabilities and Shareholders’ Equity	$ 9,514,172	$ 9,188,797	$ 9,020,725

Consolidated Statements of Fin3

Consolidated Statements of Financial Position (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Held-to-maturity, fair value	$ 568,415	$ 512,705	$ 466,578
Accumulated depreciation of premises and equipment	$ 121,890	$ 120,382	$ 111,270
Preferred stock, no par value
Preferred stock, shares authorized	2,000,000	2,000,000	2,000,000
Preferred stock, shares issued	0	0	0
Common stock, par value	$ 1	$ 1	$ 1
Common stock, shares authorized	60,000,000	60,000,000	60,000,000
Common stock, shares issued	38,267,118	38,167,861	38,110,136
Common stock, shares outstanding	38,267,118	38,167,861	38,110,136

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Interest Income
Interest and fees on loans	$ 77,578	$ 64,613	$ 151,979	$ 122,710
Interest on investment securities:
Taxable	1,798	2,202	3,727	4,509
Tax-exempt	2,640	2,185	5,305	4,091
Dividends on nonmarketable equity securities	777	551	1,033	749
Interest on deposits with the Federal Reserve Bank and other banks	144	128	357	250
Total interest income	82,937	69,679	162,401	132,309
Interest Expense
Interest on deposits	4,260	3,630	8,319	6,982
Interest on short-term borrowings	226	101	326	199
Interest Expense, Other	956	213	1,931	213
Total interest expense	5,442	3,944	10,576	7,394
Net Interest Income	77,495	65,735	151,825	124,915
Provision for loan losses	3,000	1,500	4,500	3,000
Net interest income after provision for loan losses	74,495	64,235	147,325	121,915
Noninterest Income
Service charges and fees on deposit accounts	6,337	6,445	12,057	12,361
Wealth management revenue	5,782	5,605	10,983	10,676
Other charges and fees for customer services	6,463	6,516	12,855	12,506
Mortgage banking revenue	1,595	1,688	3,000	3,091
Gain on sale of investment securities	18	28	37	607
Other	702	392	1,384	708
Total noninterest income	20,897	20,674	40,316	39,949
Operating Expenses
Salaries, wages and employee benefits	33,127	31,711	67,017	60,964
Occupancy	5,514	4,386	10,419	8,812
Equipment and software	4,875	4,480	9,279	8,878
Acquisition-related expenses	3,054	3,457	5,648	4,819
Other	12,515	12,751	25,609	24,332
Total operating expenses	59,085	56,785	117,972	107,805
Income before income taxes	36,307	28,124	69,669	54,059
Federal income tax expense	10,600	9,100	20,700	17,200
Net Income	$ 25,707	$ 19,024	$ 48,969	$ 36,859
Net Income Per Common Share:
Basic (in dollars per share)	$ 0.67	$ 0.54	$ 1.28	$ 1.08
Diluted (in dollars per share)	0.67	0.54	1.27	1.08
Cash Dividends Declared Per Common Share (dollars per share)	$ 0.26	$ 0.24	$ 0.52	$ 0.48

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net income	$ 25,707	$ 19,024	$ 48,969	$ 36,859
Other comprehensive income (loss), net of tax:
Net unrealized gains (losses) on investment securities available-for-sale, net of tax expense (benefit) of $742 and $(1,084) for the three months ended June 30, 2016 and 2015, respectively, and $2,212 and $177 for the six months ended June 30, 2016 and 2015, respectively	1,379	(2,014)	4,108	331
Reclassification adjustment for realized gain on sale of investment securities available-for-sale included in net income, net of tax expense of $6 and $10 for the three months ended June 30, 2016 and 2015, respectively, and $13 and $212 for the six months ended June 30, 2016 and 2015, respectively	(12)	(18)	(24)	(395)
Adjustment for pension and other postretirement benefits, net of tax expense (benefit) of $(202) and $380 for the three months ended June 30, 2016 and 2015, respectively, and $(404) and $761 for the six months ended June 30, 2016 and 2015, respectively	(375)	707	(750)	1,413
Total other comprehensive income (loss), net of tax	992	(1,325)	3,334	1,349
Comprehensive income	$ 26,699	$ 17,699	$ 52,303	$ 38,208

Consolidated Statements of Com6

Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Tax expense (benefit) on net unrealized gains (losses) on investment securities available-for-sale	$ 742	$ (1,084)	$ 2,212	$ 177
Tax expense (benefit) on reclassification adjustment for realized gains on sale of investment securities available-for-sale	(6)	(10)	(13)	(212)
Tax expense (benefit) on adjustment for pension and other postretirement benefits	$ (202)	$ 380	$ (404)	$ 761

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	38,208			36,859	1,349
Cash dividends declared and paid, $0.52 and $0.48 per share at June 30, 2016 and June 30, 2015, respectively.	(17,049)			(17,049)
Issuance of common stock in business acquisitions	159,904	5,183	154,721
Stock issued - stock options	1,146	88	1,058
Shares issued – directors’ stock plans	316	11	305
Shares issued – restricted stock units	(328)	53	(381)
Share-based compensation	1,461	1	1,460
Ending Balance at Jun. 30, 2015	980,791	38,110	722,329	251,456	(31,104)
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	52,303			48,969	3,334
Cash dividends declared and paid, $0.52 and $0.48 per share at June 30, 2016 and June 30, 2015, respectively.	(19,942)			(19,942)
Stock issued - stock options	528	48	480
Shares issued – directors’ stock plans	125	5	120
Shares issued – restricted stock units	(469)	45	(514)
Share-based compensation	1,780	1	1,779
Ending Balance at Jun. 30, 2016	$ 1,050,299	$ 38,267	$ 727,145	$ 310,585	$ (25,698)

Consolidated Statements of Cha8

Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Cash dividends declared per share	$ 0.26	$ 0.24	$ 0.52	$ 0.48

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Operating Activities
Net income	$ 48,969	$ 36,859
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	4,500	3,000
Gains on sales of loans	(3,431)	(3,375)
Proceeds from sales of loans	119,845	119,683
Loans originated for sale	(120,077)	(111,903)
Net gains from sales/writedowns of other real estate and repossessed assets	(2,512)	(1,578)
Depreciation of premises and equipment	5,562	5,239
Amortization of intangible assets	4,751	3,787
Net gains on sale of investment securities	(37)	(607)
Net amortization of premiums and discounts on investment securities	2,891	2,759
Share-based compensation expense	1,780	1,461
Net increase in interest receivable and other assets	(13,642)	(11,695)
Net decrease in interest payable and other liabilities	(4,139)	(15,727)
Net cash provided by operating activities	44,460	27,903
Investment securities – available-for-sale:
Proceeds from sales	0	13,173
Proceeds from maturities, calls and principal reductions	99,528	113,973
Investment securities – held-to-maturity:
Proceeds from maturities, calls and principal reductions	57,518	54,481
Purchases	(101,295)	(205,286)
Net increase in loans	(385,814)	(250,997)
Proceeds from sales of other real estate and repossessed assets	7,377	7,934
Purchases of premises and equipment, net of disposals	(3,897)	(3,333)
Cash acquired, net of cash paid, in business combinations	0	16,551
Net cash used in investing activities	(326,583)	(253,504)
Financing Activities
Net increase in interest- and noninterest-bearing demand deposits and savings accounts	95,263	217,719
Net decrease in time deposits	(87,384)	(72,795)
Net increase in securities sold under agreements to repurchase with customers and other short-term borrowings	159,014	103,824
Proceeds from long-term borrowings	150,000	25,000
Repayment of long-term borrowings	(20,558)	0
Cash dividends paid	(19,942)	(17,049)
Proceeds from directors’ stock plans and exercise of stock options, net of shares withheld	653	1,462
Cash paid for payroll taxes upon conversion of share-based awards	(752)	(546)
Net cash provided by financing activities	276,294	257,615
Net increase (decrease) in cash and cash equivalents	(5,829)	32,014
Cash and cash equivalents at beginning of period	238,789	183,020
Cash and cash equivalents at end of period	232,960	215,034
Supplemental Disclosure of Cash Flow Information:
Interest paid	10,764	6,592
Loans transferred to other real estate and repossessed assets	3,370	5,908
Closed branch offices transferred to other real estate	1,863	359
Federal income taxes paid	11,700	20,800
Fair value of tangible assets acquired (non-cash)	0	1,284,552
Goodwill and identifiable intangible assets acquired	0	116,478
Liabilities assumed	0	1,257,917
Common stock issued	$ 0	$ 159,904

Significant Accounting Policies

Significant Accounting Policies	6 Months Ended
	Jun. 30, 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 six months ended June 30, 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 nonperforming TDRs, no additional provision for loan losses has been recognized for these loans and they continue to accrue interest at their contractual interest rate. Nonperforming TDRs 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 and 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 June 30, 2016 , December 31, 2015 and June 30, 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 June 30, 2016 , December 31, 2015 or June 30, 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 $1.2 million during the three and six months ended June 30, 2016 , respectively, and $0.2 million and $0.3 million during the three and six months ended June 30, 2015 , respectively. The Corporation's remaining investment in qualified affordable housing projects accounted for under the proportional amortization method totaled $24.3 million at June 30, 2016 , $21.7 million at December 31, 2015 and $21.4 million at June 30, 2015 . 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 $7.5 million , $1.7 million and $3.3 million at June 30, 2016 , December 31, 2015 and June 30, 2015 , respectively. The Corporation's unfunded equity contributions relating to investments in qualified affordable housing projects, federal historic tax projects and new market projects is recorded in other liabilities on the consolidated statements of financial position. The Corporation's remaining unfunded equity contributions totaled $11.5 million , $8.0 million and $9.7 million at June 30, 2016 , December 31, 2015 and June 30, 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 June 30, 2016 , December 31, 2015 or June 30, 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 repurchase programs allowing management to repurchase shares of the Corporation’s common stock in the open market. The repurchased shares

Acquisitions

Acquisitions	6 Months Ended
	Jun. 30, 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 June 30, 2016, Talmer had total assets of $6.9 billion , total loans of $5.0 billion and total deposits of $5.3 billion , including brokered deposits of $389 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. At a special meeting of Talmer shareholders, held on July 14, 2016, Talmer shareholders approved the merger. And at a special meeting of Chemical shareholders, held on July 19, 2016, Chemical shareholders approved the merger. Completion of the merger is subject to regulatory approval, 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 $756 million and $734 million , respectively, at June 30, 2016 , compared to $ 864 million and $842 million , respectively, at December 31, 2015 and $990 million and $967 million , respectively, at June 30, 2015 . 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 $101 million and $94 million , respectively, at June 30, 2016 , compared to $115 million and $108 million , respectively, at December 31, 2015 and $126 million and $119 million , respectively, at June 30, 2015 . 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 $305 million and $275 million , respectively, at June 30, 2016 , compared to $361 million and $330 million , respectively, at December 31, 2015 and $415 million and $382 million , respectively, at June 30, 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 $182 million and $166 million , respectively, at June 30, 2016 , compared to $204 million and $183 million , respectively, at December 31, 2015 and $236 million and $215 million , respectively, at June 30, 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 Six Months Ended June 30, 2016 (In thousands) Balance at beginning of period $ 152,999 $ 34,558 $ 82,623 $ 28,077 $ 298,257 Additions (reductions)* (10,365 ) (863 ) (5,848 ) (201 ) (17,277 ) Accretion recognized in interest income (17,291 ) (2,836 ) (8,029 ) (6,284 ) (34,440 ) Reclassification from nonaccretable difference — — 5,000 5,000 10,000 Balance at end of period $ 125,343 $ 30,859 $ 73,746 $ 26,592 $ 256,540 Six Months Ended June 30, 2015 Balance at beginning of period $ — $ — $ 104,675 $ 33,286 $ 137,961 Additions attributable to acquisitions 190,246 37,914 — — 228,160 Additions (reductions)* 1,550 (1,141 ) (2,859 ) 5,215 2,765 Accretion recognized in interest income (3,486 ) (968 ) (10,058 ) (6,326 ) (20,838 ) Balance at end of period $ 188,310 $ 35,805 $ 91,758 $ 32,175 $ 348,048 *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. As part of its ongoing assessment of the acquired loan portfolios, management has determined that the overall credit quality of the Northwestern and OAK acquired loan portfolios has improved, which has resulted in an improvement in expected cash flows of certain loan pools in these acquired loan portfolios. Accordingly, management reclassified $5.0 million during the three months ended June 30, 2016 from the nonaccretable difference to the accretable yield for each of these acquired loan portfolios, which will increase amounts recognized into interest income over the estimated remaining lives of the loan pools within these portfolios.

Investment Securities

Investment Securities	6 Months Ended
	Jun. 30, 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 June 30, 2016 , December 31, 2015 and June 30, 2015 : Investment Securities Available-for-Sale Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) June 30, 2016 U.S. Treasury securities $ 5,781 $ 29 $ — $ 5,810 Government sponsored agencies 156,843 715 536 157,022 State and political subdivisions 12,901 319 — 13,220 Residential mortgage-backed securities 166,582 2,034 — 168,616 Collateralized mortgage obligations 100,433 611 195 100,849 Corporate bonds 9,746 30 64 9,712 Preferred stock and trust preferred securities 2,888 436 1 3,323 Total $ 455,174 $ 4,174 $ 796 $ 458,552 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 June 30, 2015 U.S. Treasury securities $ 8,270 $ 24 $ — $ 8,294 Government sponsored agencies 227,424 683 200 227,907 State and political subdivisions 26,476 503 14 26,965 Residential mortgage-backed securities 213,621 742 1,694 212,669 Collateralized mortgage obligations 167,768 245 981 167,032 Corporate bonds 39,680 76 78 39,678 Preferred stock and trust preferred securities 2,889 272 — 3,161 Total $ 686,128 $ 2,545 $ 2,967 $ 685,706 Investment Securities Held-to-Maturity Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) June 30, 2016 State and political subdivisions $ 552,328 $ 16,123 $ 321 $ 568,130 Trust preferred securities 500 — 215 285 Total $ 552,828 $ 16,123 $ 536 $ 568,415 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 June 30, 2015 State and political subdivisions $ 469,337 $ 4,853 $ 7,912 $ 466,278 Trust preferred securities 500 — 200 300 Total $ 469,837 $ 4,853 $ 8,112 $ 466,578 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). The following is a summary of the amortized cost and fair value of investment securities at June 30, 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. June 30, 2016 Amortized Cost Fair Value (In thousands) Investment Securities Available-for-Sale: Due in one year or less $ 154,820 $ 155,386 Due after one year through five years 257,040 258,856 Due after five years through ten years 37,877 38,374 Due after ten years 4,049 4,112 Preferred stock 1,388 1,824 Total $ 455,174 $ 458,552 Investment Securities Held-to-Maturity: Due in one year or less $ 59,330 $ 59,633 Due after one year through five years 275,988 280,491 Due after five years through ten years 130,304 136,879 Due after ten years 87,206 91,412 Total $ 552,828 $ 568,415 The following schedule summarizes information for both available-for-sale and held-to-maturity investment securities with gross unrealized losses at June 30, 2016 , December 31, 2015 and June 30, 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) June 30, 2016 Government sponsored agencies $ 14,110 $ 19 $ 18,787 $ 517 $ 32,897 $ 536 State and political subdivisions 73,532 237 25,713 84 99,245 321 Collateralized mortgage obligations 8,461 13 22,955 182 31,416 195 Corporate bonds — — 4,936 64 4,936 64 Preferred stock and trust preferred securities 1,499 1 285 215 1,784 216 Total $ 97,602 $ 270 $ 72,676 $ 1,062 $ 170,278 $ 1,332 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 June 30, 2015 Government sponsored agencies $ 24,789 $ 163 $ 14,715 $ 37 $ 39,504 $ 200 State and political subdivisions 258,503 5,433 63,584 2,493 322,087 7,926 Residential mortgage-backed securities 187,858 1,592 3,643 102 191,501 1,694 Collateralized mortgage obligations 49,845 155 48,881 826 98,726 981 Corporate bonds 9,670 49 14,971 29 24,641 78 Trust preferred securities — — 300 200 300 200 Total $ 530,665 $ 7,392 $ 146,094 $ 3,687 $ 676,759 $ 11,079 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 reasonably available information. The Corporation reviews factors such as financial statements, credit ratings, news releases and other pertinent information of the underlying issuer or company to make its determination. Management did not believe any individual unrealized loss on any investment security, as of June 30, 2016 , represented an other-than-temporary impairment (OTTI). Management believed that the unrealized losses on investment securities at June 30, 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 June 30, 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 June 30, 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	6 Months Ended
	Jun. 30, 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 are 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: June 30, December 31, June 30, (In thousands) Commercial loan portfolio: Commercial $ 1,953,301 $ 1,905,879 $ 1,754,873 Commercial real estate 2,157,733 2,112,162 2,243,513 Real estate construction and land development 285,848 232,076 112,312 Subtotal 4,396,882 4,250,117 4,110,698 Consumer loan portfolio: Residential mortgage 1,494,192 1,429,636 1,310,167 Consumer installment 1,048,622 877,457 887,907 Home equity 707,573 713,937 725,971 Subtotal 3,250,387 3,021,030 2,924,045 Total loans $ 7,647,269 $ 7,271,147 $ 7,034,743 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 June 30, 2016 , December 31, 2015 and June 30, 2015 : Commercial Commercial Real Estate Real Estate Construction and Land Development Total (In thousands) June 30, 2016 Originated Portfolio: Risk Grades 1-5 $ 1,537,612 $ 1,479,365 $ 239,194 $ 3,256,171 Risk Grade 6 46,202 36,814 843 83,859 Risk Grade 7 35,602 15,434 517 51,553 Risk Grade 8 14,577 21,324 496 36,397 Risk Grade 9 — 1 — 1 Subtotal 1,633,993 1,552,938 241,050 3,427,981 Acquired Portfolio: Risk Grades 1-5 292,492 554,352 40,671 887,515 Risk Grade 6 15,352 20,746 1,500 37,598 Risk Grade 7 8,448 23,879 1,229 33,556 Risk Grade 8 3,016 5,818 1,398 10,232 Risk Grade 9 — — — — Subtotal 319,308 604,795 44,798 968,901 Total $ 1,953,301 $ 2,157,733 $ 285,848 $ 4,396,882 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 June 30, 2015 Originated Portfolio: Risk Grades 1-5 $ 1,269,091 $ 1,273,725 $ 97,364 $ 2,640,180 Risk Grade 6 32,189 34,677 433 67,299 Risk Grade 7 41,316 29,737 2,127 73,180 Risk Grade 8 17,260 25,283 502 43,045 Risk Grade 9 — 4 — 4 Subtotal 1,359,856 1,363,426 100,426 2,823,708 Acquired Portfolio: Risk Grades 1-5 347,914 820,400 10,139 1,178,453 Risk Grade 6 29,412 22,796 71 52,279 Risk Grade 7 13,910 30,288 119 44,317 Risk Grade 8 3,781 6,603 1,557 11,941 Risk Grade 9 — — — — Subtotal 395,017 880,087 11,886 1,286,990 Total $ 1,754,873 $ 2,243,513 $ 112,312 $ 4,110,698 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 June 30, 2016 , December 31, 2015 and June 30, 2015 : Residential Mortgage Consumer Installment Home Equity Total Consumer (In thousands) June 30, 2016 Originated Loans: Performing $ 1,299,382 $ 1,041,978 $ 598,283 $ 2,939,643 Nonperforming 7,983 285 3,042 11,310 Subtotal 1,307,365 1,042,263 601,325 2,950,953 Acquired Loans: Performing 185,492 6,298 105,360 297,150 Nonperforming 1,335 61 888 2,284 Subtotal 186,827 6,359 106,248 299,434 Total $ 1,494,192 $ 1,048,622 $ 707,573 $ 3,250,387 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 June 30, 2015 Originated Loans: Performing $ 1,058,696 $ 871,543 $ 584,520 $ 2,514,759 Nonperforming 9,793 393 2,357 12,543 Subtotal 1,068,489 871,936 586,877 2,527,302 Acquired Loans: Performing 238,698 15,966 138,086 392,750 Nonperforming 2,980 5 1,008 3,993 Subtotal 241,678 15,971 139,094 396,743 Total $ 1,310,167 $ 887,907 $ 725,971 $ 2,924,045 Nonperforming Loans A summary of nonperforming loans follows: June 30, December 31, June 30, (In thousands) Nonaccrual loans: Commercial $ 14,577 $ 28,554 $ 17,260 Commercial real estate 21,325 25,163 25,287 Real estate construction and land development 496 521 502 Residential mortgage 5,343 5,557 6,004 Consumer installment 285 451 393 Home equity 1,971 1,979 1,769 Total nonaccrual loans 43,997 62,225 51,215 Accruing loans contractually past due 90 days or more as to interest or principal payments: Commercial 3 364 711 Commercial real estate 3 254 56 Residential mortgage 407 402 424 Home equity 1,071 1,267 588 Total accruing loans contractually past due 90 days or more as to interest or principal payments 1,484 2,287 1,779 Nonperforming TDRs: Commercial loan portfolio 14,240 16,297 14,547 Consumer loan portfolio 2,233 3,071 3,365 Total nonperforming TDRs 16,473 19,368 17,912 Total nonperforming loans $ 61,954 $ 83,880 $ 70,906 The Corporation’s nonaccrual loans at June 30, 2016 , December 31, 2015 and June 30, 2015 included $32.4 million , $35.9 million and $35.7 million , respectively, of nonaccrual TDRs. The Corporation had $0.9 million of residential mortgage loans that were in the process of foreclosure at June 30, 2016 , compared to $2.9 million and $2.0 million at December 31, 2015 and June 30, 2015 , respectively. Impaired Loans The following schedule presents impaired loans by classes of loans at June 30, 2016 , December 31, 2015 and June 30, 2015 : Recorded Investment Unpaid Principal Balance Related Valuation Allowance (In thousands) June 30, 2016 Impaired loans with a valuation allowance: Commercial $ 3,764 $ 3,769 $ 2,582 Commercial real estate 3,270 3,438 472 Residential mortgage 20,745 20,745 163 Subtotal 27,779 27,952 3,217 Impaired loans with no related valuation allowance: Commercial 34,633 43,576 — Commercial real estate 47,894 58,312 — Real estate construction and land development 2,196 3,770 — Residential mortgage 6,678 7,365 — Consumer installment 347 365 — Home equity 2,859 3,084 — Subtotal 94,607 116,472 — Total impaired loans: Commercial 38,397 47,345 2,582 Commercial real estate 51,164 61,750 472 Real estate construction and land development 2,196 3,770 — Residential mortgage 27,423 28,110 163 Consumer installment 347 365 — Home equity 2,859 3,084 — Total $ 122,386 $ 144,424 $ 3,217 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) June 30, 2015 Impaired loans with a valuation allowance: Commercial $ 4,044 $ 4,137 $ 718 Commercial real estate 2,789 2,948 603 Residential mortgage 20,970 20,970 260 Subtotal 27,803 28,055 1,581 Impaired loans with no related valuation allowance: Commercial 32,461 38,160 — Commercial real estate 56,052 78,490 — Real estate construction and land development 2,393 4,175 — Residential mortgage 8,984 8,984 — Consumer installment 398 398 — Home equity 2,778 2,778 — Subtotal 103,066 132,985 — Total impaired loans: Commercial 36,505 42,297 718 Commercial real estate 58,841 81,438 603 Real estate construction and land development 2,393 4,175 — Residential mortgage 29,954 29,954 260 Consumer installment 398 398 — Home equity 2,778 2,778 — Total $ 130,869 $ 161,040 $ 1,581 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 $22.0 million , $25.3 million and $30.2 million at June 30, 2016 , December 31, 2015 and June 30, 2015 , respectively, includes confirmed losses (partial charge-offs) of $16.3 million , $17.1 million and $15.2 million , respectively, and fair value discount adjustments of $5.7 million , $8.2 million and $15.0 million , respectively. Impaired loans included $12.5 million , $12.8 million and $15.9 million at June 30, 2016 , December 31, 2015 and June 30, 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 $49.4 million , $47.8 million and $45.8 million at June 30, 2016 , December 31, 2015 and June 30, 2015 , respectively, of performing TDRs. The following schedule presents information related to impaired loans for the three and six months ended June 30, 2016 and 2015 : Three Months Ended June 30, 2016 Six Months Ended June 30, 2016 Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status (In thousands) Commercial $ 38,606 $ 348 $ 41,811 $ 677 Commercial real estate 53,723 391 55,839 849 Real estate construction and land development 2,265 26 2,166 51 Residential mortgage 27,418 356 27,755 722 Consumer installment 330 1 359 2 Home equity 2,791 13 3,022 28 Total $ 125,133 $ 1,135 $ 130,952 $ 2,329 Three Months Ended June 30, 2015 Six Months Ended June 30, 2015 Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status (In thousands) Commercial $ 36,735 $ 263 $ 37,655 $ 552 Commercial real estate 60,393 458 60,317 983 Real estate construction and land development 2,290 36 2,403 63 Residential mortgage 29,432 380 28,392 711 Consumer installment 426 1 463 1 Home equity 2,529 14 2,440 22 Total $ 131,805 $ 1,152 $ 131,670 $ 2,332 The following schedule presents the aging status of the recorded investment in loans by classes of loans at June 30, 2016 , December 31, 2015 and June 30, 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) June 30, 2016 Originated Portfolio: Commercial $ 4,522 $ 822 $ 3 $ 14,577 $ 19,924 $ 1,614,069 $ 1,633,993 Commercial real estate 8,842 343 3 21,325 30,513 1,522,425 1,552,938 Real estate construction and land development 62 — — 496 558 240,492 241,050 Residential mortgage 1,955 — 407 5,343 7,705 1,299,660 1,307,365 Consumer installment 2,856 554 — 285 3,695 1,038,568 1,042,263 Home equity 2,594 366 1,071 1,971 6,002 595,323 601,325 Total $ 20,831 $ 2,085 $ 1,484 $ 43,997 $ 68,397 $ 6,310,537 $ 6,378,934 Acquired Portfolio: Commercial $ 547 $ — $ 3,038 $ — $ 3,585 $ 315,723 $ 319,308 Commercial real estate 90 — 5,817 — 5,907 598,888 604,795 Real estate construction and land development 389 — 1,398 — 1,787 43,011 44,798 Residential mortgage 407 — 1,335 — 1,742 185,085 186,827 Consumer installment 58 25 62 — 145 6,214 6,359 Home equity 416 38 888 — 1,342 104,906 106,248 Total $ 1,907 $ 63 $ 12,538 $ — $ 14,508 $ 1,253,827 $ 1,268,335 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 June 30, 2015 Originated Portfolio: Commercial $ 4,055 $ 2,317 $ 711 $ 17,260 $ 24,343 $ 1,335,513 $ 1,359,856 Commercial real estate 2,754 1,117 56 25,287 29,214 1,334,212 1,363,426 Real estate construction and land development 413 — — 502 915 99,511 100,426 Residential mortgage 1,536 — 424 6,004 7,964 1,060,525 1,068,489 Consumer installment 2,526 302 — 393 3,221 868,715 871,936 Home equity 2,334 204 588 1,769 4,895 581,982 586,877 Total $ 13,618 $ 3,940 $ 1,779 $ 51,215 $ 70,552 $ 5,280,458 $ 5,351,010 Acquired Portfolio: Commercial $ 690 $ — $ 3,781 $ — $ 4,471 $ 390,546 $ 395,017 Commercial real estate 969 291 6,603 — 7,863 872,224 880,087 Real estate construction and land development — — 1,557 — 1,557 10,329 11,886 Residential mortgage 1,077 138 2,980 — 4,195 237,483 241,678 Consumer installment — 56 5 — 61 15,910 15,971 Home equity 1,153 210 1,008 — 2,371 136,723 139,094 Total $ 3,889 $ 695 $ 15,934 $ — $ 20,518 $ 1,663,215 $ 1,683,733 Loans Modified Under Troubled Debt Restructurings (TDRs) The following schedule presents the Corporation’s TDRs at June 30, 2016 , December 31, 2015 and June 30, 2015 : Performing TDRs Non-Performing TDRs Nonaccrual TDRs Total (In thousands) June 30, 2016 Commercial loan portfolio $ 30,866 $ 14,240 $ 28,979 $ 74,085 Consumer loan portfolio 18,512 2,233 3,402 24,147 Total $ 49,378 $ 16,473 $ 32,381 $ 98,232 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 June 30, 2015 Commercial loan portfolio $ 28,203 $ 14,547 $ 32,001 $ 74,751 Consumer loan portfolio 17,605 3,365 3,707 24,677 Total $ 45,808 $ 17,912 $ 35,708 $ 99,428 The following schedule provides information on the Corporation's TDRs that were modified during the three and six months ended June 30, 2016 and 2015 : Three Months Ended June 30, 2016 Six Months Ended June 30, 2016 Number of Loans Pre- Modification Recorded Investment Post- Modification Recorded Investment Number of Loans Pre- Modification Recorded Investment Post- Modification Recorded Investment (Dollars in thousands) Commercial loan portfolio: Commercial 21 $ 4,149 $ 4,149 28 $ 7,981 $ 7,981 Commercial real estate 2 1,454 1,454 6 2,441 2,441 Subtotal – commercial loan portfolio 23 5,603 5,603 34 10,422 10,422 Consumer loan portfolio 14 490 490 21 694 694 Total 37 $ 6,093 $ 6,093 55 $ 11,116 $ 11,116 Three Months Ended June 30, 2015 Six Months Ended June 30, 2015 Number of Loans Pre- Modification Recorded Investment Post- Modification Recorded Investment Number of Loans Pre- Modification Recorded Investment Post- Modification Recorded Investment (Dollars in thousands) Commercial loan portfolio: Commercial 13 $ 2,332 $ 2,332 18 $ 4,264 $ 4,264 Commercial real estate 4 527 527 9 3,061 3,061 Real estate construction and land development 1 305 305 1 305 305 Subtotal – commercial loan portfolio 18 3,164 3,164 28 7,630 7,630 Consumer loan portfolio 29 1,633 1,631 39 1,969 1,967 Total 47 $ 4,797 $ 4,795 67 $ 9,599 $ 9,597 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 and six months ended June 30, 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: Three Months Ended June 30, 2016 Six Months Ended June 30, 2016 Number of Loans Principal Balance at End of Period Number of Loans Principal Balance at End of Period (Dollars in thousands) Commercial loan portfolio: Commercial — $ — — $ — Commercial real estate 1 788 2 1,721 Subtotal – commercial loan portfolio 1 788 2 1,721 Consumer loan portfolio 1 — 2 — Total 2 $ 788 4 $ 1,721 Three Months Ended June 30, 2015 Six Months Ended June 30, 2015 Number of Loans Principal Balance at End of Period Number of Loans Principal Balance at End of Period (Dollars in thousands) Commercial loan portfolio: Commercial — $ — — $ — Commercial real estate 1 183 4 942 Subtotal – commercial loan portfolio 1 183 4 942 Consumer loan portfolio — — 1 33 Total 1 $ 183 5 $ 975 Allowance for Loan Losses The following schedule presents, by loan portfolio segment, the changes in the allowance for the three and six months ended June 30, 2016 and details regarding the balance in the allowance and the recorded investment in loans at June 30, 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 June 30, 2016: Beginning balance $ 44,668 $ 25,650 $ — $ 70,318 Provision for loan losses 900 2,100 — 3,000 Charge-offs (2,542 ) (1,078 ) — (3,620 ) Recoveries 1,202 606 — 1,808 Ending balance $ 44,228 $ 27,278 $ — $ 71,506 Changes in allowance for loan losses for the six months ended June 30, 2016: Beginning balance $ 47,234 $ 26,094 $ — $ 73,328 Provision for loan losses 1,900 2,600 — 4,500 Charge-offs (6,438 ) (2,640 ) — (9,078 ) Recoveries 1,532 1,224 — 2,756 Ending balance $ 44,228 $ 27,278 $ — $ 71,506 Allowance for loan losses balance at June 30, 2016 attributable to: Loans individually evaluated for impairment $ 3,054 $ 163 $ — $ 3,217 Loans collectively evaluated for impairment 41,174 27,115 — 68,289 Loans acquired with deteriorated credit quality — — — — Total $ 44,228 $ 27,278 $ —

Intangible Assets

Intangible Assets	6 Months Ended
	Jun. 30, 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 June 30, 2016 and that the Corporation's goodwill was not impaired at June 30, 2016 . The following table shows the net carrying value of the Corporation’s intangible assets: June 30, December 31, June 30, (In thousands) Goodwill $ 286,867 $ 287,393 $ 285,512 Other intangible assets: Core deposit intangible assets $ 24,429 $ 26,654 $ 28,353 Non-compete intangible assets 164 328 541 Mortgage servicing rights 9,677 11,122 12,307 Total other intangible assets $ 34,270 $ 38,104 $ 41,201 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: June 30, December 31, June 30, (In thousands) Gross original amount $ 40,055 $ 40,055 $ 39,355 Accumulated amortization 15,626 13,401 11,002 Carrying amount $ 24,429 $ 26,654 $ 28,353 Amortization expense for the three months ended June 30 $ 1,113 $ 952 Amortization expense for the six months ended June 30 $ 2,225 $ 1,743 The estimated future amortization expense on core deposit intangible assets for periods ending after June 30, 2016 is as follows: 2016 — $2.1 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: June 30, December 31, June 30, (In thousands) Net carrying value of MSRs $ 9,677 $ 11,122 $ 12,307 Fair value of MSRs $ 12,493 $ 15,542 $ 16,602 Valuation allowance $ 412 $ — $ — Loans serviced for others that have servicing rights capitalized $ 2,014,986 $ 2,082,899 $ 2,193,067 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 a valuation allowance of $0.4 million as of June 30, 2016 related to impairment within certain pools attributable to the Corporation's servicing portfolios that were acquired in the Northwestern and Monarch transactions. There was no impairment valuation allowance recorded on the Corporation's MSRs at and December 31, 2015 and June 30, 2015 . The following table shows the activity for capitalized MSRs: Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 (In thousands) Balance at beginning of period $ 10,478 $ 11,583 $ 11,122 $ 12,217 Acquired in Monarch acquisition — 1,284 — 1,284 Additions 586 415 917 815 Amortization (975 ) (1,175 ) (1,950 ) (2,209 ) Change in valuation allowance (412 ) 200 (412 ) 200 Balance at end of period $ 9,677 $ 12,307 $ 9,677 $ 12,307

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	6 Months Ended
	Jun. 30, 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: June 30, December 31, June 30, (In thousands) Net unrealized gains (losses) on investment securities – available-for-sale, net of related tax expense (benefit) of $1,182 at June 30, 2016, $(1,017) at December 31, 2015 and $(148) at June 30, 2015 $ 2,196 $ (1,888 ) $ (274 ) Pension and other postretirement benefits adjustment, net of related tax benefit of $15,020 at June 30, 2016, $14,616 at December 31, 2015 and $16,601 at June 30, 2015 (27,894 ) (27,144 ) (30,830 ) Accumulated other comprehensive loss $ (25,698 ) $ (29,032 ) $ (31,104 )

Borrowings Borrowings (Notes)

Borrowings Borrowings (Notes)	6 Months Ended
	Jun. 30, 2016
Borrowings [Abstract]
Borrowings [Text Block]	Borrowings Short-term Borrowings The Corporation's short-term borrowings, which generally have an original term to maturity of 30 days or less, consisted of short-term FHLB advances outstanding of $300 million at June 30, 2016 , $100 million at December 31, 2015 and $205 million at June 30, 2015 , and federal funds purchased of $22 million at June 30, 2015 . There were no federal funds purchased at June 30, 2016 and December 31, 2015 . Long-term Borrowings A summary of the Corporation's long-term borrowings follows: June 30, December 31, June 30, (In thousands) Long-term borrowings: Long-term FHLB advances $ 329,320 $ 181,394 $ 81,469 Securities sold under agreements to repurchase 17,277 17,453 23,649 Non-revolving line-of-credit 25,000 25,000 25,000 Subordinated debt obligations — 18,544 18,372 Total long-term borrowings $ 371,597 $ 242,391 $ 148,490 During the second quarter of 2016, the Corporation borrowed $100 million of long-term FHLB advances which have a three-year term at a fixed-rate of 1.00% . During the first quarter of 2016, the Corporation borrowed $50 million of long-term FHLB advances which have a four-year term at a fixed-rate of 1.30% . The Corporation's long-term FHLB advances have a combined weighted-average interest rate of 1.27% as of June 30, 2016 . The Corporation's FHLB advances, including both short-term and long-term, require monthly interest payments and are collateralized by eligible loans totaling $2.98 billion as of June 30, 2016 . The scheduled reductions of long-term FHLB advances as of June 30, 2016 were as follows: 2016 - $5.1 million ; 2017 - $47.1 million ; 2018 - $67.1 million ; 2019; - $100.0 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 June 30, 2016 , these agreements had scheduled maturities of $8.1 million in 2016 and $9.2 million in 2017. The Corporation has a $25 million secured non-revolving line-of-credit with an unaffiliated third-party financial institution. The line-of-credit originally matured in May 2016 and was extended for a period of three months. The Corporation is fully drawn 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 2.41% at June 30, 2016 ). The line-of-credit agreement contains certain restrictive covenants. The Corporation was in compliance with all of the covenants at June 30, 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	6 Months Ended
	Jun. 30, 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 June 30, 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 $7.50 billion , $7.14 billion and $6.99 billion at June 30, 2016 , December 31, 2015 and June 30, 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 June 30, 2016 , December 31, 2015 and June 30, 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) June 30, 2016 Total Capital to Risk-Weighted Assets: Corporation $ 851,114 11.4 % $ 599,743 8.0 % N/A N/A Chemical Bank 854,189 11.4 598,142 8.0 $ 747,677 10.0 % Tier 1 Capital to Risk-Weighted Assets: Corporation 779,608 10.4 449,807 6.0 N/A N/A Chemical Bank 782,683 10.5 448,606 6.0 598,142 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets: Corporation 779,608 10.4 337,355 4.5 N/A N/A Chemical Bank 782,683 10.5 336,455 4.5 485,990 6.5 Leverage Ratio: Corporation 779,608 8.6 361,408 4.0 N/A N/A Chemical Bank 782,683 8.7 360,746 4.0 450,932 5.0 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) 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 June 30, 2015 Total Capital to Risk-Weighted Assets: Corporation $ 816,595 11.6 % $ 559,273 8.0 % N/A N/A Chemical Bank 713,999 12.0 471,422 8.0 $ 589,277 10.0 % The Bank of Holland 77,648 10.2 61,028 8.0 76,285 10.0 The Bank of Northern Michigan 32,779 10.1 25,878 8.0 32,347 10.0 Tier 1 Capital to Risk-Weighted Assets: Corporation 741,654 10.6 419,455 6.0 N/A N/A Chemical Bank 640,324 10.9 353,566 6.0 471,422 8.0 The Bank of Holland 76,312 10.0 45,771 6.0 61,028 8.0 The Bank of Northern Michigan 32,779 10.1 19,408 6.0 25,878 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets: Corporation 723,654 10.4 314,591 4.5 N/A N/A Chemical Bank 640,324 10.9 265,175 4.5 383,030 6.5 The Bank of Holland 76,312 10.0 34,328 4.5 49,585 6.5 The Bank of Northern Michigan 32,779 10.1 14,556 4.5 21,025 6.5 Leverage Ratio: Corporation 741,654 9.4 314,344 4.0 N/A N/A Chemical Bank 640,324 8.5 300,703 4.0 375,878 5.0 The Bank of Holland 76,312 9.9 30,710 4.0 38,388 5.0 The Bank of Northern Michigan 32,779 9.1 14,421 4.0 18,026 5.0

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 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) June 30, 2016 Investment securities – available-for-sale: U.S. Treasury securities $ 5,810 $ — $ — $ 5,810 Government sponsored agencies — 157,022 — 157,022 State and political subdivisions — 13,220 — 13,220 Residential mortgage-backed securities — 168,616 — 168,616 Collateralized mortgage obligations — 100,849 — 100,849 Corporate bonds — 9,712 — 9,712 Preferred stock and trust preferred securities — 3,323 — 3,323 Total investment securities – available-for-sale 5,810 452,742 — 458,552 Loans held-for-sale — 13,990 — 13,990 Total assets measured at fair value on a recurring basis $ 5,810 $ 466,732 $ — $ 472,542 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 June 30, 2015 Investment securities – available-for-sale: U.S. Treasury securities $ 8,294 $ — $ — $ 8,294 Government sponsored agencies — 227,907 — 227,907 State and political subdivisions — 26,965 — 26,965 Residential mortgage-backed securities — 212,669 — 212,669 Collateralized mortgage obligations — 167,032 — 167,032 Corporate bonds — 39,678 — 39,678 Preferred stock — 3,161 — 3,161 Total investment securities – available-for-sale 8,294 677,412 — 685,706 Loans held-for-sale — 7,798 — 7,798 Total assets measured at fair value on a recurring basis $ 8,294 $ 685,210 $ — $ 693,504 There were no liabilities recorded at fair value on a recurring basis at June 30, 2016 , December 31, 2015 or June 30, 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 June 30, 2016 , December 31, 2015 and June 30, 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 June 30, 2016 , December 31, 2015 and June 30, 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 June 30, 2016 , the Corporation recognized a valuation allowance of $0.4 million related to impairment within certain pools attributable to the Corporation's servicing portfolios that were acquired in the Northwestern and Monarch transactions. As a result, the MSRs related to these servicing portfolios were considered to be recorded at fair value on a nonrecurring basis as of June 30, 2016 . At December 31, 2015 and June 30, 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) June 30, 2016 Impaired originated loans $ — $ — $ 23,655 $ 23,655 Other real estate/repossessed assets — — 8,440 8,440 Mortgage servicing rights — — 6,153 6,153 Total $ — $ — $ 38,248 $ 38,248 December 31, 2015 Impaired originated loans $ — $ — $ 42,065 $ 42,065 Other real estate/repossessed assets — — 9,935 9,935 Total $ — $ — $ 52,000 $ 52,000 June 30, 2015 Impaired originated loans $ — $ — $ 24,517 $ 24,517 Other real estate/repossessed assets — — 14,197 14,197 Total $ — $ — $ 38,714 $ 38,714 There were no liabilities recorded at fair value on a nonrecurring basis at June 30, 2016 , December 31, 2015 and June 30, 2015 . The following table presents additional information about the significant unobservable inputs used in the fair value measurement of financial assets measured on a nonrecurring basis that were categorized within the Level 3 of the fair value hierarchy (fair value in thousands): Fair Value at June 30, 2016 Valuation Technique Significant Unobservable Inputs Range Impaired originated loans $ 23,655 Appraisal of collateral Discount for type of collateral and age of appraisal 20%-30% Other real estate/repossessed assets 8,440 Appraisal of property Discount for type of property and age of appraisal 25%-30% Mortgage servicing rights 6,153 Discounted cash flow Constant prepayment rate 12%-22% Discount rate 10%-11% 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 June 30, 2016 , December 31, 2015 and June 30, 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 June 30, 2016 December 31, 2015 June 30, 2015 Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value (In thousands) Assets: Cash and cash equivalents Level 1 $ 232,960 $ 232,960 $ 238,789 $ 238,789 $ 215,034 $ 215,034 Investment securities: Available-for-sale Level 1 5,810 5,810 5,765 5,765 8,294 8,294 Available-for-sale Level 2 452,742 452,742 547,966 547,966 677,412 677,412 Held-to-maturity Level 2 552,328 568,130 509,471 512,405 469,337 466,278 Held-to-maturity Level 3 500 285 500 300 500 300 Nonmarketable equity securities NA 47,775 47,775 36,907 36,907 36,142 36,142 Loans held-for-sale Level 2 13,990 13,990 10,327 10,327 7,798 7,798 Net loans Level 3 7,575,763 7,593,013 7,197,819 7,201,994 6,959,802 6,969,655 Interest receivable Level 2 23,111 23,111 21,953 21,953 21,668 21,668 Liabilities: Deposits without defined maturities Level 2 $ 5,904,618 $ 5,904,618 $ 5,809,355 $ 5,809,355 $ 5,547,764 $ 5,547,764 Time deposits Level 3 1,560,028 1,563,446 1,647,412 1,647,412 1,745,215 1,745,215 Interest payable Level 2 1,389 1,389 1,578 1,578 1,557 1,557 Short-term borrowings Level 2 556,213 556,213 397,199 397,199 532,291 532,291 Long-term borrowings Level 2 354,320 359,043 206,394 206,394 106,469 106,469 Long-term borrowings Level 3 17,277 17,228 35,997 35,997 42,021 42,021

Earnings Per Common Share

Earnings Per Common Share	6 Months Ended
	Jun. 30, 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 June 30, Six Months Ended June 30, 2016 2015 2016 2015 (In thousands, except per share data) Numerator for both basic and diluted earnings per common share, net income $ 25,707 $ 19,024 $ 48,969 $ 36,859 Denominator for basic earnings per common share, weighted average common shares outstanding 38,258 35,162 38,228 33,992 Weighted average common stock equivalents 342 235 332 235 Denominator for diluted earnings per common share 38,600 35,397 38,560 34,227 Basic earnings per common share $ 0.67 $ 0.54 $ 1.28 $ 1.08 Diluted earnings per common share $ 0.67 $ 0.54 $ 1.27 $ 1.08 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 80,700 for the three months ended June 30, 2016 and 2015 , respectively, and zero and 100,875 for the six months ended June 30, 2016 and 2015 , respectively.

Share-Based Compensation

Share-Based Compensation	6 Months Ended
	Jun. 30, 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 the three-month periods ended June 30, 2016 and 2015 , share-based compensation expense related to stock options, restricted stock units and other share-based awards totaled $1.0 million and $0.8 million , respectively. During the six months ended June 30, 2016 and 2015 , share-based compensation expense related to stock options, restricted stock units and other share-based awards totaled $1.8 million and $1.5 million , respectively. During the six-month period ended June 30, 2016 , the Corporation granted options to purchase 441,167 shares of common stock, 99,208 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 June 30, 2016 , there were 703,493 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 six months ended June 30, 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 — — — (96,058 ) 21.81 Vested (118,273 ) 28.30 8.40 — — Forfeited/expired (33,901 ) 31.00 7.25 (33,901 ) 31.00 Outstanding at June 30, 2016 768,748 $ 31.04 $ 7.21 1,365,947 $ 27.89 Exercisable/vested at June 30, 2016 597,199 $ 23.84 The weighted-average remaining contractual terms were 7.1 years for all outstanding stock options and 4.9 years for exercisable stock options at June 30, 2016 . The intrinsic value of all outstanding in-the-money stock options and exercisable in-the-money stock options was $11.2 million and $8.1 million , respectively, at June 30, 2016 . The aggregate intrinsic values of outstanding and exercisable options at June 30, 2016 were calculated based on the closing market price of the Corporation’s common stock on June 30, 2016 of $37.29 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 June 30, 2016 , unrecognized compensation expense related to stock options totaled $5.2 million and is expected to be recognized over a remaining weighted average period of 3.8 years . Stock options granted prior to 2016 contain change-of-control provisions that may get triggered if the merger with Talmer is completed. In the event the change-of control provisions are triggered, unrecognized compensation expense related to these stock options will become immediately recognized by the Corporation. The fair value of the stock options granted during the six months ended June 30, 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 six months ended June 30, 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 99,208 30.78 Converted into shares of common stock (45,787 ) 22.89 Forfeited/expired (4,126 ) 29.65 Outstanding at June 30, 2016 257,284 $ 28.67 At June 30, 2016 , unrecognized compensation expense related to restricted stock units totaled $4.9 million and is expected to be recognized over a remaining weighted average period of 2.7 years . Restricted stock units granted prior to 2016 contain change-of-control provisions that may get triggered if the merger with Talmer is completed. In the event the change-of control provisions are triggered, unrecognized compensation expense related to these restricted stock units will become immediately recognized by the Corporation.

Pension and Other Postretiremen

Pension and Other Postretirement Benefit Plans	6 Months Ended
	Jun. 30, 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 June 30, Six Months Ended June 30, 2016 2015 2016 2015 (In thousands) Defined Benefit Pension Plans Service cost $ 277 $ 273 $ 554 $ 545 Interest cost 1,358 1,332 2,716 2,664 Expected return on plan assets (2,140 ) (2,161 ) (4,281 ) (4,322 ) Amortization of prior service credit — (1 ) — (2 ) Amortization of unrecognized net loss 572 1,056 1,144 2,112 Net periodic benefit cost $ 67 $ 499 $ 133 $ 997 Postretirement Benefit Plan Service cost $ 2 $ 4 $ 4 $ 8 Interest cost 33 33 66 67 Amortization of prior service cost 29 32 58 65 Amortization of unrecognized net gain (25 ) — (49 ) (1 ) Net periodic benefit cost $ 39 $ 69 $ 79 $ 139 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 $1.4 million and $1.3 million for the three months ended June 30, 2016 and 2015 , respectively, and $2.7 million and $2.4 million for the six months ended June 30, 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 and six months ended June 30, 2016 .

Financial Guarantees

Financial Guarantees	6 Months Ended
	Jun. 30, 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 June 30, 2016 , December 31, 2015 and June 30, 2015 , the Corporation had $47 million , $39 million and $45 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 June 30, 2016 , December 31, 2015 and June 30, 2015 .

Significant Accounting Polici23

Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 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 six months ended June 30, 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 nonperforming TDRs, no additional provision for loan losses has been recognized for these loans and they continue to accrue interest at their contractual interest rate. Nonperforming TDRs 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 and 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 June 30, 2016 , December 31, 2015 and June 30, 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 June 30, 2016 , December 31, 2015 or June 30, 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 $1.2 million during the three and six months ended June 30, 2016 , respectively, and $0.2 million and $0.3 million during the three and six months ended June 30, 2015 , respectively. The Corporation's remaining investment in qualified affordable housing projects accounted for under the proportional amortization method totaled $24.3 million at June 30, 2016 , $21.7 million at December 31, 2015 and $21.4 million at June 30, 2015 . 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 $7.5 million , $1.7 million and $3.3 million at June 30, 2016 , December 31, 2015 and June 30, 2015 , respectively. The Corporation's unfunded equity contributions relating to investments in qualified affordable housing projects, federal historic tax projects and new market projects is recorded in other liabilities on the consolidated statements of financial position. The Corporation's remaining unfunded equity contributions totaled $11.5 million , $8.0 million and $9.7 million at June 30, 2016 , December 31, 2015 and June 30, 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 June 30, 2016 , December 31, 2015 or June 30, 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 June 30, 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 June 30, 2016 , no shares of preferred stock were issued and outstanding. Common Stock
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. These two cases ere consolidated as In re Talmer Bancorp Shareholder Litigation , case number 2016-151641-CB, per an order entered on May 12, 2016. 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 27, 2016, Stephen Bushansky filed a new putative class action complaint in the United State District Court for Eastern District of Michigan, styled Stephen Bushansky v. Talmer Bancorp In. et.al., Docket No. 1:16-cv-11511. This lawsuit alleged violations of Sections 14(a) and 20(a) of the Securities Exchange Act of 1934, and named Talmer, Chemical, and several individuals as defendants. The complaint alleged, among other things, that the Defendants issued materially incomplete and misleading disclosures in the preliminary Form S-4 Registration Statement relating to the proposed merger. The Federal Bushansky lawsuit was voluntarily dismissed by the plaintiff as to all defendants, without prejudice, on June 20, 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 was styled as a class action and derivative action, and alleged breach of fiduciary duties as well as violations of Sections 14(a) and 20(a) of the Securities Exchange Act of 1934. The Nicholl lawsuit was voluntarily dismissed by the plaintiff as to all defendants, with prejudice, on June 20, 2016. On June 16, 2016, a complaint was filed in the United States District Court for the Eastern District of Michigan by a purported Talmer shareholder, styled City of Livonia Employees’ Retirement System v . Chemical Financial Corporation, et. al., Docket No. 2:16-cv-12229. The plaintiff purports to bring the action “individually and on behalf of all others similarly situated,” and requests certification as a class action. This lawsuit alleges violations of Section 14(a) and 20(a) of the Securities Exchange Act of 1934. 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 unless and until additional information is provided to Talmer’s shareholders, declare that the Defendants violated the securities laws in connection with the proposed merger, award compensatory damages, interest, attorneys’ and experts’ fees, and that the Court grant such other relief as it 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. Credit Losses In June, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ("ASU 2016-13"). ASU 2016-13 changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. ASU 2016-13 requires an entity measure expected credit losses for financial assets over the estimated lifetime of expected credit loss and record an allowance that, when deducted from the amortized cost basis of the financial asset, presents the net amount expected to be collected on the financial asset. The standard includes the following core concepts in determining the expected credit loss estimate: (a) be based on an asset’s amortized cost (including premiums or discounts, net deferred fees and costs, foreign exchange and fair value hedge accounting adjustments), (b) reflect losses expected over the remaining contractual life of an asset (considering the effect of voluntary prepayments), (c) consider available relevant information about the estimated collectability of cash flows (including information about past events, current conditions, and reasonable and supportable forecasts), and (d) reflect the risk of loss, even when that risk is remote. ASU 2016-13 also amends the recording of purchased credit-deteriorated assets. Under the new guidance, an allowance will be recognized at acquisition through a gross-up approach whereby an entity will record as the initial amortized cost the sum of (a) the purchase price and (b) an estimate of credit losses as of the date of acquisition. In addition, the guidance also requires immediate recognition in earnings any subsequent changes, both favorable and unfavorable, in expected cash flows by adjusting this allowance. ASU 2016-13 amends the impairment model for available-for-sale debt securities and requires entities to determine whether all or a portion of the unrealized loss on an available-for-sale debt security is a credit loss. Management may not use the length of time a security has been in an unrealized loss position as a factor in concluding whether a credit loss exists, as is currently permitted. In addition, an entity will recognize an allowance for credit losses on available-for-sale debt securities as a contra-account to the amortized cost basis rather than as a direct reduction of the amortized cost basis of the investment, as is currently required. As a result, entities will recognize improvements to credit losses on available-for-sale debt securities immediately in earnings rather than as interest income over time under current practice. New disclosures required by ASU 2016-13 include: (a) for financial assets measured at amortized cost, an entity will be required to disclose information about how it developed its allowance, including changes in the factors that influenced management’s estimate of expected credit losses and the reasons for those changes, (b) for financial receivables and net investments in leases measured at amortized cost, an entity will be required to further disaggregate the information it currently discloses about the credit quality of these assets by year or the asset’s origination or vintage for as many as five annual periods, and (c) for available-for-sale debt securities, an entity will be required to provide a roll-forward of the allowance for credit losses and an aging analysis for securities that are past due. Upon adoption of ASU 2016-13, a cumulative-effect adjustment to retained earnings will be recorded as of the beginning of the first reporting period in which the guidance is effective. ASU 2016-13 is effective for public companies for interim and annual periods beginning after December 15, 2019, with early adoption permitted for annual periods beginning after December 15, 2018. The Corporation is currently evaluating the provisions of ASU 2016-13 to determine the potential impact on the Corporation's consolidated financial condition and results of operations.

Acquisitions (Tables)

Acquisitions (Tables)	6 Months Ended
	Jun. 30, 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 Six Months Ended June 30, 2016 (In thousands) Balance at beginning of period $ 152,999 $ 34,558 $ 82,623 $ 28,077 $ 298,257 Additions (reductions)* (10,365 ) (863 ) (5,848 ) (201 ) (17,277 ) Accretion recognized in interest income (17,291 ) (2,836 ) (8,029 ) (6,284 ) (34,440 ) Reclassification from nonaccretable difference — — 5,000 5,000 10,000 Balance at end of period $ 125,343 $ 30,859 $ 73,746 $ 26,592 $ 256,540 Six Months Ended June 30, 2015 Balance at beginning of period $ — $ — $ 104,675 $ 33,286 $ 137,961 Additions attributable to acquisitions 190,246 37,914 — — 228,160 Additions (reductions)* 1,550 (1,141 ) (2,859 ) 5,215 2,765 Accretion recognized in interest income (3,486 ) (968 ) (10,058 ) (6,326 ) (20,838 ) Balance at end of period $ 188,310 $ 35,805 $ 91,758 $ 32,175 $ 348,048 *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)	6 Months Ended
	Jun. 30, 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 June 30, 2016 , December 31, 2015 and June 30, 2015 : Investment Securities Available-for-Sale Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) June 30, 2016 U.S. Treasury securities $ 5,781 $ 29 $ — $ 5,810 Government sponsored agencies 156,843 715 536 157,022 State and political subdivisions 12,901 319 — 13,220 Residential mortgage-backed securities 166,582 2,034 — 168,616 Collateralized mortgage obligations 100,433 611 195 100,849 Corporate bonds 9,746 30 64 9,712 Preferred stock and trust preferred securities 2,888 436 1 3,323 Total $ 455,174 $ 4,174 $ 796 $ 458,552 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 June 30, 2015 U.S. Treasury securities $ 8,270 $ 24 $ — $ 8,294 Government sponsored agencies 227,424 683 200 227,907 State and political subdivisions 26,476 503 14 26,965 Residential mortgage-backed securities 213,621 742 1,694 212,669 Collateralized mortgage obligations 167,768 245 981 167,032 Corporate bonds 39,680 76 78 39,678 Preferred stock and trust preferred securities 2,889 272 — 3,161 Total $ 686,128 $ 2,545 $ 2,967 $ 685,706
Held-to-maturity Securities	Investment Securities Held-to-Maturity Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) June 30, 2016 State and political subdivisions $ 552,328 $ 16,123 $ 321 $ 568,130 Trust preferred securities 500 — 215 285 Total $ 552,828 $ 16,123 $ 536 $ 568,415 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 June 30, 2015 State and political subdivisions $ 469,337 $ 4,853 $ 7,912 $ 466,278 Trust preferred securities 500 — 200 300 Total $ 469,837 $ 4,853 $ 8,112 $ 466,578
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 June 30, 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. June 30, 2016 Amortized Cost Fair Value (In thousands) Investment Securities Available-for-Sale: Due in one year or less $ 154,820 $ 155,386 Due after one year through five years 257,040 258,856 Due after five years through ten years 37,877 38,374 Due after ten years 4,049 4,112 Preferred stock 1,388 1,824 Total $ 455,174 $ 458,552 Investment Securities Held-to-Maturity: Due in one year or less $ 59,330 $ 59,633 Due after one year through five years 275,988 280,491 Due after five years through ten years 130,304 136,879 Due after ten years 87,206 91,412 Total $ 552,828 $ 568,415
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 June 30, 2016 , December 31, 2015 and June 30, 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) June 30, 2016 Government sponsored agencies $ 14,110 $ 19 $ 18,787 $ 517 $ 32,897 $ 536 State and political subdivisions 73,532 237 25,713 84 99,245 321 Collateralized mortgage obligations 8,461 13 22,955 182 31,416 195 Corporate bonds — — 4,936 64 4,936 64 Preferred stock and trust preferred securities 1,499 1 285 215 1,784 216 Total $ 97,602 $ 270 $ 72,676 $ 1,062 $ 170,278 $ 1,332 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 June 30, 2015 Government sponsored agencies $ 24,789 $ 163 $ 14,715 $ 37 $ 39,504 $ 200 State and political subdivisions 258,503 5,433 63,584 2,493 322,087 7,926 Residential mortgage-backed securities 187,858 1,592 3,643 102 191,501 1,694 Collateralized mortgage obligations 49,845 155 48,881 826 98,726 981 Corporate bonds 9,670 49 14,971 29 24,641 78 Trust preferred securities — — 300 200 300 200 Total $ 530,665 $ 7,392 $ 146,094 $ 3,687 $ 676,759 $ 11,079

Loans (Tables)

Loans (Tables)	6 Months Ended
	Jun. 30, 2016
Receivables [Abstract]
Summary of loans under portfolio	A summary of loans follows: June 30, December 31, June 30, (In thousands) Commercial loan portfolio: Commercial $ 1,953,301 $ 1,905,879 $ 1,754,873 Commercial real estate 2,157,733 2,112,162 2,243,513 Real estate construction and land development 285,848 232,076 112,312 Subtotal 4,396,882 4,250,117 4,110,698 Consumer loan portfolio: Residential mortgage 1,494,192 1,429,636 1,310,167 Consumer installment 1,048,622 877,457 887,907 Home equity 707,573 713,937 725,971 Subtotal 3,250,387 3,021,030 2,924,045 Total loans $ 7,647,269 $ 7,271,147 $ 7,034,743
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 June 30, 2016 , December 31, 2015 and June 30, 2015 : Commercial Commercial Real Estate Real Estate Construction and Land Development Total (In thousands) June 30, 2016 Originated Portfolio: Risk Grades 1-5 $ 1,537,612 $ 1,479,365 $ 239,194 $ 3,256,171 Risk Grade 6 46,202 36,814 843 83,859 Risk Grade 7 35,602 15,434 517 51,553 Risk Grade 8 14,577 21,324 496 36,397 Risk Grade 9 — 1 — 1 Subtotal 1,633,993 1,552,938 241,050 3,427,981 Acquired Portfolio: Risk Grades 1-5 292,492 554,352 40,671 887,515 Risk Grade 6 15,352 20,746 1,500 37,598 Risk Grade 7 8,448 23,879 1,229 33,556 Risk Grade 8 3,016 5,818 1,398 10,232 Risk Grade 9 — — — — Subtotal 319,308 604,795 44,798 968,901 Total $ 1,953,301 $ 2,157,733 $ 285,848 $ 4,396,882 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 June 30, 2015 Originated Portfolio: Risk Grades 1-5 $ 1,269,091 $ 1,273,725 $ 97,364 $ 2,640,180 Risk Grade 6 32,189 34,677 433 67,299 Risk Grade 7 41,316 29,737 2,127 73,180 Risk Grade 8 17,260 25,283 502 43,045 Risk Grade 9 — 4 — 4 Subtotal 1,359,856 1,363,426 100,426 2,823,708 Acquired Portfolio: Risk Grades 1-5 347,914 820,400 10,139 1,178,453 Risk Grade 6 29,412 22,796 71 52,279 Risk Grade 7 13,910 30,288 119 44,317 Risk Grade 8 3,781 6,603 1,557 11,941 Risk Grade 9 — — — — Subtotal 395,017 880,087 11,886 1,286,990 Total $ 1,754,873 $ 2,243,513 $ 112,312 $ 4,110,698
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 June 30, 2016 , December 31, 2015 and June 30, 2015 : Residential Mortgage Consumer Installment Home Equity Total Consumer (In thousands) June 30, 2016 Originated Loans: Performing $ 1,299,382 $ 1,041,978 $ 598,283 $ 2,939,643 Nonperforming 7,983 285 3,042 11,310 Subtotal 1,307,365 1,042,263 601,325 2,950,953 Acquired Loans: Performing 185,492 6,298 105,360 297,150 Nonperforming 1,335 61 888 2,284 Subtotal 186,827 6,359 106,248 299,434 Total $ 1,494,192 $ 1,048,622 $ 707,573 $ 3,250,387 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 June 30, 2015 Originated Loans: Performing $ 1,058,696 $ 871,543 $ 584,520 $ 2,514,759 Nonperforming 9,793 393 2,357 12,543 Subtotal 1,068,489 871,936 586,877 2,527,302 Acquired Loans: Performing 238,698 15,966 138,086 392,750 Nonperforming 2,980 5 1,008 3,993 Subtotal 241,678 15,971 139,094 396,743 Total $ 1,310,167 $ 887,907 $ 725,971 $ 2,924,045
Summary of nonperforming loans	A summary of nonperforming loans follows: June 30, December 31, June 30, (In thousands) Nonaccrual loans: Commercial $ 14,577 $ 28,554 $ 17,260 Commercial real estate 21,325 25,163 25,287 Real estate construction and land development 496 521 502 Residential mortgage 5,343 5,557 6,004 Consumer installment 285 451 393 Home equity 1,971 1,979 1,769 Total nonaccrual loans 43,997 62,225 51,215 Accruing loans contractually past due 90 days or more as to interest or principal payments: Commercial 3 364 711 Commercial real estate 3 254 56 Residential mortgage 407 402 424 Home equity 1,071 1,267 588 Total accruing loans contractually past due 90 days or more as to interest or principal payments 1,484 2,287 1,779 Nonperforming TDRs: Commercial loan portfolio 14,240 16,297 14,547 Consumer loan portfolio 2,233 3,071 3,365 Total nonperforming TDRs 16,473 19,368 17,912 Total nonperforming loans $ 61,954 $ 83,880 $ 70,906
Schedule of Impaired loans by classes	The following schedule presents impaired loans by classes of loans at June 30, 2016 , December 31, 2015 and June 30, 2015 : Recorded Investment Unpaid Principal Balance Related Valuation Allowance (In thousands) June 30, 2016 Impaired loans with a valuation allowance: Commercial $ 3,764 $ 3,769 $ 2,582 Commercial real estate 3,270 3,438 472 Residential mortgage 20,745 20,745 163 Subtotal 27,779 27,952 3,217 Impaired loans with no related valuation allowance: Commercial 34,633 43,576 — Commercial real estate 47,894 58,312 — Real estate construction and land development 2,196 3,770 — Residential mortgage 6,678 7,365 — Consumer installment 347 365 — Home equity 2,859 3,084 — Subtotal 94,607 116,472 — Total impaired loans: Commercial 38,397 47,345 2,582 Commercial real estate 51,164 61,750 472 Real estate construction and land development 2,196 3,770 — Residential mortgage 27,423 28,110 163 Consumer installment 347 365 — Home equity 2,859 3,084 — Total $ 122,386 $ 144,424 $ 3,217 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) June 30, 2015 Impaired loans with a valuation allowance: Commercial $ 4,044 $ 4,137 $ 718 Commercial real estate 2,789 2,948 603 Residential mortgage 20,970 20,970 260 Subtotal 27,803 28,055 1,581 Impaired loans with no related valuation allowance: Commercial 32,461 38,160 — Commercial real estate 56,052 78,490 — Real estate construction and land development 2,393 4,175 — Residential mortgage 8,984 8,984 — Consumer installment 398 398 — Home equity 2,778 2,778 — Subtotal 103,066 132,985 — Total impaired loans: Commercial 36,505 42,297 718 Commercial real estate 58,841 81,438 603 Real estate construction and land development 2,393 4,175 — Residential mortgage 29,954 29,954 260 Consumer installment 398 398 — Home equity 2,778 2,778 — Total $ 130,869 $ 161,040 $ 1,581
Schedule presents information related to impaired loans	The following schedule presents information related to impaired loans for the three and six months ended June 30, 2016 and 2015 : Three Months Ended June 30, 2016 Six Months Ended June 30, 2016 Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status (In thousands) Commercial $ 38,606 $ 348 $ 41,811 $ 677 Commercial real estate 53,723 391 55,839 849 Real estate construction and land development 2,265 26 2,166 51 Residential mortgage 27,418 356 27,755 722 Consumer installment 330 1 359 2 Home equity 2,791 13 3,022 28 Total $ 125,133 $ 1,135 $ 130,952 $ 2,329 Three Months Ended June 30, 2015 Six Months Ended June 30, 2015 Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status (In thousands) Commercial $ 36,735 $ 263 $ 37,655 $ 552 Commercial real estate 60,393 458 60,317 983 Real estate construction and land development 2,290 36 2,403 63 Residential mortgage 29,432 380 28,392 711 Consumer installment 426 1 463 1 Home equity 2,529 14 2,440 22 Total $ 131,805 $ 1,152 $ 131,670 $ 2,332
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 June 30, 2016 , December 31, 2015 and June 30, 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) June 30, 2016 Originated Portfolio: Commercial $ 4,522 $ 822 $ 3 $ 14,577 $ 19,924 $ 1,614,069 $ 1,633,993 Commercial real estate 8,842 343 3 21,325 30,513 1,522,425 1,552,938 Real estate construction and land development 62 — — 496 558 240,492 241,050 Residential mortgage 1,955 — 407 5,343 7,705 1,299,660 1,307,365 Consumer installment 2,856 554 — 285 3,695 1,038,568 1,042,263 Home equity 2,594 366 1,071 1,971 6,002 595,323 601,325 Total $ 20,831 $ 2,085 $ 1,484 $ 43,997 $ 68,397 $ 6,310,537 $ 6,378,934 Acquired Portfolio: Commercial $ 547 $ — $ 3,038 $ — $ 3,585 $ 315,723 $ 319,308 Commercial real estate 90 — 5,817 — 5,907 598,888 604,795 Real estate construction and land development 389 — 1,398 — 1,787 43,011 44,798 Residential mortgage 407 — 1,335 — 1,742 185,085 186,827 Consumer installment 58 25 62 — 145 6,214 6,359 Home equity 416 38 888 — 1,342 104,906 106,248 Total $ 1,907 $ 63 $ 12,538 $ — $ 14,508 $ 1,253,827 $ 1,268,335 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 June 30, 2015 Originated Portfolio: Commercial $ 4,055 $ 2,317 $ 711 $ 17,260 $ 24,343 $ 1,335,513 $ 1,359,856 Commercial real estate 2,754 1,117 56 25,287 29,214 1,334,212 1,363,426 Real estate construction and land development 413 — — 502 915 99,511 100,426 Residential mortgage 1,536 — 424 6,004 7,964 1,060,525 1,068,489 Consumer installment 2,526 302 — 393 3,221 868,715 871,936 Home equity 2,334 204 588 1,769 4,895 581,982 586,877 Total $ 13,618 $ 3,940 $ 1,779 $ 51,215 $ 70,552 $ 5,280,458 $ 5,351,010 Acquired Portfolio: Commercial $ 690 $ — $ 3,781 $ — $ 4,471 $ 390,546 $ 395,017 Commercial real estate 969 291 6,603 — 7,863 872,224 880,087 Real estate construction and land development — — 1,557 — 1,557 10,329 11,886 Residential mortgage 1,077 138 2,980 — 4,195 237,483 241,678 Consumer installment — 56 5 — 61 15,910 15,971 Home equity 1,153 210 1,008 — 2,371 136,723 139,094 Total $ 3,889 $ 695 $ 15,934 $ — $ 20,518 $ 1,663,215 $ 1,683,733
Schedule of Corporation's TDRs	The following schedule presents the Corporation’s TDRs at June 30, 2016 , December 31, 2015 and June 30, 2015 : Performing TDRs Non-Performing TDRs Nonaccrual TDRs Total (In thousands) June 30, 2016 Commercial loan portfolio $ 30,866 $ 14,240 $ 28,979 $ 74,085 Consumer loan portfolio 18,512 2,233 3,402 24,147 Total $ 49,378 $ 16,473 $ 32,381 $ 98,232 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 June 30, 2015 Commercial loan portfolio $ 28,203 $ 14,547 $ 32,001 $ 74,751 Consumer loan portfolio 17,605 3,365 3,707 24,677 Total $ 45,808 $ 17,912 $ 35,708 $ 99,428
Schedule providing information on TDRs	The following schedule provides information on the Corporation's TDRs that were modified during the three and six months ended June 30, 2016 and 2015 : Three Months Ended June 30, 2016 Six Months Ended June 30, 2016 Number of Loans Pre- Modification Recorded Investment Post- Modification Recorded Investment Number of Loans Pre- Modification Recorded Investment Post- Modification Recorded Investment (Dollars in thousands) Commercial loan portfolio: Commercial 21 $ 4,149 $ 4,149 28 $ 7,981 $ 7,981 Commercial real estate 2 1,454 1,454 6 2,441 2,441 Subtotal – commercial loan portfolio 23 5,603 5,603 34 10,422 10,422 Consumer loan portfolio 14 490 490 21 694 694 Total 37 $ 6,093 $ 6,093 55 $ 11,116 $ 11,116 Three Months Ended June 30, 2015 Six Months Ended June 30, 2015 Number of Loans Pre- Modification Recorded Investment Post- Modification Recorded Investment Number of Loans Pre- Modification Recorded Investment Post- Modification Recorded Investment (Dollars in thousands) Commercial loan portfolio: Commercial 13 $ 2,332 $ 2,332 18 $ 4,264 $ 4,264 Commercial real estate 4 527 527 9 3,061 3,061 Real estate construction and land development 1 305 305 1 305 305 Subtotal – commercial loan portfolio 18 3,164 3,164 28 7,630 7,630 Consumer loan portfolio 29 1,633 1,631 39 1,969 1,967 Total 47 $ 4,797 $ 4,795 67 $ 9,599 $ 9,597
Troubled debt restructurings on financing receivables with defaults payment	The following schedule includes TDRs for which there was a payment default during the three and six months ended June 30, 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: Three Months Ended June 30, 2016 Six Months Ended June 30, 2016 Number of Loans Principal Balance at End of Period Number of Loans Principal Balance at End of Period (Dollars in thousands) Commercial loan portfolio: Commercial — $ — — $ — Commercial real estate 1 788 2 1,721 Subtotal – commercial loan portfolio 1 788 2 1,721 Consumer loan portfolio 1 — 2 — Total 2 $ 788 4 $ 1,721 Three Months Ended June 30, 2015 Six Months Ended June 30, 2015 Number of Loans Principal Balance at End of Period Number of Loans Principal Balance at End of Period (Dollars in thousands) Commercial loan portfolio: Commercial — $ — — $ — Commercial real estate 1 183 4 942 Subtotal – commercial loan portfolio 1 183 4 942 Consumer loan portfolio — — 1 33 Total 1 $ 183 5 $ 975
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 and six months ended June 30, 2016 and details regarding the balance in the allowance and the recorded investment in loans at June 30, 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 June 30, 2016: Beginning balance $ 44,668 $ 25,650 $ — $ 70,318 Provision for loan losses 900 2,100 — 3,000 Charge-offs (2,542 ) (1,078 ) — (3,620 ) Recoveries 1,202 606 — 1,808 Ending balance $ 44,228 $ 27,278 $ — $ 71,506 Changes in allowance for loan losses for the six months ended June 30, 2016: Beginning balance $ 47,234 $ 26,094 $ — $ 73,328 Provision for loan losses 1,900 2,600 — 4,500 Charge-offs (6,438 ) (2,640 ) — (9,078 ) Recoveries 1,532 1,224 — 2,756 Ending balance $ 44,228 $ 27,278 $ — $ 71,506 Allowance for loan losses balance at June 30, 2016 attributable to: Loans individually evaluated for impairment $ 3,054 $ 163 $ — $ 3,217 Loans collectively evaluated for impairment 41,174 27,115 — 68,289 Loans acquired with deteriorated credit quality — — — — Total $ 44,228 $ 27,278 $ — $ 71,506 Recorded investment (loan balance) at June 30, 2016: Loans individually evaluated for impairment $ 81,504 $ 20,745 $ — $ 102,249 Loans collectively evaluated for impairment 3,346,477 2,930,208 — 6,276,685 Loans acquired with deteriorated credit quality 968,901 299,434 — 1,268,335 Total $ 4,396,882 $ 3,250,387 $ — $ 7,647,269 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 and six months ended June 30, 2015 and details regarding the balance in the allowance and the recorded investment in loans at June 30, 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 June 30, 2015: Beginning balance $ 46,819 $ 24,579 $ 3,858 $ 75,256 Provision for loan losses (626 ) (109 ) 2,235 1,500 Charge-offs (915 ) (1,809 ) — (2,724 ) Recoveries 249 660 — 909 Ending balance $ 45,527 $ 23,321 $ 6,093 $ 74,941 Changes in allowance for loan losses for the six months ended June 30, 2015: Beginning balance $ 44,156 $ 28,803 $ 2,724 $ 75,683 Provision for loan losses 2,967 (3,336 ) 3,369 3,000 Charge-offs (2,419 ) (3,448 ) — (5,867 ) Recoveries 823 1,302 — 2,125 Ending balance $ 45,527 $ 23,321 $ 6,093 $ 74,941 Allowance for loan losses balance at June 30, 2015 attributable to: Loans individually evaluated for impairment $ 1,321 $ 260 $ — $ 1,581 Loans collectively evaluated for impairment 44,206 23,061 6,093 73,360 Loans acquired with deteriorated credit quality — — — — Total $ 45,527 $ 23,321 $ 6,093 $ 74,941 Recorded investment (loan balance) at June 30, 2015: Loans individually evaluated for impairment $ 85,799 $ 20,970 $ — $ 106,769 Loans collectively evaluated for impairment 2,737,909 2,506,332 — 5,244,241 Loans acquired with deteriorated credit quality 1,286,990 396,743 — 1,683,733 Total $ 4,110,698 $ 2,924,045 $ — $ 7,034,743

Intangible Assets (Tables)

Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 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: June 30, December 31, June 30, (In thousands) Goodwill $ 286,867 $ 287,393 $ 285,512 Other intangible assets: Core deposit intangible assets $ 24,429 $ 26,654 $ 28,353 Non-compete intangible assets 164 328 541 Mortgage servicing rights 9,677 11,122 12,307 Total other intangible assets $ 34,270 $ 38,104 $ 41,201
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: June 30, December 31, June 30, (In thousands) Gross original amount $ 40,055 $ 40,055 $ 39,355 Accumulated amortization 15,626 13,401 11,002 Carrying amount $ 24,429 $ 26,654 $ 28,353 Amortization expense for the three months ended June 30 $ 1,113 $ 952 Amortization expense for the six months ended June 30 $ 2,225 $ 1,743
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: June 30, December 31, June 30, (In thousands) Net carrying value of MSRs $ 9,677 $ 11,122 $ 12,307 Fair value of MSRs $ 12,493 $ 15,542 $ 16,602 Valuation allowance $ 412 $ — $ — Loans serviced for others that have servicing rights capitalized $ 2,014,986 $ 2,082,899 $ 2,193,067
Activity for capitalized MSRs	The following table shows the activity for capitalized MSRs: Three Months Ended June 30, Six Months Ended June 30, 2016 2015 2016 2015 (In thousands) Balance at beginning of period $ 10,478 $ 11,583 $ 11,122 $ 12,217 Acquired in Monarch acquisition — 1,284 — 1,284 Additions 586 415 917 815 Amortization (975 ) (1,175 ) (1,950 ) (2,209 ) Change in valuation allowance (412 ) 200 (412 ) 200 Balance at end of period $ 9,677 $ 12,307 $ 9,677 $ 12,307

Accumulated Other Comprehensi28

Accumulated Other Comprehensive Loss (Tables)	6 Months Ended
	Jun. 30, 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: June 30, December 31, June 30, (In thousands) Net unrealized gains (losses) on investment securities – available-for-sale, net of related tax expense (benefit) of $1,182 at June 30, 2016, $(1,017) at December 31, 2015 and $(148) at June 30, 2015 $ 2,196 $ (1,888 ) $ (274 ) Pension and other postretirement benefits adjustment, net of related tax benefit of $15,020 at June 30, 2016, $14,616 at December 31, 2015 and $16,601 at June 30, 2015 (27,894 ) (27,144 ) (30,830 ) Accumulated other comprehensive loss $ (25,698 ) $ (29,032 ) $ (31,104 )

Borrowings Borrowings (Tables)

Borrowings Borrowings (Tables)	6 Months Ended
	Jun. 30, 2016
Borrowings [Abstract]
Schedule of Other Borrowings [Table Text Block]	A summary of the Corporation's long-term borrowings follows: June 30, December 31, June 30, (In thousands) Long-term borrowings: Long-term FHLB advances $ 329,320 $ 181,394 $ 81,469 Securities sold under agreements to repurchase 17,277 17,453 23,649 Non-revolving line-of-credit 25,000 25,000 25,000 Subordinated debt obligations — 18,544 18,372 Total long-term borrowings $ 371,597 $ 242,391 $ 148,490

Regulatory Capital (Tables)

Regulatory Capital (Tables)	6 Months Ended
	Jun. 30, 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) June 30, 2016 Total Capital to Risk-Weighted Assets: Corporation $ 851,114 11.4 % $ 599,743 8.0 % N/A N/A Chemical Bank 854,189 11.4 598,142 8.0 $ 747,677 10.0 % Tier 1 Capital to Risk-Weighted Assets: Corporation 779,608 10.4 449,807 6.0 N/A N/A Chemical Bank 782,683 10.5 448,606 6.0 598,142 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets: Corporation 779,608 10.4 337,355 4.5 N/A N/A Chemical Bank 782,683 10.5 336,455 4.5 485,990 6.5 Leverage Ratio: Corporation 779,608 8.6 361,408 4.0 N/A N/A Chemical Bank 782,683 8.7 360,746 4.0 450,932 5.0 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) 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 June 30, 2015 Total Capital to Risk-Weighted Assets: Corporation $ 816,595 11.6 % $ 559,273 8.0 % N/A N/A Chemical Bank 713,999 12.0 471,422 8.0 $ 589,277 10.0 % The Bank of Holland 77,648 10.2 61,028 8.0 76,285 10.0 The Bank of Northern Michigan 32,779 10.1 25,878 8.0 32,347 10.0 Tier 1 Capital to Risk-Weighted Assets: Corporation 741,654 10.6 419,455 6.0 N/A N/A Chemical Bank 640,324 10.9 353,566 6.0 471,422 8.0 The Bank of Holland 76,312 10.0 45,771 6.0 61,028 8.0 The Bank of Northern Michigan 32,779 10.1 19,408 6.0 25,878 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets: Corporation 723,654 10.4 314,591 4.5 N/A N/A Chemical Bank 640,324 10.9 265,175 4.5 383,030 6.5 The Bank of Holland 76,312 10.0 34,328 4.5 49,585 6.5 The Bank of Northern Michigan 32,779 10.1 14,556 4.5 21,025 6.5 Leverage Ratio: Corporation 741,654 9.4 314,344 4.0 N/A N/A Chemical Bank 640,324 8.5 300,703 4.0 375,878 5.0 The Bank of Holland 76,312 9.9 30,710 4.0 38,388 5.0 The Bank of Northern Michigan 32,779 9.1 14,421 4.0 18,026 5.0

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 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) June 30, 2016 Investment securities – available-for-sale: U.S. Treasury securities $ 5,810 $ — $ — $ 5,810 Government sponsored agencies — 157,022 — 157,022 State and political subdivisions — 13,220 — 13,220 Residential mortgage-backed securities — 168,616 — 168,616 Collateralized mortgage obligations — 100,849 — 100,849 Corporate bonds — 9,712 — 9,712 Preferred stock and trust preferred securities — 3,323 — 3,323 Total investment securities – available-for-sale 5,810 452,742 — 458,552 Loans held-for-sale — 13,990 — 13,990 Total assets measured at fair value on a recurring basis $ 5,810 $ 466,732 $ — $ 472,542 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 June 30, 2015 Investment securities – available-for-sale: U.S. Treasury securities $ 8,294 $ — $ — $ 8,294 Government sponsored agencies — 227,907 — 227,907 State and political subdivisions — 26,965 — 26,965 Residential mortgage-backed securities — 212,669 — 212,669 Collateralized mortgage obligations — 167,032 — 167,032 Corporate bonds — 39,678 — 39,678 Preferred stock — 3,161 — 3,161 Total investment securities – available-for-sale 8,294 677,412 — 685,706 Loans held-for-sale — 7,798 — 7,798 Total assets measured at fair value on a recurring basis $ 8,294 $ 685,210 $ — $ 693,504
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) June 30, 2016 Impaired originated loans $ — $ — $ 23,655 $ 23,655 Other real estate/repossessed assets — — 8,440 8,440 Mortgage servicing rights — — 6,153 6,153 Total $ — $ — $ 38,248 $ 38,248 December 31, 2015 Impaired originated loans $ — $ — $ 42,065 $ 42,065 Other real estate/repossessed assets — — 9,935 9,935 Total $ — $ — $ 52,000 $ 52,000 June 30, 2015 Impaired originated loans $ — $ — $ 24,517 $ 24,517 Other real estate/repossessed assets — — 14,197 14,197 Total $ — $ — $ 38,714 $ 38,714
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 June 30, 2016 December 31, 2015 June 30, 2015 Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value (In thousands) Assets: Cash and cash equivalents Level 1 $ 232,960 $ 232,960 $ 238,789 $ 238,789 $ 215,034 $ 215,034 Investment securities: Available-for-sale Level 1 5,810 5,810 5,765 5,765 8,294 8,294 Available-for-sale Level 2 452,742 452,742 547,966 547,966 677,412 677,412 Held-to-maturity Level 2 552,328 568,130 509,471 512,405 469,337 466,278 Held-to-maturity Level 3 500 285 500 300 500 300 Nonmarketable equity securities NA 47,775 47,775 36,907 36,907 36,142 36,142 Loans held-for-sale Level 2 13,990 13,990 10,327 10,327 7,798 7,798 Net loans Level 3 7,575,763 7,593,013 7,197,819 7,201,994 6,959,802 6,969,655 Interest receivable Level 2 23,111 23,111 21,953 21,953 21,668 21,668 Liabilities: Deposits without defined maturities Level 2 $ 5,904,618 $ 5,904,618 $ 5,809,355 $ 5,809,355 $ 5,547,764 $ 5,547,764 Time deposits Level 3 1,560,028 1,563,446 1,647,412 1,647,412 1,745,215 1,745,215 Interest payable Level 2 1,389 1,389 1,578 1,578 1,557 1,557 Short-term borrowings Level 2 556,213 556,213 397,199 397,199 532,291 532,291 Long-term borrowings Level 2 354,320 359,043 206,394 206,394 106,469 106,469 Long-term borrowings Level 3 17,277 17,228 35,997 35,997 42,021 42,021
Fair Value Inputs, Assets, Quantitative Information [Table Text Block]	The following table presents additional information about the significant unobservable inputs used in the fair value measurement of financial assets measured on a nonrecurring basis that were categorized within the Level 3 of the fair value hierarchy (fair value in thousands): Fair Value at June 30, 2016 Valuation Technique Significant Unobservable Inputs Range Impaired originated loans $ 23,655 Appraisal of collateral Discount for type of collateral and age of appraisal 20%-30% Other real estate/repossessed assets 8,440 Appraisal of property Discount for type of property and age of appraisal 25%-30% Mortgage servicing rights 6,153 Discounted cash flow Constant prepayment rate 12%-22% Discount rate 10%-11%

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	6 Months Ended
	Jun. 30, 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 June 30, Six Months Ended June 30, 2016 2015 2016 2015 (In thousands, except per share data) Numerator for both basic and diluted earnings per common share, net income $ 25,707 $ 19,024 $ 48,969 $ 36,859 Denominator for basic earnings per common share, weighted average common shares outstanding 38,258 35,162 38,228 33,992 Weighted average common stock equivalents 342 235 332 235 Denominator for diluted earnings per common share 38,600 35,397 38,560 34,227 Basic earnings per common share $ 0.67 $ 0.54 $ 1.28 $ 1.08 Diluted earnings per common share $ 0.67 $ 0.54 $ 1.27 $ 1.08

Share-Based Compensation (Table

Share-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 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 six months ended June 30, 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 — — — (96,058 ) 21.81 Vested (118,273 ) 28.30 8.40 — — Forfeited/expired (33,901 ) 31.00 7.25 (33,901 ) 31.00 Outstanding at June 30, 2016 768,748 $ 31.04 $ 7.21 1,365,947 $ 27.89 Exercisable/vested at June 30, 2016 597,199 $ 23.84
Assumptions of Black-Scholes option pricing model	The fair value of the stock options granted during the six months ended June 30, 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 six months ended June 30, 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 99,208 30.78 Converted into shares of common stock (45,787 ) 22.89 Forfeited/expired (4,126 ) 29.65 Outstanding at June 30, 2016 257,284 $ 28.67

Pension and Other Postretirem34

Pension and Other Postretirement Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 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 June 30, Six Months Ended June 30, 2016 2015 2016 2015 (In thousands) Defined Benefit Pension Plans Service cost $ 277 $ 273 $ 554 $ 545 Interest cost 1,358 1,332 2,716 2,664 Expected return on plan assets (2,140 ) (2,161 ) (4,281 ) (4,322 ) Amortization of prior service credit — (1 ) — (2 ) Amortization of unrecognized net loss 572 1,056 1,144 2,112 Net periodic benefit cost $ 67 $ 499 $ 133 $ 997 Postretirement Benefit Plan Service cost $ 2 $ 4 $ 4 $ 8 Interest cost 33 33 66 67 Amortization of prior service cost 29 32 58 65 Amortization of unrecognized net gain (25 ) — (49 ) (1 ) Net periodic benefit cost $ 39 $ 69 $ 79 $ 139

Significant Accounting Polici35

Significant Accounting Policies (Details)	May 31, 2015USD ($)	Apr. 01, 2015USD ($)	Jun. 30, 2016USD ($)shares	Jun. 30, 2015USD ($)shares	Jun. 30, 2016USD ($)BankPoolsshares	Jun. 30, 2015USD ($)shares	Jul. 19, 2016shares	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	$ 0		$ 0
Expense related to qualified affordable housing projects			600,000	200,000	1,200,000	300,000
Remaining investment in qualified affordable housing projects			24,300,000	21,400,000	24,300,000	21,400,000		21,700,000
Equity Method Investments			7,500,000	3,300,000	7,500,000	3,300,000		1,700,000
Variable Interest Entity, Reporting Entity Involvement, Unfunded Obligation, Amount			11,500,000	9,700,000	11,500,000	9,700,000		8,000,000
Impairment on tax credit projects			$ 0	$ 0	$ 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		500,000
Preferred stock, shares authorized | shares			2,000,000	2,000,000	2,000,000	2,000,000		2,000,000	2,000,000	200,000
Preferred stock, shares issued | shares			0	0	0	0		0
Preferred stock, shares outstanding | shares			0		0
Common Stock, Shares, Issued | shares			38,267,118	38,110,136	38,267,118	38,110,136		38,167,861
Common Stock, Shares Authorized | shares			60,000,000	60,000,000	60,000,000	60,000,000		60,000,000
Goodwill			$ 286,867,000	$ 285,512,000	$ 286,867,000	$ 285,512,000		$ 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
Subsequent Event [Member]
Business Acquisition [Line Items]
Common Stock, Shares Authorized | shares							100,000,000

Acquisitions (Activity for Acqu

Acquisitions (Activity for Acquired Loans) (Details) - USD ($) $ in Thousands		May 31, 2015	Apr. 01, 2015	Oct. 31, 2014	Jun. 30, 2016	Jun. 30, 2015
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period					$ 298,257	$ 137,961
Additions attributable to acquisitions						228,160
Additions (reductions)	[1]				(17,277)	2,765
Accretion recognized in interest income					(34,440)	(20,838)
Reclassification from nonaccretable difference					10,000
Balance at end of period					256,540	348,048
Northwestern Bancorp [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period					82,623	104,675
Additions attributable to acquisitions				$ 110,000		0
Additions (reductions)	[1]				(5,848)	(2,859)
Accretion recognized in interest income					(8,029)	(10,058)
Reclassification from nonaccretable difference					5,000
Balance at end of period					73,746	91,758
OAK [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period					28,077	33,286
Additions attributable to acquisitions						0
Additions (reductions)	[1]				(201)	5,215
Accretion recognized in interest income					(6,284)	(6,326)
Reclassification from nonaccretable difference					5,000
Balance at end of period					26,592	32,175
Lake Michigan Financial Corp [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period					152,999	0
Additions attributable to acquisitions		$ 190,200				190,246
Additions (reductions)	[1]				(10,365)	1,550
Accretion recognized in interest income					(17,291)	(3,486)
Reclassification from nonaccretable difference					0
Balance at end of period					125,343	188,310
Monarch Community Bancorp [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period					34,558	0
Additions attributable to acquisitions			$ 37,900			37,914
Additions (reductions)	[1]				(863)	(1,141)
Accretion recognized in interest income					(2,836)	(968)
Reclassification from nonaccretable difference					0
Balance at end of period					$ 30,859	$ 35,805
[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	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Dec. 31, 2015USD ($)
Business Acquisition [Line Items]
Goodwill							$ 286,867,000	$ 285,512,000	$ 287,393,000
Additions attributable to acquisitions								228,160,000
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	6,900,000,000
Brokered deposits of acquiree company	389,000,000
Business Combination, Acquired Receivables, Fair Value	$ 5,000,000,000
Service provided by acquiree bank through number of branches | Offices	80
Deposits of acquiree company	$ 5,300,000,000
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							756,000,000	990,000,000	864,000,000
Carrying amount of acquired loan portfolio							734,000,000	967,000,000	842,000,000
Interest Payments Receivable of Acquired Loan Portfolio		190,200,000
Business Combination, Acquired Receivables, Estimated Uncollectible		22,000,000
Additions attributable to acquisitions		190,200,000						190,246,000
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							101,000,000	126,000,000	115,000,000
Carrying amount of acquired loan portfolio							94,000,000	119,000,000	108,000,000
Interest Payments Receivable of Acquired Loan Portfolio			37,800,000
Business Combination, Acquired Receivables, Estimated Uncollectible			6,300,000
Additions attributable to acquisitions			$ 37,900,000					37,914,000
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							305,000,000	415,000,000	361,000,000
Carrying amount of acquired loan portfolio							275,000,000	382,000,000	330,000,000
Interest Payments Receivable of Acquired Loan Portfolio				112,000,000
Business Combination, Acquired Receivables, Estimated Uncollectible				26,000,000
Additions attributable to acquisitions				$ 110,000,000				0
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 deposit intangible assets [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							182,000,000	236,000,000	204,000,000
Carrying amount of acquired loan portfolio							166,000,000	215,000,000	$ 183,000,000
Additions attributable to acquisitions								$ 0
OAK and Northwestern [Member]
Business Acquisition [Line Items]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Reclassifications to Nonaccretable Difference							$ 5,000,000

Investment Securities (Summary

Investment Securities (Summary of Amortized Cost and Fair Value of Available-For-Sale Investment Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	$ 455,174	$ 556,636	$ 686,128
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	4,174	1,468	2,545
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	796	4,373	2,967
Available-for-sale Securities, Total	458,552	553,731	685,706
US Treasury Securities [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	5,781	5,773	8,270
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	29	0	24
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	8	0
Available-for-sale Securities, Total	5,810	5,765	8,294
Government sponsored agencies [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	156,843	195,711	227,424
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	715	78	683
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	536	800	200
Available-for-sale Securities, Total	157,022	194,989	227,907
State and political subdivisions [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	12,901	14,731	26,476
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	319	395	503
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	6	14
Available-for-sale Securities, Total	13,220	15,120	26,965
Residential mortgage-backed securities [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	166,582	189,452	213,621
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	2,034	538	742
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	2,222	1,694
Available-for-sale Securities, Total	168,616	187,768	212,669
Collateralized Mortgage Obligations [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	100,433	133,256	167,768
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	611	111	245
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	195	1,137	981
Available-for-sale Securities, Total	100,849	132,230	167,032
Corporate bonds [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	9,746	14,825	39,680
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	30	2	76
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	64	200	78
Available-for-sale Securities, Total	9,712	14,627	39,678
Preferred stock [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	2,888	2,888	2,889
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	436	344	272
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	1	0	0
Available-for-sale Securities, Total	$ 3,323	$ 3,232	$ 3,161

Investment Securities (Summar39

Investment Securities (Summary of Amortized Cost and Fair Value of Held-To-Maturity Investment Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Held-to-maturity Securities
Investment securities held-to-maturity, Amortized Cost	$ 552,828	$ 509,971	$ 469,837
Investment securities held-to-maturity, Unrealized Gains	16,123	7,446	4,853
Investment securities held-to-maturity, Unrealized Losses	536	4,712	8,112
Total Held-to-maturity securities, Debt maturities, Fair Value	568,415	512,705	466,578
State and political subdivisions [Member]
Held-to-maturity Securities
Investment securities held-to-maturity, Amortized Cost	552,328	509,471	469,337
Investment securities held-to-maturity, Unrealized Gains	16,123	7,446	4,853
Investment securities held-to-maturity, Unrealized Losses	321	4,512	7,912
Total Held-to-maturity securities, Debt maturities, Fair Value	568,130	512,405	466,278
Trust Preferred Securities [Member]
Held-to-maturity Securities
Investment securities held-to-maturity, Amortized Cost	500	500	500
Investment securities held-to-maturity, Unrealized Gains	0	0	0
Investment securities held-to-maturity, Unrealized Losses	215	200	200
Total Held-to-maturity securities, Debt maturities, Fair Value	$ 285	$ 300	$ 300

Investment Securities (Maturiti

Investment Securities (Maturities of Debt Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Investment Securities Available-for-Sale:
Due in one year or less, Amortized Cost	$ 154,820
Due after one year through five years, Amortized Cost	257,040
Due after five years through ten years, Amortized Cost	37,877
Due after ten years, Amortized Cost	4,049
Preferred stock, Amortized Cost	1,388
Total Available-for-sale Securities, Debt Maturities, Amortized Cost	455,174
Due in one year or less , Fair Value	155,386
Due after one year through five years, Fair Value	258,856
Due after five years through ten years, Fair Value	38,374
Due after ten years, Fair Value	4,112
Preferred stock, Fair Value	1,824
Total Available-for-sale securities, Debt maturities, Fair Value	458,552
Investment Securities Held-to-Maturity:
Due in one year or less, Amortized Cost	59,330
Due after one year through five years, Amortized Cost	275,988
Due after five years through ten years, Amortized Cost	130,304
Due after ten years, Amortized Cost	87,206
Total Held-to-maturity securities, Debt maturities, Amortized Cost	552,828	$ 509,971	$ 469,837
Due in one year or less , Fair Value	59,633
Due after one year through five years, Fair Value	280,491
Due after five years through ten years, Fair Value	136,879
Due after ten years, Fair Value	91,412
Total Held-to-maturity securities, Debt maturities, Fair Value	$ 568,415	$ 512,705	$ 466,578

Investment Securities (Summar41

Investment Securities (Summary of Investment Securities with Gross Unrealized Losses) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	$ 97,602	$ 554,907	$ 530,665
Less Than 12 Months, Gross Unrealized Losses	270	5,945	7,392
12 Months or More, Fair Value	72,676	133,159	146,094
12 Months or More, Gross Unrealized Losses	1,062	3,140	3,687
Total, Fair Value	170,278	688,066	676,759
Total, Gross Unrealized Losses	1,332	9,085	11,079
Government sponsored agencies [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	14,110	114,640	24,789
Less Than 12 Months, Gross Unrealized Losses	19	292	163
12 Months or More, Fair Value	18,787	21,681	14,715
12 Months or More, Gross Unrealized Losses	517	508	37
Total, Fair Value	32,897	136,321	39,504
Total, Gross Unrealized Losses	536	800	200
State and political subdivisions [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	73,532	195,285	258,503
Less Than 12 Months, Gross Unrealized Losses	237	2,891	5,433
12 Months or More, Fair Value	25,713	68,361	63,584
12 Months or More, Gross Unrealized Losses	84	1,627	2,493
Total, Fair Value	99,245	263,646	322,087
Total, Gross Unrealized Losses	321	4,518	7,926
Residential mortgage-backed securities [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value		169,226	187,858
Less Than 12 Months, Gross Unrealized Losses		2,146	1,592
12 Months or More, Fair Value		3,435	3,643
12 Months or More, Gross Unrealized Losses		76	102
Total, Fair Value		172,661	191,501
Total, Gross Unrealized Losses		2,222	1,694
Collateralized Mortgage Obligations [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	8,461	60,459	49,845
Less Than 12 Months, Gross Unrealized Losses	13	408	155
12 Months or More, Fair Value	22,955	39,382	48,881
12 Months or More, Gross Unrealized Losses	182	729	826
Total, Fair Value	31,416	99,841	98,726
Total, Gross Unrealized Losses	195	1,137	981
Corporate bonds [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	0	9,532	9,670
Less Than 12 Months, Gross Unrealized Losses	0	200	49
12 Months or More, Fair Value	4,936	0	14,971
12 Months or More, Gross Unrealized Losses	64	0	29
Total, Fair Value	4,936	9,532	24,641
Total, Gross Unrealized Losses	64	200	78
Trust Preferred Securities [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	1,499	0	0
Less Than 12 Months, Gross Unrealized Losses	1	0	0
12 Months or More, Fair Value	285	300	300
12 Months or More, Gross Unrealized Losses	215	200	200
Total, Fair Value	1,784	300	300
Total, Gross Unrealized Losses	$ 216	200	$ 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

Loans (Summary of Loans) (Detai

Loans (Summary of Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Summary of loans under portfolio
Commercial loan	$ 4,396,882	$ 4,250,117	$ 4,110,698
Consumer loan	3,250,387	3,021,030	2,924,045
Total loans	7,647,269	7,271,147	7,034,743
Commercial [Member]
Summary of loans under portfolio
Commercial loan	1,953,301	1,905,879	1,754,873
Real estate commercial [Member]
Summary of loans under portfolio
Commercial loan	2,157,733	2,112,162	2,243,513
Real estate construction [Member]
Summary of loans under portfolio
Commercial loan	285,848	232,076	112,312
Real estate residential [Member]
Summary of loans under portfolio
Consumer loan	1,494,192	1,429,636	1,310,167
Consumer installment [Member]
Summary of loans under portfolio
Consumer loan	1,048,622	877,457	887,907
Home equity [Member]
Summary of loans under portfolio
Consumer loan	$ 707,573	$ 713,937	$ 725,971

Loans (Summary of Recorded Inve

Loans (Summary of Recorded Investment of Commercial Loans by Risk Rating Categories) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	$ 4,396,882	$ 4,250,117	$ 4,110,698
Commercial [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,953,301	1,905,879	1,754,873
Real estate commercial [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	2,157,733	2,112,162	2,243,513
Real estate construction [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	285,848	232,076	112,312
Originated Portfolio [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	3,427,981	3,130,721	2,823,708
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	3,256,171	2,942,826	2,640,180
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	83,859	65,943	67,299
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	51,553	67,714	73,180
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	36,397	52,143	43,045
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	2,095	4
Originated Portfolio [Member] | Commercial [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,633,993	1,521,515	1,359,856
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	1,537,612	1,418,301	1,269,091
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	46,202	34,727	32,189
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	35,602	39,933	41,316
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	14,577	26,459	17,260
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	0	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	1,552,938	1,424,059	1,363,426
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	1,479,365	1,341,202	1,273,725
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	36,814	31,036	34,677
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	15,434	26,658	29,737
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	21,324	25,163	25,283
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	4
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	241,050	185,147	100,426
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	239,194	183,323	97,364
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	843	180	433
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	517	1,123	2,127
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	496	521	502
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	968,901	1,119,396	1,286,990
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	887,515	1,011,895	1,178,453
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	37,598	54,803	52,279
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	33,556	43,119	44,317
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	10,232	9,579	11,941
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	319,308	384,364	395,017
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	292,492	340,782	347,914
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	15,352	28,321	29,412
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	8,448	11,607	13,910
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	3,016	3,654	3,781
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	604,795	688,103	880,087
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	554,352	629,430	820,400
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	20,746	23,926	22,796
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	23,879	29,975	30,288
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	5,818	4,772	6,603
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	44,798	46,929	11,886
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	40,671	41,683	10,139
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	1,500	2,556	71
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	1,229	1,537	119
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	1,398	1,153	1,557
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 In44

Loans (Summary of Recorded Investment of Consumer Loans by Risk Rating Categories) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 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	$ 3,250,387	$ 3,021,030	$ 2,924,045
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	1,494,192	1,429,636	1,310,167
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	1,048,622	877,457	887,907
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	707,573	713,937	725,971
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	2,950,953	2,677,213	2,527,302
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	1,307,365	1,216,975	1,068,489
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	1,042,263	869,426	871,936
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	601,325	590,812	586,877
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	2,939,643	2,664,486	2,514,759
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	1,299,382	1,207,945	1,058,696
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	1,041,978	868,975	871,543
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	598,283	587,566	584,520
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	11,310	12,727	12,543
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	7,983	9,030	9,793
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	285	451	393
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	3,042	3,246	2,357
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	299,434	343,817	396,743
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	186,827	212,661	241,678
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	6,359	8,031	15,971
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	106,248	123,125	139,094
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	297,150	340,682	392,750
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	185,492	210,580	238,698
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	6,298	7,984	15,966
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	105,360	122,118	138,086
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	2,284	3,135	3,993
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	1,335	2,081	2,980
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	61	47	5
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	$ 888	$ 1,007	$ 1,008

Loans (Summary of Nonperforming

Loans (Summary of Nonperforming Loans) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Financing Receivable, Recorded Investment [Line Items]
Modified Loans Not Reported as TDR Included in Nonaccrual Loans	$ 32,400	$ 35,900	$ 35,700
Summary of nonperforming loans
Total TDRs	98,232	103,111	99,428
Total loans	$ 7,647,269	7,271,147	7,034,743
Minimum number of days accruing loans past due move to nonaccrual status	90 days
Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	$ 74,085	78,823	74,751
Total loans	4,396,882	4,250,117	4,110,698
Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	24,147	24,288	24,677
Total loans	3,250,387	3,021,030	2,924,045
Nonperforming [Member]
Summary of nonperforming loans
Total nonaccrual loans	43,997	62,225	51,215
Total accruing loans contractually past due 90 days or more as to interest or principal payments	1,484	2,287	1,779
Total TDRs	16,473	19,368	17,912
Total loans	61,954	$ 83,880	70,906
Nonperforming [Member] | Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	14,240		14,547
Nonperforming [Member] | Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	2,233		3,365
Nonperforming [Member] | Commercial [Member]
Summary of nonperforming loans
Total nonaccrual loans	14,577		17,260
Total accruing loans contractually past due 90 days or more as to interest or principal payments	3		711
Nonperforming [Member] | Real estate commercial [Member]
Summary of nonperforming loans
Total nonaccrual loans	21,325		25,287
Total accruing loans contractually past due 90 days or more as to interest or principal payments	3		56
Nonperforming [Member] | Real Estate Construction Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	496		502
Nonperforming [Member] | Real estate residential [Member]
Summary of nonperforming loans
Total nonaccrual loans	5,343		6,004
Total accruing loans contractually past due 90 days or more as to interest or principal payments	407		424
Nonperforming [Member] | Consumer Installment Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	285		393
Nonperforming [Member] | Home Equity Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	1,971		1,769
Total accruing loans contractually past due 90 days or more as to interest or principal payments	$ 1,071		$ 588

Loans (Summary of Impaired Loan

Loans (Summary of Impaired Loans by Classes of Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Impaired loans with a valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	$ 27,779	$ 44,383	$ 27,803
Unpaid Principal Balance	27,952	45,151	28,055
Related Valuation Allowance	3,217	6,389	1,581
Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	94,607	97,815	103,066
Unpaid Principal Balance	116,472	122,367	132,985
Related Valuation Allowance	0	0	0
Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	122,386	142,198	130,869
Unpaid Principal Balance	144,424	167,518	161,040
Related Valuation Allowance	3,217	6,389	1,581
Commercial [Member] | Impaired loans with a valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	3,764	18,898	4,044
Unpaid Principal Balance	3,769	19,426	4,137
Related Valuation Allowance	2,582	5,700	718
Commercial [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	34,633	31,039	32,461
Unpaid Principal Balance	43,576	37,703	38,160
Related Valuation Allowance	0	0	0
Commercial [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	38,397	49,937	36,505
Unpaid Principal Balance	47,345	57,129	42,297
Related Valuation Allowance	2,582	5,700	718
Real estate commercial [Member] | Impaired loans with a valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	3,270	4,448	2,789
Unpaid Principal Balance	3,438	4,688	2,948
Related Valuation Allowance	472	497	603
Real estate commercial [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	47,894	53,518	56,052
Unpaid Principal Balance	58,312	69,130	78,490
Related Valuation Allowance	0	0	0
Real estate commercial [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	51,164	57,966	58,841
Unpaid Principal Balance	61,750	73,818	81,438
Related Valuation Allowance	472	497	603
Real estate construction [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	2,196	2,136	2,393
Unpaid Principal Balance	3,770	3,108	4,175
Related Valuation Allowance	0	0	0
Real estate construction [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	2,196	2,136	2,393
Unpaid Principal Balance	3,770	3,108	4,175
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	20,745	21,037	20,970
Unpaid Principal Balance	20,745	21,037	20,970
Related Valuation Allowance	163	192	260
Real estate residential [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	6,678	7,638	8,984
Unpaid Principal Balance	7,365	8,644	8,984
Related Valuation Allowance	0	0	0
Real estate residential [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	27,423	28,675	29,954
Unpaid Principal Balance	28,110	29,681	29,954
Related Valuation Allowance	163	192	260
Consumer installment [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	347	498	398
Unpaid Principal Balance	365	512	398
Related Valuation Allowance	0	0	0
Consumer installment [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	347	498	398
Unpaid Principal Balance	365	512	398
Related Valuation Allowance	0	0	0
Home equity [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	2,859	2,986	2,778
Unpaid Principal Balance	3,084	3,270	2,778
Related Valuation Allowance	0	0	0
Home equity [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	2,859	2,986	2,778
Unpaid Principal Balance	3,084	3,270	2,778
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		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	$ 125,133	$ 131,805	$ 130,952	$ 131,670
Interest income recognized related to loans with impaired status	1,135	1,152	2,329	2,332
Commercial [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	38,606	36,735	41,811	37,655
Interest income recognized related to loans with impaired status	348	263	677	552
Real estate commercial [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	53,723	60,393	55,839	60,317
Interest income recognized related to loans with impaired status	391	458	849	983
Real estate construction [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	2,265	2,290	2,166	2,403
Interest income recognized related to loans with impaired status	26	36	51	63
Real estate residential [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	27,418	29,432	27,755	28,392
Interest income recognized related to loans with impaired status	356	380	722	711
Consumer installment [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	330	426	359	463
Interest income recognized related to loans with impaired status	1	1	2	1
Home equity [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	2,791	2,529	3,022	2,440
Interest income recognized related to loans with impaired status	$ 13	$ 14	$ 28	$ 22

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	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 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	$ 20,831	$ 14,502	$ 13,618
Financing receivable, recorded investment 61 to 89 days past due	2,085	4,265	3,940
Financing receivable, recorded investment accruing loans past due 90 days or more	1,484	2,287	1,779
Financing receivable, recorded investment, Nonaccrual loans	43,997	62,225	51,215
Financing receivable recorded investment, Total past due	68,397	83,279	70,552
Financing receivable, recorded investment, current	6,310,537	5,724,655	5,280,458
Financing receivable, recorded investment, Total loans	6,378,934	5,807,934	5,351,010
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	4,522	3,685	4,055
Financing receivable, recorded investment 61 to 89 days past due	822	1,230	2,317
Financing receivable, recorded investment accruing loans past due 90 days or more	3	364	711
Financing receivable, recorded investment, Nonaccrual loans	14,577	28,554	17,260
Financing receivable recorded investment, Total past due	19,924	33,833	24,343
Financing receivable, recorded investment, current	1,614,069	1,487,682	1,335,513
Financing receivable, recorded investment, Total loans	1,633,993	1,521,515	1,359,856
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	8,842	4,168	2,754
Financing receivable, recorded investment 61 to 89 days past due	343	1,603	1,117
Financing receivable, recorded investment accruing loans past due 90 days or more	3	254	56
Financing receivable, recorded investment, Nonaccrual loans	21,325	25,163	25,287
Financing receivable recorded investment, Total past due	30,513	31,188	29,214
Financing receivable, recorded investment, current	1,522,425	1,392,871	1,334,212
Financing receivable, recorded investment, Total loans	1,552,938	1,424,059	1,363,426
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	62	0	413
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	496	521	502
Financing receivable recorded investment, Total past due	558	521	915
Financing receivable, recorded investment, current	240,492	184,626	99,511
Financing receivable, recorded investment, Total loans	241,050	185,147	100,426
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	1,955	1,737	1,536
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	407	402	424
Financing receivable, recorded investment, Nonaccrual loans	5,343	5,557	6,004
Financing receivable recorded investment, Total past due	7,705	7,696	7,964
Financing receivable, recorded investment, current	1,299,660	1,209,279	1,060,525
Financing receivable, recorded investment, Total loans	1,307,365	1,216,975	1,068,489
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	2,856	3,145	2,526
Financing receivable, recorded investment 61 to 89 days past due	554	644	302
Financing receivable, recorded investment accruing loans past due 90 days or more	0	0	0
Financing receivable, recorded investment, Nonaccrual loans	285	451	393
Financing receivable recorded investment, Total past due	3,695	4,240	3,221
Financing receivable, recorded investment, current	1,038,568	865,186	868,715
Financing receivable, recorded investment, Total loans	1,042,263	869,426	871,936
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	2,594	1,767	2,334
Financing receivable, recorded investment 61 to 89 days past due	366	788	204
Financing receivable, recorded investment accruing loans past due 90 days or more	1,071	1,267	588
Financing receivable, recorded investment, Nonaccrual loans	1,971	1,979	1,769
Financing receivable recorded investment, Total past due	6,002	5,801	4,895
Financing receivable, recorded investment, current	595,323	585,011	581,982
Financing receivable, recorded investment, Total loans	601,325	590,812	586,877
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	1,907	6,319	3,889
Financing receivable, recorded investment 61 to 89 days past due	63	1,301	695
Financing receivable, recorded investment accruing loans past due 90 days or more	12,538	12,795	15,934
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	14,508	20,415	20,518
Financing receivable, recorded investment, current	1,253,827	1,442,798	1,663,215
Financing receivable, recorded investment, Total loans	1,268,335	1,463,213	1,683,733
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	547	490	690
Financing receivable, recorded investment 61 to 89 days past due	0	532	0
Financing receivable, recorded investment accruing loans past due 90 days or more	3,038	3,735	3,781
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	3,585	4,757	4,471
Financing receivable, recorded investment, current	315,723	379,607	390,546
Financing receivable, recorded investment, Total loans	319,308	384,364	395,017
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	90	3,557	969
Financing receivable, recorded investment 61 to 89 days past due	0	691	291
Financing receivable, recorded investment accruing loans past due 90 days or more	5,817	4,771	6,603
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	5,907	9,019	7,863
Financing receivable, recorded investment, current	598,888	679,084	872,224
Financing receivable, recorded investment, Total loans	604,795	688,103	880,087
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	389	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	1,398	1,154	1,557
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	1,787	1,154	1,557
Financing receivable, recorded investment, current	43,011	45,775	10,329
Financing receivable, recorded investment, Total loans	44,798	46,929	11,886
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	407	1,370	1,077
Financing receivable, recorded investment 61 to 89 days past due	0	0	138
Financing receivable, recorded investment accruing loans past due 90 days or more	1,335	2,081	2,980
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	1,742	3,451	4,195
Financing receivable, recorded investment, current	185,085	209,210	237,483
Financing receivable, recorded investment, Total loans	186,827	212,661	241,678
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	58	55	0
Financing receivable, recorded investment 61 to 89 days past due	25	0	56
Financing receivable, recorded investment accruing loans past due 90 days or more	62	47	5
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	145	102	61
Financing receivable, recorded investment, current	6,214	7,929	15,910
Financing receivable, recorded investment, Total loans	6,359	8,031	15,971
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	416	847	1,153
Financing receivable, recorded investment 61 to 89 days past due	38	78	210
Financing receivable, recorded investment accruing loans past due 90 days or more	888	1,007	1,008
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	1,342	1,932	2,371
Financing receivable, recorded investment, current	104,906	121,193	136,723
Financing receivable, recorded investment, Total loans	$ 106,248	$ 123,125	$ 139,094

Loans (Summary of TDRs) (Detail

Loans (Summary of TDRs) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Schedule of corporation's TDRs
Total TDRs	$ 98,232	$ 103,111	$ 99,428
Commercial Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	74,085	78,823	74,751
Consumer Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	24,147	24,288	24,677
Substandard Nonaccrual [Member]
Schedule of corporation's TDRs
Total TDRs	32,381	35,933	35,708
Substandard Nonaccrual [Member] | Commercial Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	28,979	32,682	32,001
Substandard Nonaccrual [Member] | Consumer Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	3,402	3,251	3,707
Nonperforming Financial Instruments [Member]
Schedule of corporation's TDRs
Total TDRs	16,473	19,368	17,912
Nonperforming Financial Instruments [Member] | Commercial Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	14,240	16,297	14,547
Nonperforming Financial Instruments [Member] | Consumer Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	2,233	3,071	3,365
Performing Financial Instruments [Member]
Schedule of corporation's TDRs
Total TDRs	49,378	47,810	45,808
Performing Financial Instruments [Member] | Commercial Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	30,866	29,844	28,203
Performing Financial Instruments [Member] | Consumer Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	$ 18,512	$ 17,966	$ 17,605

Loans (Summary of TDRs Modified

Loans (Summary of TDRs Modified During the Period) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016USD ($)Loans	Jun. 30, 2015USD ($)Loans	Jun. 30, 2016USD ($)Loans	Jun. 30, 2015USD ($)Loans
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	37	47	55	67
Modified TDRs, Pre-modification recorded investment	$ 6,093	$ 4,797	$ 11,116	$ 9,599
Modified TDRs, Post-modification recorded investment	$ 6,093	$ 4,795	$ 11,116	$ 9,597
Subtotal-commercial loan portfolio [Member] | Commercial Loan Portfolio [Member]
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	23	18	34	28
Modified TDRs, Pre-modification recorded investment	$ 5,603	$ 3,164	$ 10,422	$ 7,630
Modified TDRs, Post-modification recorded investment	$ 5,603	$ 3,164	$ 10,422	$ 7,630
Consumer loan portfolio [Member] | Consumer Portfolio Segment [Member]
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	14	29	21	39
Modified TDRs, Pre-modification recorded investment	$ 490	$ 1,633	$ 694	$ 1,969
Modified TDRs, Post-modification recorded investment	$ 490	$ 1,631	$ 694	$ 1,967
Commercial [Member] | Commercial Loan Portfolio [Member]
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	21	13	28	18
Modified TDRs, Pre-modification recorded investment	$ 4,149	$ 2,332	$ 7,981	$ 4,264
Modified TDRs, Post-modification recorded investment	$ 4,149	$ 2,332	$ 7,981	$ 4,264
Real estate commercial [Member] | Commercial Loan Portfolio [Member]
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	2	4	6	9
Modified TDRs, Pre-modification recorded investment	$ 1,454	$ 527	$ 2,441	$ 3,061
Modified TDRs, Post-modification recorded investment	$ 1,454	$ 527	$ 2,441	$ 3,061
Real Estate Construction Loans [Member] | Commercial Loan Portfolio [Member]
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans		1		1
Modified TDRs, Pre-modification recorded investment		$ 305		$ 305
Modified TDRs, Post-modification recorded investment		$ 305		$ 305

Loans (Summary of TDRs with a P

Loans (Summary of TDRs with a Payment Default During the Period) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016USD ($)Loans	Jun. 30, 2015USD ($)Loans	Jun. 30, 2016USD ($)Loans	Jun. 30, 2015USD ($)Loans
Troubled debt restructurings on financing receivables with defaults payment
Financing receivable modifications subsequent default number of contract | Loans	2	1	4	5
Financing receivable modification subsequent default recorded investment | $	$ 788	$ 183	$ 1,721	$ 975
Consumer Portfolio Segment [Member]
Troubled debt restructurings on financing receivables with defaults payment
Financing receivable modifications subsequent default number of contract | Loans	1	0	2	1
Financing receivable modification subsequent default recorded investment | $	$ 0	$ 0	$ 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	0	0
Financing receivable modification subsequent default recorded investment | $	$ 0	$ 0	$ 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	1	2	4
Financing receivable modification subsequent default recorded investment | $	$ 788	$ 183	$ 1,721	$ 942
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	1	2	4
Financing receivable modification subsequent default recorded investment | $	$ 788	$ 183	$ 1,721	$ 942

Loans (Schedule of the Allowanc

Loans (Schedule of the Allowance for Loan Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	$ 70,318	$ 75,256	$ 73,328	$ 75,683
Provision for loan losses	3,000	1,500	4,500	3,000
Charge-offs	(3,620)	(2,724)	(9,078)	(5,867)
Recoveries	1,808	909	2,756	2,125
Ending balance	71,506	74,941	71,506	74,941
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses					$ 3,217	$ 6,389	$ 1,581
Loans collectively evaluated for impairment related to allowance for loan losses					68,289	66,939	73,360
Total	70,318	75,256	73,328	75,683	71,506	73,328	74,941
Loans individually evaluated for impairment related to recorded investment (loan balance)					102,249	121,416	106,769
Loans collectively evaluated for impairment related to recorded investment (loan balance)					6,276,685	5,686,518	5,244,241
Total loans					7,647,269	7,271,147	7,034,743
Commercial Loan Portfolio [Member]
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	44,668	46,819	47,234	44,156
Provision for loan losses	900	(626)	1,900	2,967
Charge-offs	(2,542)	(915)	(6,438)	(2,419)
Recoveries	1,202	249	1,532	823
Ending balance	44,228	45,527	44,228	45,527
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses					3,054	6,197	1,321
Loans collectively evaluated for impairment related to allowance for loan losses					41,174	41,037	44,206
Total	44,668	46,819	47,234	44,156	44,228	47,234	45,527
Loans individually evaluated for impairment related to recorded investment (loan balance)					81,504	100,379	85,799
Loans collectively evaluated for impairment related to recorded investment (loan balance)					3,346,477	3,030,342	2,737,909
Total loans					4,396,882	4,250,117	4,110,698
Consumer Loan Portfolio [Member]
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	25,650	24,579	26,094	28,803
Provision for loan losses	2,100	(109)	2,600	(3,336)
Charge-offs	(1,078)	(1,809)	(2,640)	(3,448)
Recoveries	606	660	1,224	1,302
Ending balance	27,278	23,321	27,278	23,321
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses					163	192	260
Loans collectively evaluated for impairment related to allowance for loan losses					27,115	25,902	23,061
Total	25,650	24,579	26,094	28,803	27,278	26,094	23,321
Loans individually evaluated for impairment related to recorded investment (loan balance)					20,745	21,037	20,970
Loans collectively evaluated for impairment related to recorded investment (loan balance)					2,930,208	2,656,176	2,506,332
Total loans					3,250,387	3,021,030	2,924,045
Unallocated [Member]
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	0	3,858	0	2,724
Provision for loan losses	0	2,235	0	3,369
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	0	6,093	0	6,093
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	6,093
Total	$ 0	$ 3,858	$ 0	$ 2,724	0	0	6,093
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					1,268,335	1,463,213	1,683,733
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					968,901	1,119,396	1,286,990
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					299,434	343,817	396,743
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 Thousands	6 Months Ended
	Jun. 30, 2016USD ($)SegmentLoansBaordOfDirectorsTenants	Dec. 31, 2015USD ($)	Jun. 30, 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	$ 32,400	$ 35,900	$ 35,700
Residential Mortgage Loans in Process of Foreclosure	900	2,900	2,000
Difference between recorded investment and unpaid principal balance of loan	22,000	25,300	30,200
Confirmed losses (partial charge-offs)	16,300	17,100	15,200
Fair value of discount adjustment	5,700	8,200	15,000
Acquired impaired loans	12,500	12,800	15,900
Performing trouble debt restructuring under impaired loans	49,400	47,800	45,800
Financing Receivable, Modifications, Recorded Investment	98,232	103,111	99,428
Commercial Loan Portfolio [Member]
Loans (Textual) [Abstract]
Minimum value of loan requires executive and senior officer approval	1,500
Financing Receivable, Modifications, Recorded Investment	$ 74,085	78,823	74,751
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
Financing Receivable, Modifications, Recorded Investment	$ 24,147	$ 24,288	$ 24,677
Commercial [Member]
Loans (Textual) [Abstract]
Minimum value of loan requires group loan authority approval	1,000
Maximum value of loan requires executive and senior officer approval	$ 3,500
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	$ 10,000
Other loans requiring director loan committee approval depending on risk rating and credit action required	$ 10,000
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	$ 1,000
Minimum value of loans depending on risk rating and requires credit action from board of directors	15,000
Minimum [Member] | Commercial [Member]
Loans (Textual) [Abstract]
Minimum value of loans requiring only director loan committee approval	$ 10,000
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	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2015	May 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Net carrying value of intangible assets
Goodwill	$ 286,867		$ 287,393	$ 285,512
Other intangible assets:
Total other intangible assets	34,270		38,104	41,201
Core deposit intangible assets [Member]
Other intangible assets:
Finite-Lived Core Deposits, Gross	24,429		26,654	28,353
Total other intangible assets	24,429		26,654	28,353
Noncompete Agreements [Member]
Other intangible assets:
Finite-Lived Noncompete Agreements, Gross	164		328	541
Mortgage Servicing Rights [Member]
Other intangible assets:
Servicing Asset at Amortized Cost	9,677		11,122	12,307
Total other intangible assets	$ 9,677	$ 10,478	$ 11,122	$ 12,307		$ 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		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Carrying amount	$ 34,270	$ 41,201	$ 34,270	$ 41,201	$ 38,104
Amortization of intangible assets			4,751	3,787
Core deposit intangible assets [Member]
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Gross original amount	40,055	39,355	40,055	39,355	40,055
Accumulated amortization	15,626	11,002	15,626	11,002	13,401
Carrying amount	24,429	28,353	24,429	28,353	$ 26,654
Amortization of intangible assets	$ 1,113	$ 952	$ 2,225	$ 1,743

Intangible Assets (Carrying and

Intangible Assets (Carrying and Fair Value of MSRs) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Net carrying value, fair value of MSRs and loans Corporation servicing for others
Valuation Allowance for Impairment of Recognized Servicing Assets, Balance	$ 400
Loans serviced for others that have servicing rights capitalized	2,014,986	$ 2,082,899	$ 2,193,067
Mortgage Servicing Rights [Member]
Net carrying value, fair value of MSRs and loans Corporation servicing for others
Net carrying value of MSRs	9,677	11,122	12,307
Fair value of MSRs	12,493	15,542	16,602
Valuation Allowance for Impairment of Recognized Servicing Assets, Balance	$ 412	$ 0	$ 0

Intangible Assets (Activity for

Intangible Assets (Activity for Capitalized MSRs) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Capitalized MSRs [Roll Forward]
Balance at beginning of period			$ 38,104
Amortization			(4,751)	$ (3,787)
Balance at end of period	$ 34,270	$ 41,201	34,270	41,201
Mortgage Servicing Rights [Member]
Capitalized MSRs [Roll Forward]
Balance at beginning of period	10,478	11,583	11,122	12,217
Acquired in Monarch acquisition	0	1,284	0	1,284
Additions	586	415	917	815
Amortization	(975)	(1,175)	(1,950)	(2,209)
Change in valuation allowance	(412)	200	(412)	200
Balance at end of period	$ 9,677	$ 12,307	$ 9,677	$ 12,307

Intangible Assets (Textual) (De

Intangible Assets (Textual) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2016	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Goodwill and identifiable intangible assets acquired	$ 500	$ 0	$ 116,478
Goodwill		286,867	285,512	$ 287,393
Intangible Assets (Textual) [Abstract]
Impairment valuation allowance		(400)
Core deposit intangible assets [Member]
Intangible Assets (Textual) [Abstract]
Impairment valuation allowance		0
Estimated Future Amortization Expense, Fiscal Year Maturity [Abstract]
2,016		2,100
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		$ (412)	$ 0	$ 0

Accumulated Other Comprehensi59

Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 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 $1,182 at June 30, 2016, $(1,017) at December 31, 2015 and $(148) at June 30, 2015	$ 2,196	$ (1,888)	$ (274)
Pension and other postretirement benefits adjustment, net of related tax benefit of $15,020 at June 30, 2016, $14,616 at December 31, 2015 and $16,601 at June 30, 2015	(27,894)	(27,144)	(30,830)
Accumulated other comprehensive loss	$ (25,698)	$ (29,032)	$ (31,104)

Accumulated Other Comprehensi60

Accumulated Other Comprehensive Loss (Textual) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Accumulated Other Comprehensive Loss (Textual) [Abstract]
Net unrealized gains (losses) on investment securities-available-for-sale, tax expense (benefit)	$ 1,182	$ (1,017)	$ 148
Pension and other postretirement benefits adjustment, tax benefit	$ 15,020	$ 14,616	$ 16,601

Borrowings Schedule of Short-te

Borrowings Schedule of Short-term Borrowings (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Schedule of Short-Term Borrowings [Abstract]
Federal Home Loan Bank Advances, Short Term	$ 300,000	$ 100,000	$ 205,000
Short-term borrowings	$ 300,000	$ 100,000	$ 227,000

Borrowings Schedule of Other Bo

Borrowings Schedule of Other Borrowings (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	May 31, 2015
Schedule of Other Borrowings [Abstract]
Long-term Federal Home Loan Bank Advances	$ 329,320	$ 181,394	$ 81,469
nonrevolving line of credit	25,000	25,000	25,000
Other Securities Sold under Agreements to Repurchase	17,277	17,453	23,649
Subordinated Debt	0	18,544	18,372	$ 18,600
Other Borrowings	$ 371,597	$ 242,391	$ 148,490

Borrowings Textuals (Details)

Borrowings Textuals (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	May 31, 2015
Borrowings [Line Items]
Proceeds from Federal Home Loan Bank Advances	$ 100,000	$ 50,000
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Weighted Average Interest Rate	1.00%	1.30%	1.00%
Federal Home Loan Bank, Advances, Weighted Average Interest Rate	1.27%		1.27%
Maximum original maturity term of short-term borrowings			30 days
Long-term Federal Home Loan Bank Advances	$ 329,320		$ 329,320	$ 181,394	$ 81,469
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	2,980,000		2,980,000
Federal Home Loan Bank, Advances, Maturities Summary, Due in Next Twelve Months	5,100		5,100
Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Two	47,100		47,100
Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Three	67,100		67,100
Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Four	100,000		100,000
Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Five	110,000		110,000
Securities Sold under Agreements to Repurchase	256,213		256,213	297,199	305,291
Securities Sold Under Agreements to Repurchase, Maturities Summary, Due Remainder of Current Year	8,100		8,100
Securities Sold Under Agreements to Repurchase, Maturities, Due in Year Two	9,200		9,200
nonrevolving line of credit	$ 25,000		$ 25,000	25,000	25,000
Line of Credit Facility, Interest Rate at Period End	2.41%		2.41%
Subordinated Debt	$ 0		$ 0	18,544	18,372	$ 18,600
Federal Home Loan Bank Advances	300,000		300,000	100,000	205,000
Federal Funds Purchased	$ 0		$ 0	$ 0	$ 22,000

Regulatory Capital (Details)

Regulatory Capital (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Risk weighted assets	$ 7,500,000	$ 7,140,000	$ 6,990,000
Chemical Financial Corporation [Member]
Total Capital to Risk-Weighted Assets:
Actual, Capital Amount	851,114	841,257	816,595
Minimum Required for Capital Adequacy Purposes, Capital Amount	$ 599,743	$ 571,509	$ 559,273
Actual, Ratio	11.40%	11.80%	11.60%
Minimum Required for Capital Adequacy Purposes, Ratio	8.00%	8.00%	8.00%
Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount	$ 779,608	$ 767,929	$ 741,654
Minimum Required for Capital Adequacy Purposes, Capital Amount	$ 449,807	$ 428,631	$ 419,455
Actual, Ratio	10.40%	10.70%	10.60%
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	$ 779,608	$ 753,815	$ 723,654
Minimum Required for Capital Adequacy Purposes, Capital Amount	$ 337,355	$ 321,474	$ 314,591
Actual, Ratio	10.40%	10.60%	10.40%
Minimum Required for Capital Adequacy Purposes, Ratio	4.50%	4.50%	4.50%
Leverage Ratio:
Actual, Capital Amount	$ 779,608	$ 767,929	$ 741,654
Minimum Required for Capital Adequacy Purposes, Capital Amount	$ 361,408	$ 356,396	$ 314,344
Actual, Ratio	8.60%	8.60%	9.40%
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	$ 854,189	$ 830,294	$ 713,999
Minimum Required for Capital Adequacy Purposes, Capital Amount	598,142	570,073	471,422
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 747,677	$ 712,591	$ 589,277
Actual, Ratio	11.40%	11.70%	12.00%
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	$ 782,683	$ 756,966	$ 640,324
Minimum Required for Capital Adequacy Purposes, Capital Amount	448,606	427,555	353,566
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 598,142	$ 570,073	$ 471,422
Actual, Ratio	10.50%	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	$ 782,683	$ 756,966	$ 640,324
Minimum Required for Capital Adequacy Purposes, Capital Amount	336,455	320,666	265,175
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 485,990	$ 463,184	$ 383,030
Actual, Ratio	10.50%	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	$ 782,683	$ 756,966	$ 640,324
Minimum Required for Capital Adequacy Purposes, Capital Amount	360,746	355,911	300,703
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 450,932	$ 444,888	$ 375,878
Actual, Ratio	8.70%	8.50%	8.50%
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%
The Bank of Holland [Member]
Total Capital to Risk-Weighted Assets:
Actual, Capital Amount			$ 77,648
Minimum Required for Capital Adequacy Purposes, Capital Amount			61,028
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 76,285
Actual, Ratio			10.20%
Minimum Required for Capital Adequacy Purposes, Ratio			8.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			10.00%
Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount			$ 76,312
Minimum Required for Capital Adequacy Purposes, Capital Amount			45,771
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 61,028
Actual, Ratio			10.00%
Minimum Required for Capital Adequacy Purposes, Ratio			6.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			8.00%
Common Equity Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount			$ 76,312
Minimum Required for Capital Adequacy Purposes, Capital Amount			34,328
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 49,585
Actual, Ratio			10.00%
Minimum Required for Capital Adequacy Purposes, Ratio			4.50%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			6.50%
Leverage Ratio:
Actual, Capital Amount			$ 76,312
Minimum Required for Capital Adequacy Purposes, Capital Amount			30,710
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 38,388
Actual, Ratio			9.90%
Minimum Required for Capital Adequacy Purposes, Ratio			4.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			5.00%
The Bank of Northern Michigan [Member]
Total Capital to Risk-Weighted Assets:
Actual, Capital Amount			$ 32,779
Minimum Required for Capital Adequacy Purposes, Capital Amount			25,878
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 32,347
Actual, Ratio			10.10%
Minimum Required for Capital Adequacy Purposes, Ratio			8.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			10.00%
Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount			$ 32,779
Minimum Required for Capital Adequacy Purposes, Capital Amount			19,408
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 25,878
Actual, Ratio			10.10%
Minimum Required for Capital Adequacy Purposes, Ratio			6.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			8.00%
Common Equity Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount			$ 32,779
Minimum Required for Capital Adequacy Purposes, Capital Amount			14,556
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 21,025
Actual, Ratio			10.10%
Minimum Required for Capital Adequacy Purposes, Ratio			4.50%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			6.50%
Leverage Ratio:
Actual, Capital Amount			$ 32,779
Minimum Required for Capital Adequacy Purposes, Capital Amount			14,421
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 18,026
Actual, Ratio			9.10%
Minimum Required for Capital Adequacy Purposes, Ratio			4.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			5.00%

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value of Assets on a Recurring Basis) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	$ 458,552	$ 553,731	$ 685,706
Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	458,552	553,731	685,706
Loans Held-for-sale	13,990	10,327	7,798
Total assets measured at fair value on a recurring basis	472,542	564,058	693,504
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	5,810	5,765	8,294
Loans Held-for-sale	0	0	0
Total assets measured at fair value on a recurring basis	5,810	5,765	8,294
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	452,742	547,966	677,412
Loans Held-for-sale	13,990	10,327	7,798
Total assets measured at fair value on a recurring basis	466,732	558,293	685,210
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	5,810	5,765	8,294
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	5,810	5,765	8,294
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	5,810	5,765	8,294
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	157,022	194,989	227,907
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	157,022	194,989	227,907
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	157,022	194,989	227,907
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	13,220	15,120	26,965
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	13,220	15,120	26,965
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	13,220	15,120	26,965
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	168,616	187,768	212,669
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	168,616	187,768	212,669
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	168,616	187,768	212,669
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	100,849	132,230	167,032
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	100,849	132,230	167,032
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	100,849	132,230	167,032
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	9,712	14,627	39,678
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	9,712	14,627	39,678
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	9,712	14,627	39,678
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	3,323	3,232	3,161
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	3,323	3,232	3,161
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	3,323	3,232	3,161
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 (Fair66

Fair Value Measurements (Fair Value of Assets on a Nonrecurring Basis) (Details) - Fair Value, Measurements, Nonrecurring [Member] - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	$ 38,248	$ 52,000	$ 38,714
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	38,248	52,000	38,714
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	23,655	42,065	24,517
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	23,655	42,065	24,517
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	8,440	9,935	14,197
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	8,440	$ 9,935	$ 14,197
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	6,153
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	$ 6,153

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule of Carrying Amounts and Estimated Fair Value of Financial Instruments) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Investment securities:
Available-for-sale	$ 458,552	$ 553,731	$ 685,706
Held-to-maturity	568,415	512,705	466,578
Carrying Amount [Member]
Investment securities:
Nonmarketable equity securities	47,775	36,907	36,142
Carrying Amount [Member] | Level 1[Member]
Assets:
Cash and cash equivalents	232,960	238,789	215,034
Investment securities:
Available-for-sale	5,810	5,765	8,294
Carrying Amount [Member] | Level 2 [Member]
Investment securities:
Available-for-sale	452,742	547,966	677,412
Held-to-maturity	552,328	509,471	469,337
Loans Held-for-sale	13,990	10,327	7,798
Interest receivable	23,111	21,953	21,668
Liabilities:
Deposits without defined maturities	5,904,618	5,809,355	5,547,764
Interest payable	1,389	1,578	1,557
Short-term borrowings	556,213	397,199	532,291
Long-term borrowings	354,320	206,394	106,469
Carrying Amount [Member] | Level 3 [Member]
Investment securities:
Held-to-maturity	500	500	500
Net loans	7,575,763	7,197,819	6,959,802
Liabilities:
Time deposits	1,560,028	1,647,412	1,745,215
Long-term borrowings	17,277	35,997	42,021
Fair Value [Member]
Investment securities:
Nonmarketable equity securities	47,775	36,907	36,142
Fair Value [Member] | Level 1[Member]
Assets:
Cash and cash equivalents	232,960	238,789	215,034
Investment securities:
Available-for-sale	5,810	5,765	8,294
Fair Value [Member] | Level 2 [Member]
Investment securities:
Available-for-sale	452,742	547,966	677,412
Held-to-maturity	568,130	512,405	466,278
Loans Held-for-sale	13,990	10,327	7,798
Interest receivable	23,111	21,953	21,668
Liabilities:
Deposits without defined maturities	5,904,618	5,809,355	5,547,764
Interest payable	1,389	1,578	1,557
Short-term borrowings	556,213	397,199	532,291
Long-term borrowings	359,043	206,394	106,469
Fair Value [Member] | Level 3 [Member]
Investment securities:
Held-to-maturity	285	300	300
Net loans	7,593,013	7,201,994	6,969,655
Liabilities:
Time deposits	1,563,446	1,647,412	1,745,215
Long-term borrowings	$ 17,228	$ 35,997	$ 42,021

Fair Value Measurements (Textua

Fair Value Measurements (Textual) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Fair Value Measurements (Textual) [Abstract]
Impairment of goodwill	$ 0	$ 0	$ 0
Valuation Allowance for Impairment of Recognized Servicing Assets, Balance	400
Impairment identified for intangible assets	0
Core deposit intangible assets [Member]
Fair Value Measurements (Textual) [Abstract]
Valuation Allowance for Impairment of Recognized Servicing Assets, Balance	0
Impairment identified for intangible assets		0	0
Mortgage Servicing Rights [Member]
Fair Value Measurements (Textual) [Abstract]
Valuation Allowance for Impairment of Recognized Servicing Assets, Balance	$ 412	0	0
Minimum [Member]
Fair Value Measurements (Textual) [Abstract]
Expected life of intangible assets	10 years
Maximum [Member]
Fair Value Measurements (Textual) [Abstract]
Expected life of intangible assets	15 years
Impaired Originated Loans [Member] | Minimum [Member]
Fair Value Measurements (Textual) [Abstract]
Fair Value Inputs, Discount Rate	20.00%
Impaired Originated Loans [Member] | Maximum [Member]
Fair Value Measurements (Textual) [Abstract]
Fair Value Inputs, Discount Rate	30.00%
Total Impaired Loans [Member] | Minimum [Member]
Fair Value Measurements (Textual) [Abstract]
Percentage of discount factors used to determine fair value	70.00%
Total Impaired Loans [Member] | Maximum [Member]
Fair Value Measurements (Textual) [Abstract]
Percentage of discount factors used to determine fair value	80.00%
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 Inputs, Discount Rate	25.00%
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%
Fair Value Inputs, Discount Rate	30.00%
Fair Value Inputs, Prepayment Rate	22.00%
Mortgage Servicing Rights [Member] | Minimum [Member]
Fair Value Measurements (Textual) [Abstract]
Fair Value Inputs, Discount Rate	10.00%
Fair Value Inputs, Prepayment Rate	12.00%
Mortgage Servicing Rights [Member] | Maximum [Member]
Fair Value Measurements (Textual) [Abstract]
Fair Value Inputs, Discount Rate	11.00%
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		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 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	$ 25,707	$ 19,024	$ 48,969	$ 36,859
Denominator for basic earnings per common share, weighted average common shares outstanding	38,258,000	35,162,000	38,228,000	33,992,000
Weighted average common stock equivalents	342,000	235,000	332,000	235,000
Denominator for diluted earnings per common share	38,600,000	35,397,000	38,560,000	34,227,000
Basic earnings per common share (dollars per share)	$ 0.67	$ 0.54	$ 1.28	$ 1.08
Diluted earnings per common share (dollars per share)	$ 0.67	$ 0.54	$ 1.27	$ 1.08
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	80,700	0	100,875

Share-Based Compensation (Stock

Share-Based Compensation (Stock Option Activity) (Details)	6 Months Ended
	Jun. 30, 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	(33,901)
Ending balance, Number of Options | shares	768,748
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	31
Ending balance, Weighted Average Exercise Price	31.04
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	7.25
Ending balance, Weighted average grant date fair value	$ 7.21
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	(96,058)
Vested, Number of Options | shares	0
Forfeited/expired, Number of Options | shares	(33,901)
Ending balance, Number of Options | shares	1,365,947
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	21.81
Vested, Weighted Average Exercise Price	0
Forfeited/expired, Weighted Average Exercise Price	31
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	597,199
Exercisable/vested, Weighted Average Exercise Price	$ 23.84

Share-Based Compensation (Black

Share-Based Compensation (Black-Scholes Pricing Model Assumptions) (Details)	6 Months Ended
	Jun. 30, 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]	6 Months Ended
	Jun. 30, 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	99,208
Converted into shares of common stock, Number of shares | shares	(45,787)
Forfeited/expired, Number of shares | shares	(4,126)
Ending balance, Number of shares | shares	257,284
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	30.78
Converted into shares of common stock, Weighted average grant date fair value | $ / shares	22.89
Forfeited/expired, Weighted average grant date fair value | $ / shares	29.65
Ending balance, Weighted average grant date fair value | $ / shares	$ 28.67

(Textual) (Details)

(Textual) (Details) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016USD ($)$ / sharesshares	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)$ / sharesshares	Jun. 30, 2015USD ($)	Apr. 20, 2015shares
Share-Based Compensation Plans (Textual) [Abstract]
Share-based compensation expense | $	$ 1	$ 0.8	$ 1.8	$ 1.5
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			99,208
Unrecognized compensation expense | $	$ 4.9		$ 4.9
Unrecognized compensation expense, period for recognition			2 years 8 months 12 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	703,493		703,493
Weighted-average remaining contractual terms for outstanding stock options			7 years 1 month 6 days
Weighted-average remaining contractual terms for exercisable stock options			4 years 10 months 24 days
Outstanding in-the-money stock options, intrinsic value | $	$ 11.2		$ 11.2
Exercisable in-the-money stock options, intrinsic value | $	$ 8.1		$ 8.1
Closing price of common stock | $ / shares	$ 37.29		$ 37.29
Unrecognized compensation expense | $	$ 5.2		$ 5.2
Unrecognized compensation expense, period for recognition			3 years 9 months 18 days
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 Postretirem74

Pension and Other Postretirement Benefit Plans (Components of Net Periodic Benefit Cost (Income)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 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	$ 554	$ 545
Interest cost	1,358	1,332	2,716	2,664
Expected return on plan assets	(2,140)	(2,161)	(4,281)	(4,322)
Amortization of prior service cost	0	(1)	0	(2)
Amortization of unrecognized net loss (gain)	572	1,056	1,144	2,112
Net periodic benefit cost	67	499	133	997
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	4	8
Interest cost	33	33	66	67
Amortization of prior service cost	29	32	58	65
Amortization of unrecognized net loss (gain)	(25)	0	(49)	(1)
Net periodic benefit cost	$ 39	$ 69	$ 79	$ 139

Pension and Other Postretirem75

Pension and Other Postretirement Benefit Plans (Textual) (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended	12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2016	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	$ 1.4	$ 1.3	$ 2.4	$ 2.7

Financial Guarantees (Textual)

Financial Guarantees (Textual) (Details) - Financial Standby Letter of Credit [Member] - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Financial Guarantees (Textual) [Abstract]
Letters of credit outstanding	$ 47	$ 39	$ 45
Expiration period for letters of credit, maximum	5 years