TCF Financial 10-Q 5 Aug 15 2015 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Jul. 24, 2015
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, 2015
Amendment Flag	false
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		38,112,634

Consolidated Statements of Fina

Consolidated Statements of Financial Position - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Cash and cash equivalents:
Cash and cash due from banks	$ 167,054	$ 144,892	$ 139,023
Interest-bearing deposits with the Federal Reserve Bank and other banks	47,980	38,128	1,271
Total cash and cash equivalents	215,034	183,020	140,294
Investment securities:
Available-for-sale, at fair value	685,706	748,864	615,975
Held-to-maturity (fair value - $466,578 at June 30, 2015, $315,740 at December 31, 2014 and $303,961 at June 30, 2014)	469,837	316,413	308,130
Total investment securities	1,155,543	1,065,277	924,105
Loans held-for-sale, at fair value	7,798	9,128	6,329
Loans	7,034,743	5,688,230	4,898,804
Allowance for loan losses	(74,941)	(75,683)	(77,793)
Net loans	6,959,802	5,612,547	4,821,011
Premises and equipment (net of accumulated depreciation of $112,530 at June 30, 2015, $108,826 at December 31, 2014 and $104,225 at June 30, 2014)	111,968	97,496	74,291
Goodwill	285,512	180,128	120,164
Other intangible assets	41,201	33,080	12,454
Interest receivable and other assets	243,867	141,467	133,327
Total Assets	9,020,725	7,322,143	6,231,975
Deposits:
Noninterest-bearing	1,860,863	1,591,661	1,283,439
Interest-bearing	5,432,116	4,487,310	3,809,474
Total deposits	7,292,979	6,078,971	5,092,913
Interest payable and other liabilities	66,174	56,572	40,142
Short-term borrowings	532,291	389,467	305,422
Other Borrowings	148,490	0	0
Total liabilities	8,039,934	6,525,010	5,438,477
Shareholders’ equity:
Preferred Stock, No Par Value: Authorized – 2,000,000 shares at June 30, 2015 and 200,000 shares at both December 31, 2014 and June 30, 2014, none issued	0	0	0
Common Stock, $1 par value: Issued and outstanding — 38,110,136 shares at June 30, 2015, 32,774,420 shares at December 31, 2014 and 32,760,088 shares at June 30, 2014	38,110	32,774	32,760
Additional paid-in capital	722,329	565,166	563,393
Retained earnings	251,456	231,646	215,333
Accumulated other comprehensive loss	(31,104)	(32,453)	(17,988)
Total shareholders’ equity	980,791	797,133	793,498
Total Liabilities and Shareholders’ Equity	$ 9,020,725	$ 7,322,143	$ 6,231,975

Consolidated Statements of Fin3

Consolidated Statements of Financial Position (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Held-to-maturity, fair value	$ 466,578	$ 315,740	$ 303,961
Accumulated depreciation of premises and equipment	$ 112,530	$ 108,826	$ 104,225
Preferred stock, no par value
Preferred stock, shares authorized	2,000,000	200,000	200,000
Preferred stock, shares issued	0	0	0
Common stock, par value	$ 1	$ 1	$ 1
Common stock, shares authorized	60,000,000	45,000,000	45,000,000
Common stock, shares issued	38,110,136	32,774,420	32,760,088
Common stock, shares outstanding	38,110,136	32,774,420	32,760,088

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Interest Income
Interest and fees on loans	$ 64,613	$ 50,751	$ 122,710	$ 99,946
Interest on investment securities:
Taxable	2,202	2,248	4,509	4,631
Tax-exempt	2,185	1,671	4,091	3,375
Dividends on nonmarketable equity securities	551	411	749	649
Interest on deposits with the Federal Reserve Bank and other banks	128	99	250	224
Total interest income	69,679	55,180	132,309	108,825
Interest Expense
Interest on deposits	3,630	3,626	6,982	7,371
Interest on short-term borrowings	101	94	199	215
Interest on other borrowings	213	0	213	0
Total interest expense	3,944	3,720	7,394	7,586
Net Interest Income	65,735	51,460	124,915	101,239
Provision for loan losses	1,500	1,500	3,000	3,100
Net interest income after provision for loan losses	64,235	49,960	121,915	98,139
Noninterest Income
Service charges and fees on deposit accounts	6,445	5,486	12,361	10,416
Wealth management revenue	5,605	3,958	10,676	7,589
Other charges and fees for customer services	6,516	4,682	12,506	8,876
Mortgage banking revenue	1,688	1,491	3,091	2,285
Gain on sale of investment securities	28	0	607	0
Other	392	184	708	351
Total noninterest income	20,674	15,801	39,949	29,517
Operating Expenses
Salaries, wages and employee benefits	31,711	24,860	60,964	49,044
Occupancy	4,386	3,638	8,812	8,012
Equipment and software	4,480	3,413	8,878	6,874
Business Combination, Acquisition Related Costs	3,457	647	4,819	970
Other	12,751	9,867	24,332	19,707
Total operating expenses	56,785	42,425	107,805	84,607
Income before income taxes	28,124	23,336	54,059	43,049
Federal income tax expense	9,100	7,100	17,200	13,000
Net Income	$ 19,024	$ 16,236	$ 36,859	$ 30,049
Net Income Per Common Share:
Basic (in dollars per share)	$ 0.54	$ 0.54	$ 1.08	$ 1
Diluted (in dollars per share)	0.54	0.54	1.08	1
Cash Dividends Declared Per Common Share (dollars per share)	$ 0.24	$ 0.23	$ 0.48	$ 0.46

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net income	$ 19,024	$ 16,236	$ 36,859	$ 30,049
Other comprehensive income (loss), net of tax:
Net unrealized gains (losses) on investment securities available-for-sale, net of tax expense (benefit) of $(1,084) and $909 for the three months ended June 30, 2015 and 2014, respectively, and $177 and $1,766 for the six months ended June 30, 2015 and 2014, respectively	(2,014)	1,687	331	3,280
Reclassification adjustment for realized gain on sale of investment securities available-for-sale included in net income, net of tax expense of $10 for the three months ended June 30, 2015 and $212 for the six months ended June 30, 2015	(18)	0	(395)	0
Adjustment for pension and other postretirement benefits, net of tax expense (benefit) of $380 and $(202) for the three months ended June 30, 2015 and 2014, respectively, and $761 and $(403) for the six months ended June 30, 2015 and 2014, respectively	707	(374)	1,413	(748)
Total other comprehensive income (loss), net of tax	(1,325)	1,313	1,349	2,532
Comprehensive income	$ 17,699	$ 17,549	$ 38,208	$ 32,581

Consolidated Statements of Com6

Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Tax expense (benefit) on net unrealized gains (losses) on investment securities available-for-sale	$ (1,084)	$ 909	$ 177	$ 1,766
Tax expense (benefit) on reclassification adjustment for realized gains on sale of investment securities available-for-sale	(10)	0	(212)	0
Tax expense (benefit) on adjustment for pension and other postretirement benefits	$ 380	$ (202)	$ 761	$ (403)

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, 2013	$ 696,500	$ 29,790	$ 488,177	$ 199,053	$ (20,520)
Changes in Stockholders' Equity [Roll Forward]
Comprehensive income	32,581			30,049	2,532
Cash dividends declared per share: $0.48 and $0.46 per share for the six months ended June 30, 2015 and June 30, 2014, respectively	(13,769)			(13,769)
Stock Issued During Period, Value, New Issues	76,175	2,875	73,300
Stock issued - stock options	854	41	813
Shares issued – directors’ stock plans	468	18	450
Shares issued – restricted stock units	(484)	$ 36	(520)
Share-based compensation	1,173		1,173
Ending Balance at Jun. 30, 2014	793,498	$ 32,760	563,393	215,333	(17,988)
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 per share: $0.48 and $0.46 per share for the six months ended June 30, 2015 and June 30, 2014, respectively	(17,049)			(17,049)
Stock Issued During Period, Value, 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)

Consolidated Statements of Cha8

Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Cash dividends declared per share	$ 0.24	$ 0.23	$ 0.48	$ 0.46

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating Activities
Net income	$ 36,859	$ 30,049
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	3,000	3,100
Gains on sales of loans	(3,375)	(1,680)
Proceeds from sales of loans	119,683	59,490
Loans originated for sale	(111,903)	(58,920)
Net gains from sales/writedowns of other real estate and repossessed assets	(1,578)	(856)
Depreciation of premises and equipment	5,239	4,238
Amortization of intangible assets	3,787	1,391
Net gains on sale of investment securities	(607)	0
Net amortization of premiums and discounts on investment securities	2,759	2,129
Share-based compensation expense	1,461	1,173
Net increase in interest receivable and other assets	(11,695)	(1,503)
Net increase (decrease) in interest payable and other liabilities	(15,727)	754
Net cash provided by operating activities	27,903	39,365
Investment securities – available-for-sale:
Proceeds from sales	13,173	0
Proceeds from maturities, calls and principal reductions	113,973	71,919
Investment securities – held-to-maturity:
Proceeds from maturities, calls and principal reductions	54,481	66,230
Purchases	(205,286)	(100,862)
Net increase in loans	(250,997)	(260,201)
Proceeds from sales of other real estate and repossessed assets	7,934	4,879
Purchases of premises and equipment, net of disposals	(3,333)	(3,221)
Cash Acquired in Excess of Payments to Acquire Business	16,551	0
Net cash used in investing activities	(253,504)	(221,256)
Financing Activities
Net increase in interest- and noninterest-bearing demand deposits and savings accounts	217,719	23,559
Net decrease in time deposits	(72,795)	(53,031)
Net increase (decrease) in short-term borrowings	103,824	(22,006)
Proceeds from (Repayments of) Other Debt	25,000	0
Cash dividends paid	(17,049)	(13,769)
Proceeds from Issuance of Common Stock	0	76,175
Proceeds from directors’ stock plans and exercise of stock options, net of shares withheld	1,462	1,163
Cash paid for payroll taxes upon conversion of share-based awards	(546)	(694)
Net cash provided by financing activities	257,615	11,397
Net increase (decrease) in cash and cash equivalents	32,014	(170,494)
Cash and cash equivalents at beginning of period	183,020	310,788
Cash and cash equivalents at end of period	215,034	140,294
Supplemental Disclosure of Cash Flow Information:
Interest paid	6,592	7,719
Loans transferred to other real estate and repossessed assets	5,908	4,639
Transfer Of Other Real Estate, Closed Branch Offices	359	0
Income Taxes Paid	20,800	12,900
Fair Value of Tangible Assets Acquired	1,284,552	0
Goodwill and Identifiable Intangible Assets Acquired	116,478	0
Liabilities Assumed	1,257,917	0
Stock Issued	$ 159,904	$ 0

Significant Accounting Policies

Significant Accounting Policies	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Nature of Operations Chemical Financial Corporation (Corporation) operates in a single operating segment — commercial banking. The Corporation is a financial holding company, headquartered in Midland, Michigan, that operates through three commercial banks, Chemical Bank, The Bank of Holland and The Bank of Northern Michigan. The Bank of Holland and The Bank of Northern Michigan, which were acquired in the May 31, 2015 acquisition of Lake Michigan Financial Corporation (Lake Michigan), are expected to be consolidated with and into Chemical Bank during the fourth quarter of 2015 in conjunction with the conversion of their core data systems to Chemical Bank's. In addition, the Corporation acquired Monarch Community Bank as part of its April 1, 2015 acquisition of Monarch Community Bancorp, Inc. (Monarch). Monarch Community Bank was consolidated with and into Chemical Bank during the second quarter of 2015. 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, 2014. 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, 2015 are not necessarily indicative of the results that may be expected for the year ending December 31, 2015 . 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 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. 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 . The Corporation recorded $100 million of goodwill in conjunction with the acquisition, which represented the purchase price over the fair value of identifiable net assets acquired. Additionally, the Corporation recorded $7.9 million of core deposit and other intangible assets in conjunction with the acquisition. On April 1, 2015, the Corporation acquired all the outstanding stock of Monarch in an all-stock transaction valued at $27.2 million . The Corporation recorded $5.4 million of goodwill in conjunction with the acquisition, which represented the purchase price over the fair value of identifiable net assets acquired. Additionally, the Corporation recorded $1.9 million of core deposit intangible assets in conjunction with the acquisition. 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 Northwestern Bancorp, Inc. (Northwestern), which occurred on October 31, 2014, Lake Michigan, and Monarch, 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. See Note 2 for further information regarding the Corporation's acquisitions. Originated Loans Originated loans include all of the Corporation's portfolio loans, excluding loans acquired on May 31, 2015 in the acquisition of Lake Michigan, on April 1, 2015 in the acquisition of Monarch, on October 31, 2014 in the acquisition of Northwestern and on April 30, 2010 in the acquisition of O.A.K. Financial Corporation (OAK). Originated loans include loans acquired as part of the Corporation's branch acquisition on December 7, 2012, as these loans were performing and were considered high-quality loans in accordance with the Corporation's credit underwriting standards at that date. 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, on October 31, 2014 in the acquisition of Northwestern, and on April 30, 2010 in the acquisition of 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 Accounting Standards Codification (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 refinancing is no longer reported as a TDR. Loans in the Corporation’s commercial loan portfolio (comprised of commercial, commercial real estate, real estate construction and land development loans) that meet the definition of a TDR generally consist of loans where the Corporation has allowed borrowers to defer scheduled principal payments and make interest-only payments for a specified period of time at the stated interest rate of the original loan agreement or reduced payments due to a moderate extension of the loan’s contractual term. If the Corporation does not expect to collect all principal and interest on the loan, the modified loan is classified as a nonaccrual TDR. If the Corporation does not expect to incur a loss on the loan based on its assessment of the borrowers’ expected cash flows, as the pre- and post-modification effective yields are approximately the same, the loan is classified as a nonperforming TDR until a six-month payment history is sustained, at which time the loan is classified as a performing TDR. Since no loss is expected to be incurred on these loans, no additional provision for loan losses has been recognized related to these loans, and these loans accrue interest at their contractual interest rate. These loans are individually evaluated for impairment and transferred to nonaccrual status if they become 90 days past due as to principal or interest payments or if it is probable that any remaining principal and interest payments due on the loan will not be collected in accordance with the modified terms of the loan. Loans in the Corporation’s consumer loan portfolio (comprised of residential mortgage, consumer installment and home equity loans) that meet the definition of a performing or nonperforming TDR generally consist of residential mortgage loans that include a concession that reduces a borrower’s monthly payments by decreasing the interest rate charged on the loan for a specified period of time (generally 24 months ) under a formal modification agreement. The Corporation recognizes an additional provision for loan losses related to impairment on these loans on an individual basis based on the present value of expected future cash flows discounted at the loan’s original effective interest rate. These loans continue to accrue interest at their effective interest rate, which consists of contractual interest under the terms of the modification agreement in addition to an adjustment for the accretion of computed impairment. These loans are moved to nonaccrual status if they become 90 days past due as to principal or interest payments, or sooner if conditions warrant. Impaired Loans A loan is defined to be impaired when it is probable that payment of principal and interest will not be paid in accordance with the original contractual terms of the loan agreement. Impaired loans include nonaccrual loans (including nonaccrual TDRs), performing and nonperforming TDRs and acquired loans that were not performing in accordance with original contractual terms. Impaired loans are accounted for at the lower of the present value of expected cash flows discounted at the loan's original effective interest rate or the estimated fair value of the collateral, if the loan is collateral dependent. When the present value of expected cash flows or the fair value of collateral of an impaired loan in the originated loan portfolio is less than the amount of unpaid principal outstanding on the loan, the principal balance of the loan is reduced to its carrying value through either an allocation of the allowance for loan losses or a partial charge-off of the loan balance. Nonperforming Loans Nonperforming loans are comprised of loans for which the accrual of interest has been discontinued (nonaccrual loans, including nonaccrual TDRs), accruing originated loans contractually past due 90 days or more as to interest or principal payments and nonperforming TDRs. Acquired loans that were classified as nonperforming loans prior to being acquired and acquired loans that are not performing in accordance with contractual terms subsequent to acquisition are not classified as nonperforming loans subsequent to acquisition because the loans are recorded in pools at net realizable value based on the principal and interest the Corporation expects to collect on such loans. Allowance for Loan Losses The allowance for loan losses (allowance) is presented as a reserve against loans. The allowance represents management’s assessment of probable loan losses inherent in the Corporation’s loan portfolio. Management’s evaluation of the adequacy of the allowance is based on a continuing review of the loan portfolio, actual loan loss experience, the underlying value of the collateral, risk characteristics of the loan portfolio, the level and composition of nonperforming loans, the financial condition of the borrowers, the balance of the loan portfolio, loan growth, economic conditions, employment levels in the Corporation’s local markets, and special factors affecting specific business sectors. The Corporation maintains formal policies and procedures to monitor and control credit risk. Management evaluates the allowance on a quarterly basis in an effort to ensure the level is appropriate to absorb probable losses inherent in the loan portfolio. The allowance provides for probable losses that have been identified with specific customer relationships and for probable losses believed to be incurred in the remainder of the originated loan portfolio, but that have not been specifically identified. The Corporation utilizes its own loss experience to estimate inherent losses on loans. Internal risk ratings are assigned to each loan in the commercial loan portfolio (commercial, commercial real estate, real estate construction and land development loans) at the time of origination and are subject to subsequent periodic reviews by senior management. The Corporation performs a detailed credit quality review quarterly on all loans greater than $0.25 million that have deteriorated below certain levels of credit risk, and may allocate a specific portion of the allowance to such loans based upon this review. A portion of the allowance is allocated to the remaining loans by applying projected loss ratios, based on numerous factors. Projected loss ratios incorporate factors such as charge-off experience, trends with respect to adversely risk-rated loans in the commercial loan portfolio, trends with respect to past due and nonaccrual loans, changes in economic conditions and trends, changes in the value of underlying collateral and other credit risk factors. This evaluation involves a high degree of uncertainty. In determining the allowance and the related provision for loan losses, the Corporation considers four principal elements: (i) valuation allowances based upon probable losses identified during the review of impaired loans in the commercial loan portfolio, (ii) reserves established for adversely-rated loans in the commercial loan portfolio and nonaccrual residential mortgage, consumer installment and home equity loans based on loan loss experience of other adversely-rated loans, (iii) reserves, by loan classes, on all other loans based principally on a five -year historical loan loss experience, with higher weighting placed on the most recent years, loan loss trends giving consideration to estimated loss emergence periods and (iv) an unallocated allowance based on the imprecision in the overall allowance methodology for loans collectively evaluated for impairment. 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, 2015 , December 31, 2014 and June 30, 2014 , 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 its bank subsidiaries. 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. In conjunction with the acquisition of Monarch, the Corporation has net operating loss carryforwards, which are limited under Internal Revenue Code (IRC) Section 382, included in deferred tax assets. See Note 2 for further information regarding the net operating loss carryforward. 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, 2015 , December 31, 2014 or June 30, 2014 . Tax returns open to examination by the Internal Revenue Service (IRS) include those for the calendar years ended December 31, 2014 , 2013 , 2012 and 2011 for the Corporation, Lake Michigan, Monarch and Northwestern. Monarch's tax returns for the calendar years ended 2009-2013 are currently under an IRS examination. 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 of these projects comes in the form of the tax credits and 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 $0.2 million and $0.3 million during the three and six months ended June 30, 2015 , respectively, and $0.1 million and $0.2 million during the three and six months ended June 30, 2014 , respectively. The Corporation's remaining investment in qualified affordable housing projects accounted for under the proportional amortization method totaled $21.4 million at June 30, 2015 , $4.9 million at December 31, 2014 and $3.1 million at June 30, 2014 . The increase in qualified affordable housing project investments at June 30, 2015, compared to December 31, 2014 and June 30, 2014, was attributable to investments acquired as part of the Lake Michigan transaction. Under the equity method, the Corporation's share of the earnings or losses are included in other operating expenses on the consolidated statements of income. The Corporation's investment in new market projects accounted for under the equity method totaled $3.3 million at June 30, 2015. There were no investments in such projects accounted for under the equity method as of December 31, 2014 or June 30, 2

Acquisitions

Acquisitions	6 Months Ended
	Jun. 30, 2015
Business Combinations [Abstract]
Acquisitions	Acquisitions Acquisition of Lake Michigan Financial Corporation On May 31, 2015, the Corporation acquired all the outstanding stock consideration of Lake Michigan Financial Corporation (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 will be operated as separate subsidiaries of the Corporation until their planned consolidation with and into Chemical Bank in the fourth quarter of 2015 in conjunction with conversion of their core data systems to Chemical Bank's. 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 $ 100 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 $7.9 million of core deposit and other intangible assets in conjunction with the acquisition. The results of the merged Lake Michigan operations are presented within the Corporation's consolidated financial statements from the acquisition date. The Bank of Holland and The Bank of Northern Michigan collectively contributed $3.2 million of net interest income, $0.3 million of noninterest income and $1.1 million of net income to the Corporation's consolidated statements of income for the one month period from the acquisition date of May 31, 2015 to June 30, 2015. Nonrecurring transaction-related expenses associated with the Lake Michigan transaction totaled $2.0 million and $2.3 million during the three and six months ended June 30, 2015, respectively. The summary computation of the purchase price, including adjustments to reflect Lake Michigan's assets acquired and liabilities assumed at fair value and the allocation of the purchase price to the net assets of Lake Michigan is presented below. The acquisition accounting presented below may be further adjusted during a measurement period of up to one year beyond the acquisition date that provides the Corporation with 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. A summary of the purchase price and the excess of the purchase price over the fair value of adjusted net assets acquired (goodwill) follows (in thousands): Fair value of the Corporation's common shares issued on May 31, 2015 (4,322,101 shares at a market price of $30.29 per share) $ 130,916 Fair value of Lake Michigan options converted to the Corporation's options 2,000 Cash paid to acquire outstanding stock 54,478 Total purchase price $ 187,394 Net assets acquired: Lake Michigan shareholders' equity $ 89,280 Adjustments to reflect fair value of net assets acquired: Loans (22,600 ) Allowance for loan losses 15,888 Premises and equipment (2,333 ) Core deposit intangibles 7,303 Deferred tax assets, net 2,269 Deposits and borrowings, net (3,048 ) Other assets and other liabilities 633 Fair value of adjusted net assets acquired 87,392 Goodwill recognized as a result of the Lake Michigan transaction $ 100,002 Allocation of Purchase Price The preliminary acquisition date estimated fair values of the assets acquired and liabilities assumed of Lake Michigan were as follows (in thousands): Assets Cash and cash equivalents $ 39,301 Investment securities 66,699 Loans 985,542 Premises and equipment 13,673 Deferred tax asset, net 14,888 Goodwill 100,002 Core deposit intangible asset 7,303 Bank-owned life insurance 23,844 Other assets 38,449 Assets acquired, at fair value 1,289,701 Liabilities Deposits 924,697 Short-term borrowings 30,000 Other borrowings 124,723 Other liabilities 22,887 Total liabilities acquired, at fair value 1,102,307 Total purchase price $ 187,394 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. At June 30, 2015, the outstanding contractual principal balance and the carrying amount of the Lake Michigan acquired loan portfolio were $990 million and $967 million , respectively, and there was no related allowance for loan losses at that date. Acquisition of Monarch Community Bancorp, Inc. On April 1, 2015, the Corporation acquired all of the outstanding stock of Monarch Community Bancorp, Inc. (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. 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. Monarch Community Bank was consolidated with and into Chemical Bank on May 8, 2015. In connection with the acquisition of Monarch, the Corporation recorded $5.4 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. The results of the merged Monarch operations are presented within the Corporation's consolidated financial statements from the acquisition date. The disclosure of Monarch's post-acquisition revenue and net income is not practical due to the combining of Monarch's operations with and into Chemical Bank early in the second quarter of 2015. Nonrecurring transaction-related expenses associated with the Monarch acquisition totaled $ 1.5 million and $2.3 million during the three and six months ended June 30, 2015, respectively. The summary computation of the purchase price, including adjustments to reflect Monarch's assets acquired and liabilities assumed at fair value and the allocation of the purchase price to the net assets of Monarch is presented below. The acquisition accounting presented below may be further adjusted during a measurement period of up to one year beyond the acquisition date that provide the Corporation with 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. A summary of the purchase price and the excess of the purchase price over the fair value of adjusted net assets acquired (goodwill) follows (in thousands): Fair value of the Corporation's common shares issued on April 1, 2015 (860,575 shares at a market price of $31.36 per share) $ 26,988 Cash paid 203 Total purchase price $ 27,191 Net assets acquired: Monarch shareholders' equity 15,270 Adjustments to reflect fair value of net assets acquired: Loans (7,150 ) Allowance for loan losses 2,128 Deferred tax assets, net: Net operating loss carryforward 7,900 Other 1,748 Premises and equipment (370 ) Core deposit intangibles 1,930 Mortgage servicing rights 315 Other assets and other liabilities 37 Fair value of adjusted net assets acquired 21,808 Goodwill recognized as a result of the Monarch transaction $ 5,383 Allocation of Purchase Price The preliminary acquisition date estimated fair values of the assets acquired and liabilities assumed of Monarch were as follows (in thousands): Assets Cash and cash equivalents $ 32,171 Loans 121,783 Premises and equipment 3,064 Deferred tax assets, net Net operating loss carryforward 7,900 Other 2,314 Interest receivable and other assets 6,972 Goodwill 5,383 Core deposit intangibles 1,930 Mortgage servicing rights 1,284 Assets acquired, at fair value 182,801 Liabilities Deposits 144,311 FHLB advances 8,000 Interest payable and other liabilities 3,299 Total liabilities acquired, at fair value 155,610 Total purchase price $ 27,191 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. At June 30, 2015, the outstanding contractual principal balance and the carrying amount of the Monarch acquired loan portfolio were $126 million and $119 million , respectively, and there was no related allowance for loan losses at that date. Upon acquisition, Monarch incurred an ownership change within the meaning of IRC Section 382. At April 1, 2015, Monarch had $22.6 million in gross federal net operating loss carryforwards that expire between 2028-2034, which the Corporation expects to utilize. The Corporation expects to utilize these net operating losses, in part, as Monarch was in a net unrealized built-in gain position as of the acquisition date. Monarch also had $1.7 million of general business credits that expire between 2026-2032, which the Corporation does not expect to utilize. Unaudited Pro Forma Combined Results of Operations The following presentation of unaudited pro forma combined results of operations of Chemical, Lake Michigan, Monarch, and Northwestern presents these results as if the acquisitions had been completed as of the beginning of each period indicated. The unaudited pro forma combined results of operations are presented solely for information purposes and are not intended to represent or be indicative of the consolidated results of operations that Chemical would have reported had this transaction been completed as of the dates and for the periods presented, nor are they indicative of future results. In particular, no adjustments have been made to eliminate the amount of Lake Michigan's, Monarch's, or Northwestern's provision for loan losses incurred prior to the acquisition date that would not have been necessary had the acquired loans been recorded at fair value as of the beginning of each period indicated. In addition, no adjustment has been made for the lost opportunity cost associated with the all-cash purchase of Northwestern. In accordance with Article 11 of SEC Regulation S-X, transaction costs directly attributable to the acquisition have been excluded. Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 (In thousands, except per share data) Interest income $ 78,137 $ 74,842 $ 154,261 $ 148,089 Interest expense 5,483 6,748 11,363 13,627 Net interest income 72,654 68,094 142,898 134,462 Provision for loan losses 1,500 1,860 3,000 4,035 Net interest income after provision for loan losses 71,154 66,234 139,898 130,427 Noninterest income 21,153 23,713 43,180 43,487 Operating expenses 62,394 59,915 123,042 121,241 Income before income taxes 29,913 30,032 60,036 52,673 Federal income tax expense 7,525 9,048 16,736 15,807 Net income $ 22,388 $ 20,984 $ 43,300 $ 36,866 Net income per common share: Basic $ 0.59 $ 0.60 $ 1.14 $ 1.05 Diluted 0.58 0.59 1.13 1.04 Weighted average shares outstanding: Basic 38,044 35,251 38,024 35,129 Diluted 38,279 35,462 38,259 35,398 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 $60.0 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 $415 million and $382 million , respectively, at June 30, 2015 , compared to $485 million and $452 million , respectively, at December 31, 2014 . 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 (OAK) 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 $236 million and $215 million , respectively, at June 30, 2015 , compared to $268 million and $246 million , respectively, at December 31, 2014 and $298 million and $274 million , respectively, at June 30, 2014 . 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: Six Months Ended June 30, 2015 2014 Lake Michigan Monarch North-western OAK Total OAK (In thousands) Balance at beginning of period $ — $ — $ 104,675 $ 33,286 137,961 $ 32,610 Additions attributable to acquisitions 190,246 37,914 — — 228,160 — Additions (reductions)* 1,550 (1,141 ) (2,859 ) 5,215 2,765 2,333 Accretion recognized in interest income (3,486 ) (968 ) (10,058 ) (6,326 ) (20,838 ) (7,594 ) Reclassification from nonaccretable difference — — — — — 10,000 Balance at end of period $ 188,310 $ 35,805 $ 91,758 $ 32,175 $ 348,048 $ 37,349 *Represents additions of estimated contractual interest expected to be collected from acquired loans being renewed or extended, less reductions in contractual interest resulting from the early payoff of acquired loans.

Investment Securities

Investment Securities	6 Months Ended
	Jun. 30, 2015
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, 2015 , December 31, 2014 and June 30, 2014 : Investment Securities Available-for-Sale Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) 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 December 31, 2014 U.S. Treasury securities $ 8,272 $ — $ 13 $ 8,259 Government sponsored agencies 263,658 356 511 263,503 State and political subdivisions 45,157 1,087 17 46,227 Residential mortgage-backed securities 240,465 885 1,543 239,807 Collateralized mortgage obligations 145,316 261 1,194 144,383 Corporate bonds 44,930 213 48 45,095 Preferred stock 1,389 201 — 1,590 Total $ 749,187 $ 3,003 $ 3,326 $ 748,864 June 30, 2014 Government sponsored agencies $ 88,503 $ 346 $ 141 $ 88,708 State and political subdivisions 40,165 1,443 — 41,608 Residential mortgage-backed securities 265,673 1,117 1,422 265,368 Collateralized mortgage obligations 154,035 376 1,128 153,283 Corporate bonds 64,979 456 83 65,352 Preferred stock 1,389 267 — 1,656 Total $ 614,744 $ 4,005 $ 2,774 $ 615,975 Investment Securities Held-to-Maturity Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) 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 December 31, 2014 State and political subdivisions $ 305,913 $ 7,294 $ 4,557 $ 308,650 Trust preferred securities 10,500 — 3,410 7,090 Total $ 316,413 $ 7,294 $ 7,967 $ 315,740 June 30, 2014 State and political subdivisions $ 297,630 $ 5,885 $ 6,329 $ 297,186 Trust preferred securities 10,500 — 3,725 6,775 Total $ 308,130 $ 5,885 $ 10,054 $ 303,961 The majority of the Corporation’s residential mortgage-backed securities and collateralized mortgage obligations are backed by a U.S. government agency (Government National Mortgage Association) or a government sponsored enterprise (Federal Home Loan Mortgage Corporation or Federal National Mortgage Association). As of December 31, 2014 and June 30, 2014, the Corporation held a $10.0 million trust preferred investment security of Lake Michigan. With the acquisition of Lake Michigan, this investment was settled as of the acquisition date at par. The following is a summary of the amortized cost and fair value of investment securities at June 30, 2015 , 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, 2015 Amortized Cost Fair Value (In thousands) Investment Securities Available-for-Sale: Due in one year or less $ 198,939 $ 198,680 Due after one year through five years 411,399 411,247 Due after five years through ten years 68,583 68,295 Due after ten years 5,818 5,823 Preferred stock 1,389 1,661 Total $ 686,128 $ 685,706 Investment Securities Held-to-Maturity: Due in one year or less $ 55,922 $ 56,043 Due after one year through five years 209,886 209,768 Due after five years through ten years 127,398 125,775 Due after ten years 76,631 74,992 Total $ 469,837 $ 466,578 The following schedule summarizes information for both available-for-sale and held-to-maturity investment securities with gross unrealized losses at June 30, 2015 , December 31, 2014 and June 30, 2014 , 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, 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 December 31, 2014 U.S. Treasury securities $ 8,259 $ 13 $ — $ — $ 8,259 $ 13 Government sponsored agencies 166,963 406 31,927 105 198,890 511 State and political subdivisions 62,310 3,348 36,847 1,226 99,157 4,574 Residential mortgage-backed securities 17,276 52 180,194 1,491 197,470 1,543 Collateralized mortgage obligations 63,077 179 31,620 1,015 94,697 1,194 Corporate bonds — — 14,952 48 14,952 48 Trust preferred securities — — 7,090 3,410 7,090 3,410 Total $ 317,885 $ 3,998 $ 302,630 $ 7,295 $ 620,515 $ 11,293 June 30, 2014 Government sponsored agencies $ 2,377 $ 2 $ 44,786 $ 139 $ 47,163 $ 141 State and political subdivisions 92,279 4,047 71,421 2,282 163,700 6,329 Residential mortgage-backed securities 10,144 60 197,042 1,362 207,186 1,422 Collateralized mortgage obligations 47,142 68 35,722 1,060 82,864 1,128 Corporate bonds 4,996 5 14,922 78 19,918 83 Trust preferred securities — — 6,775 3,725 6,775 3,725 Total $ 156,938 $ 4,182 $ 370,668 $ 8,646 $ 527,606 $ 12,828 An assessment is performed quarterly by the Corporation to determine whether unrealized losses in its investment securities portfolio are temporary or other-than-temporary by carefully considering all available information. The Corporation reviews factors such as financial statements, credit ratings, news releases and other pertinent information of the underlying issuer or company to make its determination. Management did not believe any individual unrealized loss on any investment security, as of June 30, 2015 , represented an other-than-temporary impairment (OTTI). Management believed that the unrealized losses on investment securities at June 30, 2015 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, 2015 , 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, 2015 , 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, 2015
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 seven 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 — 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 — Secured development loans made to borrowers for the purpose of infrastructure improvements to vacant land to create finished marketable residential and commercial lots/land. Most land development loans are originated with the intention that the loans will be paid through the sale of developed lots/land by the developers within twelve months of the completion date. Land development loans at June 30, 2015 , December 31, 2014 and June 30, 2014 were primarily comprised of loans to develop residential properties. Residential mortgage — Loans secured by one - to four -family residential properties, generally with fixed interest rates for periods of fifteen years or less. The loan-to-value ratio at the time of origination is generally 80% or less. Residential mortgage loans with a loan-to-value ratio of more than 80% generally require private mortgage insurance. Consumer installment — Loans to consumers primarily for the purpose of acquiring automobiles, recreational vehicles and personal watercraft and comprised primarily of indirect loans purchased from dealers. These loans consist of relatively small amounts that are spread across many individual borrowers. Home equity — Loans and lines of credit whereby consumers utilize equity in their personal residence, generally through a second mortgage, as collateral to secure the loan. Commercial, commercial real estate, real estate construction and land development loans are referred to as the Corporation’s commercial loan portfolio, while residential mortgage, consumer installment and home equity loans are referred to as the Corporation’s consumer loan portfolio. A summary of loans follows: June 30, December 31, June 30, (In thousands) Commercial loan portfolio: Commercial $ 1,754,873 $ 1,354,881 $ 1,212,383 Commercial real estate 2,243,513 1,557,648 1,298,365 Real estate construction 101,717 152,745 101,168 Land development 10,595 18,750 10,956 Subtotal 4,110,698 3,084,024 2,622,872 Consumer loan portfolio: Residential mortgage 1,310,167 1,110,390 970,397 Consumer installment 887,907 829,570 744,781 Home equity 725,971 664,246 560,754 Subtotal 2,924,045 2,604,206 2,275,932 Total loans $ 7,034,743 $ 5,688,230 $ 4,898,804 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 its subsidiary banks, 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 limits exceeding $1.5 million and up to $3.5 million . During the first quarter of 2015, the Corporation increased the upper range for each level of group loan authority by $5.0 million , resulting in group loan authorities as follows. 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 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 majority approval of the board of directors of Chemical Bank. The approval authorities of relationship managers at The Bank of Holland and The Bank of Northern Michigan are similar to those at Chemical Bank, while approval authority for the loan committees at The Bank of Holland and The Bank of Northern Michigan are lower than those at Chemical Bank. Further, certain loan relationships of The Bank of Holland and The Bank of Northern Michigan, depending on a loan’s risk rating and credit action needed, require approval by the directors' loan committee of Chemical Bank, in addition to approval by the respective board of directors of The Bank of Holland or The Bank of Northern Michigan. 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, which 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, 2015 , December 31, 2014 and June 30, 2014 : Commercial Commercial Real Estate Real Estate Construction Land Development Total (In thousands) June 30, 2015 Originated Portfolio: Risk Grades 1-5 $ 1,269,091 $ 1,273,725 $ 94,894 $ 2,470 $ 2,640,180 Risk Grade 6 32,189 34,677 — 433 67,299 Risk Grade 7 41,316 29,737 1,249 878 73,180 Risk Grade 8 17,260 25,283 247 255 43,045 Risk Grade 9 — 4 — — 4 Subtotal 1,359,856 1,363,426 96,390 4,036 2,823,708 Acquired Portfolio: Risk Grades 1-5 347,914 820,400 5,122 5,017 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 6,603 205 1,352 11,941 Risk Grade 9 — — — — — Subtotal 395,017 880,087 5,327 6,559 1,286,990 Total $ 1,754,873 $ 2,243,513 $ 101,717 $ 10,595 $ 4,110,698 December 31, 2014 Originated Portfolio: Risk Grades 1-5 $ 1,171,817 $ 1,114,529 $ 134,668 $ 2,952 $ 2,423,966 Risk Grade 6 37,800 34,996 1,408 738 74,942 Risk Grade 7 29,863 29,935 2,502 613 62,913 Risk Grade 8 16,417 24,958 162 225 41,762 Risk Grade 9 1 8 — — 9 Subtotal 1,255,898 1,204,426 138,740 4,528 2,603,592 Acquired Portfolio: Risk Grades 1-5 76,780 321,018 14,005 11,789 423,592 Risk Grade 6 12,687 8,698 — 583 21,968 Risk Grade 7 4,089 12,478 — 197 16,764 Risk Grade 8 5,427 11,028 — 1,653 18,108 Risk Grade 9 — — — — — Subtotal 98,983 353,222 14,005 14,222 480,432 Total $ 1,354,881 $ 1,557,648 $ 152,745 $ 18,750 $ 3,084,024 June 30, 2014 Originated Portfolio: Risk Grades 1-5 $ 1,067,000 $ 1,063,555 $ 85,754 $ 2,514 $ 2,218,823 Risk Grade 6 15,459 30,053 666 965 47,143 Risk Grade 7 37,291 35,946 1,995 627 75,859 Risk Grade 8 18,560 25,347 160 2,184 46,251 Risk Grade 9 213 14 — — 227 Subtotal 1,138,523 1,154,915 88,575 6,290 2,388,303 Acquired Portfolio: Risk Grades 1-5 59,993 132,898 12,593 2,546 208,030 Risk Grade 6 6,769 3,822 — — 10,591 Risk Grade 7 3,197 6,730 — 143 10,070 Risk Grade 8 3,901 — — 1,977 5,878 Risk Grade 9 — — — — — Subtotal 73,860 143,450 12,593 4,666 234,569 Total $ 1,212,383 $ 1,298,365 $ 101,168 $ 10,956 $ 2,622,872 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 in a nonperforming status until they meet the Corporation’s definition of a performing TDR, at which time they are considered 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, 2015 , December 31, 2014 and June 30, 2014 : Residential Mortgage Consumer Installment Home Equity Total Consumer (In thousands) 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 December 31, 2014 Originated Loans: Performing $ 987,542 $ 818,878 $ 566,083 $ 2,372,503 Nonperforming 10,459 500 3,013 13,972 Subtotal 998,001 819,378 569,096 2,386,475 Acquired Loans: Performing 111,101 10,174 94,696 215,971 Nonperforming 1,288 18 454 1,760 Subtotal 112,389 10,192 95,150 217,731 Total $ 1,110,390 $ 829,570 $ 664,246 $ 2,604,206 June 30, 2014 Originated Loans: Performing $ 947,768 $ 743,121 $ 529,093 $ 2,219,982 Nonperforming 12,217 536 3,371 16,124 Subtotal 959,985 743,657 532,464 2,236,106 Acquired Loans: Performing 10,343 1,124 28,227 39,694 Nonperforming 69 — 63 132 Subtotal 10,412 1,124 28,290 39,826 Total $ 970,397 $ 744,781 $ 560,754 $ 2,275,932 Nonperforming Loans A summary of nonperforming loans follows: June 30, December 31, June 30, (In thousands) Nonaccrual loans: Commercial $ 17,260 $ 16,418 $ 18,773 Commercial real estate 25,287 24,966 25,361 Real estate construction 247 162 160 Land development 255 225 2,184 Residential mortgage 6,004 6,706 6,325 Consumer installment 393 500 536 Home equity 1,769 1,667 2,296 Total nonaccrual loans 51,215 50,644 55,635 Accruing loans contractually past due 90 days or more as to interest or principal payments: Commercial 711 170 15 Commercial real estate 56 — 69 Real estate construction — — — Land development — — — Residential mortgage 424 557 376 Consumer installment — — — Home equity 588 1,346 1,075 Total accruing loans contractually past due 90 days or more as to interest or principal payments 1,779 2,073 1,535 Nonperforming TDRs: Commercial loan portfolio 14,547 15,271 11,049 Consumer loan portfolio 3,365 3,196 5,516 Total nonperforming TDRs 17,912 18,467 16,565 Total nonperforming loans $ 70,906 $ 71,184 $ 73,735 The Corporation’s nonaccrual loans at June 30, 2015 , December 31, 2014 and June 30, 2014 included $35.7 million , $37.2 million and $43.7 million , respectively, of nonaccrual TDRs. The Corporation had $2.0 million of residential mortgage loans that were in the process of foreclosure at June 30, 2015 , compared to $2.3 million and $3.6 million at December 31, 2014 and June 30, 2014 , respectively. Impaired Loans The following schedule presents impaired loans by classes of loans at June 30, 2015 , December 31, 2014 and June 30, 2014 : 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 451 531 — Land development 1,942 3,644 — 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 451 531 — Land development 1,942 3,644 — Residential mortgage 29,954 29,954 260 Consumer installment 398 398 — Home equity 2,778 2,778 — Total $ 130,869 $ 161,040 $ 1,581 December 31, 2014 Impaired loans with a valuation allowance: Commercial $ 966 $ 1,040 $ 293 Commercial real estate 2,587 2,927 710 Residential mortgage 19,681 19,681 335 Subtotal 23,234 23,648 1,338 Impaired loans with no related valuation allowance: Commercial 38,094 44,557 — Commercial real estate 60,616 82,693 — Real estate construction 162 255 — Land development 1,928 3,484 — Residential mortgage 7,994 7,994 — Consumer installment 518 518 — Home equity 2,121 2,121 — Subtotal 111,433 141,622 — Total impaired loans: Commercial 39,060 45,597 293 Commercial real estate 63,203 85,620 710 Real estate construction 162 255 — Land development 1,928 3,484 — Residential mortgage 27,675 27,675 335 Consumer installment 518 518 — Home equity 2,121 2,121 — Total $ 134,667 $ 165,270 $ 1,338 Recorded Investment Unpaid Principal Balance Related Valuation Allowance (In thousands) June 30, 2014 Impaired loans with a valuation allowance: Commercial $ 2,905 $ 3,258 $ 563 Commercial real estate 4,369 5,605 777 Residential mortgage 20,353 20,353 379 Subtotal 27,627 29,216 1,719 Impaired loans with no related valuation allowance: Commercial 39,420 43,463 — Commercial real estate 46,205 58,997 — Real estate construction 160 366 — Land development 4,211 7,506 — Residential mortgage 6,325 6,325 — Consumer installment 536 536 — Home equity 2,296 2,296 — Subtotal 99,153 119,489 — Total impaired loans: Commercial 42,325 46,721 563 Commercial real estate 50,574 64,602 777 Real estate construction 160 366 — Land development 4,211 7,506 — Residential mortgage 26,678 26,678 379 Consumer installment 536 536 — Home equity 2,296 2,296 — Total $ 126,780 $ 148,705 $ 1,719 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 $30.2 million , $30.6 million and $21.9 million at June 30, 2015 , December 31, 2014 and June 30, 2014 , respectively, includes confirmed losses (partial charge-offs) of $15.2 million , $15.4 million and $18.2 million , respectively, and fair value discount adjustments of $15.0 million , $15.2 million and $3.7 million , respectively. Impaired loans included $15.9 million , $19.9 million and $10.4 million at June 30, 2015 , December 31, 2014 and June 30, 2014 , 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 $45.8 million , $45.7 million and $44.1 million at June 30, 2015 , December 31, 2014 and June 30, 2014 , respectively, of performing TDRs. The following schedule presents information related to impaired loans for the three and six months ended June 30, 2015 and 2014 : 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 390 2 515 2 Land development 1,900 34 1,888 61 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 Three Months Ended June 30, 2014 Six Months Ended June 30, 2014 Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status (In thousands) Commercial $ 42,629 $ 347 $ 42,118 $ 680 Commercial real estate 51,260 366 52,290 727 Real estate construction 163 — 165 — Land development 4,312 34 4,478 71 Residential mortgage 26,737 328 26,758 631 Consumer installment 634 — 704 — Home equity 2,221 — 2,194 — Total $ 127,956 $ 1,075 $ 128,707 $ 2,109 The following schedule presents the aging status of the recorded investment in loans by classes of loans at June 30, 2015 , December 31, 2014 and June 30, 2014 : 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, 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 413 — — 247 660 95,730 96,390 Land development — — — 255 255 3,781 4,036 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 — — 205 — 205 5,122 5,327 Land development — — 1,352 — 1,352 5,207 6,559 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 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, 2014 Originated Portfolio: Commercial $ 4,033 $ 743 $ 170 $ 16,418 $ 21,364 $ 1,234,534 $ 1,255,898 Commercial real estate 7,515 1,383 — 24,966 33,864 1,170,562 1,204,426 Real estate construction 262 — — 162 424 138,316 138,740 Land development — — — 225 225 4,303 4,528 Residential mortgage 2,126 54 557 6,706 9,443 988,558 998,001 Consumer installment 3,620 512 — 500 4,632 814,746 819,378 Home equity 3,039 660 1,346 1,667 6,712 562,384 569,096 Total $ 20,595 $ 3,352 $ 2,073 $ 50,644 $ 76,664 $ 4,913,403 $ 4,990,067 Acquired Portfolio: Commercial $ 133 $ — $ 5,427 $ — $ 5,560 $ 93,423 $ 98,983 Commercial real estate 2,014 352 11,052 — 13,418 339,804 353,222 Real estate construction — — — — — 14,005 14,005 Land development — — 1,653 — 1,653 12,569 14,222 Residential mortgage 156 — 18 — 174 112,215 112,389 Consumer installment 55 3 454 — 512 9,680 10,192 Home equity 636 106 1,288 — 2,030 93,120 95,150 Total $ 2,994 $ 461 $ 19,892 $ — $ 23,347 $ 674,816 $ 698,163 June 30, 2014 Originated Portfolio: Commercial $ 4,149 $ 1,901 $ 15 $ 18,773 $ 24,838 $ 1,113,685 $ 1,138,523 Commercial real estate 5,933 233 69 25,361 31,596 1,123,319 1,154,915 Real estate construction — — — 160 160 88,415 88,575 Land development — — — 2,184 2,184 4,106 6,290 Residential mortgage 2,515 — 376 6,325 9,216 950,769 959,985 Consumer installment 2,513 313 — 536 3,362 740,295 743,657 Home equity 2,002 985 1,075 2,296 6,358 526,106 532,464 Total $ 17,112 $ 3,432 $ 1,535 $ 55,635 $ 77,714 $ 4,546,695 $ 4,624,409 Acquired Portfolio: Commercial $ — $ — $ 6,744 $ — $ 6,744 $ 67,116 $ 73,860 Commercial real estate — — 1,594 — 1,594 141,856 143,450 Real estate construction — — — — — 12,593 12,593 Land development — — 1,977 — 1,977 2,689 4,666 Residential mortgage — — 69 — 69 10,343 10,412 Consumer installment 20 — — — 20 1,104 1,124 Home equity 325 49 63 — 437 27,853 28,290 Total $ 345 $ 49 $ 10,447 $ — $ 10,841 $ 263,554 $ 274,395 Loans Modified Under Troubled Debt Restructurings (TDRs) The following schedule presents the Corporation’s loans reported as TDRs at June 30, 2015 , December 31, 2014 and June 30, 2014 : Performing TDRs Non-Performing TDRs Nonaccrual TDRs Total (In thousands) 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 December 31, 2014 Commercial loan portfolio $ 29,179 $ 15,271 $ 32,597 $ 77,047 Consumer loan portfolio 16,485 3,196 4,594 24,275 Total $ 45,664 $ 18,467 $ 37,191 $ 101,322 June 30, 2014 Commercial loan portfolio $ 29,296 $ 11,049 $ 40,351 $ 80,696 Consumer loan portfolio 14,837 5,516 3,334 23,687 Total $ 44,133 $ 16,565 $ 43,685 $ 104,383 The following schedule provides information on the Corporation's TDRs that were modified during the three and six months ended June 30, 2015 and 2014 : 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 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 Three Months Ended June 30, 2014 Six Months Ended June 30, 2014 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 15 $ 3,575 $ 3,575 27 $ 11,931 $ 11,931 Commercial real estate 12 3,134 3,134 21 5,924 5,924 Land development — — — 1 72 72 Subtotal – commercial loan portfolio 27 6,709 6,709 49 17,927 17,927 Consumer loan portfolio 63 1,649 1,648 93 2,636 2,626 Total 90 $ 8,358 $ 8,357 142 $ 20,563 $ 20,553 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, 2015 and 2014 , 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, 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 Three Months Ended June 30, 2014 Six Months Ended June 30, 2014 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 5 $ 771 6 $ 875 Commercial real estate 3 603 5 2,273 Subtotal – commercial loan portfolio 8 1,374 11 3,148 Consumer loan portfolio 3 80 3 80 Total 11 $ 1,454 14 $ 3,228 Allowance for Loan Losses The following schedule presents, by loan portfolio segment, the changes in the allowance for the three and s

Intangible Assets

Intangible Assets	6 Months Ended
	Jun. 30, 2015
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. The majority of the MSRs recorded at June 30, 2015 were acquired as a result of the Northwestern and Monarch acquisitions. 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. During the second quarter of 2015, the Corporation acquired Lake Michigan and Monarch, which resulted in the recognition of $100.0 million and $5.4 million in goodwill, respectively. No amount of goodwill recorded in conjunction with these acquisitions is deductible for tax purposes. 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, 2014 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, 2015 and that the Corporation's goodwill was not impaired at June 30, 2015 . The following table shows the net carrying value of the Corporation’s intangible assets: June 30, December 31, June 30, (In thousands) Goodwill $ 285,512 $ 180,128 $ 120,164 Other intangible assets: Core deposit intangible assets $ 28,353 $ 20,863 $ 9,110 Non-compete intangible assets 541 — — Mortgage servicing rights 12,307 12,217 3,344 Total other intangible assets $ 41,201 $ 33,080 $ 12,454 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 $ 39,355 $ 31,550 $ 18,659 Accumulated amortization 11,002 10,687 9,549 Carrying amount $ 28,353 $ 20,863 $ 9,110 Amortization expense for the three months ended June 30 $ 952 $ 446 Amortization expense for the six months ended June 30 $ 1,743 $ 891 In conjunction with the acquisition of Lake Michigan on May 31, 2015 and Monarch on April 1, 2015, the Corporation recorded $7.3 million and $1.9 million , respectively, in core deposit intangible assets. These core deposit intangible assets are being amortized over a period of 10 years on an accelerated basis. There were no additions of core deposit intangible assets during the three and six months ended June 30, 2014. The estimated future amortization expense on core deposit intangible assets for periods ending after June 30, 2015 is as follows: 2015 — $2.4 million ; 2016 — $4.3 million ; 2017 — $3.7 million ; 2018 — $3.5 million ; 2019 — $3.3 million ; 2020 and thereafter — $11.2 million . In conjunction with the acquisition of Lake Michigan on May 31, 2015, the Corporation recorded $0.6 million in non-compete intangible assets with an amortization period of one year. There were no additions of non-compete intangible assets during the three and six months ended June 30, 2014. 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 $ 12,307 $ 12,217 $ 3,344 Fair value of MSRs $ 16,602 $ 14,979 $ 6,433 Loans serviced for others that have servicing rights capitalized $ 2,193,067 $ 2,093,140 $ 871,158 The following table shows the activity for capitalized MSRs: Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 (In thousands) Balance at beginning of period $ 11,583 $ 3,316 $ 12,217 $ 3,423 Acquired in Monarch acquisition 1,284 — 1,284 — Additions 415 278 815 421 Amortization (1,175 ) (250 ) (2,209 ) (500 ) Change in valuation allowance 200 — 200 — Balance at end of period $ 12,307 $ 3,344 $ 12,307 $ 3,344 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 $0.2 million as of December 31, 2014 related to impairment within certain pools attributable to the Corporation's servicing portfolio that was acquired in the Northwestern transaction. There was no impairment valuation allowance recorded on the Corporation's MSRs at June 30, 2015 and June 30, 2014 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	6 Months Ended
	Jun. 30, 2015
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 $(148) at June 30, 2015, $(113) at December 31, 2014 and $431 at June 30, 2014 $ (274 ) $ (210 ) $ 800 Pension and other postretirement benefits adjustment, net of related tax benefit of $16,601 at June 30, 2015, $17,362 at December 31, 2014 and $10,117 at June 30, 2014 (30,830 ) (32,243 ) (18,788 ) Accumulated other comprehensive loss $ (31,104 ) $ (32,453 ) $ (17,988 )

Borrowings Borrowings (Notes)

Borrowings Borrowings (Notes)	6 Months Ended
	Jun. 30, 2015
Borrowings [Abstract]
Borrowings [Text Block]	Borrowings Short-term Borrowings A summary of the Corporation's short-term borrowings, which generally have an original term to maturity of 30 days or less, follows: June 30, December 31, June 30, (In thousands) Short-term borrowings: Securities sold under agreements to repurchase with customers $ 305,291 $ 304,467 $ 293,422 Short-term FHLB advances 205,000 60,000 — Federal funds purchased 22,000 25,000 12,000 Total short-term borrowings $ 532,291 $ 389,467 $ 305,422 Other Borrowings The Corporation's other borrowings were obtained as a result of the acquisitions of Lake Michigan and Monarch. A summary of the Corporation's other borrowings follows: June 30, December 31, June 30, (In thousands) Other borrowings: Long-term FHLB advances $ 81,469 $ — $ — Securities sold under agreements to repurchase 23,649 — — Line of credit 25,000 — — Subordinated debentures 18,372 — — Total other borrowings $ 148,490 $ — $ — In conjunction with the Lake Michigan and Monarch acquisitions, the Corporation acquired long-term FHLB advances totaling $81.5 million . These advances have a weighted average interest rate of 1.33% at June 30, 2015 . The Corporation's FHLB advances, including both short-term and long-term, require monthly interest payments and are collateralized by eligible loans totaling $1.24 billion as of June 30, 2015 . The scheduled reductions of long-term FHLB advances as of June 30, 2015 were as follows: 2015 - $0.1 million ; 2016 - $7.1 million ; 2017 - $47.1 million ; 2018 - $17.1 million ; 2019; - $0.1 million ; and 2020 - $10.0 million . In conjunction with the Lake Michigan acquisition, the Company acquired securities sold under agreements to repurchase with an unaffiliated financial institution of $23.7 million as of acquisition date. These agreements are secured by available for-sale-securities. The scheduled reductions of securities sold under agreements to repurchase as of June 30, 2015 were as follows: 2015 - $3.2 million ; 2016 - $8.3 million ; and 2017 - $12.1 million . The Corporation entered into a $25 million secured non-revolving line-of-credit in May 2015 with an unaffiliated third-party financial institution. The Corporation drew on the entire amount of the line-of-credit in order to partially fund the cash portion of the purchase price consideration for the Lake Michigan transaction. 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 2.134% at June 30, 2015), and matures in May 2016. The line-of-credit agreement contains certain restrictive covenants. The Corporation was in compliance with all of the covenants at June 30, 2015 . In conjunction with the acquisition of Lake Michigan on May 31, 2015, the Corporation acquired Lake Michigan Financial Capital Trust I (LMFCTI), Lake Michigan Financial Capital Trust II (LMFCTII), and Lake Michigan Financial Capital Trust III (LMFCTIII). LMFCTIII, which held the $10.0 million trust preferred security due to the Corporation, was repaid and settled as of the Lake Michigan acquisition date, and the entity was subsequently dissolved. All of the common securities of the remaining two special purpose trusts are owned by the Corporation. The trusts exist solely to issue capital securities in the form of cumulative preferred securities (trust preferred securities) with a par value of $1,000 per security. The proceeds from the sale of the trust preferred securities were used by each trust to purchase an equivalent amount of subordinated debentures from Lake Michigan. Lake Michigan guaranteed the payment of distributions on the trust preferred securities issued by LMFCTI and LMFCTII. At the acquisition date, the Corporation assumed responsibility of the guarantees. LMFCTI issued $10.3 million in preferred securities in October 2002. This trust preferred subordinated debt pays interest based on a floating rate tied to the three-month LIBOR plus 3.45% (effective interest rate of 3.73% as of June 30, 2015). The maturity date of this trust preferred subordinated debt is October 2032. LMFCTII issued $8.2 million in preferred securities in May 2004. This trust preferred subordinated debt pays interest based on a floating rate tied to the three-month LIBOR plus 2.7% (effective interest rate of 2.98% as of June 30, 2015). The maturity date of this trust preferred subordinated debt is May 2034. The Corporation may, at any time, redeem the LMFCTI or LMFCTII subordinated debentures at par.

Regulatory Capital

Regulatory Capital	6 Months Ended
	Jun. 30, 2015
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, The Bank of Holland and The Bank of Northern Michigan to the Corporation. As of June 30, 2015 , substantially all of the assets of Chemical Bank, The Bank of Holland and The Bank of Northern Michigan 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, The Bank of Holland, and The Bank of Northern Michigan prior to making any cash dividend decisions. The Corporation, Chemical Bank, The Bank of Holland and The Bank of Northern Michigan are subject to various regulatory capital requirements administered by federal banking agencies. Under these capital requirements, Chemical Bank, The Bank of Holland and The Bank of Northern Michigan 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 $6.99 billion , $5.70 billion and $4.90 billion at June 30, 2015 , December 31, 2014 and June 30, 2014 , respectively. In July 2013, the Federal Reserve Board and FDIC approved final rules implementing the Basel Committee on Banking Supervision's (BCBS) capital guidelines for U.S. banks. Beginning January 1, 2015,the final rules include a new minimum common equity Tier 1 capital to risk-weighted assets (CET) 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 final 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, 2015 , December 31, 2014 and June 30, 2014 , Chemical Bank’s capital ratios exceeded the quantitative capital ratios required for an institution to be considered “well-capitalized.” At June 30, 2015 , The Bank of Northern Michigan's capital ratios exceeded the quantitative capital ratios required for an institution to be considered "well-capitalized." At June 30, 2015 , The Bank of Holland was considered "adequately-capitalized" due to the impact of push down accounting of the purchase accounting adjustments related to the Lake Michigan acquisition. 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, 2015 Total Capital to Risk-Weighted Assets: Corporation $ 816,595 11.7 % $ 559,273 8.0 % N/A N/A Chemical Bank 713,999 12.1 471,422 8.0 $ 589,277 10.0 % The Bank of Holland 72,506 9.5 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 72,506 9.5 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 72,506 9.5 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 72,506 9.4 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 December 31, 2014 Total Capital to Risk-Weighted Assets: Corporation $ 705,130 12.4 % $ 456,302 8.0 % N/A N/A Chemical Bank 654,031 11.5 455,633 8.0 $ 569,541 10.0 % Tier 1 Capital to Risk-Weighted Assets: Corporation 633,779 11.1 228,151 4.0 N/A N/A Chemical Bank 582,783 10.2 227,816 4.0 341,725 6.0 Leverage Ratio: Corporation 633,779 9.3 273,226 4.0 N/A N/A Chemical Bank 582,783 8.5 273,048 4.0 341,310 5.0 June 30, 2014 Total Capital to Risk-Weighted Assets: Corporation $ 748,332 15.3 % $ 391,911 8.0 % N/A N/A Chemical Bank 601,561 12.3 391,305 8.0 $ 489,131 10.0 % Tier 1 Capital to Risk-Weighted Assets: Corporation 686,892 14.0 195,955 4.0 N/A N/A Chemical Bank 540,214 11.0 195,653 4.0 293,479 6.0 Leverage Ratio: Corporation 686,892 11.2 244,757 4.0 N/A N/A Chemical Bank 540,214 8.8 244,604 4.0 305,755 5.0

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2015
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 certain 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, 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, 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 and trust preferred securities — 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 December 31, 2014 Investment securities – available-for-sale: U.S. Treasury securities $ 8,259 $ — $ — $ 8,259 Government sponsored agencies — 263,503 — 263,503 State and political subdivisions — 46,227 — 46,227 Residential mortgage-backed securities — 239,807 — 239,807 Collateralized mortgage obligations — 144,383 — 144,383 Corporate bonds — 45,095 — 45,095 Preferred stock — 1,590 — 1,590 Total investment securities – available-for-sale 8,259 740,605 — 748,864 Loans held-for-sale — 9,128 — 9,128 Total assets measured at fair value on a recurring basis $ 8,259 $ 749,733 $ — $ 757,992 June 30, 2014 Investment securities – available-for-sale: Government sponsored agencies $ — $ 88,708 $ — $ 88,708 State and political subdivisions — 41,608 — 41,608 Residential mortgage-backed securities — 265,368 — 265,368 Collateralized mortgage obligations — 153,283 — 153,283 Corporate bonds — 65,352 — 65,352 Preferred stock — 1,656 — 1,656 Total investment securities – available-for-sale — 615,975 — 615,975 Loans held-for-sale — 6,329 — 6,329 Total assets measured at fair value on a recurring basis $ — $ 622,304 $ — $ 622,304 There were no liabilities recorded at fair value on a recurring basis at June 30, 2015 , December 31, 2014 or June 30, 2014 . 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, 2015 , December 31, 2014 and June 30, 2014 , 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, 2015 , December 31, 2014 and June 30, 2014 , 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 December 31, 2014 , the Corporation recognized a valuation allowance of $0.2 million related to impairment within certain pools attributable to the Corporation's servicing portfolio that was acquired in the Northwestern transaction. At June 30, 2015 and June 30, 2014 , there was no impairment identified for MSRs and, therefore, no other intangible assets were recorded at fair value on a nonrecurring basis at those dates. 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, 2015 Impaired originated loans $ — $ — $ 24,517 $ 24,517 Other real estate/repossessed assets — — 14,197 14,197 Total $ — $ — $ 38,714 $ 38,714 December 31, 2014 Impaired originated loans $ — $ — $ 21,323 $ 21,323 Other real estate/repossessed assets — — 14,205 14,205 Mortgage servicing rights — — 8,691 8,691 Total $ — $ — $ 44,219 $ 44,219 June 30, 2014 Impaired originated loans $ — $ — $ 29,789 $ 29,789 Other real estate/repossessed assets — — 10,392 10,392 Total $ — $ — $ 40,181 $ 40,181 There were no liabilities recorded at fair value on a nonrecurring basis at June 30, 2015 , December 31, 2014 and June 30, 2014 . 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, 2015 , December 31, 2014 and June 30, 2014 , 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. 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. The fair values for variable-interest rate time deposits with defined maturities approximate their carrying amounts. 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. Other 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 debentures. Fair value measurements for other 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 other borrowings are Level 2 valuations, while securities sold under agreements to repurchase with an unaffiliated financial institution and subordinated debentures 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, 2015 December 31, 2014 June 30, 2014 Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value (In thousands) Assets: Cash and cash equivalents Level 1 $ 215,034 $ 215,034 $ 183,020 $ 183,020 $ 140,294 $ 140,294 Investment securities: Available-for-sale Level 1 8,294 8,294 8,259 8,259 — — Available-for-sale Level 2 677,412 677,412 740,605 740,605 615,975 615,975 Held-to-maturity Level 2 469,337 466,278 305,913 308,650 297,630 297,186 Held-to-maturity Level 3 500 300 10,500 7,090 10,500 6,775 Nonmarketable equity securities NA 36,142 36,142 27,369 27,369 25,572 25,572 Loans held-for-sale Level 2 7,798 7,798 9,128 9,128 6,329 6,329 Net loans Level 3 6,959,802 6,969,655 5,612,547 5,623,454 4,821,011 4,826,672 Interest receivable Level 2 21,668 21,668 17,492 17,492 15,827 15,827 Liabilities: Deposits without defined maturities Level 2 $ 5,547,764 $ 5,547,764 $ 4,741,024 $ 4,741,024 $ 3,814,013 $ 3,814,013 Time deposits Level 3 1,745,215 1,745,215 1,337,947 1,340,015 1,278,900 1,285,992 Interest payable Level 2 1,557 1,557 755 755 735 735 Short-term borrowings Level 2 532,291 532,291 389,467 389,467 305,422 305,422 Other borrowings Level 2 106,469 106,469 — — — — Other borrowings Level 3 42,021 42,021 — — — —

Earnings Per Common Share

Earnings Per Common Share	6 Months Ended
	Jun. 30, 2015
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, stock to be issued under the deferred stock compensation plan for non-employee directors and stock to be issued under the stock purchase plan for non-employee advisory 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 and the stock purchase 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, 2015 2014 2015 2014 (In thousands, except per share data) Numerator for both basic and diluted earnings per common share, net income $ 19,024 $ 16,236 $ 36,859 $ 30,049 Denominator for basic earnings per common share, weighted average common shares outstanding 35,162 30,068 33,992 29,947 Weighted average common stock equivalents 235 211 235 212 Denominator for diluted earnings per common share 35,397 30,279 34,227 30,159 Basic earnings per common share $ 0.54 $ 0.54 $ 1.08 $ 1.00 Diluted earnings per common share 0.54 0.54 1.08 1.00 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 80,700 and 249,150 for the three months ended June 30, 2015 and 2014 , respectively, and 100,875 and 252,529 for six-month period ended June 30, 2015 and 2014 , respectively.

Share-Based Compensation

Share-Based Compensation	6 Months Ended
	Jun. 30, 2015
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, 2015 and 2014 , share-based compensation expense related to stock options, restricted stock units and other share-based awards totaled $0.8 million and $0.6 million , respectively. During the six-month periods ended June 30, 2015 and 2014 , share-based compensation expense related to stock options, restricted stock units and other share-based awards totaled $1.5 million and $1.2 million , respectively. During the six-month period ended June 30, 2015 , the Corporation granted options to purchase 244,165 shares of common stock and 79,202 restricted stock units to certain officers. 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, 2015 , there were 1,295,145 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. In conjunction with the acquisition of Lake Michigan, the Corporation assumed the Lake Michigan Financial Corporation Stock Incentive Plan of 2012 and the Lake Michigan Financial Corporation Stock Incentive Plan of 2003 (collectively referred to as the Lake Michigan Stock Option Plans). On the date of acquisition, all outstanding Lake Michigan stock options became immediately vested, if not already vested, and were converted into 132,883 stock options for the Corporation. The converted options continue to have and are subject to the same terms of the Lake Michigan Stock Option Plans. No additional share-based awards may be granted under the Lake Michigan Stock Option Plans. A summary of activity for the Corporation’s stock options as of and for the six months ended June 30, 2015 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, 2014 432,199 $ 26.75 $ 8.30 1,037,311 $ 25.90 Granted 244,165 30.18 8.40 244,165 30.18 Lake Michigan converted options — — — 132,883 12.93 Exercised — — — (216,690 ) 23.99 Vested (150,224 ) 25.57 7.80 — — Forfeited/expired (9,175 ) 28.21 8.52 (9,175 ) 28.21 Outstanding at June 30, 2015 516,965 $ 28.69 $ 8.49 1,188,494 $ 25.66 Exercisable/vested at June 30, 2015 671,529 $ 23.32 The weighted-average remaining contractual terms were 6.6 years for all outstanding stock options and 4.8 years for exercisable stock options at June 30, 2015 . The intrinsic value of all outstanding in-the-money stock options and exercisable in-the-money stock options was $6.9 million and $4.7 million , respectively, at June 30, 2015 . The aggregate intrinsic values of outstanding and exercisable options at June 30, 2015 were calculated based on the closing market price of the Corporation’s common stock on June 30, 2015 of $33.06 per share less the exercise price. Options with intrinsic values less than zero, or “out-of-the-money” options, were not included in the aggregate intrinsic value reported. At June 30, 2015 , unrecognized compensation expense related to stock options totaled $4.0 million and is expected to be recognized over a remaining weighted average period of 3.9 years . The fair value of the stock options granted during the six months ended June 30, 2015 was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions. Expected dividend yield 3.50 % Risk-free interest rate 1.78 % Expected stock price volatility 39.1 % Expected life of options – in years 7.0 Weighted average fair value of options granted $ 8.40 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 0.25 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, 2015 is presented below: Number of Units Weighted- Average Grant Date Fair Value Per Unit Outstanding at December 31, 2014 204,319 $ 24.14 Granted 79,202 28.25 Converted into shares of common stock (67,489 ) 22.32 Forfeited/expired (1,427 ) 25.13 Outstanding at June 30, 2015 214,605 $ 26.23 At June 30, 2015 , unrecognized compensation expense related to restricted stock unit awards totaled $3.7 million and is expected to be recognized over a remaining weighted average period of 2.8 years .

Pension and Other Postretiremen

Pension and Other Postretirement Benefit Plans	6 Months Ended
	Jun. 30, 2015
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, 2015 2014 2015 2014 (In thousands) Defined Benefit Pension Plans Service cost $ 273 $ 251 $ 545 $ 501 Interest cost 1,332 1,312 2,664 2,624 Expected return on plan assets (2,161 ) (2,079 ) (4,322 ) (4,157 ) Amortization of prior service credit (1 ) (1 ) (2 ) (1 ) Amortization of unrecognized net loss 1,056 569 2,112 1,138 Net periodic benefit cost $ 499 $ 52 $ 997 $ 105 Postretirement Benefit Plan Service cost $ 4 $ 4 $ 8 $ 9 Interest cost 33 36 67 71 Amortization of prior service cost 32 33 65 65 Amortization of unrecognized net gain — (26 ) (1 ) (52 ) Net periodic benefit cost $ 69 $ 47 $ 139 $ 93 The Corporation’s pension plan does not have a contribution requirement in 2015 . The Corporation did no t make a contribution to the pension plan during 2014 . The discount rate used to compute the Corporation's pension plan expense for 2015 is 4.15% . 401(k) Savings Plan 401(k) Savings Plan expense for the Corporation’s match of participants’ base compensation contributions and a 4% of eligible pay contribution to certain employees who are not grandfathered under the pension plan was $1.3 million and $1.0 million for the three months ended June 30, 2015 and 2014 , respectively, and $2.4 million and $1.7 million for the six-month period ended June 30, 2015 and 2014 , 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 Plan is a single plan under IRC Section 413(c) and, as a result, all the plan's assets stand behind all of the plan's liabilities. Accordingly, contributions made by a participating employer may be used to provide benefits to participants of other participating employers. No contributions were made by the Corporation to the Pentegra DB Plan for the three months ended June 30, 2015.

Financial Guarantees

Financial Guarantees	6 Months Ended
	Jun. 30, 2015
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, 2015 , December 31, 2014 and June 30, 2014 , the Corporation had $45 million , $41 million and $37 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, 2015 , December 31, 2014 and June 30, 2014 .

Significant Accounting Polici23

Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations Chemical Financial Corporation (Corporation) operates in a single operating segment — commercial banking. The Corporation is a financial holding company, headquartered in Midland, Michigan, that operates through three commercial banks, Chemical Bank, The Bank of Holland and The Bank of Northern Michigan. The Bank of Holland and The Bank of Northern Michigan, which were acquired in the May 31, 2015 acquisition of Lake Michigan Financial Corporation (Lake Michigan), are expected to be consolidated with and into Chemical Bank during the fourth quarter of 2015 in conjunction with the conversion of their core data systems to Chemical Bank's. In addition, the Corporation acquired Monarch Community Bank as part of its April 1, 2015 acquisition of Monarch Community Bancorp, Inc. (Monarch). Monarch Community Bank was consolidated with and into Chemical Bank during the second quarter of 2015. 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, 2014. 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, 2015 are not necessarily indicative of the results that may be expected for the year ending December 31, 2015 .
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 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. 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 . The Corporation recorded $100 million of goodwill in conjunction with the acquisition, which represented the purchase price over the fair value of identifiable net assets acquired. Additionally, the Corporation recorded $7.9 million of core deposit and other intangible assets in conjunction with the acquisition. On April 1, 2015, the Corporation acquired all the outstanding stock of Monarch in an all-stock transaction valued at $27.2 million . The Corporation recorded $5.4 million of goodwill in conjunction with the acquisition, which represented the purchase price over the fair value of identifiable net assets acquired. Additionally, the Corporation recorded $1.9 million of core deposit intangible assets in conjunction with the acquisition. 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 Northwestern Bancorp, Inc. (Northwestern), which occurred on October 31, 2014, Lake Michigan, and Monarch, 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. See Note 2 for further information regarding the Corporation's acquisitions.
Originated Loans	Originated Loans Originated loans include all of the Corporation's portfolio loans, excluding loans acquired on May 31, 2015 in the acquisition of Lake Michigan, on April 1, 2015 in the acquisition of Monarch, on October 31, 2014 in the acquisition of Northwestern and on April 30, 2010 in the acquisition of O.A.K. Financial Corporation (OAK). Originated loans include loans acquired as part of the Corporation's branch acquisition on December 7, 2012, as these loans were performing and were considered high-quality loans in accordance with the Corporation's credit underwriting standards at that date. 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, on October 31, 2014 in the acquisition of Northwestern, and on April 30, 2010 in the acquisition of 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 Accounting Standards Codification (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 refinancing is no longer reported as a TDR. Loans in the Corporation’s commercial loan portfolio (comprised of commercial, commercial real estate, real estate construction and land development loans) that meet the definition of a TDR generally consist of loans where the Corporation has allowed borrowers to defer scheduled principal payments and make interest-only payments for a specified period of time at the stated interest rate of the original loan agreement or reduced payments due to a moderate extension of the loan’s contractual term. If the Corporation does not expect to collect all principal and interest on the loan, the modified loan is classified as a nonaccrual TDR. If the Corporation does not expect to incur a loss on the loan based on its assessment of the borrowers’ expected cash flows, as the pre- and post-modification effective yields are approximately the same, the loan is classified as a nonperforming TDR until a six-month payment history is sustained, at which time the loan is classified as a performing TDR. Since no loss is expected to be incurred on these loans, no additional provision for loan losses has been recognized related to these loans, and these loans accrue interest at their contractual interest rate. These loans are individually evaluated for impairment and transferred to nonaccrual status if they become 90 days past due as to principal or interest payments or if it is probable that any remaining principal and interest payments due on the loan will not be collected in accordance with the modified terms of the loan. Loans in the Corporation’s consumer loan portfolio (comprised of residential mortgage, consumer installment and home equity loans) that meet the definition of a performing or nonperforming TDR generally consist of residential mortgage loans that include a concession that reduces a borrower’s monthly payments by decreasing the interest rate charged on the loan for a specified period of time (generally 24 months ) under a formal modification agreement. The Corporation recognizes an additional provision for loan losses related to impairment on these loans on an individual basis based on the present value of expected future cash flows discounted at the loan’s original effective interest rate. These loans continue to accrue interest at their effective interest rate, which consists of contractual interest under the terms of the modification agreement in addition to an adjustment for the accretion of computed impairment. These loans are moved to nonaccrual status if they become 90 days past due as to principal or interest payments, or sooner if conditions warrant.
Impaired Loans	Impaired Loans A loan is defined to be impaired when it is probable that payment of principal and interest will not be paid in accordance with the original contractual terms of the loan agreement. Impaired loans include nonaccrual loans (including nonaccrual TDRs), performing and nonperforming TDRs and acquired loans that were not performing in accordance with original contractual terms. Impaired loans are accounted for at the lower of the present value of expected cash flows discounted at the loan's original effective interest rate or the estimated fair value of the collateral, if the loan is collateral dependent. When the present value of expected cash flows or the fair value of collateral of an impaired loan in the originated loan portfolio is less than the amount of unpaid principal outstanding on the loan, the principal balance of the loan is reduced to its carrying value through either an allocation of the allowance for loan losses or a partial charge-off of the loan balance.
Nonperforming Loans	Nonperforming Loans Nonperforming loans are comprised of loans for which the accrual of interest has been discontinued (nonaccrual loans, including nonaccrual TDRs), accruing originated loans contractually past due 90 days or more as to interest or principal payments and nonperforming TDRs. Acquired loans that were classified as nonperforming loans prior to being acquired and acquired loans that are not performing in accordance with contractual terms subsequent to acquisition are not classified as nonperforming loans subsequent to acquisition because the loans are recorded in pools at net realizable value based on the principal and interest the Corporation expects to collect on such loans.
Allowance for Loan Losses	Allowance for Loan Losses The allowance for loan losses (allowance) is presented as a reserve against loans. The allowance represents management’s assessment of probable loan losses inherent in the Corporation’s loan portfolio. Management’s evaluation of the adequacy of the allowance is based on a continuing review of the loan portfolio, actual loan loss experience, the underlying value of the collateral, risk characteristics of the loan portfolio, the level and composition of nonperforming loans, the financial condition of the borrowers, the balance of the loan portfolio, loan growth, economic conditions, employment levels in the Corporation’s local markets, and special factors affecting specific business sectors. The Corporation maintains formal policies and procedures to monitor and control credit risk. Management evaluates the allowance on a quarterly basis in an effort to ensure the level is appropriate to absorb probable losses inherent in the loan portfolio. The allowance provides for probable losses that have been identified with specific customer relationships and for probable losses believed to be incurred in the remainder of the originated loan portfolio, but that have not been specifically identified. The Corporation utilizes its own loss experience to estimate inherent losses on loans. Internal risk ratings are assigned to each loan in the commercial loan portfolio (commercial, commercial real estate, real estate construction and land development loans) at the time of origination and are subject to subsequent periodic reviews by senior management. The Corporation performs a detailed credit quality review quarterly on all loans greater than $0.25 million that have deteriorated below certain levels of credit risk, and may allocate a specific portion of the allowance to such loans based upon this review. A portion of the allowance is allocated to the remaining loans by applying projected loss ratios, based on numerous factors. Projected loss ratios incorporate factors such as charge-off experience, trends with respect to adversely risk-rated loans in the commercial loan portfolio, trends with respect to past due and nonaccrual loans, changes in economic conditions and trends, changes in the value of underlying collateral and other credit risk factors. This evaluation involves a high degree of uncertainty. In determining the allowance and the related provision for loan losses, the Corporation considers four principal elements: (i) valuation allowances based upon probable losses identified during the review of impaired loans in the commercial loan portfolio, (ii) reserves established for adversely-rated loans in the commercial loan portfolio and nonaccrual residential mortgage, consumer installment and home equity loans based on loan loss experience of other adversely-rated loans, (iii) reserves, by loan classes, on all other loans based principally on a five -year historical loan loss experience, with higher weighting placed on the most recent years, loan loss trends giving consideration to estimated loss emergence periods and (iv) an unallocated allowance based on the imprecision in the overall allowance methodology for loans collectively evaluated for impairment. 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, 2015 , December 31, 2014 and June 30, 2014 , 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 its bank subsidiaries. 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. In conjunction with the acquisition of Monarch, the Corporation has net operating loss carryforwards, which are limited under Internal Revenue Code (IRC) Section 382, included in deferred tax assets. See Note 2 for further information regarding the net operating loss carryforward. 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, 2015 , December 31, 2014 or June 30, 2014 . Tax returns open to examination by the Internal Revenue Service (IRS) include those for the calendar years ended December 31, 2014 , 2013 , 2012 and 2011 for the Corporation, Lake Michigan, Monarch and Northwestern. Monarch's tax returns for the calendar years ended 2009-2013 are currently under an IRS examination.
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 of these projects comes in the form of the tax credits and 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 $0.2 million and $0.3 million during the three and six months ended June 30, 2015 , respectively, and $0.1 million and $0.2 million during the three and six months ended June 30, 2014 , respectively. The Corporation's remaining investment in qualified affordable housing projects accounted for under the proportional amortization method totaled $21.4 million at June 30, 2015 , $4.9 million at December 31, 2014 and $3.1 million at June 30, 2014 . The increase in qualified affordable housing project investments at June 30, 2015, compared to December 31, 2014 and June 30, 2014, was attributable to investments acquired as part of the Lake Michigan transaction. Under the equity method, the Corporation's share of the earnings or losses are included in other operating expenses on the consolidated statements of income. The Corporation's investment in new market projects accounted for under the equity method totaled $3.3 million at June 30, 2015. There were no investments in such projects accounted for under the equity method as of December 31, 2014 or June 30, 2014. 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 $9.7 million at 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, 2015, December 31, 2014 or June 30, 2014. 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, 2015 , there were 500,000 remaining shares available for repurchase under the Corporation’s stock repurchase program. Underwritten Public Offerings of Common Stock On June 24, 2014, the Corporation issued and sold 2,500,000 shares of common stock at a public offering price of $28.00 per share. An additional 375,000 shares were issued and sold on June 30, 2014 upon the exercise in full of the underwriters' over-allotment option. The net proceeds from the issuance and sale of the common stock of this $80.5 million offering, after deducting the underwriting discount and issuance-related expenses, totaled $76.2 million . On September 18, 2013, the Corporation issued and sold 2,213,750 shares of common stock, including 288,750 shares of common stock that were issued and sold upon the exercise in full of the underwriters' over-allotment option, at a public offering price of $26.00 per share. The net proceeds from the issuance and sale of the common stock, after deducting the underwriting discount and issuance-related expenses, totaled $53.9 million . 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, 2015 , no shares of preferred stock were issued and outstanding. Common Stock On April 20, 2015, the shareholders of the Corporation approved an amendment to the restated articles of incorporation to increase the number of authorized shares of common stock from 45,000,000 to 60,000,000 .
Legal Matters	Legal Matters 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 In-Substance Foreclosures In January 2014, the FASB issued ASU 2014-04, Receivables — Troubled Debt Restructurings by Creditors (Subtopic 310-40): Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure, a consensus of the FASB Emerging Issues Task Force (ASU 2014-04). ASU 2014-04 clarifies that an in-substance foreclosure occurs, and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan, upon either (i) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or (ii) the borrower conveying all interest in the residential real estate property to the creditor to satisfy the loan through completion of a deed in lieu of foreclosure or similar legal agreement. ASU 2014-04 also requires disclosure of both the amount of foreclosed residential real estate property held by the creditor and the recorded investment in loans collateralized by residential real estate property that are in the process of foreclosure. ASU 2014-04 is effective for public companies for interim and annual periods beginning after December 15, 2014, with early adoption permitted. Once adopted, an entity can elect either (i) a modified retrospective transition method or (ii) a prospective transition method. The modified retrospective transition method is applied by means of a cumulative-effect adjustment to residential mortgage loans and foreclosed residential real estate properties existing as of the beginning of the period for which the amendments of ASU 2014-04 are effective, with real estate reclassified to loans measured at the carrying value of the real estate at the date of adoption and loans reclassified to real estate measured at the lower of net carrying value of the loan or the fair value of the real estate less costs to sell at the date of adoption. The prospective transition method is applied by means of applying the amendments of ASU 2014-04 to all instances of receiving physical possession of residential real estate properties that occur after the date of adoption. The adoption of ASU 2014-04 on January 1, 2015 did not have a material impact on the Corporation's consolidated financial condition or results of operations. Share-Based Compensation In June 2014, the FASB issued ASU 2014-12, Compensation — Stock Compensation (Topic 718): Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period, a consensus of the FASB Emerging Issues Task Force (ASU 2014-12). ASU 2014-12 requires that a performance target that affects vesting of share-based payment awards and that could be achieved after the requisite service period be treated as a performance condition. Compensation cost should be recognized in the period in which it becomes probable that the performance target will be achieved and should represent the compensation cost attributable to the periods for which the requisite service has already been rendered. If the performance target becomes probable of being achieved before the end of the requisite service period, the remaining unrecognized compensation cost should be recognized prospectively over the remaining requisite service period. The total amount of compensation cost recognized during and after the requisite service period should reflect the number of awards that are expected to vest and should be adjusted to reflect those awards that ultimately vest. The requisite service period ends when the employee can cease rendering service and still be eligible to vest in the award if the performance target is achieved. ASU 2014-12 is effective for all entities for interim and annual periods beginning after December 15, 2015, with early adoption permitted. An entity may apply the amendments in ASU 2014-12 either (i) prospectively to all awards granted or modified after the effective date or (ii) retrospectively to all awards with performance targets that are outstanding as of the beginning of the earliest annual period presented in the financial statements and to all new or modified awards thereafter. The Corporation's early adoption of ASU 2014-12 on January 1, 2015 did not have a material impact on the Corporation's consolidated financial condition or results of operations. Government-Guaranteed Mortgage Loans In August 2014, the FASB issued ASU 2014-14, Receivables-Troubled Debt Restructurings by Creditors (Subtopic 310-40): Classification of Certain Government Guaranteed Mortgage Loans upon Foreclosure, a consensus of the FASB Emerging Issues Task Force (ASU 2014-14). ASU 2014-14 provides clarifying guidance related to how creditors classify government-guaranteed loans upon foreclosure. Upon foreclosure of a government-guaranteed mortgage loan, the loan should be derecognized and a separate other receivable should be recognized if the following conditions are met: (i) the loan has a government guarantee that is not separable from the loan before foreclosure; (ii) at the time of foreclosure, the creditor has the intent to convey the real estate property to the guarantor and make a claim on the guarantee, and the creditor has the ability to recover under that claim; and (iii) at the time of foreclosure, any amount of the claim that is determined on the basis of the fair value of the real estate is fixed. The separate other receivable should be measured based on the amount of the loan balance (principal and interest) expected to be recovered from the guarantor at the time of foreclosure. ASU 2014-14 is effective for public companies for interim and annual periods beginning after December 15, 2014. An entity should adopt using either the modified retrospective method or the prospective transition method. An entity must apply the same method elected under ASU 2014-04. Early adoption is permitted if the entity has already adopted ASU 2014-04. The adoption of ASU 2014-14 on January 1, 2015 did not have a material impact on the Corporation's consolidated financial condition or results of operations.
Pending Accounting Pronouncements	Pending Accounting Pronouncements There are no recent accounting pronouncements that have been issued by the FASB that would have a material impact on the financial statements of the Corporation.

Acquisitions (Tables)

Acquisitions (Tables)	6 Months Ended
	Jun. 30, 2015
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Information [Table Text Block]	Unaudited Pro Forma Combined Results of Operations The following presentation of unaudited pro forma combined results of operations of Chemical, Lake Michigan, Monarch, and Northwestern presents these results as if the acquisitions had been completed as of the beginning of each period indicated. The unaudited pro forma combined results of operations are presented solely for information purposes and are not intended to represent or be indicative of the consolidated results of operations that Chemical would have reported had this transaction been completed as of the dates and for the periods presented, nor are they indicative of future results. In particular, no adjustments have been made to eliminate the amount of Lake Michigan's, Monarch's, or Northwestern's provision for loan losses incurred prior to the acquisition date that would not have been necessary had the acquired loans been recorded at fair value as of the beginning of each period indicated. In addition, no adjustment has been made for the lost opportunity cost associated with the all-cash purchase of Northwestern. In accordance with Article 11 of SEC Regulation S-X, transaction costs directly attributable to the acquisition have been excluded. Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 (In thousands, except per share data) Interest income $ 78,137 $ 74,842 $ 154,261 $ 148,089 Interest expense 5,483 6,748 11,363 13,627 Net interest income 72,654 68,094 142,898 134,462 Provision for loan losses 1,500 1,860 3,000 4,035 Net interest income after provision for loan losses 71,154 66,234 139,898 130,427 Noninterest income 21,153 23,713 43,180 43,487 Operating expenses 62,394 59,915 123,042 121,241 Income before income taxes 29,913 30,032 60,036 52,673 Federal income tax expense 7,525 9,048 16,736 15,807 Net income $ 22,388 $ 20,984 $ 43,300 $ 36,866 Net income per common share: Basic $ 0.59 $ 0.60 $ 1.14 $ 1.05 Diluted 0.58 0.59 1.13 1.04 Weighted average shares outstanding: Basic 38,044 35,251 38,024 35,129 Diluted 38,279 35,462 38,259 35,398
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: Six Months Ended June 30, 2015 2014 Lake Michigan Monarch North-western OAK Total OAK (In thousands) Balance at beginning of period $ — $ — $ 104,675 $ 33,286 137,961 $ 32,610 Additions attributable to acquisitions 190,246 37,914 — — 228,160 — Additions (reductions)* 1,550 (1,141 ) (2,859 ) 5,215 2,765 2,333 Accretion recognized in interest income (3,486 ) (968 ) (10,058 ) (6,326 ) (20,838 ) (7,594 ) Reclassification from nonaccretable difference — — — — — 10,000 Balance at end of period $ 188,310 $ 35,805 $ 91,758 $ 32,175 $ 348,048 $ 37,349 *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.
Lake Michigan Financial Corp [Member]
Business Acquisition [Line Items]
Purchase Accounting Fair Value Adjustments [Table Text Block]	A summary of the purchase price and the excess of the purchase price over the fair value of adjusted net assets acquired (goodwill) follows (in thousands): Fair value of the Corporation's common shares issued on May 31, 2015 (4,322,101 shares at a market price of $30.29 per share) $ 130,916 Fair value of Lake Michigan options converted to the Corporation's options 2,000 Cash paid to acquire outstanding stock 54,478 Total purchase price $ 187,394 Net assets acquired: Lake Michigan shareholders' equity $ 89,280 Adjustments to reflect fair value of net assets acquired: Loans (22,600 ) Allowance for loan losses 15,888 Premises and equipment (2,333 ) Core deposit intangibles 7,303 Deferred tax assets, net 2,269 Deposits and borrowings, net (3,048 ) Other assets and other liabilities 633 Fair value of adjusted net assets acquired 87,392 Goodwill recognized as a result of the Lake Michigan transaction $ 100,002
Schedule of Purchase Price Allocation [Table Text Block]	The preliminary acquisition date estimated fair values of the assets acquired and liabilities assumed of Lake Michigan were as follows (in thousands): Assets Cash and cash equivalents $ 39,301 Investment securities 66,699 Loans 985,542 Premises and equipment 13,673 Deferred tax asset, net 14,888 Goodwill 100,002 Core deposit intangible asset 7,303 Bank-owned life insurance 23,844 Other assets 38,449 Assets acquired, at fair value 1,289,701 Liabilities Deposits 924,697 Short-term borrowings 30,000 Other borrowings 124,723 Other liabilities 22,887 Total liabilities acquired, at fair value 1,102,307 Total purchase price $ 187,394
Monarch Community Bancorp [Member]
Business Acquisition [Line Items]
Purchase Accounting Fair Value Adjustments [Table Text Block]	A summary of the purchase price and the excess of the purchase price over the fair value of adjusted net assets acquired (goodwill) follows (in thousands): Fair value of the Corporation's common shares issued on April 1, 2015 (860,575 shares at a market price of $31.36 per share) $ 26,988 Cash paid 203 Total purchase price $ 27,191 Net assets acquired: Monarch shareholders' equity 15,270 Adjustments to reflect fair value of net assets acquired: Loans (7,150 ) Allowance for loan losses 2,128 Deferred tax assets, net: Net operating loss carryforward 7,900 Other 1,748 Premises and equipment (370 ) Core deposit intangibles 1,930 Mortgage servicing rights 315 Other assets and other liabilities 37 Fair value of adjusted net assets acquired 21,808 Goodwill recognized as a result of the Monarch transaction $ 5,383
Schedule of Purchase Price Allocation [Table Text Block]	The preliminary acquisition date estimated fair values of the assets acquired and liabilities assumed of Monarch were as follows (in thousands): Assets Cash and cash equivalents $ 32,171 Loans 121,783 Premises and equipment 3,064 Deferred tax assets, net Net operating loss carryforward 7,900 Other 2,314 Interest receivable and other assets 6,972 Goodwill 5,383 Core deposit intangibles 1,930 Mortgage servicing rights 1,284 Assets acquired, at fair value 182,801 Liabilities Deposits 144,311 FHLB advances 8,000 Interest payable and other liabilities 3,299 Total liabilities acquired, at fair value 155,610 Total purchase price $ 27,191

Investment Securities (Tables)

Investment Securities (Tables)	6 Months Ended
	Jun. 30, 2015
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, 2015 , December 31, 2014 and June 30, 2014 : Investment Securities Available-for-Sale Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) 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 December 31, 2014 U.S. Treasury securities $ 8,272 $ — $ 13 $ 8,259 Government sponsored agencies 263,658 356 511 263,503 State and political subdivisions 45,157 1,087 17 46,227 Residential mortgage-backed securities 240,465 885 1,543 239,807 Collateralized mortgage obligations 145,316 261 1,194 144,383 Corporate bonds 44,930 213 48 45,095 Preferred stock 1,389 201 — 1,590 Total $ 749,187 $ 3,003 $ 3,326 $ 748,864 June 30, 2014 Government sponsored agencies $ 88,503 $ 346 $ 141 $ 88,708 State and political subdivisions 40,165 1,443 — 41,608 Residential mortgage-backed securities 265,673 1,117 1,422 265,368 Collateralized mortgage obligations 154,035 376 1,128 153,283 Corporate bonds 64,979 456 83 65,352 Preferred stock 1,389 267 — 1,656 Total $ 614,744 $ 4,005 $ 2,774 $ 615,975
Held-to-maturity Securities	Investment Securities Held-to-Maturity Amortized Cost Unrealized Gains Unrealized Losses Fair Value (In thousands) 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 December 31, 2014 State and political subdivisions $ 305,913 $ 7,294 $ 4,557 $ 308,650 Trust preferred securities 10,500 — 3,410 7,090 Total $ 316,413 $ 7,294 $ 7,967 $ 315,740 June 30, 2014 State and political subdivisions $ 297,630 $ 5,885 $ 6,329 $ 297,186 Trust preferred securities 10,500 — 3,725 6,775 Total $ 308,130 $ 5,885 $ 10,054 $ 303,961
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, 2015 , 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, 2015 Amortized Cost Fair Value (In thousands) Investment Securities Available-for-Sale: Due in one year or less $ 198,939 $ 198,680 Due after one year through five years 411,399 411,247 Due after five years through ten years 68,583 68,295 Due after ten years 5,818 5,823 Preferred stock 1,389 1,661 Total $ 686,128 $ 685,706 Investment Securities Held-to-Maturity: Due in one year or less $ 55,922 $ 56,043 Due after one year through five years 209,886 209,768 Due after five years through ten years 127,398 125,775 Due after ten years 76,631 74,992 Total $ 469,837 $ 466,578
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, 2015 , December 31, 2014 and June 30, 2014 , 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, 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 December 31, 2014 U.S. Treasury securities $ 8,259 $ 13 $ — $ — $ 8,259 $ 13 Government sponsored agencies 166,963 406 31,927 105 198,890 511 State and political subdivisions 62,310 3,348 36,847 1,226 99,157 4,574 Residential mortgage-backed securities 17,276 52 180,194 1,491 197,470 1,543 Collateralized mortgage obligations 63,077 179 31,620 1,015 94,697 1,194 Corporate bonds — — 14,952 48 14,952 48 Trust preferred securities — — 7,090 3,410 7,090 3,410 Total $ 317,885 $ 3,998 $ 302,630 $ 7,295 $ 620,515 $ 11,293 June 30, 2014 Government sponsored agencies $ 2,377 $ 2 $ 44,786 $ 139 $ 47,163 $ 141 State and political subdivisions 92,279 4,047 71,421 2,282 163,700 6,329 Residential mortgage-backed securities 10,144 60 197,042 1,362 207,186 1,422 Collateralized mortgage obligations 47,142 68 35,722 1,060 82,864 1,128 Corporate bonds 4,996 5 14,922 78 19,918 83 Trust preferred securities — — 6,775 3,725 6,775 3,725 Total $ 156,938 $ 4,182 $ 370,668 $ 8,646 $ 527,606 $ 12,828

Loans (Tables)

Loans (Tables)	6 Months Ended
	Jun. 30, 2015
Receivables [Abstract]
Summary of loans under portfolio	A summary of loans follows: June 30, December 31, June 30, (In thousands) Commercial loan portfolio: Commercial $ 1,754,873 $ 1,354,881 $ 1,212,383 Commercial real estate 2,243,513 1,557,648 1,298,365 Real estate construction 101,717 152,745 101,168 Land development 10,595 18,750 10,956 Subtotal 4,110,698 3,084,024 2,622,872 Consumer loan portfolio: Residential mortgage 1,310,167 1,110,390 970,397 Consumer installment 887,907 829,570 744,781 Home equity 725,971 664,246 560,754 Subtotal 2,924,045 2,604,206 2,275,932 Total loans $ 7,034,743 $ 5,688,230 $ 4,898,804
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, 2015 , December 31, 2014 and June 30, 2014 : Commercial Commercial Real Estate Real Estate Construction Land Development Total (In thousands) June 30, 2015 Originated Portfolio: Risk Grades 1-5 $ 1,269,091 $ 1,273,725 $ 94,894 $ 2,470 $ 2,640,180 Risk Grade 6 32,189 34,677 — 433 67,299 Risk Grade 7 41,316 29,737 1,249 878 73,180 Risk Grade 8 17,260 25,283 247 255 43,045 Risk Grade 9 — 4 — — 4 Subtotal 1,359,856 1,363,426 96,390 4,036 2,823,708 Acquired Portfolio: Risk Grades 1-5 347,914 820,400 5,122 5,017 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 6,603 205 1,352 11,941 Risk Grade 9 — — — — — Subtotal 395,017 880,087 5,327 6,559 1,286,990 Total $ 1,754,873 $ 2,243,513 $ 101,717 $ 10,595 $ 4,110,698 December 31, 2014 Originated Portfolio: Risk Grades 1-5 $ 1,171,817 $ 1,114,529 $ 134,668 $ 2,952 $ 2,423,966 Risk Grade 6 37,800 34,996 1,408 738 74,942 Risk Grade 7 29,863 29,935 2,502 613 62,913 Risk Grade 8 16,417 24,958 162 225 41,762 Risk Grade 9 1 8 — — 9 Subtotal 1,255,898 1,204,426 138,740 4,528 2,603,592 Acquired Portfolio: Risk Grades 1-5 76,780 321,018 14,005 11,789 423,592 Risk Grade 6 12,687 8,698 — 583 21,968 Risk Grade 7 4,089 12,478 — 197 16,764 Risk Grade 8 5,427 11,028 — 1,653 18,108 Risk Grade 9 — — — — — Subtotal 98,983 353,222 14,005 14,222 480,432 Total $ 1,354,881 $ 1,557,648 $ 152,745 $ 18,750 $ 3,084,024 June 30, 2014 Originated Portfolio: Risk Grades 1-5 $ 1,067,000 $ 1,063,555 $ 85,754 $ 2,514 $ 2,218,823 Risk Grade 6 15,459 30,053 666 965 47,143 Risk Grade 7 37,291 35,946 1,995 627 75,859 Risk Grade 8 18,560 25,347 160 2,184 46,251 Risk Grade 9 213 14 — — 227 Subtotal 1,138,523 1,154,915 88,575 6,290 2,388,303 Acquired Portfolio: Risk Grades 1-5 59,993 132,898 12,593 2,546 208,030 Risk Grade 6 6,769 3,822 — — 10,591 Risk Grade 7 3,197 6,730 — 143 10,070 Risk Grade 8 3,901 — — 1,977 5,878 Risk Grade 9 — — — — — Subtotal 73,860 143,450 12,593 4,666 234,569 Total $ 1,212,383 $ 1,298,365 $ 101,168 $ 10,956 $ 2,622,872
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, 2015 , December 31, 2014 and June 30, 2014 : Residential Mortgage Consumer Installment Home Equity Total Consumer (In thousands) 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 December 31, 2014 Originated Loans: Performing $ 987,542 $ 818,878 $ 566,083 $ 2,372,503 Nonperforming 10,459 500 3,013 13,972 Subtotal 998,001 819,378 569,096 2,386,475 Acquired Loans: Performing 111,101 10,174 94,696 215,971 Nonperforming 1,288 18 454 1,760 Subtotal 112,389 10,192 95,150 217,731 Total $ 1,110,390 $ 829,570 $ 664,246 $ 2,604,206 June 30, 2014 Originated Loans: Performing $ 947,768 $ 743,121 $ 529,093 $ 2,219,982 Nonperforming 12,217 536 3,371 16,124 Subtotal 959,985 743,657 532,464 2,236,106 Acquired Loans: Performing 10,343 1,124 28,227 39,694 Nonperforming 69 — 63 132 Subtotal 10,412 1,124 28,290 39,826 Total $ 970,397 $ 744,781 $ 560,754 $ 2,275,932
Summary of nonperforming loans	A summary of nonperforming loans follows: June 30, December 31, June 30, (In thousands) Nonaccrual loans: Commercial $ 17,260 $ 16,418 $ 18,773 Commercial real estate 25,287 24,966 25,361 Real estate construction 247 162 160 Land development 255 225 2,184 Residential mortgage 6,004 6,706 6,325 Consumer installment 393 500 536 Home equity 1,769 1,667 2,296 Total nonaccrual loans 51,215 50,644 55,635 Accruing loans contractually past due 90 days or more as to interest or principal payments: Commercial 711 170 15 Commercial real estate 56 — 69 Real estate construction — — — Land development — — — Residential mortgage 424 557 376 Consumer installment — — — Home equity 588 1,346 1,075 Total accruing loans contractually past due 90 days or more as to interest or principal payments 1,779 2,073 1,535 Nonperforming TDRs: Commercial loan portfolio 14,547 15,271 11,049 Consumer loan portfolio 3,365 3,196 5,516 Total nonperforming TDRs 17,912 18,467 16,565 Total nonperforming loans $ 70,906 $ 71,184 $ 73,735
Schedule of Impaired loans by classes	The following schedule presents impaired loans by classes of loans at June 30, 2015 , December 31, 2014 and June 30, 2014 : 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 451 531 — Land development 1,942 3,644 — 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 451 531 — Land development 1,942 3,644 — Residential mortgage 29,954 29,954 260 Consumer installment 398 398 — Home equity 2,778 2,778 — Total $ 130,869 $ 161,040 $ 1,581 December 31, 2014 Impaired loans with a valuation allowance: Commercial $ 966 $ 1,040 $ 293 Commercial real estate 2,587 2,927 710 Residential mortgage 19,681 19,681 335 Subtotal 23,234 23,648 1,338 Impaired loans with no related valuation allowance: Commercial 38,094 44,557 — Commercial real estate 60,616 82,693 — Real estate construction 162 255 — Land development 1,928 3,484 — Residential mortgage 7,994 7,994 — Consumer installment 518 518 — Home equity 2,121 2,121 — Subtotal 111,433 141,622 — Total impaired loans: Commercial 39,060 45,597 293 Commercial real estate 63,203 85,620 710 Real estate construction 162 255 — Land development 1,928 3,484 — Residential mortgage 27,675 27,675 335 Consumer installment 518 518 — Home equity 2,121 2,121 — Total $ 134,667 $ 165,270 $ 1,338 Recorded Investment Unpaid Principal Balance Related Valuation Allowance (In thousands) June 30, 2014 Impaired loans with a valuation allowance: Commercial $ 2,905 $ 3,258 $ 563 Commercial real estate 4,369 5,605 777 Residential mortgage 20,353 20,353 379 Subtotal 27,627 29,216 1,719 Impaired loans with no related valuation allowance: Commercial 39,420 43,463 — Commercial real estate 46,205 58,997 — Real estate construction 160 366 — Land development 4,211 7,506 — Residential mortgage 6,325 6,325 — Consumer installment 536 536 — Home equity 2,296 2,296 — Subtotal 99,153 119,489 — Total impaired loans: Commercial 42,325 46,721 563 Commercial real estate 50,574 64,602 777 Real estate construction 160 366 — Land development 4,211 7,506 — Residential mortgage 26,678 26,678 379 Consumer installment 536 536 — Home equity 2,296 2,296 — Total $ 126,780 $ 148,705 $ 1,719
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, 2015 and 2014 : 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 390 2 515 2 Land development 1,900 34 1,888 61 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 Three Months Ended June 30, 2014 Six Months Ended June 30, 2014 Average Recorded Investment Interest Income Recognized While on Impaired Status Average Recorded Investment Interest Income Recognized While on Impaired Status (In thousands) Commercial $ 42,629 $ 347 $ 42,118 $ 680 Commercial real estate 51,260 366 52,290 727 Real estate construction 163 — 165 — Land development 4,312 34 4,478 71 Residential mortgage 26,737 328 26,758 631 Consumer installment 634 — 704 — Home equity 2,221 — 2,194 — Total $ 127,956 $ 1,075 $ 128,707 $ 2,109
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, 2015 , December 31, 2014 and June 30, 2014 : 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, 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 413 — — 247 660 95,730 96,390 Land development — — — 255 255 3,781 4,036 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 — — 205 — 205 5,122 5,327 Land development — — 1,352 — 1,352 5,207 6,559 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 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, 2014 Originated Portfolio: Commercial $ 4,033 $ 743 $ 170 $ 16,418 $ 21,364 $ 1,234,534 $ 1,255,898 Commercial real estate 7,515 1,383 — 24,966 33,864 1,170,562 1,204,426 Real estate construction 262 — — 162 424 138,316 138,740 Land development — — — 225 225 4,303 4,528 Residential mortgage 2,126 54 557 6,706 9,443 988,558 998,001 Consumer installment 3,620 512 — 500 4,632 814,746 819,378 Home equity 3,039 660 1,346 1,667 6,712 562,384 569,096 Total $ 20,595 $ 3,352 $ 2,073 $ 50,644 $ 76,664 $ 4,913,403 $ 4,990,067 Acquired Portfolio: Commercial $ 133 $ — $ 5,427 $ — $ 5,560 $ 93,423 $ 98,983 Commercial real estate 2,014 352 11,052 — 13,418 339,804 353,222 Real estate construction — — — — — 14,005 14,005 Land development — — 1,653 — 1,653 12,569 14,222 Residential mortgage 156 — 18 — 174 112,215 112,389 Consumer installment 55 3 454 — 512 9,680 10,192 Home equity 636 106 1,288 — 2,030 93,120 95,150 Total $ 2,994 $ 461 $ 19,892 $ — $ 23,347 $ 674,816 $ 698,163 June 30, 2014 Originated Portfolio: Commercial $ 4,149 $ 1,901 $ 15 $ 18,773 $ 24,838 $ 1,113,685 $ 1,138,523 Commercial real estate 5,933 233 69 25,361 31,596 1,123,319 1,154,915 Real estate construction — — — 160 160 88,415 88,575 Land development — — — 2,184 2,184 4,106 6,290 Residential mortgage 2,515 — 376 6,325 9,216 950,769 959,985 Consumer installment 2,513 313 — 536 3,362 740,295 743,657 Home equity 2,002 985 1,075 2,296 6,358 526,106 532,464 Total $ 17,112 $ 3,432 $ 1,535 $ 55,635 $ 77,714 $ 4,546,695 $ 4,624,409 Acquired Portfolio: Commercial $ — $ — $ 6,744 $ — $ 6,744 $ 67,116 $ 73,860 Commercial real estate — — 1,594 — 1,594 141,856 143,450 Real estate construction — — — — — 12,593 12,593 Land development — — 1,977 — 1,977 2,689 4,666 Residential mortgage — — 69 — 69 10,343 10,412 Consumer installment 20 — — — 20 1,104 1,124 Home equity 325 49 63 — 437 27,853 28,290 Total $ 345 $ 49 $ 10,447 $ — $ 10,841 $ 263,554 $ 274,395
Schedule of Corporation's TDRs	The following schedule presents the Corporation’s loans reported as TDRs at June 30, 2015 , December 31, 2014 and June 30, 2014 : Performing TDRs Non-Performing TDRs Nonaccrual TDRs Total (In thousands) 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 December 31, 2014 Commercial loan portfolio $ 29,179 $ 15,271 $ 32,597 $ 77,047 Consumer loan portfolio 16,485 3,196 4,594 24,275 Total $ 45,664 $ 18,467 $ 37,191 $ 101,322 June 30, 2014 Commercial loan portfolio $ 29,296 $ 11,049 $ 40,351 $ 80,696 Consumer loan portfolio 14,837 5,516 3,334 23,687 Total $ 44,133 $ 16,565 $ 43,685 $ 104,383
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, 2015 and 2014 : 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 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 Three Months Ended June 30, 2014 Six Months Ended June 30, 2014 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 15 $ 3,575 $ 3,575 27 $ 11,931 $ 11,931 Commercial real estate 12 3,134 3,134 21 5,924 5,924 Land development — — — 1 72 72 Subtotal – commercial loan portfolio 27 6,709 6,709 49 17,927 17,927 Consumer loan portfolio 63 1,649 1,648 93 2,636 2,626 Total 90 $ 8,358 $ 8,357 142 $ 20,563 $ 20,553
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, 2015 and 2014 , 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, 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 Three Months Ended June 30, 2014 Six Months Ended June 30, 2014 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 5 $ 771 6 $ 875 Commercial real estate 3 603 5 2,273 Subtotal – commercial loan portfolio 8 1,374 11 3,148 Consumer loan portfolio 3 80 3 80 Total 11 $ 1,454 14 $ 3,228
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, 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 The following schedule presents, by loan portfolio segment, details regarding the balance in the allowance and the recorded investment in loans at December 31, 2014 by impairment evaluation method. Commercial Loan Portfolio Consumer Loan Portfolio Unallocated Total (In thousands) Allowance for loan losses balance at December 31, 2014 attributable to: Loans individually evaluated for impairment $ 1,003 $ 335 $ — $ 1,338 Loans collectively evaluated for impairment 43,153 27,968 2,724 73,845 Loans acquired with deteriorated credit quality — 500 — 500 Total $ 44,156 $ 28,803 $ 2,724 $ 75,683 Recorded investment (loan balance) at December 31, 2014: Loans individually evaluated for impairment $ 86,221 $ 19,681 $ — $ 105,902 Loans collectively evaluated for impairment 2,517,371 2,366,794 — 4,884,165 Loans acquired with deteriorated credit quality 480,432 217,731 — 698,163 Total $ 3,084,024 $ 2,604,206 $ — $ 5,688,230 The following schedule presents, by loan portfolio segment, the changes in the allowance for the three and six months ended June 30, 2014 and details regarding the balance in the allowance and the recorded investment in loans at June 30, 2014 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, 2014: Beginning balance $ 45,010 $ 29,233 $ 4,230 $ 78,473 Provision for loan losses 439 1,287 (226 ) 1,500 Charge-offs (1,814 ) (1,561 ) — (3,375 ) Recoveries 589 606 — 1,195 Ending balance $ 44,224 $ 29,565 $ 4,004 $ 77,793 Changes in allowance for loan losses for the six months ended June 30, 2014: Beginning balance $ 44,482 $ 30,145 $ 4,445 $ 79,072 Provision for loan losses 1,399 2,142 (441 ) 3,100 Charge-offs (3,023 ) (3,824 ) — (6,847 ) Recoveries 1,366 1,102 — 2,468 Ending balance $ 44,224 $ 29,565 $ 4,004 $ 77,793 Allowance for loan losses balance at June 30, 2014 attributable to: Loans individually evaluated for impairment $ 1,340 $ 379 $ — $ 1,719 Loans collectively evaluated for impairment 42,884 28,686 4,004 75,574 Loans acquired with deteriorated credit quality — 500 — 500 Total $ 44,224 $ 29,565 $ 4,004 $ 77,793 Recorded investment (loan balance) at June 30, 2014: Loans individually evaluated for impairment $ 86,823 $ 20,353 $ — $ 107,176 Loans collectively evaluated for impairment 2,301,480 2,215,753 — 4,517,233 Loans acquired with deteriorated credit quality 234,569 39,826 — 274,395 Total $ 2,622,872 $ 2,275,932 $ — $ 4,898,804

Intangible Assets (Tables)

Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2015
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 $ 285,512 $ 180,128 $ 120,164 Other intangible assets: Core deposit intangible assets $ 28,353 $ 20,863 $ 9,110 Non-compete intangible assets 541 — — Mortgage servicing rights 12,307 12,217 3,344 Total other intangible assets $ 41,201 $ 33,080 $ 12,454
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 $ 39,355 $ 31,550 $ 18,659 Accumulated amortization 11,002 10,687 9,549 Carrying amount $ 28,353 $ 20,863 $ 9,110 Amortization expense for the three months ended June 30 $ 952 $ 446 Amortization expense for the six months ended June 30 $ 1,743 $ 891
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 $ 12,307 $ 12,217 $ 3,344 Fair value of MSRs $ 16,602 $ 14,979 $ 6,433 Loans serviced for others that have servicing rights capitalized $ 2,193,067 $ 2,093,140 $ 871,158
Activity for capitalized MSRs	The following table shows the activity for capitalized MSRs: Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 (In thousands) Balance at beginning of period $ 11,583 $ 3,316 $ 12,217 $ 3,423 Acquired in Monarch acquisition 1,284 — 1,284 — Additions 415 278 815 421 Amortization (1,175 ) (250 ) (2,209 ) (500 ) Change in valuation allowance 200 — 200 — Balance at end of period $ 12,307 $ 3,344 $ 12,307 $ 3,344

Accumulated Other Comprehensi28

Accumulated Other Comprehensive Loss (Tables)	6 Months Ended
	Jun. 30, 2015
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 $(148) at June 30, 2015, $(113) at December 31, 2014 and $431 at June 30, 2014 $ (274 ) $ (210 ) $ 800 Pension and other postretirement benefits adjustment, net of related tax benefit of $16,601 at June 30, 2015, $17,362 at December 31, 2014 and $10,117 at June 30, 2014 (30,830 ) (32,243 ) (18,788 ) Accumulated other comprehensive loss $ (31,104 ) $ (32,453 ) $ (17,988 )

Borrowings Borrowings (Tables)

Borrowings Borrowings (Tables)	6 Months Ended
	Jun. 30, 2015
Borrowings [Abstract]
Schedule of Short-term Debt [Table Text Block]	A summary of the Corporation's short-term borrowings, which generally have an original term to maturity of 30 days or less, follows: June 30, December 31, June 30, (In thousands) Short-term borrowings: Securities sold under agreements to repurchase with customers $ 305,291 $ 304,467 $ 293,422 Short-term FHLB advances 205,000 60,000 — Federal funds purchased 22,000 25,000 12,000 Total short-term borrowings $ 532,291 $ 389,467 $ 305,422
Schedule of Other Borrowings [Table Text Block]	The Corporation's other borrowings were obtained as a result of the acquisitions of Lake Michigan and Monarch. A summary of the Corporation's other borrowings follows: June 30, December 31, June 30, (In thousands) Other borrowings: Long-term FHLB advances $ 81,469 $ — $ — Securities sold under agreements to repurchase 23,649 — — Line of credit 25,000 — — Subordinated debentures 18,372 — — Total other borrowings $ 148,490 $ — $ —

Regulatory Capital (Tables)

Regulatory Capital (Tables)	6 Months Ended
	Jun. 30, 2015
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, 2015 Total Capital to Risk-Weighted Assets: Corporation $ 816,595 11.7 % $ 559,273 8.0 % N/A N/A Chemical Bank 713,999 12.1 471,422 8.0 $ 589,277 10.0 % The Bank of Holland 72,506 9.5 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 72,506 9.5 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 72,506 9.5 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 72,506 9.4 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 December 31, 2014 Total Capital to Risk-Weighted Assets: Corporation $ 705,130 12.4 % $ 456,302 8.0 % N/A N/A Chemical Bank 654,031 11.5 455,633 8.0 $ 569,541 10.0 % Tier 1 Capital to Risk-Weighted Assets: Corporation 633,779 11.1 228,151 4.0 N/A N/A Chemical Bank 582,783 10.2 227,816 4.0 341,725 6.0 Leverage Ratio: Corporation 633,779 9.3 273,226 4.0 N/A N/A Chemical Bank 582,783 8.5 273,048 4.0 341,310 5.0 June 30, 2014 Total Capital to Risk-Weighted Assets: Corporation $ 748,332 15.3 % $ 391,911 8.0 % N/A N/A Chemical Bank 601,561 12.3 391,305 8.0 $ 489,131 10.0 % Tier 1 Capital to Risk-Weighted Assets: Corporation 686,892 14.0 195,955 4.0 N/A N/A Chemical Bank 540,214 11.0 195,653 4.0 293,479 6.0 Leverage Ratio: Corporation 686,892 11.2 244,757 4.0 N/A N/A Chemical Bank 540,214 8.8 244,604 4.0 305,755 5.0

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2015
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, 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 and trust preferred securities — 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 December 31, 2014 Investment securities – available-for-sale: U.S. Treasury securities $ 8,259 $ — $ — $ 8,259 Government sponsored agencies — 263,503 — 263,503 State and political subdivisions — 46,227 — 46,227 Residential mortgage-backed securities — 239,807 — 239,807 Collateralized mortgage obligations — 144,383 — 144,383 Corporate bonds — 45,095 — 45,095 Preferred stock — 1,590 — 1,590 Total investment securities – available-for-sale 8,259 740,605 — 748,864 Loans held-for-sale — 9,128 — 9,128 Total assets measured at fair value on a recurring basis $ 8,259 $ 749,733 $ — $ 757,992 June 30, 2014 Investment securities – available-for-sale: Government sponsored agencies $ — $ 88,708 $ — $ 88,708 State and political subdivisions — 41,608 — 41,608 Residential mortgage-backed securities — 265,368 — 265,368 Collateralized mortgage obligations — 153,283 — 153,283 Corporate bonds — 65,352 — 65,352 Preferred stock — 1,656 — 1,656 Total investment securities – available-for-sale — 615,975 — 615,975 Loans held-for-sale — 6,329 — 6,329 Total assets measured at fair value on a recurring basis $ — $ 622,304 $ — $ 622,304
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, 2015 Impaired originated loans $ — $ — $ 24,517 $ 24,517 Other real estate/repossessed assets — — 14,197 14,197 Total $ — $ — $ 38,714 $ 38,714 December 31, 2014 Impaired originated loans $ — $ — $ 21,323 $ 21,323 Other real estate/repossessed assets — — 14,205 14,205 Mortgage servicing rights — — 8,691 8,691 Total $ — $ — $ 44,219 $ 44,219 June 30, 2014 Impaired originated loans $ — $ — $ 29,789 $ 29,789 Other real estate/repossessed assets — — 10,392 10,392 Total $ — $ — $ 40,181 $ 40,181
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, 2015 December 31, 2014 June 30, 2014 Carrying Amount Fair Value Carrying Amount Fair Value Carrying Amount Fair Value (In thousands) Assets: Cash and cash equivalents Level 1 $ 215,034 $ 215,034 $ 183,020 $ 183,020 $ 140,294 $ 140,294 Investment securities: Available-for-sale Level 1 8,294 8,294 8,259 8,259 — — Available-for-sale Level 2 677,412 677,412 740,605 740,605 615,975 615,975 Held-to-maturity Level 2 469,337 466,278 305,913 308,650 297,630 297,186 Held-to-maturity Level 3 500 300 10,500 7,090 10,500 6,775 Nonmarketable equity securities NA 36,142 36,142 27,369 27,369 25,572 25,572 Loans held-for-sale Level 2 7,798 7,798 9,128 9,128 6,329 6,329 Net loans Level 3 6,959,802 6,969,655 5,612,547 5,623,454 4,821,011 4,826,672 Interest receivable Level 2 21,668 21,668 17,492 17,492 15,827 15,827 Liabilities: Deposits without defined maturities Level 2 $ 5,547,764 $ 5,547,764 $ 4,741,024 $ 4,741,024 $ 3,814,013 $ 3,814,013 Time deposits Level 3 1,745,215 1,745,215 1,337,947 1,340,015 1,278,900 1,285,992 Interest payable Level 2 1,557 1,557 755 755 735 735 Short-term borrowings Level 2 532,291 532,291 389,467 389,467 305,422 305,422 Other borrowings Level 2 106,469 106,469 — — — — Other borrowings Level 3 42,021 42,021 — — — —

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	6 Months Ended
	Jun. 30, 2015
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, 2015 2014 2015 2014 (In thousands, except per share data) Numerator for both basic and diluted earnings per common share, net income $ 19,024 $ 16,236 $ 36,859 $ 30,049 Denominator for basic earnings per common share, weighted average common shares outstanding 35,162 30,068 33,992 29,947 Weighted average common stock equivalents 235 211 235 212 Denominator for diluted earnings per common share 35,397 30,279 34,227 30,159 Basic earnings per common share $ 0.54 $ 0.54 $ 1.08 $ 1.00 Diluted earnings per common share 0.54 0.54 1.08 1.00

Share-Based Compensation (Table

Share-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2015
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, 2015 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, 2014 432,199 $ 26.75 $ 8.30 1,037,311 $ 25.90 Granted 244,165 30.18 8.40 244,165 30.18 Lake Michigan converted options — — — 132,883 12.93 Exercised — — — (216,690 ) 23.99 Vested (150,224 ) 25.57 7.80 — — Forfeited/expired (9,175 ) 28.21 8.52 (9,175 ) 28.21 Outstanding at June 30, 2015 516,965 $ 28.69 $ 8.49 1,188,494 $ 25.66 Exercisable/vested at June 30, 2015 671,529 $ 23.32
Assumptions of Black-Scholes option pricing model	The fair value of the stock options granted during the six months ended June 30, 2015 was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions. Expected dividend yield 3.50 % Risk-free interest rate 1.78 % Expected stock price volatility 39.1 % Expected life of options – in years 7.0 Weighted average fair value of options granted $ 8.40
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, 2015 is presented below: Number of Units Weighted- Average Grant Date Fair Value Per Unit Outstanding at December 31, 2014 204,319 $ 24.14 Granted 79,202 28.25 Converted into shares of common stock (67,489 ) 22.32 Forfeited/expired (1,427 ) 25.13 Outstanding at June 30, 2015 214,605 $ 26.23

Pension and Other Postretirem34

Pension and Other Postretirement Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2015
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, 2015 2014 2015 2014 (In thousands) Defined Benefit Pension Plans Service cost $ 273 $ 251 $ 545 $ 501 Interest cost 1,332 1,312 2,664 2,624 Expected return on plan assets (2,161 ) (2,079 ) (4,322 ) (4,157 ) Amortization of prior service credit (1 ) (1 ) (2 ) (1 ) Amortization of unrecognized net loss 1,056 569 2,112 1,138 Net periodic benefit cost $ 499 $ 52 $ 997 $ 105 Postretirement Benefit Plan Service cost $ 4 $ 4 $ 8 $ 9 Interest cost 33 36 67 71 Amortization of prior service cost 32 33 65 65 Amortization of unrecognized net gain — (26 ) (1 ) (52 ) Net periodic benefit cost $ 69 $ 47 $ 139 $ 93

Significant Accounting Polici35

Significant Accounting Policies (Details)	May. 31, 2015USD ($)	Apr. 01, 2015USD ($)	Jun. 30, 2015USD ($)shares	Jun. 30, 2014USD ($)shares	Jun. 30, 2015USD ($)BankPoolsshares	Jun. 30, 2014USD ($)shares	Apr. 20, 2015shares	Mar. 31, 2015shares	Dec. 31, 2014USD ($)shares	Jun. 24, 2014USD ($)$ / sharesshares	Sep. 18, 2013USD ($)$ / sharesshares	Apr. 20, 2009shares	Jan. 31, 2008shares
Business Acquisition [Line Items]
Goodwill			$ 285,512,000	$ 120,164,000	$ 285,512,000	$ 120,164,000			$ 180,128,000
Number of banks through which company operates | Bank					3
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			200,000	100,000	300,000	200,000
Remaining investment in qualified affordable housing projects, proportional amortization method			21,400,000	3,100,000	21,400,000	3,100,000			4,900,000
Investment in tax credit projects, equity method			3,300,000	$ 0	3,300,000	$ 0			$ 0
Variable Interest Entity, Reporting Entity Involvement, Unfunded Obligation, Amount			$ 9,700,000		$ 9,700,000
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
Common Stock, Shares, Issued | shares			38,110,136	32,760,088	38,110,136	32,760,088			32,774,420	2,500,000	2,213,750
CommonStockIssuedOverAllotment | shares										375,000	288,750
Gross Value of Common Stock sold in public stock offering										$ 80,500,000
Shares Issued, Price Per Share | $ / shares										$ 28	$ 26
Issuance of common stock, net of issuance costs										$ 76,200,000	$ 53,900,000
Preferred stock, shares authorized | shares			2,000,000	200,000	2,000,000	200,000			200,000			200,000
Preferred stock, shares issued | shares			0	0	0	0			0
Preferred stock, shares outstanding | shares			0		0
Common Stock, Shares Authorized | shares			60,000,000	45,000,000	60,000,000	45,000,000		45,000,000	45,000,000
Impairment on tax credit projects			$ 0	$ 0	$ 0	$ 0			$ 0
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
Shareholder Approved Proposal [Member]
Business Acquisition [Line Items]
Preferred stock, shares authorized | shares							2,000,000
Common Stock, Shares Authorized | shares							60,000,000
Monarch Community Bancorp [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred		$ 27,191,000
Business Combination, Consideration Transferred, Cash Paid for Outstanding Stock		203,000
Goodwill		5,383,000
Core deposit intangible assets acquired, business combination		$ 1,930,000
Lake Michigan Financial Corp [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 187,394,000
Business Combination, Consideration Transferred, Value of Stock and Options Issued	132,900,000
Business Combination, Consideration Transferred, Cash Paid for Outstanding Stock	54,478,000
Goodwill	100,002,000
Core deposit and other intangible assets acquired in business combination	7,900,000
Core deposit intangible assets acquired, business combination	$ 7,303,000

Acquisitions Purchase Accountin

Acquisitions Purchase Accounting Fair Value Adjustments (Details) - USD ($) $ / shares in Units, $ in Thousands	May. 31, 2015	Apr. 01, 2015	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Purchase Accounting Fair Value Adjustments [Line Items]
Goodwill			$ 285,512	$ 180,128	$ 120,164
Monarch Community Bancorp [Member]
Purchase Accounting Fair Value Adjustments [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares		860,575
Business Combination, Consideration Transferred, Value of Stock Issued		$ 26,988
Business Combination, Consideration Transferred, Cash Paid for Outstanding Stock		203
Business Combination, Consideration Transferred		27,191
Net Assets Acquired, Acquiree Shareholders Equity		15,270
Purchase Accounting Fair Value Adjustment, Loans		(7,150)
Purchase Accounting Fair Value Adjustment, Allowance for Loan Losses		2,128
Business Combination, Fair Value Adjustment, Deferred Tax Asset NOL		7,900
Purchase Accounting Fair Value Adjustment, Premises and Equipment		(370)
Purchase Accounting Fair Value Adjustment, Core Deposit Intangible Asset		1,930
Purchase Accounting Fair Value Adjustment, Mortgage Servicing Rights Asset		315
Purchase Accounting Fair Value Adjustment, Deferred Tax Asset, Net		1,748
Purchase Accounting Fair Value Adjustment, Other Assets and Liabilities, Net		37
Net Assets Acquired After Purchase Accounting Fair Value Adjustments		21,808
Goodwill		$ 5,383
Business Acquisition, Price Per Share of Common Stock Issued		$ 31.36
Lake Michigan Financial Corp [Member]
Purchase Accounting Fair Value Adjustments [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	4,322,101
Business Combination, Consideration Transferred, Value of Stock Issued	$ 130,916
Business Combination, Consideration Transferred, Value of Stock Options	2,000
Business Combination, Consideration Transferred, Cash Paid for Outstanding Stock	54,478
Business Combination, Consideration Transferred	187,394
Net Assets Acquired, Acquiree Shareholders Equity	89,280
Purchase Accounting Fair Value Adjustment, Loans	(22,600)
Purchase Accounting Fair Value Adjustment, Allowance for Loan Losses	15,888
Purchase Accounting Fair Value Adjustment, Premises and Equipment	(2,333)
Purchase Accounting Fair Value Adjustment, Core Deposit Intangible Asset	7,303
Purchase Accounting Fair Value Adjustment, Deferred Tax Asset, Net	2,269
Purchase Accounting Fair Value Adjustment, Deposits and Other Borrowings	(3,048)
Purchase Accounting Fair Value Adjustment, Other Assets and Liabilities, Net	(633)
Net Assets Acquired After Purchase Accounting Fair Value Adjustments	87,392
Goodwill	$ 100,002
Business Acquisition, Price Per Share of Common Stock Issued	$ 30.29

Acquisitions Allocation of Purc

Acquisitions Allocation of Purchase Price (Details) - USD ($) $ in Thousands	May. 31, 2015	Apr. 01, 2015	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Schedule of Purchase Price Allocation [Line Items]
Goodwill			$ 285,512	$ 180,128	$ 120,164
Short-term borrowings			532,291	389,467	305,422
Other Borrowings			$ 148,490	$ 0	$ 0
Monarch Community Bancorp [Member]
Schedule of Purchase Price Allocation [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents		$ 32,171
Business Combination, Acquired Receivables, Fair Value		121,783
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		3,064
Business Combination, Deferred Tax Asset, Net Operating Loss		7,900
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets Noncurrent		2,314
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables		6,972
Goodwill		5,383
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Mortgage Servicing Rights Asset		1,284
Core deposit intangible assets acquired, business combination		1,930
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		182,801
Business Combination Deposits Assumed		144,311
Other Borrowings		8,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other		3,299
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities		155,610
Business Combination, Consideration Transferred		$ 27,191
Lake Michigan Financial Corp [Member]
Schedule of Purchase Price Allocation [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	$ 39,301
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities	66,699
Business Combination, Acquired Receivables, Fair Value	985,542
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	13,673
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets Noncurrent	14,888
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	38,449
Goodwill	100,002
Core deposit intangible assets acquired, business combination	7,303
Bank Owned Life Insurance	23,844
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	1,289,701
Business Combination Deposits Assumed	924,697
Short-term borrowings	30,000
Other Borrowings	124,723
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other	22,887
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	1,102,307
Business Combination, Consideration Transferred	$ 187,394

Acquisitions Unaudited Pro Form

Acquisitions Unaudited Pro Forma Information (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Business Acquisition [Line Items]
Business Acquisition, Pro Forma interest and dividend income	$ 78,137	$ 74,842	$ 154,261	$ 148,089
Business Acquisition, Pro Forma interest expense	5,483	6,748	11,363	13,627
Business Acquisition, Pro Forma net interest income	72,654	68,094	142,898	134,462
Business Acquisition, Pro Forma provision for loan losses	1,500	1,860	3,000	4,035
Business Acquisition, Pro Forma net interest income after provision for loan losses	71,154	66,234	139,898	130,427
Business Acquisition, Pro Forma noninterest income	21,153	23,713	43,180	43,487
Business Acquisition, Pro Forma noninterest expense	62,394	59,915	123,042	121,241
Business Acquisition, Pro Forma pre-tax net income	29,913	30,032	60,036	52,673
Business Acquisition, Pro Forma federal income tax expense	7,525	9,048	16,736	15,807
Business Acquisition, Pro Forma Net Income (Loss)	$ 22,388	$ 20,984	$ 43,300	$ 36,866
Business Acquisition, Pro Forma Earnings Per Share, Basic	$ 0.59	$ 0.60	$ 1.14	$ 1.05
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$ 0.58	$ 0.59	$ 1.13	$ 1.04
Weighted Average Number of Shares Outstanding, Basic	35,162	30,068	33,992	29,947
Weighted Average Number of Shares Outstanding, Diluted	35,397	30,279	34,227	30,159
Lake Michigan, Monarch and Northwestern [Member]
Business Acquisition [Line Items]
Weighted Average Number of Shares Outstanding, Basic	38,044	35,251	38,024	35,129
Weighted Average Number of Shares Outstanding, Diluted	38,279	35,462	38,259	35,398

Acquisitions (Activity for Acqu

Acquisitions (Activity for Acquired Loans) (Details) - USD ($) $ in Thousands		May. 31, 2015	Apr. 01, 2015	Oct. 31, 2014	Jun. 30, 2015	Jun. 30, 2014
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period					$ 137,961
Additions attributable to acquisitions					228,160
Accretable Yield Additions, Net of Reductions	[1]				2,765
Accretion recognized in interest income					(20,838)
Reclassification from nonaccretable difference					0
Balance at end of period					348,048
Northwestern Bancorp [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period					104,675
Additions attributable to acquisitions				$ 110,000	0
Accretable Yield Additions, Net of Reductions	[1]				(2,859)
Accretion recognized in interest income					(10,058)
Reclassification from nonaccretable difference					0
Balance at end of period					91,758
OAK [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period					33,286	$ 32,610
Additions attributable to acquisitions					0	0
Accretable Yield Additions, Net of Reductions	[1]				5,215	2,333
Accretion recognized in interest income					(6,326)	(7,594)
Reclassification from nonaccretable difference					0	10,000
Balance at end of period					32,175	$ 37,349
Lake Michigan Financial Corp [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period					0
Additions attributable to acquisitions		$ 190,246			190,246
Accretable Yield Additions, Net of Reductions	[1]				1,550
Accretion recognized in interest income					(3,486)
Reclassification from nonaccretable difference					0
Balance at end of period					188,310
Monarch Community Bancorp [Member]
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period					0
Additions attributable to acquisitions			$ 37,914		37,914
Accretable Yield Additions, Net of Reductions	[1]				(1,141)
Accretion recognized in interest income					(968)
Reclassification from nonaccretable difference					0
Balance at end of period					$ 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) $ / shares in Units, $ in Thousands	May. 31, 2015USD ($)Offices$ / sharesshares	Apr. 01, 2015USD ($)Officesshares	Oct. 31, 2014USD ($)Offices	Dec. 07, 2012USD ($)Branches	Apr. 30, 2010USD ($)Offices	Jun. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Dec. 31, 2014USD ($)	Jun. 30, 2014USD ($)
Business Acquisition [Line Items]
Goodwill						$ 285,512	$ 285,512	$ 180,128	$ 120,164
Lake Michigan Financial Corp [Member]
Business Acquisition [Line Items]
Expected Principal Cash Flows of Contractually Required Acquired Loan Portfolio	$ 986,100
Expected Interest Cash Flows of Contractually Required Acquired Loan Portfolio	$ 189,600
Business Acquisition, Share Price | $ / shares	$ 16.64
Exchange Ratio of Common Stock Issued, Business Combinations	1.326
Business Combination, Acquired Receivables, Fair Value	$ 985,542
Certain Loans Acquired in Transfer, Nonaccretable Difference	22,600
Acquisition purchase price	$ 187,394
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	4,322,101
Goodwill	$ 100,002
Purchase Accounting Fair Value Adjustment, Core Deposit Intangible Asset	(7,303)
Intangibles acquired	$ 7,303
Service provided by acquiree bank through number of branches | Offices	5
Assets of acquiree company	$ 1,240,000
Deposits of acquiree company	924,697
Core deposit and other intangible assets acquired in business combination	7,900
Business Combination, Pro Forma Information, Net Interest Income of Acquiree since Acquisition Date						3,200
Business Combination, Pro Forma Information, Noninterest Income of Acquiree since Acquisition Date						300
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual						1,100
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed						2,000	2,300
Outstanding contractual principal balance of acquired loan portfolio						990,000	990,000
Carrying amount of acquired loan portfolio						967,000	967,000
Business Combination, Acquired Receivables, Gross Contractual Amount	1,010,000
Interest Payments Receivable of Acquired Loan Portfolio	190,200
Business Combination, Acquired Receivables, Estimated Uncollectible	22,000
Business Combination, Consideration Transferred, Value of Stock and Options Issued	132,900
Business Combination, Consideration Transferred, Cash Paid for Outstanding Stock	$ 54,478
Monarch Community Bancorp [Member]
Business Acquisition [Line Items]
Expected Principal Cash Flows of Contractually Required Acquired Loan Portfolio		$ 122,600
Expected Interest Cash Flows of Contractually Required Acquired Loan Portfolio		$ 37,100
Exchange Ratio of Common Stock Issued, Business Combinations		0.0982
Business Combination, Acquired Receivables, Fair Value		$ 121,783
Certain Loans Acquired in Transfer, Nonaccretable Difference		7,100
Acquisition purchase price		$ 27,191
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares		860,575
Goodwill		$ 5,383
Purchase Accounting Fair Value Adjustment, Core Deposit Intangible Asset		(1,930)
Intangibles acquired		$ 1,930
Service provided by acquiree bank through number of branches | Offices		5
Assets of acquiree company		$ 183,000
Deposits of acquiree company		144,311
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed						1,500	2,300
Outstanding contractual principal balance of acquired loan portfolio						126,000	126,000
Carrying amount of acquired loan portfolio						119,000	119,000
Business Combination, Acquired Receivables, Gross Contractual Amount		128,900
Interest Payments Receivable of Acquired Loan Portfolio		37,800
Business Combination, Acquired Receivables, Estimated Uncollectible		6,300
Business Combination, Consideration Transferred, Cash Paid for Outstanding Stock		203
Operating Loss Carryforwards		22,600
Tax Credit Carryforwards Not Expected to Be Utilized		$ 1,700
Northwestern Bancorp [Member]
Business Acquisition [Line Items]
Expected Principal Cash Flows of Contractually Required Acquired Loan Portfolio			$ 481,000
Expected Interest Cash Flows of Contractually Required Acquired Loan Portfolio			104,000
Business Combination, Acquired Receivables, Fair Value			475,000
Certain Loans Acquired in Transfer, Nonaccretable Difference			34,000
Acquisition purchase price			121,000
Goodwill			60,000
Intangibles acquired			$ 12,900
Service provided by acquiree bank through number of branches | Offices			25
Assets of acquiree company			$ 815,000
Deposits of acquiree company			794,000
Outstanding contractual principal balance of acquired loan portfolio						415,000	415,000	485,000
Carrying amount of acquired loan portfolio						382,000	382,000	452,000
Business Combination, Acquired Receivables, Gross Contractual Amount			507,000
Interest Payments Receivable of Acquired Loan Portfolio			112,000
Business Combination, Acquired Receivables, Estimated Uncollectible			$ 26,000
Independent Bank [Member]
Business Acquisition [Line Items]
Number of branches acquired (branches) | Branches				21
Deposits acquired				$ 404,000
Loans acquired				44,000
Acquisition purchase price				8,100
Premium paid on deposits purchased				$ 11,500
Premium paid as a percentage of deposits purchased (percent)				2.85%
Discount on loans purchased (percent)				1.75%
Goodwill				$ 6,800
Independent Bank [Member] | Core Deposits [Member]
Business Acquisition [Line Items]
Intangibles acquired				$ 5,600
OAK [Member]
Business Acquisition [Line Items]
Loans acquired					$ 627,000
Acquisition purchase price					$ 83,700
Service provided by acquiree bank through number of branches | Offices					14
Assets of acquiree company					$ 820,000
Deposits of acquiree company					693,000
Brokered deposits of acquiree company					193,000
Contractually required principal payments of loan portfolio, acquisition date					683,000
Acquired loan portfolio acquisition date fair value					$ 627,000
Outstanding contractual principal balance of acquired loan portfolio						236,000	236,000	268,000	298,000
Carrying amount of acquired loan portfolio						$ 215,000	$ 215,000	$ 246,000	$ 274,000

Investment Securities (Summary

Investment Securities (Summary of Amortized Cost and Fair Value of Available-For-Sale Investment Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	$ 686,128	$ 749,187	$ 614,744
Investment securities available-for-sale, Unrealized Gains	2,545	3,003	4,005
Investment securities available-for-sale, Unrealized Losses	2,967	3,326	2,774
Available-for-sale Securities, Total	685,706	748,864	615,975
US Treasury Securities [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	8,270	8,272
Investment securities available-for-sale, Unrealized Gains	24	0
Investment securities available-for-sale, Unrealized Losses	0	13
Available-for-sale Securities, Total	8,294	8,259
Government sponsored agencies [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	227,424	263,658	88,503
Investment securities available-for-sale, Unrealized Gains	683	356	346
Investment securities available-for-sale, Unrealized Losses	200	511	141
Available-for-sale Securities, Total	227,907	263,503	88,708
State and political subdivisions [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	26,476	45,157	40,165
Investment securities available-for-sale, Unrealized Gains	503	1,087	1,443
Investment securities available-for-sale, Unrealized Losses	14	17	0
Available-for-sale Securities, Total	26,965	46,227	41,608
Residential mortgage-backed securities [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	213,621	240,465	265,673
Investment securities available-for-sale, Unrealized Gains	742	885	1,117
Investment securities available-for-sale, Unrealized Losses	1,694	1,543	1,422
Available-for-sale Securities, Total	212,669	239,807	265,368
Collateralized Mortgage Obligations [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	167,768	145,316	154,035
Investment securities available-for-sale, Unrealized Gains	245	261	376
Investment securities available-for-sale, Unrealized Losses	981	1,194	1,128
Available-for-sale Securities, Total	167,032	144,383	153,283
Corporate bonds [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	39,680	44,930	64,979
Investment securities available-for-sale, Unrealized Gains	76	213	456
Investment securities available-for-sale, Unrealized Losses	78	48	83
Available-for-sale Securities, Total	39,678	45,095	65,352
Preferred stock [Member]
Available-for-sale Securities
Investment securities available-for-sale, Amortized Cost	2,889	1,389	1,389
Investment securities available-for-sale, Unrealized Gains	272	201	267
Investment securities available-for-sale, Unrealized Losses	0	0	0
Available-for-sale Securities, Total	$ 3,161	$ 1,590	$ 1,656

Investment Securities (Summar42

Investment Securities (Summary of Amortized Cost and Fair Value of Held-To-Maturity Investment Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Held-to-maturity Securities
Investment securities held-to-maturity, Amortized Cost	$ 469,837	$ 316,413	$ 308,130
Investment securities held-to-maturity, Unrealized Gains	4,853	7,294	5,885
Investment securities held-to-maturity, Unrealized Losses	8,112	7,967	10,054
Total Held-to-maturity securities, Debt maturities, Fair Value	466,578	315,740	303,961
State and political subdivisions [Member]
Held-to-maturity Securities
Investment securities held-to-maturity, Amortized Cost	469,337	305,913	297,630
Investment securities held-to-maturity, Unrealized Gains	4,853	7,294	5,885
Investment securities held-to-maturity, Unrealized Losses	7,912	4,557	6,329
Total Held-to-maturity securities, Debt maturities, Fair Value	466,278	308,650	297,186
Trust Preferred Securities [Member]
Held-to-maturity Securities
Investment securities held-to-maturity, Amortized Cost	500	10,500	10,500
Investment securities held-to-maturity, Unrealized Gains	0	0	0
Investment securities held-to-maturity, Unrealized Losses	200	3,410	3,725
Total Held-to-maturity securities, Debt maturities, Fair Value	$ 300	$ 7,090	$ 6,775

Investment Securities (Maturiti

Investment Securities (Maturities of Debt Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Investment Securities Available-for-Sale:
Due in one year or less, Amortized Cost	$ 198,939
Due after one year through five years, Amortized Cost	411,399
Due after five years through ten years, Amortized Cost	68,583
Due after ten years, Amortized Cost	5,818
Preferred stock, Amortized Cost	1,389
Total Available-for-sale Securities, Debt Maturities, Amortized Cost	686,128
Due in one year or less , Fair Value	198,680
Due after one year through five years, Fair Value	411,247
Due after five years through ten years, Fair Value	68,295
Due after ten years, Fair Value	5,823
Preferred stock, Fair Value	1,661
Total Available-for-sale securities, Debt maturities, Fair Value	685,706
Investment Securities Held-to-Maturity:
Due in one year or less, Amortized Cost	55,922
Due after one year through five years, Amortized Cost	209,886
Due after five years through ten years, Amortized Cost	127,398
Due after ten years, Amortized Cost	76,631
Total Held-to-maturity securities, Debt maturities, Amortized Cost	469,837	$ 316,413	$ 308,130
Due in one year or less , Fair Value	56,043
Due after one year through five years, Fair Value	209,768
Due after five years through ten years, Fair Value	125,775
Due after ten years, Fair Value	74,992
Total Held-to-maturity securities, Debt maturities, Fair Value	$ 466,578	$ 315,740	$ 303,961

Investment Securities (Summar44

Investment Securities (Summary of Investment Securities with Gross Unrealized Losses) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	$ 530,665	$ 317,885	$ 156,938
Less Than 12 Months, Gross Unrealized Losses	7,392	3,998	4,182
12 Months or More, Fair Value	146,094	302,630	370,668
12 Months or More, Gross Unrealized Losses	3,687	7,295	8,646
Total, Fair Value	676,759	620,515	527,606
Total, Gross Unrealized Losses	11,079	11,293	12,828
Government sponsored agencies [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	24,789	166,963	2,377
Less Than 12 Months, Gross Unrealized Losses	163	406	2
12 Months or More, Fair Value	14,715	31,927	44,786
12 Months or More, Gross Unrealized Losses	37	105	139
Total, Fair Value	39,504	198,890	47,163
Total, Gross Unrealized Losses	200	511	141
State and political subdivisions [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	258,503	62,310	92,279
Less Than 12 Months, Gross Unrealized Losses	5,433	3,348	4,047
12 Months or More, Fair Value	63,584	36,847	71,421
12 Months or More, Gross Unrealized Losses	2,493	1,226	2,282
Total, Fair Value	322,087	99,157	163,700
Total, Gross Unrealized Losses	7,926	4,574	6,329
Residential mortgage-backed securities [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	187,858	17,276	10,144
Less Than 12 Months, Gross Unrealized Losses	1,592	52	60
12 Months or More, Fair Value	3,643	180,194	197,042
12 Months or More, Gross Unrealized Losses	102	1,491	1,362
Total, Fair Value	191,501	197,470	207,186
Total, Gross Unrealized Losses	1,694	1,543	1,422
Collateralized Mortgage Obligations [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	49,845	63,077	47,142
Less Than 12 Months, Gross Unrealized Losses	155	179	68
12 Months or More, Fair Value	48,881	31,620	35,722
12 Months or More, Gross Unrealized Losses	826	1,015	1,060
Total, Fair Value	98,726	94,697	82,864
Total, Gross Unrealized Losses	981	1,194	1,128
Corporate bonds [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	9,670	0	4,996
Less Than 12 Months, Gross Unrealized Losses	49	0	5
12 Months or More, Fair Value	14,971	14,952	14,922
12 Months or More, Gross Unrealized Losses	29	48	78
Total, Fair Value	24,641	14,952	19,918
Total, Gross Unrealized Losses	78	48	83
Trust Preferred Securities [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	0	0	0
Less Than 12 Months, Gross Unrealized Losses	0	0	0
12 Months or More, Fair Value	300	7,090	6,775
12 Months or More, Gross Unrealized Losses	200	3,410	3,725
Total, Fair Value	300	7,090	6,775
Total, Gross Unrealized Losses	$ 200	3,410	$ 3,725
US Treasury Securities [Member]
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value		8,259
Less Than 12 Months, Gross Unrealized Losses		13
12 Months or More, Fair Value		0
12 Months or More, Gross Unrealized Losses		0
Total, Fair Value		8,259
Total, Gross Unrealized Losses		$ 13

Investment Securities (Textual)

Investment Securities (Textual) (Details) - USD ($) $ in Millions	May. 31, 2015	Dec. 31, 2014	Jun. 30, 2014
Schedule of Investments [Line Items]
Trust preferred investment security of Non Public bank company	$ 10	$ 10	$ 10

Loans (Summary of Loans) (Detai

Loans (Summary of Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Summary of loans under portfolio
Commercial loan	$ 4,110,698	$ 3,084,024	$ 2,622,872
Consumer loan	2,924,045	2,604,206	2,275,932
Total loans	7,034,743	5,688,230	4,898,804
Commercial [Member]
Summary of loans under portfolio
Commercial loan	1,754,873	1,354,881	1,212,383
Real estate commercial [Member]
Summary of loans under portfolio
Commercial loan	2,243,513	1,557,648	1,298,365
Real estate construction [Member]
Summary of loans under portfolio
Commercial loan	101,717	152,745	101,168
Land development [Member]
Summary of loans under portfolio
Commercial loan	10,595	18,750	10,956
Real estate residential [Member]
Summary of loans under portfolio
Consumer loan	1,310,167	1,110,390	970,397
Consumer installment [Member]
Summary of loans under portfolio
Consumer loan	887,907	829,570	744,781
Home equity [Member]
Summary of loans under portfolio
Consumer loan	$ 725,971	$ 664,246	$ 560,754

Loans (Summary of Recorded Inve

Loans (Summary of Recorded Investment of Commercial Loans by Risk Rating Categories) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	$ 4,110,698	$ 3,084,024	$ 2,622,872
Commercial [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,754,873	1,354,881	1,212,383
Real estate commercial [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	2,243,513	1,557,648	1,298,365
Real estate construction [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	101,717	152,745	101,168
Land development [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	10,595	18,750	10,956
Originated Portfolio [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	2,823,708	2,603,592	2,388,303
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	2,640,180	2,423,966	2,218,823
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	67,299	74,942	47,143
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	73,180	62,913	75,859
Originated Portfolio [Member] | Risk Grade 8 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	43,045	41,762	46,251
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	4	9	227
Originated Portfolio [Member] | Commercial [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,359,856	1,255,898	1,138,523
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	1,269,091	1,171,817	1,067,000
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	32,189	37,800	15,459
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	41,316	29,863	37,291
Originated Portfolio [Member] | Commercial [Member] | Risk Grade 8 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	17,260	16,417	18,560
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	1	213
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	1,363,426	1,204,426	1,154,915
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	1,273,725	1,114,529	1,063,555
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	34,677	34,996	30,053
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	29,737	29,935	35,946
Originated Portfolio [Member] | Real estate commercial [Member] | Risk Grade 8 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	25,283	24,958	25,347
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	4	8	14
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	96,390	138,740	88,575
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	94,894	134,668	85,754
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	0	1,408	666
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	1,249	2,502	1,995
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	247	162	160
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
Originated Portfolio [Member] | Land development [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	4,036	4,528	6,290
Originated Portfolio [Member] | Land development [Member] | Risk Grades 1-5 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	2,470	2,952	2,514
Originated Portfolio [Member] | Land development [Member] | Risk Grade 6 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	433	738	965
Originated Portfolio [Member] | Land development [Member] | Risk Grade 7 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	878	613	627
Originated Portfolio [Member] | Land development [Member] | Risk Grade 8 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	255	225	2,184
Originated Portfolio [Member] | Land development [Member] | Risk Grade 9 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	0	0	0
Acquired Portfolio [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,286,990	480,432	234,569
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	1,178,453	423,592	208,030
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	52,279	21,968	10,591
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	44,317	16,764	10,070
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	11,941	18,108	5,878
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	395,017	98,983	73,860
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	347,914	76,780	59,993
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	29,412	12,687	6,769
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	13,910	4,089	3,197
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	3,781	5,427	3,901
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	880,087	353,222	143,450
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	820,400	321,018	132,898
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	22,796	8,698	3,822
Acquired Portfolio [Member] | Real estate commercial [Member] | Risk Grade 7 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	30,288	12,478	6,730
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	6,603	11,028	0
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	5,327	14,005	12,593
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	5,122	14,005	12,593
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	0	0	0
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	0	0	0
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	205	0	0
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
Acquired Portfolio [Member] | Land development [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	6,559	14,222	4,666
Acquired Portfolio [Member] | Land development [Member] | Risk Grades 1-5 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	5,017	11,789	2,546
Acquired Portfolio [Member] | Land development [Member] | Risk Grade 6 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	71	583	0
Acquired Portfolio [Member] | Land development [Member] | Risk Grade 7 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	119	197	143
Acquired Portfolio [Member] | Land development [Member] | Risk Grade 8 [Member]
Recorded investment of loans in commercial loan portfolio by risk rating categories
Recorded investment (loan balance), Commercial, Total	1,352	1,653	1,977
Acquired Portfolio [Member] | Land development [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 In48

Loans (Summary of Recorded Investment of Consumer Loans by Risk Rating Categories) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
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	$ 2,924,045	$ 2,604,206	$ 2,275,932
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	1,310,167	1,110,390	970,397
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	887,907	829,570	744,781
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	725,971	664,246	560,754
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	2,527,302	2,386,475	2,236,106
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	1,068,489	998,001	959,985
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	871,936	819,378	743,657
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	586,877	569,096	532,464
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	2,514,759	2,372,503	2,219,982
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	1,058,696	987,542	947,768
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	871,543	818,878	743,121
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	584,520	566,083	529,093
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	12,543	13,972	16,124
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	9,793	10,459	12,217
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	393	500	536
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	2,357	3,013	3,371
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	396,743	217,731	39,826
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	241,678	112,389	10,412
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	15,971	10,192	1,124
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	139,094	95,150	28,290
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	392,750	215,971	39,694
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	238,698	111,101	10,343
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	15,966	10,174	1,124
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	138,086	94,696	28,227
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	3,993	1,760	132
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	2,980	1,288	69
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	5	18	0
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	$ 1,008	$ 454	$ 63

Loans (Summary of Nonperforming

Loans (Summary of Nonperforming Loans) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Summary of nonperforming loans
Total TDRs	$ 99,428	$ 101,322	$ 104,383
Total loans	$ 7,034,743	5,688,230	4,898,804
Minimum number of days accruing loans past due move to nonaccrual status	90 days
Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	$ 74,751	77,047	80,696
Total loans	4,110,698	3,084,024	2,622,872
Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	24,677	24,275	23,687
Total loans	2,924,045	2,604,206	2,275,932
Nonperforming [Member]
Summary of nonperforming loans
Total nonaccrual loans	51,215	50,644	55,635
Total accruing loans contractually past due 90 days or more as to interest or principal payments	1,779	2,073	1,535
Total TDRs	17,912	18,467	16,565
Total loans	70,906	71,184	73,735
Nonperforming [Member] | Commercial Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	14,547	15,271	11,049
Nonperforming [Member] | Consumer Loan Portfolio [Member]
Summary of nonperforming loans
Total TDRs	3,365	3,196	5,516
Nonperforming [Member] | Commercial [Member]
Summary of nonperforming loans
Total nonaccrual loans	17,260	16,418	18,773
Total accruing loans contractually past due 90 days or more as to interest or principal payments	711	170	15
Nonperforming [Member] | Real estate commercial [Member]
Summary of nonperforming loans
Total nonaccrual loans	25,287	24,966	25,361
Total accruing loans contractually past due 90 days or more as to interest or principal payments	56	0	69
Nonperforming [Member] | Real Estate Construction Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	247	162	160
Total accruing loans contractually past due 90 days or more as to interest or principal payments	0	0	0
Nonperforming [Member] | Land Development Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	255	225	2,184
Total accruing loans contractually past due 90 days or more as to interest or principal payments	0	0	0
Nonperforming [Member] | Real estate residential [Member]
Summary of nonperforming loans
Total nonaccrual loans	6,004	6,706	6,325
Total accruing loans contractually past due 90 days or more as to interest or principal payments	424	557	376
Nonperforming [Member] | Consumer Installment Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	393	500	536
Total accruing loans contractually past due 90 days or more as to interest or principal payments	0	0	0
Nonperforming [Member] | Home Equity Loans [Member]
Summary of nonperforming loans
Total nonaccrual loans	1,769	1,667	2,296
Total accruing loans contractually past due 90 days or more as to interest or principal payments	$ 588	$ 1,346	$ 1,075

Loans (Summary of Impaired Loan

Loans (Summary of Impaired Loans by Classes of Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Impaired loans with a valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	$ 27,803	$ 23,234	$ 27,627
Unpaid Principal Balance	28,055	23,648	29,216
Related Valuation Allowance	1,581	1,338	1,719
Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	103,066	111,433	99,153
Unpaid Principal Balance	132,985	141,622	119,489
Related Valuation Allowance	0	0	0
Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	130,869	134,667	126,780
Unpaid Principal Balance	161,040	165,270	148,705
Related Valuation Allowance	1,581	1,338	1,719
Commercial [Member] | Impaired loans with a valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	4,044	966	2,905
Unpaid Principal Balance	4,137	1,040	3,258
Related Valuation Allowance	718	293	563
Commercial [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	32,461	38,094	39,420
Unpaid Principal Balance	38,160	44,557	43,463
Related Valuation Allowance	0	0	0
Commercial [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	36,505	39,060	42,325
Unpaid Principal Balance	42,297	45,597	46,721
Related Valuation Allowance	718	293	563
Real estate commercial [Member] | Impaired loans with a valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	2,789	2,587	4,369
Unpaid Principal Balance	2,948	2,927	5,605
Related Valuation Allowance	603	710	777
Real estate commercial [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	56,052	60,616	46,205
Unpaid Principal Balance	78,490	82,693	58,997
Related Valuation Allowance	0	0	0
Real estate commercial [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	58,841	63,203	50,574
Unpaid Principal Balance	81,438	85,620	64,602
Related Valuation Allowance	603	710	777
Real estate construction [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	451	162	160
Unpaid Principal Balance	531	255	366
Related Valuation Allowance	0	0	0
Real estate construction [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	451	162	160
Unpaid Principal Balance	531	255	366
Related Valuation Allowance	0	0	0
Land development [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	1,942	1,928	4,211
Unpaid Principal Balance	3,644	3,484	7,506
Related Valuation Allowance	0	0	0
Land development [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	1,942	1,928	4,211
Unpaid Principal Balance	3,644	3,484	7,506
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	20,970	19,681	20,353
Unpaid Principal Balance	20,970	19,681	20,353
Related Valuation Allowance	260	335	379
Real estate residential [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	8,984	7,994	6,325
Unpaid Principal Balance	8,984	7,994	6,325
Related Valuation Allowance	0	0	0
Real estate residential [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	29,954	27,675	26,678
Unpaid Principal Balance	29,954	27,675	26,678
Related Valuation Allowance	260	335	379
Consumer installment [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	398	518	536
Unpaid Principal Balance	398	518	536
Related Valuation Allowance	0	0	0
Consumer installment [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	398	518	536
Unpaid Principal Balance	398	518	536
Related Valuation Allowance	0	0	0
Home equity [Member] | Impaired loans with no valuation allowance [Member]
Schedule of Impaired loans by classes
Recorded Investment	2,778	2,121	2,296
Unpaid Principal Balance	2,778	2,121	2,296
Related Valuation Allowance	0	0	0
Home equity [Member] | Total Impaired Loans [Member]
Schedule of Impaired loans by classes
Recorded Investment	2,778	2,121	2,296
Unpaid Principal Balance	2,778	2,121	2,296
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, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	$ 131,805	$ 127,956	$ 131,670	$ 128,707
Interest income recognized related to loans with impaired status	1,152	1,075	2,332	2,109
Commercial [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	36,735	42,629	37,655	42,118
Interest income recognized related to loans with impaired status	263	347	552	680
Real estate commercial [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	60,393	51,260	60,317	52,290
Interest income recognized related to loans with impaired status	458	366	983	727
Real estate construction [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	390	163	515	165
Interest income recognized related to loans with impaired status	2	0	2	0
Land development [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	1,900	4,312	1,888	4,478
Interest income recognized related to loans with impaired status	34	34	61	71
Real estate residential [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	29,432	26,737	28,392	26,758
Interest income recognized related to loans with impaired status	380	328	711	631
Consumer installment [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	426	634	463	704
Interest income recognized related to loans with impaired status	1	0	1	0
Home equity [Member]
Schedule representing information related to impaired loans
Average recorded investment related to impaired loans	2,529	2,221	2,440	2,194
Interest income recognized related to loans with impaired status	$ 14	$ 0	$ 22	$ 0

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, 2015	Dec. 31, 2014	Jun. 30, 2014
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	$ 13,618	$ 20,595	$ 17,112
Financing receivable, recorded investment 61 to 89 days past due	3,940	3,352	3,432
Financing receivable, recorded investment accruing loans past due 90 days or more	1,779	2,073	1,535
Financing receivable, recorded investment, Nonaccrual loans	51,215	50,644	55,635
Financing receivable recorded investment, Total past due	70,552	76,664	77,714
Financing receivable, recorded investment, current	5,280,458	4,913,403	4,546,695
Financing receivable, recorded investment, Total loans	5,351,010	4,990,067	4,624,409
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	4,055	4,033	4,149
Financing receivable, recorded investment 61 to 89 days past due	2,317	743	1,901
Financing receivable, recorded investment accruing loans past due 90 days or more	711	170	15
Financing receivable, recorded investment, Nonaccrual loans	17,260	16,418	18,773
Financing receivable recorded investment, Total past due	24,343	21,364	24,838
Financing receivable, recorded investment, current	1,335,513	1,234,534	1,113,685
Financing receivable, recorded investment, Total loans	1,359,856	1,255,898	1,138,523
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	2,754	7,515	5,933
Financing receivable, recorded investment 61 to 89 days past due	1,117	1,383	233
Financing receivable, recorded investment accruing loans past due 90 days or more	56	0	69
Financing receivable, recorded investment, Nonaccrual loans	25,287	24,966	25,361
Financing receivable recorded investment, Total past due	29,214	33,864	31,596
Financing receivable, recorded investment, current	1,334,212	1,170,562	1,123,319
Financing receivable, recorded investment, Total loans	1,363,426	1,204,426	1,154,915
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	413	262	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	0	0	0
Financing receivable, recorded investment, Nonaccrual loans	247	162	160
Financing receivable recorded investment, Total past due	660	424	160
Financing receivable, recorded investment, current	95,730	138,316	88,415
Financing receivable, recorded investment, Total loans	96,390	138,740	88,575
Originated Portfolio [Member] | Land development [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	0	0	0
Financing receivable, recorded investment 61 to 89 days past due	0	0	0
Financing receivable, recorded investment accruing loans past due 90 days or more	0	0	0
Financing receivable, recorded investment, Nonaccrual loans	255	225	2,184
Financing receivable recorded investment, Total past due	255	225	2,184
Financing receivable, recorded investment, current	3,781	4,303	4,106
Financing receivable, recorded investment, Total loans	4,036	4,528	6,290
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	1,536	2,126	2,515
Financing receivable, recorded investment 61 to 89 days past due	0	54	0
Financing receivable, recorded investment accruing loans past due 90 days or more	424	557	376
Financing receivable, recorded investment, Nonaccrual loans	6,004	6,706	6,325
Financing receivable recorded investment, Total past due	7,964	9,443	9,216
Financing receivable, recorded investment, current	1,060,525	988,558	950,769
Financing receivable, recorded investment, Total loans	1,068,489	998,001	959,985
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	2,526	3,620	2,513
Financing receivable, recorded investment 61 to 89 days past due	302	512	313
Financing receivable, recorded investment accruing loans past due 90 days or more	0	0	0
Financing receivable, recorded investment, Nonaccrual loans	393	500	536
Financing receivable recorded investment, Total past due	3,221	4,632	3,362
Financing receivable, recorded investment, current	868,715	814,746	740,295
Financing receivable, recorded investment, Total loans	871,936	819,378	743,657
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	2,334	3,039	2,002
Financing receivable, recorded investment 61 to 89 days past due	204	660	985
Financing receivable, recorded investment accruing loans past due 90 days or more	588	1,346	1,075
Financing receivable, recorded investment, Nonaccrual loans	1,769	1,667	2,296
Financing receivable recorded investment, Total past due	4,895	6,712	6,358
Financing receivable, recorded investment, current	581,982	562,384	526,106
Financing receivable, recorded investment, Total loans	586,877	569,096	532,464
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	3,889	2,994	345
Financing receivable, recorded investment 61 to 89 days past due	695	461	49
Financing receivable, recorded investment accruing loans past due 90 days or more	15,934	19,892	10,447
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	20,518	23,347	10,841
Financing receivable, recorded investment, current	1,663,215	674,816	263,554
Financing receivable, recorded investment, Total loans	1,683,733	698,163	274,395
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	690	133	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	3,781	5,427	6,744
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	4,471	5,560	6,744
Financing receivable, recorded investment, current	390,546	93,423	67,116
Financing receivable, recorded investment, Total loans	395,017	98,983	73,860
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	969	2,014	0
Financing receivable, recorded investment 61 to 89 days past due	291	352	0
Financing receivable, recorded investment accruing loans past due 90 days or more	6,603	11,052	1,594
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	7,863	13,418	1,594
Financing receivable, recorded investment, current	872,224	339,804	141,856
Financing receivable, recorded investment, Total loans	880,087	353,222	143,450
Acquired Portfolio [Member] | Real estate construction [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	0	0	0
Financing receivable, recorded investment 61 to 89 days past due	0	0	0
Financing receivable, recorded investment accruing loans past due 90 days or more	205	0	0
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	205	0	0
Financing receivable, recorded investment, current	5,122	14,005	12,593
Financing receivable, recorded investment, Total loans	5,327	14,005	12,593
Acquired Portfolio [Member] | Land development [Member]
Schedule representing the aging status of the recorded investment in loans by classes
Financing receivable, recorded investment 31 to 60 days past due	0	0	0
Financing receivable, recorded investment 61 to 89 days past due	0	0	0
Financing receivable, recorded investment accruing loans past due 90 days or more	1,352	1,653	1,977
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	1,352	1,653	1,977
Financing receivable, recorded investment, current	5,207	12,569	2,689
Financing receivable, recorded investment, Total loans	6,559	14,222	4,666
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	1,077	156	0
Financing receivable, recorded investment 61 to 89 days past due	138	0	0
Financing receivable, recorded investment accruing loans past due 90 days or more	2,980	18	69
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	4,195	174	69
Financing receivable, recorded investment, current	237,483	112,215	10,343
Financing receivable, recorded investment, Total loans	241,678	112,389	10,412
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	0	55	20
Financing receivable, recorded investment 61 to 89 days past due	56	3	0
Financing receivable, recorded investment accruing loans past due 90 days or more	5	454	0
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	61	512	20
Financing receivable, recorded investment, current	15,910	9,680	1,104
Financing receivable, recorded investment, Total loans	15,971	10,192	1,124
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	1,153	636	325
Financing receivable, recorded investment 61 to 89 days past due	210	106	49
Financing receivable, recorded investment accruing loans past due 90 days or more	1,008	1,288	63
Financing receivable, recorded investment, Nonaccrual loans	0	0	0
Financing receivable recorded investment, Total past due	2,371	2,030	437
Financing receivable, recorded investment, current	136,723	93,120	27,853
Financing receivable, recorded investment, Total loans	$ 139,094	$ 95,150	$ 28,290

Loans (Summary of TDRs) (Detail

Loans (Summary of TDRs) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Schedule of corporation's TDRs
Total TDRs	$ 99,428	$ 101,322	$ 104,383
Commercial Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	74,751	77,047	80,696
Consumer Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	24,677	24,275	23,687
Performing [Member]
Schedule of corporation's TDRs
Total TDRs	45,808	45,664	44,133
Performing [Member] | Commercial Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	28,203	29,179	29,296
Performing [Member] | Consumer Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	17,605	16,485	14,837
Nonperforming [Member]
Schedule of corporation's TDRs
Total TDRs	17,912	18,467	16,565
Nonperforming [Member] | Commercial Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	14,547	15,271	11,049
Nonperforming [Member] | Consumer Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	3,365	3,196	5,516
Substandard Nonaccrual [Member]
Schedule of corporation's TDRs
Total TDRs	35,708	37,191	43,685
Substandard Nonaccrual [Member] | Commercial Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	32,001	32,597	40,351
Substandard Nonaccrual [Member] | Consumer Loan Portfolio [Member]
Schedule of corporation's TDRs
Total TDRs	$ 3,707	$ 4,594	$ 3,334

Loans (Summary of TDRs Modified

Loans (Summary of TDRs Modified During the Period) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)Loans	Jun. 30, 2014USD ($)Loans	Jun. 30, 2015USD ($)Loans	Jun. 30, 2014USD ($)Loans
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	47	90	67	142
Modified TDRs, Pre-modification recorded investment	$ 4,797	$ 8,358	$ 9,599	$ 20,563
Modified TDRs, Post-modification recorded investment	$ 4,795	$ 8,357	$ 9,597	$ 20,553
Subtotal-commercial loan portfolio [Member] | Commercial Loan Portfolio [Member]
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	18	27	28	49
Modified TDRs, Pre-modification recorded investment	$ 3,164	$ 6,709	$ 7,630	$ 17,927
Modified TDRs, Post-modification recorded investment	$ 3,164	$ 6,709	$ 7,630	$ 17,927
Consumer loan portfolio [Member] | Consumer Portfolio Segment [Member]
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	29	63	39	93
Modified TDRs, Pre-modification recorded investment	$ 1,633	$ 1,649	$ 1,969	$ 2,636
Modified TDRs, Post-modification recorded investment	$ 1,631	$ 1,648	$ 1,967	$ 2,626
Commercial [Member] | Commercial Loan Portfolio [Member]
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	13	15	18	27
Modified TDRs, Pre-modification recorded investment	$ 2,332	$ 3,575	$ 4,264	$ 11,931
Modified TDRs, Post-modification recorded investment	$ 2,332	$ 3,575	$ 4,264	$ 11,931
Real estate commercial [Member] | Commercial Loan Portfolio [Member]
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	4	12	9	21
Modified TDRs, Pre-modification recorded investment	$ 527	$ 3,134	$ 3,061	$ 5,924
Modified TDRs, Post-modification recorded investment	$ 527	$ 3,134	$ 3,061	$ 5,924
Land development [Member] | Commercial Loan Portfolio [Member]
Schedule providing information on TDRs
Modified TDRs, Number of loans | Loans	1	0	1	1
Modified TDRs, Pre-modification recorded investment	$ 305	$ 0	$ 305	$ 72
Modified TDRs, Post-modification recorded investment	$ 305	$ 0	$ 305	$ 72

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, 2015USD ($)Loans	Jun. 30, 2014USD ($)Loans	Jun. 30, 2015USD ($)Loans	Jun. 30, 2014USD ($)Loans
Troubled debt restructurings on financing receivables with defaults payment
Financing receivable modifications subsequent default number of contract	1	11	5	14
Financing receivable modification subsequent default recorded investment | $	$ 183	$ 1,454	$ 975	$ 3,228
Consumer Portfolio Segment [Member]
Troubled debt restructurings on financing receivables with defaults payment
Financing receivable modifications subsequent default number of contract	0	3	1	3
Financing receivable modification subsequent default recorded investment | $	$ 0	$ 80	$ 33	$ 80
Commercial [Member] | Commercial Loan Portfolio [Member]
Troubled debt restructurings on financing receivables with defaults payment
Financing receivable modifications subsequent default number of contract	0	5	0	6
Financing receivable modification subsequent default recorded investment | $	$ 0	$ 771	$ 0	$ 875
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	1	3	4	5
Financing receivable modification subsequent default recorded investment | $	$ 183	$ 603	$ 942	$ 2,273
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	1	8	4	11
Financing receivable modification subsequent default recorded investment | $	$ 183	$ 1,374	$ 942	$ 3,148

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, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	$ 75,256	$ 78,473	$ 75,683	$ 79,072
Provision for loan losses	1,500	1,500	3,000	3,100
Charge-offs	(2,724)	(3,375)	(5,867)	(6,847)
Recoveries	909	1,195	2,125	2,468
Ending balance	74,941	77,793	74,941	77,793
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses					$ 1,581	$ 1,338	$ 1,719
Loans collectively evaluated for impairment related to allowance for loan losses					73,360	73,845	75,574
Loans acquired with deteriorated credit quality related to allowance for loan losses					0	500	500
Total	75,256	78,473	75,683	79,072	74,941	75,683	77,793
Loans individually evaluated for impairment related to recorded investment (loan balance)					106,769	105,902	107,176
Loans collectively evaluated for impairment related to recorded investment (loan balance)					5,244,241	4,884,165	4,517,233
Loans acquired with deteriorated credit quality related to recorded investment (loan balance)					1,683,733	698,163	274,395
Total loans					7,034,743	5,688,230	4,898,804
Commercial Loan Portfolio [Member]
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	46,819	45,010	44,156	44,482
Provision for loan losses	(626)	439	2,967	1,399
Charge-offs	(915)	(1,814)	(2,419)	(3,023)
Recoveries	249	589	823	1,366
Ending balance	45,527	44,224	45,527	44,224
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses					1,321	1,003	1,340
Loans collectively evaluated for impairment related to allowance for loan losses					44,206	43,153	42,884
Loans acquired with deteriorated credit quality related to allowance for loan losses					0	0	0
Total	46,819	45,010	44,156	44,482	45,527	44,156	44,224
Loans individually evaluated for impairment related to recorded investment (loan balance)					85,799	86,221	86,823
Loans collectively evaluated for impairment related to recorded investment (loan balance)					2,737,909	2,517,371	2,301,480
Loans acquired with deteriorated credit quality related to recorded investment (loan balance)					1,286,990	480,432	234,569
Total loans					4,110,698	3,084,024	2,622,872
Consumer Loan Portfolio [Member]
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	24,579	29,233	28,803	30,145
Provision for loan losses	(109)	1,287	(3,336)	2,142
Charge-offs	(1,809)	(1,561)	(3,448)	(3,824)
Recoveries	660	606	1,302	1,102
Ending balance	23,321	29,565	23,321	29,565
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses					260	335	379
Loans collectively evaluated for impairment related to allowance for loan losses					23,061	27,968	28,686
Loans acquired with deteriorated credit quality related to allowance for loan losses					0	500	500
Total	24,579	29,233	28,803	30,145	23,321	28,803	29,565
Loans individually evaluated for impairment related to recorded investment (loan balance)					20,970	19,681	20,353
Loans collectively evaluated for impairment related to recorded investment (loan balance)					2,506,332	2,366,794	2,215,753
Loans acquired with deteriorated credit quality related to recorded investment (loan balance)					396,743	217,731	39,826
Total loans					2,924,045	2,604,206	2,275,932
Unallocated [Member]
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	3,858	4,230	2,724	4,445
Provision for loan losses	2,235	(226)	3,369	(441)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	6,093	4,004	6,093	4,004
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					6,093	2,724	4,004
Loans acquired with deteriorated credit quality related to allowance for loan losses					0	0	0
Total	$ 3,858	$ 4,230	$ 2,724	$ 4,445	6,093	2,724	4,004
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
Loans acquired with deteriorated credit quality related to recorded investment (loan balance)					0	0	0
Total loans					$ 0	$ 0	$ 0

Loans (Textual) (Details)

Loans (Textual) (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2015USD ($)	Jun. 30, 2015USD ($)SegmentLoansBaordOfDirectorsTenants	Dec. 31, 2014USD ($)	Jun. 30, 2014USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality	$ 0	$ 0	$ 500	$ 500
Loans (Textual) [Abstract]
Number of portfolio segment | Segment		2
Number of classes of loans | Loans		7
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	35,700	$ 35,700	37,200	43,700
Difference between recorded investment and unpaid principal balance of loan	30,200	30,200	30,600	21,900
Confirmed losses (partial charge-offs)	15,200	15,200	15,400	18,200
Fair value of discount adjustment	15,000	15,000	15,200	3,700
Acquired impaired loans	15,900	15,900	19,900	10,400
Performing trouble debt restructuring under impaired loans	45,800	45,800	45,700	44,100
Financing receivable allowance for acquired loans			500	500
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Reclassifications from Nonaccretable Difference		0
Residential Mortgage Loans in Process of Foreclosure	2,000	2,000	2,300	3,600
Commercial Loan Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality	0	0	0	0
Loans (Textual) [Abstract]
Minimum value of loan requires executive and senior officer approval	1,500	1,500
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality	0	$ 0	$ 500	$ 500
Loans (Textual) [Abstract]
Maximum due period of loans consider in performing status		90 days
Minimum due period of loans consider in a nonperforming status		90 days
Commercial [Member]
Loans (Textual) [Abstract]
Minimum value of loan requires group loan authority approval	1,000	$ 1,000
Maximum value of loan requires executive and senior officer approval	3,500	$ 3,500
Increase in Minimum Value of Loans Requiring Group Loan Authority Approval	5,000
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	$ 10,000
Other loans requiring director loan committee approval depending on risk rating and credit action required	10,000	$ 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	$ 1,000
Minimum value of loans depending on risk rating and requires credit action from board of directors	15,000	15,000
Minimum [Member] | Commercial [Member]
Loans (Textual) [Abstract]
Minimum value of loans requiring only director loan committee approval	$ 10,000	$ 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, 2015	May. 31, 2015	Mar. 31, 2015	Dec. 31, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Net carrying value of intangible assets
Goodwill	$ 285,512			$ 180,128	$ 120,164
Other intangible assets:
Total other intangible assets	41,201			33,080	12,454
Core deposit intangible assets [Member]
Other intangible assets:
Finite-Lived Core Deposits, Gross	28,353			20,863	9,110
Total other intangible assets	28,353			20,863	9,110
Noncompete Agreements [Member]
Other intangible assets:
Finite-Lived Noncompete Agreements, Gross					0			$ 0
Mortgage servicing rights [Member]
Other intangible assets:
Servicing Asset at Amortized Cost	12,307			12,217	3,344
Total other intangible assets	12,307		$ 11,583	$ 12,217	$ 3,344	$ 3,316	$ 3,423
Lake Michigan Financial Corp [Member]
Net carrying value of intangible assets
Goodwill		$ 100,002
Other intangible assets:
Finite-Lived Noncompete Agreements, Gross	$ 541	$ 600

Intangible Assets (Amortization

Intangible Assets (Amortization Expense of Core Deposit Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Carrying amount	$ 41,201	$ 12,454	$ 41,201	$ 12,454	$ 33,080
Amortization of intangible assets			3,787	1,391
Core deposit intangible assets [Member]
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Gross original amount	39,355	18,659	39,355	18,659	31,550
Accumulated amortization	11,002	9,549	11,002	9,549	10,687
Carrying amount	28,353	9,110	28,353	9,110	$ 20,863
Amortization of intangible assets	$ 952	$ 446	$ 1,743	$ 891

Intangible Assets (Carrying and

Intangible Assets (Carrying and Fair Value of MSRs) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Net carrying value, fair value of MSRs and loans Corporation servicing for others
Loans serviced for others that have servicing rights capitalized	$ 2,193,067	$ 2,093,140	$ 871,158
Mortgage servicing rights [Member]
Net carrying value, fair value of MSRs and loans Corporation servicing for others
Net carrying value of MSRs	12,307	12,217	3,344
Fair value of MSRs	$ 16,602	$ 14,979	$ 6,433

Intangible Assets (Activity for

Intangible Assets (Activity for Capitalized MSRs) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Capitalized MSRs [Roll Forward]
Balance at beginning of period			$ 33,080
Amortization			(3,787)	$ (1,391)
Balance at end of period	$ 41,201	$ 12,454	41,201	12,454
Mortgage servicing rights [Member]
Capitalized MSRs [Roll Forward]
Balance at beginning of period	11,583	3,316	12,217	3,423
Acquired in Monarch acquisition	1,284	0	1,284	0
Additions	415	278	815	421
Amortization	(1,175)	(250)	(2,209)	(500)
Change in Valuation Allowance for Impairment of MSRs	(200)	0	(200)	0
Balance at end of period	$ 12,307	$ 3,344	$ 12,307	$ 3,344

Intangible Assets (Textual) (De

Intangible Assets (Textual) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	May. 31, 2015	Apr. 01, 2015	Dec. 31, 2014	Jun. 30, 2014
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 285,512			$ 180,128	$ 120,164
Finite-Lived Intangible Assets, Remaining Amortization Period	10 years
Intangible Assets (Textual) [Abstract]
Impairment valuation allowance	$ 0			200	0
Core deposit intangible assets [Member]
Estimated Future Amortization Expense, Fiscal Year Maturity [Abstract]
2,015	2,400
2,016	4,300
2,017	3,700
2,018	3,500
2,019	3,300
2020 and thereafter	11,200
Mortgage servicing rights [Member]
Intangible Assets (Textual) [Abstract]
Impairment valuation allowance	$ 0			$ 200	$ 0
Lake Michigan Financial Corp [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill		$ 100,002
Core deposit intangible assets acquired, business combination		$ 7,303
Monarch Community Bancorp [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill			$ 5,383
Core deposit intangible assets acquired, business combination			$ 1,930

Accumulated Other Comprehensi63

Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
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 $(148) at June 30, 2015, $(113) at December 31, 2014 and $431 at June 30, 2014	$ (274)	$ (210)	$ 800
Pension and other postretirement benefits adjustment, net of related tax benefit of $16,601 at June 30, 2015, $17,362 at December 31, 2014 and $10,117 at June 30, 2014	(30,830)	(32,243)	(18,788)
Accumulated other comprehensive loss	$ (31,104)	$ (32,453)	$ (17,988)

Accumulated Other Comprehensi64

Accumulated Other Comprehensive Loss (Textual) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Accumulated Other Comprehensive Loss (Textual) [Abstract]
Net unrealized gains (losses) on investment securities-available-for-sale, tax expense (benefit)	$ (148)	$ (113)	$ 431
Pension and other postretirement benefits adjustment, tax benefit	$ 16,601	$ 17,362	$ 10,117

Borrowings Schedule of Short-te

Borrowings Schedule of Short-term Borrowings (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Schedule of Short-Term Borrowings [Abstract]
Securities sold under repurchase agreements with customers	$ 305,291	$ 304,467	$ 293,422
Federal Home Loan Bank Advances, Short Term	205,000	60,000	0
Federal Funds Purchased	22,000	25,000	12,000
Short-term borrowings	$ 532,291	$ 389,467	$ 305,422

Borrowings Schedule of Other Bo

Borrowings Schedule of Other Borrowings (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Schedule of Other Borrowings [Abstract]
Long-term Federal Home Loan Bank Advances	$ 81,469	$ 0	$ 0
Securities Sold under Agreements to Repurchase	23,649	0	0
nonrevolving line of credit	25,000	0	0
Subordinated Debt	18,372	0	0
Other Borrowings	$ 148,490	$ 0	$ 0

Borrowings Textuals (Details)

Borrowings Textuals (Details) - USD ($)	6 Months Ended
	Jun. 30, 2015	May. 31, 2015	Dec. 31, 2014	Jun. 30, 2014
Borrowings [Line Items]
Maximum original maturity term of short-term borrowings	30 days
Long-term Federal Home Loan Bank Advances	$ 81,469,000		$ 0	$ 0
Federal Home Loan Bank, Advances, Weighted Average Interest Rate	1.33%
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	$ 1,240,000,000
Federal Home Loan Bank, Advances, Maturities Summary, Due Remainder of Current Year	100,000
Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Two	7,100,000
Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Three	47,100,000
Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Four	17,100,000
Federal Home Loan Bank, Advances, Maturities Summary, Due in Year Five	100,000
Federal Home Loan Bank, Advances, Maturities Summary, Floating Rate, after Five Years	10,000,000
Securities Sold under Agreements to Repurchase	23,649,000		0	0
Securities Sold Under Agreements to Repurchase, Maturities Summary, Due Remainder of Current Year	3,200,000
Securities Sold Under Agreements to Repurchase, Maturities, Due in Year Two	8,300,000
Securities Sold Under Agreements to Repurchase, Maturities, Due in Year Three	12,100,000
nonrevolving line of credit	$ 25,000,000		0	0
Line of Credit Facility, Interest Rate at Period End	2.134%
Trust Preferred Investment Security of Non Public Bank Company		$ 10,000,000	10,000,000	10,000,000
subordinated debt par value	$ 1,000
Subordinated Debt	18,372,000		$ 0	$ 0
Lake Michigan Financial Corp [Member]
Borrowings [Line Items]
Long-term Federal Home Loan Bank Advances		81,500,000
Securities Sold under Agreements to Repurchase		$ 23,700,000
LMFCTI [Member]
Borrowings [Line Items]
Subordinated Debt	$ 10,300,000
Subordinated Borrowing, Minimum Interest Rate plus LIBOR	3.45%
Subordinated Borrowing, Interest Rate, Effective Percentage	3.73%
LMFCTII [Member]
Borrowings [Line Items]
Subordinated Debt	$ 8,200,000
Subordinated Borrowing, Minimum Interest Rate plus LIBOR	2.70%
Subordinated Borrowing, Interest Rate, Effective Percentage	2.98%

Regulatory Capital (Details)

Regulatory Capital (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Risk weighted assets	$ 6,990,000	$ 5,700,000	$ 4,900,000
Chemical Financial Corporation [Member]
Total Capital to Risk-Weighted Assets:
Actual, Capital Amount	816,595	705,130	748,332
Minimum Required for Capital Adequacy Purposes, Capital Amount	$ 559,273	$ 456,302	$ 391,911
Actual, Ratio	11.70%	12.40%	15.30%
Minimum Required for Capital Adequacy Purposes, Ratio	8.00%	8.00%	8.00%
Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount	$ 741,654	$ 633,779	$ 686,892
Minimum Required for Capital Adequacy Purposes, Capital Amount	$ 419,455	$ 228,151	$ 195,955
Actual, Ratio	10.60%	11.10%	14.00%
Minimum Required for Capital Adequacy Purposes, Ratio	6.00%	4.00%	4.00%
Common Equity Tier One Risk Based Capital	$ 723,654
Common Equity Tier One Risk Based Capital to Risk Weighted Assets	10.40%
Common Equity Tier One Risk Based Capital for Capital Adequacy	$ 314,591
Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%
Leverage Ratio:
Actual, Capital Amount	$ 741,654	$ 633,779	$ 686,892
Minimum Required for Capital Adequacy Purposes, Capital Amount	$ 314,344	$ 273,226	$ 244,757
Actual, Ratio	9.40%	9.30%	11.20%
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	$ 713,999	$ 654,031	$ 601,561
Minimum Required for Capital Adequacy Purposes, Capital Amount	471,422	455,633	391,305
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 589,277	$ 569,541	$ 489,131
Actual, Ratio	12.10%	11.50%	12.30%
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	$ 640,324	$ 582,783	$ 540,214
Minimum Required for Capital Adequacy Purposes, Capital Amount	353,566	227,816	195,653
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 471,422	$ 341,725	$ 293,479
Actual, Ratio	10.90%	10.20%	11.00%
Minimum Required for Capital Adequacy Purposes, Ratio	6.00%	4.00%	4.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio	8.00%	6.00%	6.00%
Common Equity Tier One Risk Based Capital	$ 640,324
Common Equity Tier One Risk Based Capital to Risk Weighted Assets	10.90%
Common Equity Tier One Risk Based Capital for Capital Adequacy	$ 265,175
Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%
Common Equity Tier One Risk Based Capital to be Well Capitalized	$ 383,030
Common Equity Tier One Risk Based Capital Required to Be Well Capitalized to Risk Weighted Assets	6.50%
Leverage Ratio:
Actual, Capital Amount	$ 640,324	$ 582,783	$ 540,214
Minimum Required for Capital Adequacy Purposes, Capital Amount	300,703	273,048	244,604
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 375,878	$ 341,310	$ 305,755
Actual, Ratio	8.50%	8.50%	8.80%
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	$ 72,506
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	9.50%
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	$ 72,506
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	9.50%
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 One Risk Based Capital	$ 72,506
Common Equity Tier One Risk Based Capital to Risk Weighted Assets	9.50%
Common Equity Tier One Risk Based Capital for Capital Adequacy	$ 34,328
Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%
Common Equity Tier One Risk Based Capital to be Well Capitalized	$ 49,585
Common Equity Tier One Risk Based Capital Required to Be Well Capitalized to Risk Weighted Assets	6.50%
Leverage Ratio:
Actual, Capital Amount	$ 72,506
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	9.40%
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 One Risk Based Capital	$ 32,779
Common Equity Tier One Risk Based Capital to Risk Weighted Assets	10.10%
Common Equity Tier One Risk Based Capital for Capital Adequacy	$ 14,556
Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%
Common Equity Tier One Risk Based Capital to be Well Capitalized	$ 21,025
Common Equity Tier One Risk Based Capital Required to Be Well Capitalized to Risk Weighted Assets	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, 2015	Dec. 31, 2014	Jun. 30, 2014
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	$ 685,706	$ 748,864	$ 615,975
Fair Value Measurements Recurring [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	685,706	748,864	615,975
Loans Held-for-sale	7,798	9,128	6,329
Total assets measured at fair value on a recurring basis	693,504	757,992	622,304
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	8,294	8,259	0
Loans Held-for-sale	0	0	0
Total assets measured at fair value on a recurring basis	8,294	8,259	0
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	677,412	740,605	615,975
Loans Held-for-sale	7,798	9,128	6,329
Total assets measured at fair value on a recurring basis	685,210	749,733	622,304
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	8,294	8,259
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	8,294	8,259
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	8,294	8,259
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
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
Government sponsored agencies [Member]
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	227,907	263,503	88,708
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	227,907	263,503	88,708
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	227,907	263,503	88,708
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	26,965	46,227	41,608
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	26,965	46,227	41,608
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	26,965	46,227	41,608
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	212,669	239,807	265,368
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	212,669	239,807	265,368
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	212,669	239,807	265,368
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	167,032	144,383	153,283
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	167,032	144,383	153,283
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	167,032	144,383	153,283
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	39,678	45,095	65,352
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	39,678	45,095	65,352
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	39,678	45,095	65,352
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	3,161	1,590	1,656
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	3,161	1,590	1,656
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	3,161	1,590	1,656
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 (Fair70

Fair Value Measurements (Fair Value of Assets on a Nonrecurring Basis) (Details) - Fair Value Measurements Nonrecurring [Member] - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	$ 38,714	$ 44,219	$ 40,181
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	38,714	44,219	40,181
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	24,517	21,323	29,789
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	24,517	21,323	29,789
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	14,197	14,205	10,392
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	$ 14,197	14,205	$ 10,392
Mortgage Servicing Rights [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis		8,691
Mortgage Servicing Rights [Member] | Quoted Prices In Active Markets for Identical Assets (Level 1) [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis		0
Mortgage Servicing Rights [Member] | Significant Other Observable Inputs (Level 2) [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis		0
Mortgage Servicing Rights [Member] | Significant Unobservable Inputs (Level 3) [Member]
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis		$ 8,691

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule of Carrying Amounts and Estimated Fair Value of Financial Instruments) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Investment securities:
Available-for-sale	$ 685,706	$ 748,864	$ 615,975
Held-to-maturity	466,578	315,740	303,961
Carrying Amount [Member]
Investment securities:
Nonmarketable equity securities	36,142	27,369	25,572
Carrying Amount [Member] | Level 1[Member]
Assets:
Cash and cash equivalents	215,034	183,020	140,294
Investment securities:
Available-for-sale	8,294	8,259	0
Carrying Amount [Member] | Level 2 [Member]
Investment securities:
Available-for-sale	677,412	740,605	615,975
Held-to-maturity	469,337	305,913	297,630
Loans Held-for-sale	7,798	9,128	6,329
Interest receivable	21,668	17,492	15,827
Liabilities:
Deposits without defined maturities	5,547,764	4,741,024	3,814,013
Interest payable	1,557	755	735
Short-term borrowings, fair value disclosure	532,291	389,467	305,422
Other Liabilities, Fair Value Disclosure	106,469	0	0
Carrying Amount [Member] | Level 3 [Member]
Investment securities:
Held-to-maturity	500	10,500	10,500
Net loans	6,959,802	5,612,547	4,821,011
Liabilities:
Time deposits	1,745,215	1,337,947	1,278,900
Other Liabilities, Fair Value Disclosure	42,021	0	0
Fair Value [Member]
Investment securities:
Nonmarketable equity securities	36,142	27,369	25,572
Fair Value [Member] | Level 1[Member]
Assets:
Cash and cash equivalents	215,034	183,020	140,294
Investment securities:
Available-for-sale	8,294	8,259	0
Fair Value [Member] | Level 2 [Member]
Investment securities:
Available-for-sale	677,412	740,605	615,975
Held-to-maturity	466,278	308,650	297,186
Loans Held-for-sale	7,798	9,128	6,329
Interest receivable	21,668	17,492	15,827
Liabilities:
Deposits without defined maturities	5,547,764	4,741,024	3,814,013
Interest payable	1,557	755	735
Short-term borrowings, fair value disclosure	532,291	389,467	305,422
Other Liabilities, Fair Value Disclosure	106,469	0	0
Fair Value [Member] | Level 3 [Member]
Investment securities:
Held-to-maturity	300	7,090	6,775
Net loans	6,969,655	5,623,454	4,826,672
Liabilities:
Time deposits	1,745,215	1,340,015	1,285,992
Other Liabilities, Fair Value Disclosure	$ 42,021	$ 0	$ 0

Fair Value Measurements (Textua

Fair Value Measurements (Textual) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Fair Value Measurements (Textual) [Abstract]
Impairment of goodwill	$ 0	$ 0	$ 0
Valuation Allowance on Mortgage Servicing Rights	0	200	0
Impairment identified for intangible assets	0		0
Core deposit intangible assets [Member]
Fair Value Measurements (Textual) [Abstract]
Impairment identified for intangible assets	$ 0	0	0
Maximum [Member]
Fair Value Measurements (Textual) [Abstract]
Expected life of intangible assets	15 years
Minimum [Member]
Fair Value Measurements (Textual) [Abstract]
Expected life of intangible assets	10 years
Total Impaired Loans [Member] | Maximum [Member]
Fair Value Measurements (Textual) [Abstract]
Percentage of discount factors used to determine fair value	80.00%
Total Impaired Loans [Member] | Minimum [Member]
Fair Value Measurements (Textual) [Abstract]
Percentage of discount factors used to determine fair value	70.00%
Other Real Estate and Repossessed Assets [Member] | Maximum [Member]
Fair Value Measurements (Textual) [Abstract]
Percentage of discount factors used to determine fair value	75.00%
Other Real Estate and Repossessed Assets [Member] | Minimum [Member]
Fair Value Measurements (Textual) [Abstract]
Percentage of discount factors used to determine fair value	70.00%
Fair Value Measurements Recurring [Member]
Fair Value Measurements (Textual) [Abstract]
Liabilities recorded at fair value	$ 0	0	0
Fair Value Measurements Nonrecurring [Member]
Fair Value Measurements (Textual) [Abstract]
Liabilities recorded at fair value	$ 0	$ 0	$ 0

Earnings Per Common Share (Deta

Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
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	$ 19,024	$ 16,236	$ 36,859	$ 30,049
Denominator for basic earnings per common share, weighted average common shares outstanding	35,162,000	30,068,000	33,992,000	29,947,000
Weighted average common stock equivalents	235,000	211,000	235,000	212,000
Denominator for diluted earnings per common share	35,397,000	30,279,000	34,227,000	30,159,000
Basic earnings per common share (dollars per share)	$ 0.54	$ 0.54	$ 1.08	$ 1
Diluted earnings per common share (dollars per share)	$ 0.54	$ 0.54	$ 1.08	$ 1
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	80,700	249,150	100,875	252,529

Share-Based Compensation (Stock

Share-Based Compensation (Stock Option Activity) (Details) - Jun. 30, 2015 - $ / shares	Total
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	$ 8.40
Stock Options [Member] | Non Vested [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance, Number of Options	432,199
Granted, Number of Options	244,165
Converted, Number of Options from Lake Michigan Acquisition	0
Exercised, Number of Options	0
Vested, Number of Options	(150,224)
Forfeited/expired, Number of Options	(9,175)
Ending balance, Number of Options	516,965
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Beginning balance, Weighted Average Exercise Price	$ 26.75
Granted, Weighted Average Exercise Price	30.18
Converted options from Lake Michigan acquisition, Weighted Average Exercise Price	0
Exercised, Weighted Average Exercise Price	0
Vested, Weighted Average Exercise Price	25.57
Forfeited/expired, Weighted Average Exercise Price	28.21
Ending balance, Weighted Average Exercise Price	28.69
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	8.30
Weighted average fair value of options granted	8.40
Converted options from acquisitions, Wtd Avg Grant Date Fair Value	0
Exercised, Weighted Average Grant Date Fair Value	0
Vested, Weighted Average Grant Date Fair Value	7.80
Forfeited/expired, Weighted Average Grant Date Fair Value	8.52
Ending balance, Weighted average grant date fair value	$ 8.49
Stock Options [Member] | Vested & Nonvested [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance, Number of Options	1,037,311
Granted, Number of Options	244,165
Converted, Number of Options from Lake Michigan Acquisition	132,883
Exercised, Number of Options	(216,690)
Vested, Number of Options	0
Forfeited/expired, Number of Options	(9,175)
Ending balance, Number of Options	1,188,494
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Beginning balance, Weighted Average Exercise Price	$ 25.90
Granted, Weighted Average Exercise Price	30.18
Converted options from Lake Michigan acquisition, Weighted Average Exercise Price	12.93
Exercised, Weighted Average Exercise Price	23.99
Vested, Weighted Average Exercise Price	0
Forfeited/expired, Weighted Average Exercise Price	28.21
Ending balance, Weighted Average Exercise Price	$ 25.66
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	671,529
Exercisable/vested, Weighted Average Exercise Price	$ 23.32

Share-Based Compensation (Black

Share-Based Compensation (Black-Scholes Pricing Model Assumptions) (Details) - 6 months ended Jun. 30, 2015 - $ / shares	Total
Assumptions of Black-Scholes option pricing model
Expected dividend yield	3.50%
Risk-free interest rate	1.78%
Expected stock price volatility	39.10%
Expected life of options - in years	7 years
Weighted average fair value of options granted	$ 8.40

Share-Based Compensation (Restr

Share-Based Compensation (Restricted Stock Unit Activity) (Details) - 6 months ended Jun. 30, 2015 - Restricted Stock Units (RSUs) [Member] - $ / shares	Total
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Number of Shares [Roll Forward]
Beginning balance, Number of shares	204,319
Granted, Number of shares	79,202
Converted into shares of common stock, Number of shares	(67,489)
Forfeited/expired, Number of shares	(1,427)
Ending balance, Number of shares	214,605
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	$ 24.14
Granted, Weighted Average grant date fair value	28.25
Converted into shares of common stock, Weighted average grant date fair value	22.32
Forfeited/expired, Weighted average grant date fair value	25.13
Ending balance, Weighted average grant date fair value	$ 26.23

(Textual) (Details)

(Textual) (Details) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015USD ($)$ / sharesshares	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)$ / sharesshares	Jun. 30, 2014USD ($)	Apr. 20, 2015shares
Share-Based Compensation Plans (Textual) [Abstract]
Share-based compensation expense | $	$ 0.8	$ 0.6	$ 1.5	$ 1.2
Common stock available for future grants under share-based compensation plans					1,300,000
Restricted Stock Units (RSUs) [Member]
Share-Based Compensation Plans (Textual) [Abstract]
Corporation granted options to purchase restricted stock performance units			79,202
Unrecognized compensation expense | $	$ 3.7		$ 3.7
Unrecognized compensation expense, period for recognition			2 years 9 months 18 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			0.25
Equity Option [Member]
Share-Based Compensation Plans (Textual) [Abstract]
Common stock available for future grants under share-based compensation plans	1,295,145		1,295,145
Weighted-average remaining contractual terms for outstanding stock options			6 years 7 months 6 days
Weighted-average remaining contractual terms for exercisable stock options			4 years 9 months 18 days
Outstanding in-the-money stock options, intrinsic value | $	$ 6.9		$ 6.9
Exercisable in-the-money stock options, intrinsic value | $	$ 4.7		$ 4.7
Closing price of common stock | $ / shares	$ 33.06		$ 33.06
Unrecognized compensation expense | $	$ 4		$ 4
Unrecognized compensation expense, period for recognition			3 years 10 months 24 days
Vested & Nonvested [Member] | Employee Stock Option [Member]
Share-Based Compensation Plans (Textual) [Abstract]
Corporation granted options to purchase common stock			244,165
Converted, Number of Options from Lake Michigan Acquisition			132,883

Pension and Other Postretirem78

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, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
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	$ 273	$ 251	$ 545	$ 501
Interest cost	1,332	1,312	2,664	2,624
Expected return on plan assets	(2,161)	(2,079)	(4,322)	(4,157)
Amortization of prior service cost	(1)	(1)	(2)	(1)
Amortization of unrecognized net loss (gain)	1,056	569	2,112	1,138
Net periodic benefit cost	499	52	997	105
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	4	4	8	9
Interest cost	33	36	67	71
Amortization of prior service cost	32	33	65	65
Amortization of unrecognized net loss (gain)	0	(26)	(1)	(52)
Net periodic benefit cost	$ 69	$ 47	$ 139	$ 93

Pension and Other Postretirem79

Pension and Other Postretirement Benefit Plans (Textual) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Contribution to corporation's pension plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to defined benefit pension plan			$ 0	$ 0
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate			4.15%
Multi-Employer Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to defined benefit pension plan			$ 0
Chemical Financial Corporation [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of eligible pay contribution to certain employees			4.00%
Defined Contribution Plan, Employer Total Contribution Amount	$ 1.3	$ 1	$ 2.4	$ 1.7

Financial Guarantees (Textual)

Financial Guarantees (Textual) (Details) - Financial Standby Letter of Credit [Member] - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Financial Guarantees (Textual) [Abstract]
Letters of credit outstanding	$ 45	$ 41	$ 37
Expiration period for letters of credit, maximum	5 years