TCF Financial 10-K 1 Mar 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Feb. 27, 2017	Jun. 30, 2016
Document and Entity Information [Abstract]
Entity Registrant Name	CHEMICAL FINANCIAL CORP
Entity Central Index Key	19,612
Document Type	10-K
Document Period End Date	Dec. 31, 2016
Amendment Flag	false
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 1,350
Entity Common Stock, Shares Outstanding		71,068,446

Consolidated Statements of Fina

Consolidated Statements of Financial Position - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Cash and cash equivalents:
Cash and cash due from banks	$ 237,758	$ 194,136
Interest-bearing deposits with the Federal Reserve Bank and other banks	236,644	44,653
Total cash and cash equivalents	474,402	238,789
Investment securities:
Available-for-sale, at fair value	1,234,964	553,731
Held-to-maturity, at amortized cost (fair value of $608,531 at 12/31/16 and $512,705 at 12/31/15)	623,427	509,971
Total investment securities	1,858,391	1,063,702
Loans held-for-sale, at fair value	81,830	10,327
Loans	12,990,779	7,271,147
Allowance for loan losses	(78,268)	(73,328)
Net loans	12,912,511	7,197,819
Premises and equipment	145,012	106,317
Loan servicing rights	58,315	11,122
Goodwill	1,133,534	287,393
Other intangible assets	40,211	26,982
Interest receivable and other assets	650,973	246,346
Total assets	17,355,179	9,188,797
Deposits:
Noninterest-bearing	3,341,520	1,934,583
Interest-bearing	9,531,602	5,522,184
Total deposits	12,873,122	7,456,767
Interest payable and other liabilities	134,637	76,466
Securities sold under agreements to repurchase with customers	343,047	297,199
Short-term borrowings	825,000	100,000
Long-term borrowings	597,847	242,391
Total liabilities	14,773,653	8,172,823
Shareholders' equity
Preferred stock, no par value: Authorized – 2,000,000 shares at 12/31/16 and 12/31/15	0	0
Common stock, $1 par value per share: Authorized — 100,000,000 shares at 12/31/16 and 60,000,000 shares at 12/31/15, Issued and outstanding — 70,599,133 shares at 12/31/16 and 38,167,861 shares at 12/31/15	70,599	38,168
Additional paid in capital	2,210,762	725,280
Retained earnings	340,201	281,558
Accumulated other comprehensive loss	(40,036)	(29,032)
Total shareholders' equity	2,581,526	1,015,974
Total liabilities and shareholders' equity	$ 17,355,179	$ 9,188,797

Consolidated Statements of Fin3

Consolidated Statements of Financial Position (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Held-to-maturity, fair value	$ 608,531	$ 512,705
Preferred stock, no par value (in dollars per share)	$ 0	$ 0
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized	100,000,000	60,000,000
Common stock, shares issued	70,599,133	38,167,861
Common stock, shares outstanding	70,599,133	38,167,861

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest Income
Interest and fees on loans	$ 383,545	$ 271,772	$ 209,429
Interest on investment securities:
Taxable	10,989	8,786	9,147
Tax-exempt	12,317	9,073	7,054
Dividends on nonmarketable equity securities	1,973	1,648	1,224
Interest on deposits with the Federal Reserve Bank, other banks and Federal funds sold	1,555	510	407
Total interest income	410,379	291,789	227,261
Interest Expense
Interest on deposits	23,021	15,406	14,254
Interest on short-term borrowings	1,660	453	414
Interest on long-term borrowings	4,617	1,922	42
Total Interest Expense	29,298	17,781	14,710
Net Interest Income	381,081	274,008	212,551
Provision for loan losses	14,875	6,500	6,100
Net interest income after provision for loan losses	366,206	267,508	206,451
Noninterest Income
Service charges and fees on deposit accounts	28,136	25,481	22,414
Wealth management revenue	22,601	20,552	16,015
Other charges and fees for customer services	30,246	25,513	18,928
Mortgage banking revenue	21,859	6,133	5,041
Net gain on sale of investment securities	129	630	0
Gain on sale of branch offices	7,391	0	0
Other	11,988	1,907	697
Total noninterest income	122,350	80,216	63,095
Operating Expenses
Salaries, wages and employee benefits	165,213	127,920	102,557
Occupancy	23,525	18,213	15,842
Equipment and software	24,408	18,569	14,737
Merger and acquisition-related transaction expenses	61,134	7,804	6,388
Other	64,138	51,388	40,401
Total operating expenses	338,418	223,894	179,925
Income before income taxes	150,138	123,830	89,621
Income tax expense	42,106	37,000	27,500
Net income	$ 108,032	$ 86,830	$ 62,121
Earnings per common share:
Basic (in dollars per share)	$ 2.21	$ 2.41	$ 1.98
Diluted (in dollars per share)	2.17	2.39	1.97
Cash Dividends Declared Per Common Share (in dollars per share)	$ 1.06	$ 1	$ 0.94

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net Income	$ 108,032	$ 86,830	$ 62,121
Other Comprehensive Income (Loss), Net of Tax:
Unrealized holding gains (losses) on securities available-for-sale arising during the period	(18,723)	(1,952)	3,492
Reclassification adjustment for gains on realized income	(129)	(630)	0
Tax effect	6,598	904	(1,222)
Net unrealized gains (losses) on securities available-for-sale, net of tax	(12,254)	(1,678)	2,270
Pension plan remeasurement	(707)	0	0
Adjustment for pension and other postretirement benefits	2,630	7,845	(21,851)
Tax effect	(673)	(2,746)	7,648
Net adjustment for pension and other postretirement benefits	1,250	5,099	(14,203)
Other comprehensive income (loss), net of tax	(11,004)	3,421	(11,933)
Total comprehensive income, net of tax	$ 97,028	$ 90,251	$ 50,188

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Restricted Stock Units	Restricted Stock Awards	Common Stock	Common StockRestricted Stock Units	Common StockRestricted Stock Awards	Additional Paid in Capital	Additional Paid in CapitalRestricted Stock Units	Additional Paid in CapitalRestricted Stock Awards	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2013	$ 696,500			$ 29,790			$ 488,177			$ 199,053	$ (20,520)
Changes in Stockholders' Equity
Comprehensive income	50,188									62,121	(11,933)
Cash dividends declared per share: $0.94 per share in 2014, $1.00 per share in 2015 and $1.06 per share in 2016	(29,528)									(29,528)
Issuance of common stock, net of issuance costs	76,175			2,875			73,300
Shares issued — stock options	931			44			887
Shares issued — directors' stock plans	438			18			420
Shares issued — restricted stock units/awards		$ (502)			$ 37			$ (539)
Share-based compensation expense	2,931			10			2,921
Ending balance at Dec. 31, 2014	797,133			32,774			565,166			231,646	(32,453)
Changes in Stockholders' Equity
Comprehensive income	90,251									86,830	3,421
Cash dividends declared per share: $0.94 per share in 2014, $1.00 per share in 2015 and $1.06 per share in 2016	(36,918)									(36,918)
Issuance of common stock and common stock equivalents in business combinations	159,904			5,183			154,721
Shares issued — stock options	2,157			135			2,022
Shares issued — directors' stock plans	316			11			305
Shares issued — restricted stock units/awards		(347)			54			(401)
Share-based compensation expense	3,478			11			3,467
Ending balance at Dec. 31, 2015	1,015,974			38,168			725,280			281,558	(29,032)
Changes in Stockholders' Equity
Comprehensive income	97,028									108,032	(11,004)
Cash dividends declared per share: $0.94 per share in 2014, $1.00 per share in 2015 and $1.06 per share in 2016	(49,389)									(49,389)
Issuance of common stock and common stock equivalents in business combinations	1,504,811			32,074			1,472,737
Shares issued — stock options	(427)			229			(656)
Shares issued — directors' stock plans	2,597			95			2,502
Shares issued — restricted stock units/awards		$ (1,065)	$ (1,455)		$ 60	$ (33)		$ (1,125)	$ (1,422)
Share-based compensation expense	13,452			6			13,446
Ending balance at Dec. 31, 2016	$ 2,581,526			$ 70,599			$ 2,210,762			$ 340,201	$ (40,036)

Consolidated Statements of Cha7

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Stockholders' Equity [Abstract]
Cash dividends declared per share (in dollars per share)	$ 0.27	$ 0.27	$ 0.26	$ 0.26	$ 0.26	$ 0.26	$ 0.24	$ 0.24	$ 1.06	$ 1	$ 0.94

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities
Net Income	$ 108,032	$ 86,830	$ 62,121
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	14,875	6,500	6,100
Gains on sales of loans	(15,686)	(6,354)	(4,451)
Proceeds from sales of loans	723,521	228,995	153,743
Loans originated for sale	(534,422)	(220,765)	(150,795)
Net gains on sale of investment securities	(129)	(630)	0
Net gains from sales/writedowns of other real estate and repossessed assets	(5,212)	(2,681)	(1,886)
Depreciation	13,270	11,028	8,980
Amortization of intangible assets	10,046	8,444	3,345
Additions to loan servicing rights	(4,333)	(1,476)	(1,075)
Valuation change in loan servicing rights	(4,585)	(200)	200
Net amortization of premiums and discounts on investment securities	9,713	6,007	4,497
Share-based compensation expense	13,452	3,478	2,931
Deferred income tax expense (benefit)	24,091	5,700	(1,700)
Net (increase) decrease in interest receivable and other assets	(25,606)	(19,027)	2,322
Net increase (decrease) in interest payable and other liabilities	(46,449)	(2,800)	5,893
Net cash from operating activities	280,578	103,049	90,225
Investment securities — available-for-sale:
Proceeds from maturities, calls and principal reductions	248,772	212,051	165,749
Proceeds from sales and redemptions	41,446	40,301	0
Purchases	(187,702)	0	0
Investment securities — held-to-maturity:
Proceeds from maturities, calls and principal reductions	90,933	87,189	83,989
Purchases	(206,023)	(279,226)	(127,187)
Net increase in loans	(860,135)	(493,776)	(586,121)
Proceeds from sales of other real estate and repossessed assets	22,147	16,653	12,192
Purchases of premises and equipment, net of disposals	(18,098)	(8,527)	(13,411)
Net cash acquired (paid) in business combinations	325,714	16,551	(14,260)
Net cash used in investing activities	(542,946)	(408,784)	(479,049)
Cash flows from financing activities
Net increase in interest- and noninterest-bearing demand deposits and savings accounts	672,584	479,386	277,781
Net decrease in time deposits	(550,847)	(170,598)	(115,642)
Net increase (decrease) in securities sold under agreements to repurchase with customers and other short-term borrowings	401,144	(31,268)	62,039
Proceeds from issuance of long-term borrowings	375,000	125,000	0
Repayment of long-term borrowings	(351,018)	(6,000)	(10,310)
Cash dividends paid	(49,389)	(36,918)	(29,528)
Proceeds from issuance of common stock, net of issuance costs	0	0	76,175
Proceeds from directors' stock plans and exercise of stock options, net of shares withheld	1,572	2,473	1,242
Cash paid for payroll taxes upon conversion of share-based awards	(1,065)	(571)	(701)
Net cash from financing activities	497,981	361,504	261,056
Net increase (decrease) in cash and cash equivalents	235,613	55,769	(127,768)
Cash and cash equivalents at beginning of year	238,789	183,020	310,788
Cash and cash equivalents at end of year	474,402	238,789	183,020
Supplemental disclosures of cash flow information:
Interest paid	25,460	16,958	14,823
Income taxes paid, net of refunds	22,200	41,450	25,900
Loans transferred to other real estate and repossessed assets	12,970	9,329	11,308
Closed branch offices transferred to other assets	4,846	2,692	841
Business combinations:
Fair value of tangible assets acquired (noncash)	6,371,781	1,282,420	747,181
Goodwill, loan servicing rights and other identifiable intangible assets acquired	908,217	118,744	82,090
Liabilities assumed	6,100,901	1,258,051	815,011
Common stock and stock options issued	$ 1,504,811	$ 159,904	$ 0

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Nature of Operations Chemical Financial Corporation ("Corporation" or "Chemical") operates in a single operating segment — commercial banking. The Corporation is a financial holding company, headquartered in Midland, Michigan, that operates through one commercial bank, Chemical Bank. Chemical Bank operates within Michigan, Ohio and Indiana as a state-chartered commercial bank. Chemical Bank operates through an internal organizational structure of seven 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, wealth management revenue and mortgage banking revenue. Basis of Presentation and Principles of Consolidation The accounting and reporting policies of the Corporation and its subsidiaries have been prepared in accordance with U.S.generally accepted accounting principles ("GAAP"), Securities and Exchange Commission ("SEC") rules and interpretive releases and prevailing practices within the banking industry. The consolidated financial statements of the Corporation include the accounts of the Corporation and its wholly owned subsidiaries. All significant income and expenses are recorded on the accrual basis. Intercompany accounts and transactions have been eliminated in preparing the consolidated financial statements. Use of Estimates Management makes estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying footnotes. Estimates that are particularly susceptible to significant change include the determination of the allowance for loan losses, expected cash flows from acquired loans, 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 the Financial Accounting Standards Board's ("FASB") Accounting Standards Codification ("ASC") Topic 805, Business Combinations ("ASC 805"), the Corporation recognizes assets acquired, including identified intangible assets, and the liabilities assumed in acquisitions at their fair values as of the acquisition date, with the acquisition-related transaction and restructuring costs expensed in the period incurred. On August 31, 2016, the Corporation acquired all the outstanding stock of Talmer Bancorp, Inc. ("Talmer") for total consideration of $1.61 billion , which included stock consideration of $1.50 billion and cash consideration of $107.6 million . The Corporation recorded $846.7 million of goodwill in conjunction with the merger, which represented the purchase price over the fair value of identifiable net assets acquired. Additionally, the Corporation recorded $19.1 million of core deposit intangible assets in conjunction with the acquisition related to total deposits acquired of $5.29 billion . ASC 805 affords a measurement period beyond the acquisition date that allows the Corporation the opportunity to finalize the acquisition accounting in the event that new information is identified that existed as of the acquisition date but was not known by the Corporation at that time. The Corporation anticipates that measurement period adjustments may arise from adjustments to the fair values of assets and liabilities recognized at the acquisition date for its August 31, 2016 merger with Talmer, as additional information is obtained, such as appraisals of collateral securing loans and other borrower information. In the event that a measurement period adjustment is identified, the Corporation will recognize the adjustment as part of its acquisition accounting, which may result in an adjustment to goodwill being recorded in the period the adjustment was identified. See Note 2 for further information regarding the Corporation's mergers and acquisitions. Cash and Cash Equivalents For purposes of reporting cash flows, cash and cash equivalents include cash on hand and interest-bearing deposits held at the Federal Reserve Bank ("FRB"). Investment Securities Investment securities include investments in debt, trust preferred and preferred stock securities. Investment securities are accounted for in accordance with ASC Topic 320, Investments — Debt and Equity Securities ("ASC 320"), which requires investments to be classified within one of three categories (trading, held-to-maturity or available-for-sale). The Corporation held no trading investment securities at December 31, 2016 or 2015 . Designation as an investment security held-to-maturity is based on the Corporation's intent and ability to hold the security to maturity. Investment securities held-to-maturity are stated at cost, adjusted for purchase price premiums and discounts. Investment securities that are not held-to-maturity are accounted for as securities available-for-sale, and are stated at estimated fair value, with the aggregate unrealized gains and losses, not deemed other-than-temporary, classified as a component of accumulated other comprehensive income (loss), net of income taxes. Realized gains and losses on the sale of investment securities and other-than-temporary impairment ("OTTI") charges are determined using the specific identification method and are included within noninterest income in the consolidated statements of income. Premiums and discounts on investment securities are amortized over the estimated lives of the related investment securities based on the effective interest yield method and are included in interest income in the consolidated statements of income. The Corporation assesses equity and debt securities that have fair values below amortized cost basis to determine whether declines (impairment) are other-than-temporary. If the Corporation intends to sell an impaired security or it is more-likely-than-not that the Corporation will be required to sell an impaired security prior to the recovery of its amortized cost, an OTTI write-down is recognized in earnings equal to the entire difference between the security's amortized cost basis and its fair value. If the Corporation does not intend to sell an impaired security and it is not more-likely-than-not that the Corporation would be required to sell an impaired security before the recovery of its amortized cost basis, then the recognition of the impairment is bifurcated if a credit loss is deemed to have occurred. For a security where the impairment is bifurcated, the impairment is separated into an amount representing the credit loss, which is recognized in earnings, and an amount related to all other factors, which is recognized in other comprehensive income. In assessing whether OTTI exists, management considers, among other things, (i) the length of time and the extent to which the fair value has been less than cost, (ii) the financial condition and near-term prospects of the issuer, (iii) the potential for impairments in an entire industry or sub-sector and (iv) the potential for impairments in certain economically depressed geographical locations. Nonmarketable Equity Securities The Corporation is required to hold non-marketable equity securities, comprised of Federal Home Loan Bank of Indianapolis ("FHLB") and FRB stock, as a condition of membership. These securities are accounted for at cost, which equals par or redemption value. These securities do not have a readily determinable fair value as their ownership is restricted and there is no market for these securities. These securities can only be redeemed or sold at their par value and only to the respective issuing government supported institution or to another member institution. FHLB stock can only be redeemed upon giving five -years written notice and FRB stock can only be redeemed upon giving six months written notice, with no more than 25.0% eligible for redemption in any calendar year. The Corporation records these non-marketable equity securities as a component of other assets and they are periodically evaluated for impairment. Management considers these non-marketable equity securities to be long-term investments. Accordingly, when evaluating these securities for impairment, management considers the ultimate recoverability of the par value rather than recognizing temporary declines in value, if applicable. The Corporation's ownership of FHLB stock totaled $58.0 million at December 31, 2016 and $23.9 million at December 31, 2015 . The Corporation's ownership of FRB stock totaled $39.4 million at December 31, 2016 and $13.0 million at December 31, 2015 . Loans Held for Sale Mortgage and construction loans intended for sale in the secondary market are carried at fair value based on the Corporation's election of the fair value option. The fair value includes the servicing value of the loans as well as any accrued interest. These loans are sold both with servicing rights retained and with servicing rights released. Originated Loans Originated loans include all of the Corporation's portfolio loans, excluding loans acquired in business combinations, as further discussed below. Originated loans are stated at their principal amount outstanding, net of unearned income, charge-offs and unamortized deferred fees and costs. Loan interest income is recognized on the accrual basis. Deferred loan fees and costs are amortized over the loan term based on the level-yield method. Net loan commitment fees are deferred and amortized into fee income on a straight-line basis over the commitment period. The past due status of a loan is based on the loan's contractual terms. A loan is placed in nonaccrual status (accrual of interest is discontinued) when principal or interest is past due 90 days or more, 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 August 31, 2016 in the merger with Talmer, on May 31, 2015 in the acquisition of Lake Michigan Financial Corporation ("Lake Michigan"), on April 1, 2015 in the acquisition of Monarch Community Bancorp, Inc. ("Monarch"), on October 31, 2014 in the acquisition of Northwestern Bancorp, Inc. ("Northwestern"), and on April 30, 2010 in the acquisition of O.A.K. Financial Corporation ("OAK"). Acquired loans were recorded at fair value at the date of acquisition, without a carryover of the associated allowance for loan losses related to these loans. The Corporation accounts for acquired loans, which are recorded at fair value at acquisition, in accordance with ASC Topic 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality ("ASC 310-30"). ASC 310-30 allows investors to aggregate loans acquired into loan pools that have common risk characteristics and thereby use a composite interest rate and expectation of cash flows expected to be collected for the loan pools. Under the provisions of ASC 310-30, the Corporation aggregated acquired loans into pools within each merger or acquisition based upon common risk characteristics, including types of loans, commercial type loans with similar risk grades and whether loans were performing or nonperforming. A pool is considered a single unit of accounting for the purposes of applying the guidance prescribed in ASC 310-30. A loan will be removed from a pool of acquired loans only if the loan is sold, foreclosed, paid off or written off, and will be removed from the pool at the carrying value. 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 estimate of expected credit losses was determined based on due diligence performed by executive and senior officers of the Corporation, with assistance from third-party consultants. The Corporation estimated the cash flows expected to be collected over the life of the pools of loans at acquisition and estimates expected cash flows quarterly thereafter, based on a set of assumptions including expectations as to default rates, prepayment rates and loss severities. The Corporation must make numerous assumptions, interpretations and judgments using internal and third-party credit quality information to determine whether it is probable that the Corporation will be able to collect all contractually required payments. This is a point in time assessment and inherently subjective due to the nature of the available information and judgment involved. The calculation of the fair value of the acquired loan pools entails estimating the amount and timing of cash flows attributable to both principal and interest expected to be collected on such loan pools and then discounting those cash flows at market interest rates. The excess of a loan pool's expected cash flows at the acquisition date over its estimated fair value is referred to as the "accretable yield," which is recognized into interest income over the estimated remaining life of the loan pool on a level-yield basis. The difference between a loan pool's contractually required principal and interest payments at the acquisition date and the cash flows expected to be collected at the acquisition date is referred to as the "nonaccretable difference," which includes an estimate of future credit losses expected to be incurred over the estimated life of the loan pool and interest payments that are not expected to be collected. Decreases to the expected cash flows in each loan pool in subsequent periods will require the Corporation to record a provision for loan losses and establish an allowance for loan loss. 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 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 accruing TDRs, which consist of originated loans that continue to accrue interest as the Corporation expects to collect the remaining principal and interest on the loan, and nonaccrual TDRs, which include originated loans that are in a nonaccrual status and are no longer accruing interest, as the Corporation does not expect to collect the full amount of principal and interest owed from the borrower on these loans. All TDRs are accounted for as impaired loans and are included in the Corporation's analysis of the allowance for loan losses. A TDR that has been renewed by a borrower who is no longer experiencing financial difficulty and which yields a market rate of interest at the time of a renewal is no longer reported as a TDR. 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 current and a six-month payment history has been sustained, the loan is classified as an accruing TDR. Since no loss is expected to be incurred on these loans, no additional provision for loan losses has been recognized for these loans and they continue to accrue interest at their contractual interest rate. Accruing TDRs are transferred to nonaccrual status if they become 90 days past due as to principal or interest payments or if it is probable that any remaining principal and interest payments due on the loan will not be collected in accordance with the modified terms of the loan. Loans in the Corporation's consumer loan portfolio (comprised of residential mortgage, consumer installment and home equity loans) that meet the definition of a TDR 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. TDRs are placed on nonaccrual status if they become 90 days past due as to principal or interest payments, or sooner if conditions warrant. Impaired Loans Impaired loans include loans on nonaccrual status and TDRs. Loans are considered impaired when based on current information and events it is probable the Corporation will be unable to collect all amounts due in accordance with the original contractual terms of the loan agreements. Impaired loans are accounted for at the lower of the present value of expected cash flows discounted at the loan's original effective interest rate or the estimated fair value of the collateral, if the loan is collateral dependent. When the present value of expected cash flows or the fair value of collateral of an impaired loan in the originated loan portfolio is less than the amount of unpaid principal outstanding on the loan, the principal balance of the loan is reduced to its carrying value through either a specific allowance for loan losses or a partial charge-off of the loan balance. Nonperforming Loans Nonperforming loans are comprised of loans for which the accrual of interest has been discontinued (nonaccrual loans, including nonaccrual TDRs). Acquired loans that were classified as nonperforming loans prior to being acquired and acquired loans that are not performing in accordance with contractual terms subsequent to acquisition are not classified as nonperforming loans subsequent to acquisition because the loans are recorded in pools at net realizable value based on the principal and interest the Corporation expects to collect on such loans. 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 originated loan portfolio. Management's evaluation of the adequacy of the allowance is based on a continuing review of the originated 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 originated 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 credit quality review quarterly on impaired loans, and may establish 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 historical experience and other 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 consumer 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 look-back period, with equal weighting placed on all of the years and giving consideration to estimated loss emergence periods, and (iv) a reserve for qualitative factors that take into consideration risks inherent in the originated loan portfolio that differ from historical loan loss experience. The first element reflects the Corporation's estimate of probable losses based upon the systematic review of individually impaired loans in the originated loan portfolio. These estimates are based upon a number of objective factors, such as payment history, financial condition of the borrower and discounted collateral exposure. The Corporation measures the investment in an impaired loan based on one of three methods: the loan's observable market price; the fair value of the collateral; or the present value of expected future cash flows discounted at the loan's effective interest rate. Loans in the commercial loan portfolio that were in nonaccrual status (including nonaccrual TDRs) were valued based on the fair value of the collateral securing the loan, while accruing TDRs in the commercial loan portfolio and consumer loans were valued based on the present value of expected future cash flows discounted at the loan's effective interest rate. It is the Corporation's general policy to obtain new appraisals at least annually on nonaccrual loans in the commercial loan portfolio. Appraisals on nonaccrual loans in the consumer loan portfolio are generally updated annually where there is a delay in the foreclosure process. When the Corporation determines that the fair value of the collateral is less than the carrying value of an impaired loan and a portion is deemed not collectible, the portion of the impairment that is deemed not collectible is charged off (confirmed loss) and deducted from the allowance. The remaining carrying value of the impaired loan is classified as a nonperforming loan. When the Corporation determines that the fair value of the collateral is less than the carrying value of an impaired loan but believes it is probable it will recover this impairment, the Corporation establishes a valuation allowance for such impairment. The second element reflects the application of the Corporation's loan grade risk rating system. This risk rating system is similar to those employed by state and federal banking regulators. Loans in the commercial loan portfolio that are risk rated below a certain predetermined risk grade are assigned a loss allocation factor that is based upon a historical analysis of actual loan losses incurred and a valuation of the type of collateral securing the loans. The third element is determined by assigning allocations based principally upon a five -year average of loss experience for each class of loan. Average losses may be adjusted based on current loan loss experience, delinquency trends, estimated loss emergence periods and other industry specific environmental factors. This component considers the lagging impact of historical charge-off ratios in periods where future loan charge-offs are expected to increase or decrease, trends in delinquencies and nonaccrual loans, the changing portfolio mix in terms of collateral, average loan balance, loan growth and the degree of seasoning in the various loan portfolios. Loan loss analyses are performed quarterly and certain inputs and parameters are updated as necessary to reflect the current credit environment. The fourth element is based on qualitative factors that cannot be associated with a specific credit or loan class and reflects an attempt to ensure that the overall allowance appropriately reflects additional losses that are inherent in the Corporation's loan portfolio. Determination of the probable losses inherent in the portfolio, which are not necessarily captured by the allocation methodology discussed above, involves the exercise of judgment. This qualitative portion of the allowance is judgmentally determined and generally serves to compensate for the uncertainty in estimating inherent losses, particularly in times of changing economic conditions, and also considers the inherent judgment associated with risk rating commercial loans. The qualitative portion of the allowance also takes into consideration, among other things, economic conditions within our geographic areas and nationwide, including unemployment levels, industry-wide and Corporation specific loan delinquency rates, changes in composition of and growth in the Corporation's loan portfolio and changing commercial and residential real estate values. Although the Corporation allocates portions of the allowance to specific loans and loan types, the entire allowance attributable to originated loans is available for any loan losses that occur in the originated portfolio. Loans that are deemed not collectible are charged off and reduce the allowance. The provision for loan losses and recoveries on loans previously charged off increase the allowance. Collection efforts may continue and recoveries may occur after a loan is charged off. Acquired loans are aggregated into pools based upon common risk characteristics. An allowance may be recorded related to an acquired loan pool if it experiences a decrease in expected cash flows, as compared to those projected at the acquisition date. On a quarterly basis, the expected future cash flow of each pool is estimated based on various factors, including changes in property values of collateral dependent loans, default rates, loss severities and prepayment speeds. Decreases in estimates of expected cash flows within a pool generally result in a charge to the provision for loan losses and a corresponding increase in the allowance allocated to acquired loans for the particular pool. Increases in estimates of expected cash flows within a pool generally result in a reduction in the allowance allocated to acquired loans for the particular pool, if applicable, and then an adjustment to the accretable yield for the pool, which will increase amounts recognized in interest income in subsequent periods. Various regulatory agencies, as an integral part of their examination processes, periodically review the allowance. Such agencies may require additions to the allowance, based on their judgment, reflecting information available to them at the time of their examinations. Mortgage Banking Operations The origination of residential mortgage loans is a large component of the business of the Corporation. The Corporation generally sells conforming long-term fixed interest rate mortgage loans it originates in the secondary market. Gains on the sales of these loans are determined using the specific identification method. The Corporation sells residential mortgage loans in the secondary market on either a servicing retained or released basis. The Corporation elected the fair value measurement option, as prescribed by ASC Topic 820, Fair Value Measurements and Disclosures ("ASC 820"), for all residential mortgage loans held-for-sale originated on or after July 1, 2012. This election allows for a more effective offset of the changes in fair value of residential mortgage loans held-for-sale and the derivative instruments used to economically hedge them without having to apply complex hedge accounting provisions. Residential mortgage loans held-for-sale are carried at fair value, with changes in fair value recorded through earnings. Residential mortgage loan commitments, forward commitments, are generally entered into at the time customer applications are accepted to protect the value of the mortgage loans from increases in market interest rates during the period held and are generally settled with the investor in the secondary market within 90 days after entering into the forward commitment. Forward loan commitments are accounted for as derivatives and recorded at fair value, with changes in fair value recorded through earnings. The Corporation recognizes revenue associated with the expected future cash flows of servicing loans for loans held-for-sale at the time a forward loan commitment is made to originate a held-for-sale loan, as required under SEC Staff Accounting Bulletin No. 109, Written Loan Commitments Recorded at Fair Value Through Earnings. The Corporation accounts for loan servicing rights ("LSRs") by separately recognizing servicing assets at the date of sale. An asset is recognized for the rights to service mortgage loans that are created by the origination of mortgage loans that are sold with the servicing retained by the Corporation. The Corporation elected to account for LSRs acquired related to the merger with Talmer under the fair value measurement method. Loan servicing rights are established and recorded at the estimated fair value by calculating the present fair value of estimated future net servicing cash flows, taking into consideration actual and expected mortgage loan prepayment rates, discount rates, servicing costs, and other economic factors, which are determined based on current market conditions. The Corporation continues to account for all other LSRs at the lower of amortized cost or fair value ("Amortized LSRs") and amortizes LSRs in proportion to and over the period of net servicing income. Unexpected prepayments of mortgage loans result

Mergers and Acquisitions

Mergers and Acquisitions	12 Months Ended
	Dec. 31, 2016
Business Combinations [Abstract]
Mergers and Acquisitions	Mergers and Acquisitions Merger with Talmer Bancorp, Inc. On August 31, 2016, the Corporation completed the merger with Talmer for total consideration of $1.61 billion . As a result of the merger, the Corporation issued 32.1 million shares of its common stock based on an exchange ratio where each Talmer shareholder received 0.4725 shares of the Corporation's common stock, and $ 1.61 in cash, for each share of Talmer common stock. In conjunction with the merger, the Corporation entered into and drew on a $125.0 million credit facility, which is described in more detail in Note 14. The proceeds from the credit facility were used to pay off the Corporation's $25.0 million line-of-credit and a $ 37.5 million line-of-credit of Talmer, with the remaining proceeds used to partially fund the cash portion of the merger consideration. The Corporation incurred $61.1 million of merger and acquisition-related transaction expenses during the year ended December 31, 2016, primarily related to the merger with Talmer. As a result of the merger, Talmer Bank and Trust became a wholly-owned subsidiary of the Corporation. Subsequent to the merger with Talmer, in the fourth quarter of 2016, the Corporation sold the Talmer Bank and Trust single branch locations in Chicago, Illinois and Las Vegas, Nevada. Talmer Bank and Trust was consolidated with and into Chemical Bank during the fourth quarter of 2016. The Company determined that the merger with Talmer constitutes a business combination as defined by ASC 805. Accordingly, the assets acquired and liabilities assumed were recorded at their fair values on the date of acquisition. Fair values were determined in accordance with the guidance provided in ASC Topic 820, Fair Value Measurements. In many cases the determination of the fair values required management to make estimates about discount rates, future expected cash flows, market conditions and other future events that are highly subjective in nature and subject to change. The following allocation is based on the information that was available to make preliminary estimates of the fair value and may change as additional information becomes available and additional analyses are completed. While the Corporation believes that information provided a reasonable basis for estimating the fair values, it expects that it could obtain additional information and evidence during the measurement period that may result in changes to the estimated fair value amounts. This measurement period ends on the earlier of one year after the merger date or the date we receive the information about the facts and circumstances that existed at the merger date. Subsequent adjustments, if necessary, will be reflected in future filings. These refinements include: (1) changes in the estimated fair value of loans acquired; (2) changes in the estimated fair value of intangible assets acquired; (3) changes in deferred tax assets related to fair value estimates and a change in the expected realization of items considered to be net operating loss carry forwards and (4) a change in the goodwill caused by the net effect of these adjustments. (Dollars in thousands) Consideration paid: Stock $ 1,504,811 Cash 107,638 Total consideration 1,612,449 Fair value of identifiable assets acquired (1) : Cash and cash equivalents 433,352 Investment securities: Available-for-sale 808,894 Held-to-maturity 1,657 Loans held-for-sale 244,916 Loans (2) 4,882,402 Premises and equipment 38,793 Loan servicing rights 42,462 Other intangible assets (2) 19,088 Interest receivable and other assets (2) 395,119 Total identifiable assets acquired 6,866,683 Fair value of liabilities assumed (1) : Noninterest-bearing deposits 1,236,902 Interest-bearing deposits 4,057,716 Interest payable and other liabilities (2) 99,482 Securities sold under agreements to repurchase with customers 19,704 Short-term borrowings 387,500 Long-term borrowings 299,597 Total liabilities assumed 6,100,901 Fair value of net identifiable assets acquired 765,782 Goodwill resulting from acquisition $ 846,667 (1) All amounts were previously reported in the Corporation's Quarterly Report on Form 10-Q for the three- and nine-month periods ended September 30, 2016, with the exception of loans, other intangible assets, interest receivable and other assets and interest payable and other liabilities. (2) Includes adjustments to the fair value as a result of additional valuation information obtained during the fourth quarter of 2016, including the corresponding tax effects. During the fourth quarter of 2016, additional valuation information was obtained related to the fair value of the core deposit intangible and deferred tax assets, which resulted in an adjustment to goodwill acquired in the Talmer transaction. The adjustments recorded during the fourth quarter of 2016, which resulted in a $3.6 million decrease to the preliminary amount of goodwill recorded for the Talmer transaction, included a $6.7 million increase in the fair value of the other intangible assets related to updated information obtained regarding the fair market value of the core deposit intangible and a $2.5 million decrease in the amount of recognizable deferred tax assets primarily based on the tax impact of the core deposit intangible adjustment. Information regarding loans accounted for under ASC 310-30 at the merger date is as follows: (Dollars in thousands) Accounted for under ASC 310-30: Contractual cash flows $ 5,968,488 Contractual cash flows not expected to be collected (nonaccretable difference) 223,959 Expected cash flows 5,744,529 Interest component of expected cash flows (accretable yield) 862,127 Fair value at acquisition $ 4,882,402 At December 31, 2016, the outstanding contractual principal balance and the carrying amount of the Talmer acquired loan portfolio were $ 4.5 billion and $ 4.4 billion , respectively. Acquisition of Lake Michigan Financial Corporation On May 31, 2015, the Corporation acquired all of the outstanding stock 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 were consolidated with and into Chemical Bank on November 13, 2015. At the acquisition date, Lake Michigan added total assets of $1.24 billion , including total loans of $985.5 million , and total deposits of $924.7 million to the Corporation's consolidated statement of financial position. The Corporation recorded $101.1 million of goodwill, which was primarily attributable to the synergies and economies of scale expected from combining the operations of the Corporation and Lake Michigan. In addition, the Corporation recorded $8.6 million of core deposit and other intangible assets in conjunction with the acquisition. The results of the merged Lake Michigan operations are presented in the Corporation's consolidated financial statements from the date of acquisition. Acquisition-related expenses associated with the Lake Michigan transaction totaled $5.5 million during 2015. 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. During the first quarter of 2016, the Corporation obtained additional information regarding the valuation of deferred tax assets, which resulted in a decrease to goodwill recognized in the transaction of $0.6 million . A summary of the purchase price and the excess of the purchase price over the fair value of adjusted net assets acquired (goodwill) follows: (Dollars in thousands) Stock $ 132,916 Cash 54,478 Total consideration 187,394 Net assets acquired (1) : 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 (5,031 ) Core deposit intangibles 8,003 Deferred tax assets, net (2) 4,096 Deposits and borrowings, net (3,182 ) Other assets and other liabilities (2) (121 ) Fair value of adjusted net assets acquired 86,333 Goodwill recognized as a result of the Lake Michigan transaction $ 101,061 (1) All amounts were previously reported in the Corporation's Annual Report on Form 10-K for the year ended December 31, 2015, with the exception of deferred tax assets, net and other assets and other liabilities. (2) Includes adjustments to the fair value as a result of additional valuation information obtained during the first quarter of 2016, including the corresponding tax effects. Allocation of Purchase Price The following schedule summarizes the revised acquisition date estimated fair values, including the adjustments to the fair values identified and recorded from the acquisition date through December 31, 2016, of assets acquired and liabilities assumed from Lake Michigan (in thousands): (Dollars in thousands) Assets Cash and cash equivalents $ 39,301 Investment securities 66,699 Loans 985,542 Premises and equipment 10,975 Deferred tax asset, net 16,715 Goodwill 101,061 Core deposit intangible asset 8,003 Bank-owned life insurance 23,844 Other assets 37,695 Assets acquired, at fair value 1,289,835 Liabilities Deposits 924,697 Short-term borrowings 30,000 Other borrowings 124,857 Other liabilities 22,887 Total liabilities acquired, at fair value 1,102,441 Total purchase price $ 187,394 Information regarding loans accounted for under ASC 310-30 at the merger date is as follows: (Dollars in thousands) Accounted for under ASC 310-30: Contractual cash flows $ 1,198,388 Contractual cash flows not expected to be collected (nonaccretable difference) 22,600 Expected cash flows 1,175,788 Interest component of expected cash flows (accretable yield) 190,246 Fair value at acquisition $ 985,542 The outstanding contractual principal balance and the carrying amount of the Lake Michigan acquired loan portfolio were $ 656.1 million and $ 634.2 million , respectively, at December 31, 2016 , compared to $864.4 million and $841.8 million , respectively, at December 31, 2015 . 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. Monarch Community Bank was consolidated with and into Chemical Bank on May 8, 2015. At the acquisition date, Monarch added total assets of $182.8 million , including total loans of $121.8 million , and total deposits of $144.3 million to the Corporation's consolidated statement of financial position. In connection with the acquisition of Monarch, the Corporation recorded $5.3 million of goodwill, which was primarily attributable to the synergies and economies of scale expected from combining the operations of the Corporation and Monarch. In addition, the Corporation recorded $1.9 million of core deposit intangible assets in conjunction with the acquisition. The results of the merged Monarch operations are presented in the Corporation's consolidated financial statements from the date of acquisition. 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 during the second quarter of 2015. Acquisition-related expenses associated with the Monarch transaction totaled $2.3 million during 2015. 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. A summary of the purchase price and the excess of the purchase price over the fair value of adjusted net assets acquired (goodwill) follows: (Dollars in thousands) Stock $ 26,988 Cash 203 Total consideration $ 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 1,826 Premises and equipment (415 ) Core deposit intangibles 1,930 Mortgage servicing rights 315 Other assets and other liabilities 48 Fair value of adjusted net assets acquired 21,852 Goodwill recognized as a result of the Monarch transaction $ 5,339 Allocation of Purchase Price The following schedule summarizes the revised acquisition date estimated fair values, including the adjustments to the fair values identified and recorded from the acquisition date through December 31, 2015, of assets acquired and liabilities assumed from Monarch. (Dollars in thousands) Assets Cash and cash equivalents $ 32,171 Loans 121,783 Premises and equipment 3,019 Deferred tax assets, net Net operating loss carryforward 7,900 Other 2,392 Interest receivable and other assets 6,972 Goodwill 5,339 Core deposit intangibles 1,930 Mortgage servicing rights 1,284 Assets acquired, at fair value 182,790 Liabilities Deposits 144,300 FHLB advances 8,000 Interest payable and other liabilities 3,299 Total liabilities acquired, at fair value 155,599 Total purchase price $ 27,191 Information regarding loans accounted for under ASC 310-30 at the merger date is as follows: (Dollars in thousands) Accounted for under ASC 310-30: Contractual cash flows $ 166,797 Contractual cash flows not expected to be collected (nonaccretable difference) 7,100 Expected cash flows 159,697 Interest component of expected cash flows (accretable yield) 37,914 Fair value at acquisition $ 121,783 The outstanding contractual principal balance and the carrying amount of the Monarch acquired loan portfolio were $ 92.4 million and $ 86.4 million , respectively, at December 31, 2016 , compared to $114.9 million and $108.3 million , respectively, at December 31, 2015 . 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 $121.0 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 $815.0 million , including total loans of $475.3 million , and total deposits of $794.4 million to the Corporation. Northwestern Bank was consolidated with and into Chemical Bank as of the acquisition date. In connection with the acquisition of Northwestern, the Corporation recorded $60.3 million of goodwill, which was primarily attributable to the synergies and economies of scale expected from combining the operations of the Corporation and Northwestern. In addition, the Corporation recorded $12.9 million of core deposit intangible assets in conjunction with the acquisition. The results of the merged Northwestern operations are presented within the Corporation’s consolidated financial statements from the acquisition date. Acquisition-related expenses associated with the Northwestern acquisition totaled $5.8 million during 2014. Information regarding loans accounted for under ASC 310-30 at the merger date is as follows: (Dollars in thousands) Accounted for under ASC 310-30: Contractual cash flows $ 618,788 Contractual cash flows not expected to be collected (nonaccretable difference) 33,500 Expected cash flows 585,288 Interest component of expected cash flows (accretable yield) 110,003 Fair value at acquisition $ 475,285 The outstanding contractual principal balance and the carrying amount of the Northwestern acquired loan portfolio were $283.1 million and $254.1 million , respectively, at December 31, 2016, compared to $361.3 million and $329.9 million , respectively, at December 31, 2015. Unaudited Pro Forma Combined Results of Operations The following unaudited pro forma financial information presents the consolidated results of operation of the Corporation and Talmer as if the merger had occurred as of January 1, 2015, Lake Michigan and Monarch as if the acquisitions had occurred as of January 1, 2014 and Northwestern as if the acquisition had occurred as of January 1, 2013. The unaudited pro forma combined results of operations are presented solely for information purposes and are not intended to represent or be indicative of the consolidated results of operations that Chemical would have reported had these transactions been completed as of the dates and for the periods presented, nor are they necessarily indicative of future results. In particular, no adjustments have been made to eliminate the amount of Talmer, 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 accordance with Article 11 of SEC Regulation S-X, transaction costs directly attributable to the acquisitions have been excluded. Years ended December 31, (In thousands, except per share data) 2016 2015 2014 Net interest and other income $ 492,323 $ 654,962 $ 361,695 Net Income 115,847 142,504 79,455 Earnings per share: Basic $ 1.65 $ 2.03 $ 2.17 Diluted $ 1.62 $ 2.01 $ 2.16 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: (Dollars in thousands) Talmer Lake Michigan Monarch Northwestern OAK Total Year Ended December 31, 2016 Balance at beginning of period $ — $ 152,999 $ 34,558 $ 82,623 $ 28,077 $ 298,257 Addition attributable to acquisitions 862,127 — — — — 862,127 Additions, net of reductions* — (3,552 ) (1,908 ) (6,985 ) 1,091 (11,354 ) Accretion recognized in interest income (63,917 ) (33,031 ) (5,468 ) (15,791 ) (13,352 ) (131,559 ) Reclassification from nonaccretable difference — 5,000 — 10,000 7,500 22,500 Balance at end of period $ 798,210 $ 121,416 $ 27,182 $ 69,847 $ 23,316 $ 1,039,971 Year Ended December 31, 2015 Balance at beginning of period $ — $ — $ — $ 104,675 $ 33,286 $ 137,961 Addition attributable to acquisitions — 190,246 37,914 — — 228,160 Additions, net of reductions* — (12,991 ) 1,336 (3,396 ) 6,601 (8,450 ) Accretion recognized in interest income — (24,256 ) (4,692 ) (18,656 ) (11,810 ) (59,414 ) Balance at end of period $ — $ 152,999 $ 34,558 $ 82,623 $ 28,077 $ 298,257 * Represents additions in 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.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair value, as defined by GAAP, is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. A fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability. The price in the principal (or most advantageous) market used to measure the fair value of the asset or liability is not adjusted for transaction costs. An orderly transaction is a transaction that assumes exposure to the market for a period prior to the measurement date to allow for market activities that are usual and customary for transactions involving such assets and liabilities; it is not a forced transaction. Market participants are buyers and sellers in the principal market that are (i) independent, (ii) knowledgeable, (iii) able to transact and (iv) willing to transact. The Corporation utilizes fair value measurements to record fair value adjustments to certain assets and to determine fair value disclosures. Investment securities — available-for-sale, loans held-for-sale, certain loan servicing rights and derivatives are recorded at fair value on a recurring basis. Additionally, the Corporation may be required to record other assets, such as impaired loans, goodwill, other intangible assets, other real estate and repossessed assets, at fair value on a nonrecurring basis. These nonrecurring fair value adjustments typically involve the application of lower of cost or market accounting or write-downs of individual assets. The Corporation determines the fair value of its financial instruments based on a three-level hierarchy established by GAAP. The classification and disclosure of assets and liabilities within the hierarchy is based on whether the inputs to the valuation methodology used for measurement are observable or unobservable. Observable inputs reflect market-derived or market-based information obtained from independent sources, while unobservable inputs reflect management's estimates about market data. The three levels of inputs that may be used to measure fair value within the GAAP hierarchy are as follows: Level 1 Valuation is based upon quoted prices for identical instruments traded in active markets. Level 1 valuations for the Corporation include U.S. Treasury securities that are traded by dealers or brokers in active over-the-counter markets. Valuations are obtained from a third-party pricing service for these investment securities. Level 2 Valuation is based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant assumptions are observable in the market. Level 2 valuations for the Corporation include government sponsored agency securities, including securities issued by the Federal Home Loan Bank, Federal Home Loan Mortgage Corporation, Federal National Mortgage Association, Federal Farm Credit Bank, Student Loan Marketing Corporation and the Small Business Administration, securities issued by certain state and political subdivisions, residential mortgage-backed securities, collateralized mortgage obligations, corporate bonds, preferred stock and available-for-sale trust preferred securities. Valuations are obtained from a third-party pricing service for these investment securities. Additionally included in Level 2 valuations are loans held-for-sale and derivative assets and liabilities. Level 3 Valuation is generated from model-based techniques that use at least one significant assumption not observable in the market. These unobservable assumptions reflect estimates of assumptions that market participants would use in pricing the asset or liability. Valuation techniques include use of option pricing models, discounted cash flow models, yield curves and similar techniques. The determination of fair value requires management judgment or estimation and generally is corroborated by external data, which includes third-party pricing services. Level 3 valuations for the Corporation include securities issued by certain state and political subdivisions, held-to-maturity trust preferred investment securities, impaired loans, goodwill, core deposit intangible assets, non-compete intangible assets, LSRs and other real estate and repossessed assets. A description of the valuation methodologies used for instruments measured at fair value, as well as the general classification of such instruments pursuant to the valuation hierarchy, is set forth below. These valuation methodologies were applied to all of the Corporation's financial assets and financial liabilities carried at fair value and all financial instruments disclosed at fair value. Transfers of asset or liabilities between levels of the fair value hierarchy are recognized at the beginning of the reporting period, when applicable. In general, fair value is based upon quoted market prices, where available. If quoted market prices are not available, fair value is based upon third-party pricing services when available. Fair value may also be based on internally developed models that primarily use, as inputs, observable market-based parameters. Valuation adjustments may be required to record financial instruments at fair value. Any such valuation adjustments are applied consistently over time. The Corporation's valuation methodologies may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. While management believes the Corporation's valuation methodologies are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date. Furthermore, the fair value amounts may change significantly after the date of the statement of financial position from the amounts reported in the consolidated financial statements and related notes. Assets and Liabilities Recorded at Fair Value on a Recurring Basis Investment securities: Investment securities classified as 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. Loans held-for-sale: 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. Loan servicing rights: LSRs acquired related to the merger with Talmer effective August 31, 2016 are accounted for under the fair value measurement method based on accounting election. A third party valuation model is used to determine the fair value at the end of each reporting period utilizing a discounted cash flow analysis using interest rates and prepayment speed assumptions currently quoted for comparable instruments and a discount rate determined by management. Because of the nature of the valuation inputs, the Corporation classifies loan servicing rights as Level 3. Refer to Note 9, “Loan Servicing Rights”, for the assumptions included in the valuation of loan servicing rights. Derivatives: The Corporation enters into interest rate lock commitments with prospective borrowers to be sold into the secondary market and forward commitments for the future delivery of mortgage loans to third party investors, which are carried at fair value on a recurring basis. The fair value of these commitments is based on the fair value of related mortgage loans determined using observable market data. Interest rate lock commitments are adjusted for expectations of exercise and funding. This adjustment is not considered to be a material input. The Corporation classifies interest rate lock commitments and forward contracts related to mortgage loans to be delivered for sale as recurring Level 2. Derivative instruments held or issued for customer-initiated activities are traded in over-the counter markets where quoted market prices are not readily available. Fair value for over-the-counter derivative instruments is measured on a recurring basis using third party models that use primarily market observable inputs, such as yield curves and option volatilities. The fair value for these derivatives may include a credit valuation adjustment that is determined by applying a credit spread for the counterparty or the Corporation, as appropriate, to the total expected exposure of the derivative after considering collateral and other master netting arrangements. These adjustments, which are considered Level 3 inputs, are based on estimates of current credit spreads to evaluate the likelihood of default. The Corporation assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions at both December 31, 2016 and 2015 and it was determined that the credit valuation adjustments were not significant to the overall valuation of its derivatives. As a result, the Corporation classifies its customer-initiated derivatives valuations in Level 2 of the fair value hierarchy. Written and purchased option derivatives consist of instruments to facilitate an equity-linked time deposit product (the "Power Equity CD"). The Power Equity CD is a time deposit that provides the purchaser a guaranteed return of principal at maturity plus a potential equity return, while the Corporation receives a known stream of funds based on equity returns. The written and purchased options are mirror derivative instruments which are carried at fair value on the Consolidated Statements of Financial Position. Fair value measurements for the Power Equity CD are determined using quoted prices of underlying stocks, along with other terms and features of the derivative instrument. As a result, the Power Equity CD derivatives are classified as Level 2 valuations. Disclosure of Recurring Basis Fair Value Measurements For assets measured at fair value on a recurring basis, quantitative disclosures about the fair value measurements for each major category of assets follow: (Dollars in thousands) Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total December 31, 2016 Investment securities — available-for-sale: U.S. Treasury securities $ 5,793 $ — $ — $ 5,793 Government sponsored agencies — 215,011 — 215,011 State and political subdivisions — 300,088 — 300,088 Residential mortgage-backed securities — 272,282 — 272,282 Collateralized mortgage obligations — 320,025 — 320,025 Corporate bonds — 89,474 — 89,474 Preferred stock and trust preferred securities — 32,291 — 32,291 Total investment securities — available-for-sale 5,793 1,229,171 — 1,234,964 Loans held-for-sale — 81,830 — 81,830 Loan servicing rights — — 48,085 48,085 Derivative assets: Customer-initiated derivatives — 4,406 — 4,406 Forward contracts related to mortgage loans to be delivered for sale — 635 — 635 Interest rate lock commitments — 956 — 956 Power Equity CD — 2,218 — 2,218 Total derivatives — 8,215 — 8,215 Total assets at fair value $ 5,793 $ 1,319,216 $ 48,085 $ 1,373,094 Derivative liabilities: Customer-initiated derivatives — 4,141 — 4,141 Power Equity CD — 2,218 — 2,218 Total derivatives — 6,359 — 6,359 Total liabilities at fair value $ — $ 6,359 $ — $ 6,359 (Dollars in thousands) Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total December 31, 2015 Investment securities — available-for-sale: U.S. Treasury securities $ 5,765 $ — $ — $ 5,765 Government sponsored agencies — 194,989 — 194,989 State and political subdivisions — 15,120 — 15,120 Residential mortgage-backed securities — 187,768 — 187,768 Collateralized mortgage obligations — 132,230 — 132,230 Corporate bonds — 14,627 — 14,627 Preferred stock and trust preferred securities — 3,232 — 3,232 Total investment securities — available-for-sale 5,765 547,966 — 553,731 Loans held-for-sale — 10,327 — 10,327 Derivative assets: Forward contracts related to mortgage loans to be delivered for sale — 144 — 144 Interest rate lock commitments — 42 — 42 Power Equity CD — 1,832 — 1,832 Total derivatives — 2,018 — 2,018 Total assets at fair value $ 5,765 $ 560,311 $ — $ 566,076 Derivative liabilities: Forward contracts related to mortgage loans to be delivered for sale — 57 — 57 Interest rate lock commitments — 90 — 90 Power Equity CD — 1,832 — 1,832 Total derivatives — 1,979 — 1,979 Total liabilities at fair value $ — $ 1,979 $ — $ 1,979 There were no transfers between levels within the fair value hierarchy during the year ended December 31, 2016 . The following table summarizes the changes in Level 3 assets measured at fair value on a recurring basis. Year ended December 31, 2016 (Dollars in thousands) Loan servicing rights Balance, beginning of period $ — Additions due to acquisition 42,462 Gains (losses): Recorded in earnings (realized): Recorded in “Mortgage banking revenue” 4,593 New originations 1,030 Balance, end of period $ 48,085 The Corporation has elected the fair value option for loans held-for-sale. These loans are intended for sale and the Corporation believes that the fair value is the best indicator of the resolution of these loans. Interest income is recorded based on the contractual terms of the loans in accordance with the Corporation's policy on loans held for investment in “Interest and fees on loans” in the Consolidated Statements of Income. There were no loans held-for-sale that were on nonaccrual status or 90 days past due and on accrual status as of December 31, 2016 and 2015 . The aggregate fair value, contractual balance (including accrued interest), and gain or loss for loans held-for-sale carried at fair value was as follows: December 31, (Dollars in thousands) 2016 2015 Aggregate fair value $ 81,830 $ 10,327 Contractual balance 81,009 10,366 Unrealized gain (loss) 821 (39 ) The total amount of gains (losses) from loans held for sale included in the Consolidated Statements of Income were as follows: For the years ended December 31, (Dollars in thousands) 2016 2015 2014 Interest income (1) $ 1,606 $ 83 $ 66 Change in fair value (2) 39 (61 ) 110 Total included in earnings $ 1,645 $ 22 $ 176 (1) Included in "Interest and fees on loans" in the Consolidated Statements of Income. (2) Included in "Mortgage banking revenue" in the Consolidated Statements of Income. Assets and Liabilities Recorded at Fair Value on a Nonrecurring Basis Loans: The Corporation does not record loans held for investment at fair value on a recurring basis. However, from time to time, a loan is considered impaired and an allocation of the allowance (valuation allowance) may be established or a portion of the loan is charged off. Loans for which it is probable that payment of interest and principal will not be made in accordance with the contractual terms of the loan agreement are considered impaired. The fair value of impaired loans is estimated using one of several methods, including the loan's observable market price, the fair value of the collateral or the present value of the expected future cash flows discounted at the loan's effective interest rate. Those impaired loans not requiring a valuation allowance represent loans for which the fair value of the expected repayments or collateral exceed the remaining carrying amount of such loans. Impaired loans where a valuation allowance is established or a portion of the loan is charged off based on the fair value of collateral are subject to nonrecurring fair value measurement and require classification in the fair value hierarchy. The Corporation records impaired loans as Level 3 valuations as there is generally no observable market price or management determines the fair value of the collateral is further impaired below the independent appraised value. When management determines the fair value of the collateral is further impaired below the appraised value, discount factors ranging between 75% and 90% of the appraised value are used depending on the nature of the collateral and the age of the most recent appraisal. Goodwill: Goodwill is subject to impairment testing on an annual basis. The assessment of goodwill for impairment requires a significant degree of judgment. In the event the assessment indicates that it is more-likely-than-not that the fair value is less than the carrying value, the asset is considered impaired and recorded at fair value. Goodwill that is impaired and subject to nonrecurring fair value measurements is a Level 3 valuation. At December 31, 2016 and 2015 , no goodwill was impaired. Other intangible assets: Other intangible assets consist of core deposit intangible assets and non-compete intangible assets. These items are recorded at fair value when initially recorded. Subsequently, core deposit intangible assets and non-compete intangible assets are amortized primarily on an accelerated basis over periods ranging from ten to fifteen years and are subject to impairment testing whenever events or changes in circumstances indicate that the carrying amount exceeds the fair value of the asset. If core deposit intangible asset or non-compete intangible asset impairment is identified, the Corporation classifies impaired core deposit intangible assets and impaired non-compete intangible assets subject to nonrecurring fair value measurements as Level 3 valuations. At December 31, 2016 and 2015 , there was no impairment identified for core deposit intangible assets or non-compete intangible assets. Loan servicing rights: LSRs originated by the Corporation and those acquired in acquisitions of other institutions prior to the merger with Talmer are accounted for under the amortization method. The fair value of these LSRs 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, LSRs are adjusted to fair value, as determined by the model, through a valuation allowance. The Corporation classifies the LSRs subject to nonrecurring fair value measurements as Level 3 valuations. At December 31, 2016 , the Corporation recognized a valuation allowance of $8 thousand related to impairment within certain pools attributable to the Corporation's servicing portfolios. As a result, the LSRs related to these servicing portfolios were considered to be recorded at fair value on a nonrecurring basis as of December 31, 2016 . At December 31, 2015 , there was no impairment identified for LSRs. Other real estate owned and repossessed assets : The carrying amounts for other real estate and repossessed assets are reported in the Consolidated Statements of Financial Position under "Interest receivable and other assets." Other real estate and repossessed assets include real estate and other types of assets repossessed by the Corporation. Other real estate and repossessed assets are recorded at the lower of cost or fair value upon the transfer of a loan to other real estate and repossessed assets and, subsequently, continue to be measured and carried at the lower of cost or fair value. Fair value is based upon independent market prices, appraised values of the property or management's estimation of the value of the property. The Corporation records other real estate and repossessed assets as Level 3 valuations as management generally determines that the fair value of the property is impaired below the appraised value. When management determines the fair value of the property is further impaired below appraised value, discount factors ranging between 75% and 90% 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 follow: (Dollars in thousands) Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total December 31, 2016 Impaired originated loans $ — $ — $ 62,184 $ 62,184 Other real estate/repossessed assets — — 1,386 1,386 Loan servicing rights — — 2 2 Total $ — $ — $ 63,572 $ 63,572 December 31, 2015 Impaired originated loans $ — $ — $ 42,065 $ 42,065 Other real estate/repossessed assets — — 3,068 3,068 Total $ — $ — $ 45,133 $ 45,133 There were no liabilities recorded at fair value on a nonrecurring basis at December 31, 2016 and 2015 . The following table presents additional information about the significant unobservable inputs used in the fair value measurement of financial assets measured on a nonrecurring basis that were categorized within the Level 3 of the fair value hierarchy: (Dollars in thousands) Fair Value at December 31, 2016 Valuation Technique Significant Unobservable Inputs Range Impaired originated loans $ 62,184 Appraisal of collateral Discount for type of collateral and age of appraisal 10%-25% Other real estate/repossessed assets 1,386 Appraisal of property Discount for type of property and age of appraisal 10%-25% Loan servicing rights 2 Discounted cash flow Constant prepayment rate 9%-18% Discount rate 10%-11% Disclosures About Fair Value of Financial Instruments GAAP requires disclosures about the estimated fair value of the Corporation's financial instruments, including those financial assets and liabilities that are not measured and reported at fair value on a recurring or nonrecurring basis. However, the method of estimating fair value for certain financial instruments, such as loans, that are not required to be measured on a recurring or nonrecurring basis, as prescribed by FASB ASC Topic 820, " Fair Value Measurement ", 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 December 31, 2016 and 2015 , the estimated fair values of cash and cash equivalents, interest receivable and interest payable approximated their carrying values at those dates. The methodologies for other financial assets and financial liabilities follow. Investment securities — held-to-maturity : Fair value measurement for investment securities — held-to-maturity 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 investment securities issued by state and political subdivisions. Level 3 valuations include trust preferred investment securities. Nonmarketable equity securities: Fair value measurements of nonmarketable equity securities, which consist 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: The fair values of loans that are not considered impaired are estimated using a discounted cash flow model. The cash flows take into consideration current portfolio interest rates and repricing characteristics as well as assumptions relating to prepayment speeds. The discount rates take into consideration the current market interest rate environment, a credit risk component based on the credit characteristics of each loan portfolio, and a liquidity premium reflecting the liquidity or illiquidity of the market. The fair value measurements for loans are Level 3 valuations. Deposits: The fair values of deposit accounts without defined maturities, such as interest-and noninterest-bearing checking, savings and money market accounts, are estimated to be the amounts payable on demand. The fair values for variable-interest rate time deposits with defined maturities approximate their carrying amounts. Fair value measurements for fixed-interest rate time deposits with defined maturities are based on the discounted value of contractual cash flows, using the Corporation's interest rates currently being offered for deposits of similar maturities, and are therefore classified as Level 2 valuations. However, if the estimated fair value is less than the carrying value, the carrying value is reported as the fair value. Securities sold under agreements to repurchase: Fair value measurements are based on the present value of future estimated cash flows using current interest rates offered to the Corporation under similar terms and are Level 2 valuations. Short-term borrowings: Short-term borrowings consist of short-term FHLB advances. 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. Lon g -term borrowings: Long-term borrowings consist of long-term FHLB advances, securities sold under agreements to repurchase with an unaffiliated financial institution, a term line-of-credit and subordinated debt obligations. Fair value measurements for long-term borrowings are based on the present value of future estimated cash flows using current interest rates offered to the Corporation for debt with similar terms and are therefore classified as Level 2 valuations. Financial guarantees : 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. A summary of carrying amounts and estimated fair values of the Corporation's financial instruments not recorded at fair value in their entirety on a recurring basis on the Consolidated Statements of Financial Position was as follows: December 31, Level in Fair Value Measurement Hierarchy 2016 2015 (Dollars in thousands) Carrying Amount Fair Value Carrying Amount Fair Value Financial assets: Cash and cash equivalents Level 1 $ 474,402 $ 474,402 $ 238,789 $ 238,789 Investment securities: Held-to-maturity Level 2 622,927 608,221 509,471 512,405 Held-to-maturity Level 3 500 310 500 7,090 Nonmarketable equity securities NA 97,350 97,350 36,907 36,907 Net loans (1) Level 3 12,912,511 13,069,315 7,197,819 7,201,994 Interest receivable Level 2 42,235 42,235 21,953 21,953 Financial liabilities: Deposits: Deposits without defined maturities Level 2 $ 9,862,755 $ 9,862,755 $ 5,809,355 $ 5,809,355 Time deposits Level 2 3,010,367 3,010,048 1,647,412 1,647,412 Total deposits 12,873,122 12,872,803 7,456,767 7,456,767 Interest payable Level 2 5,415 5,415 1,578 1,578 Securities sold under agreements to repurchase with customers Level 2 343,047 343,047 297,199 297,199 Short-term borrowings Level 2 825,000 825,000 100,000 100,000 Long-term borrowings Level 2 597,847 591,227 242,391 242,391 (1) Included $62.2 million and $42.1 million of impaired loans recorded at fair value on a nonrecurring basis at December 31, 2016 and 2015 , respectively.

Investment Securities

Investment Securities	12 Months Ended
	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities The following is a summary of the amortized cost and fair value of investment securities available-for-sale and investment securities held-to-maturity at December 31, 2016 and 2015 : Investment Securities Available-for-Sale (Dollars in thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2016 U.S. Treasury securities $ 5,788 $ 5 $ — $ 5,793 Government sponsored agencies 216,890 189 2,068 215,011 State and political subdivisions 311,704 163 11,779 300,088 Residential mortgage-backed securities 276,162 112 3,992 272,282 Collateralized mortgage obligations 323,965 63 4,003 320,025 Corporate bonds 90,859 16 1,401 89,474 Preferred stock and trust preferred securities 31,353 1,018 80 32,291 Total $ 1,256,721 $ 1,566 $ 23,323 $ 1,234,964 December 31, 2015 U.S. Treasury securities $ 5,773 $ — $ 8 $ 5,765 Government sponsored agencies 195,711 78 800 194,989 State and political subdivisions 14,731 395 6 15,120 Residential mortgage-backed securities 189,452 538 2,222 187,768 Collateralized mortgage obligations 133,256 111 1,137 132,230 Corporate bonds 14,825 2 200 14,627 Preferred stock and trust preferred securities 2,888 344 — 3,232 Total $ 556,636 $ 1,468 $ 4,373 $ 553,731 Investment Securities Held-to-Maturity (Dollars in thousands) Amortized Cost Unrecognized Gains Unrecognized Losses Fair Value December 31, 2016 State and political subdivisions $ 622,927 $ 2,648 $ 17,354 $ 608,221 Trust preferred securities 500 — 190 310 Total $ 623,427 $ 2,648 $ 17,544 $ 608,531 December 31, 2015 State and political subdivisions $ 509,471 $ 7,446 $ 4,512 $ 512,405 Trust preferred securities 500 — 200 300 Total $ 509,971 $ 7,446 $ 4,712 $ 512,705 The majority of the Corporation's residential mortgage-backed securities and collateralized mortgage obligations are backed by a U.S. government agency (Government National Mortgage Association) or a government sponsored enterprise (Federal Home Loan Mortgage Corporation or Federal National Mortgage Association). Proceeds from sales of securities and the associated gains and losses recorded in earnings are listed below: For the years ended December 31, (Dollars in thousands) 2016 2015 2014 Proceeds $ 41,446 $ 40,301 $ — Gross gains 325 631 — Gross losses (196 ) (1 ) — The following is a summary of the amortized cost and fair value of investment securities at December 31, 2016 , by maturity, for both available-for-sale and held-to-maturity investment securities. The maturities of residential mortgage-backed securities and collateralized mortgage obligations are based on scheduled principal payments. The maturities of all other debt securities are based on final contractual maturity. December 31, 2016 (Dollars in thousands) Amortized Cost Fair Value Investment Securities Available-for-Sale: Due in one year or less $ 237,047 $ 235,845 Due after one year through five years 490,634 485,221 Due after five years through ten years 339,222 329,879 Due after ten years 188,429 182,281 Preferred stock 1,389 1,738 Total $ 1,256,721 $ 1,234,964 Investment Securities Held-to-Maturity: Due in one year or less $ 66,090 $ 65,954 Due after one year through five years 262,136 257,936 Due after five years through ten years 145,225 139,320 Due after ten years 149,976 145,321 Total $ 623,427 $ 608,531 Securities with a carrying value of $794.0 million and $530.8 million were pledged at December 31, 2016 and 2015 , respectively, to secure borrowings and deposits. At December 31, 2016 and 2015 , there were no holdings of securities of any one issuer, other than U.S. government and its agencies, in an amount greater than 10% of shareholders' equity. The following schedule summarizes information for both available-for-sale and held-to-maturity investment securities with gross unrealized losses at December 31, 2016 and 2015 , aggregated by category and length of time that individual securities have been in a continuous unrealized loss position. As of December 31, 2016 , the Corporation's securities portfolio consisted of 2,504 securities, 1,563 of which were in an unrealized loss position. Less Than 12 Months 12 Months or More Total (Dollars in thousands) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses December 31, 2016 Government sponsored agencies $ 105,702 $ 1,707 $ 15,023 $ 361 $ 120,725 $ 2,068 State and political subdivisions 758,063 28,158 26,810 975 784,873 29,133 Residential mortgage-backed securities 244,239 3,992 — — 244,239 3,992 Collateralized mortgage obligations 279,001 3,778 14,754 225 293,755 4,003 Corporate bonds 80,536 1,401 — — 80,536 1,401 Trust preferred securities 10,699 80 310 190 11,009 270 Total $ 1,478,240 $ 39,116 $ 56,897 $ 1,751 $ 1,535,137 $ 40,867 December 31, 2015 U.S. Treasury securities $ 5,765 $ 8 $ — $ — $ 5,765 $ 8 Government sponsored agencies 114,640 292 21,681 508 136,321 800 State and political subdivisions 195,285 2,891 68,361 1,627 263,646 4,518 Residential mortgage-backed securities 169,226 2,146 3,435 76 172,661 2,222 Collateralized mortgage obligations 60,459 408 39,382 729 99,841 1,137 Corporate bonds 9,532 200 — — 9,532 200 Trust preferred securities — — 300 200 300 200 Total $ 554,907 $ 5,945 $ 133,159 $ 3,140 $ 688,066 $ 9,085 An assessment is performed quarterly by the Corporation to determine whether unrealized losses in its investment securities portfolio are temporary or other-than-temporary by carefully considering all reasonably available information. The Corporation reviews factors such as financial statements, credit ratings, news releases and other pertinent information of the underlying issuer or company to make its determination. Management did not believe any individual unrealized loss on any investment security at December 31, 2016 , represented an other-than-temporary impairment (OTTI) as the unrealized losses for these securities resulted primarily from changes in benchmark U.S. Treasury interest rates and not credit issues. Management believed that the unrealized losses on investment securities at December 31, 2016 were temporary in nature and due primarily to changes in interest rates and reduced market liquidity and not as a result of credit-related issues. At December 31, 2016 , the Corporation did not have the intent to sell any of its impaired investment securities and believed that it was more-likely-than-not that the Corporation will not have to sell any such investment securities before a full recovery of amortized cost. Accordingly, at December 31, 2016 , the Corporation believed the impairments in its investment securities portfolio were temporary in nature. However, there is no assurance that OTTI may not occur in the future.

Loans

Loans	12 Months Ended
	Dec. 31, 2016
Receivables [Abstract]
Loans	Loans Loan portfolio segments are defined as the level at which an entity develops and documents a systematic methodology to determine its allowance. The Corporation has two loan portfolio segments (commercial loans and consumer loans) that it uses in determining the allowance. Both quantitative and qualitative factors are used by management at the loan portfolio segment level in determining the adequacy of the allowance for the Corporation. Classes of loans are a disaggregation of an entity's loan portfolio segments. Classes of loans are defined as a group of loans which share similar initial measurement attributes, risk characteristics and methods for monitoring and assessing credit risk. The Corporation has six classes of loans, which are set forth below. Commercial — Loans and lines of credit to varying types of businesses, including municipalities, school districts and nonprofit organizations, for the purpose of supporting working capital, operational needs and term financing of equipment. Repayment of such loans is generally provided through operating cash flows of the business. Commercial loans are predominately secured by equipment, inventory, accounts receivable, personal guarantees of the owner and other sources of repayment, although the Corporation may also secure commercial loans with real estate. Commercial real estate — Loans secured by real estate occupied by the borrower for ongoing operations, non-owner occupied real estate leased to one or more tenants and vacant land that has been acquired for investment or future land development. Real estate construction and land development — Real estate construction loans represent secured loans for the construction of business properties. Real estate construction loans often convert to a commercial real estate loan at the completion of the construction period. Land development loans represent secured development loans made to borrowers for the purpose of infrastructure improvements to vacant land to create finished marketable residential and commercial lots/land. Most land development loans are originated with the intention that the loans will be paid through the sale of developed lots/land by the developers within twelve months of the completion date. Land development loans at December 31, 2016 and 2015 were primarily comprised of loans to develop residential properties. Residential mortgage — Loans secured by one - to four -family residential properties, generally with fixed interest rates for periods of fifteen years or less. The loan-to-value ratio at the time of origination is generally 80% or less. Residential mortgage loans with a loan-to-value ratio of more than 80% generally require private mortgage insurance. Consumer installment — Loans to consumers primarily for the purpose of acquiring automobiles, recreational vehicles and personal watercraft and comprised primarily of indirect loans purchased from dealers. These loans consist of relatively small amounts that are spread across many individual borrowers. Home equity — Loans and lines of credit whereby consumers utilize equity in their personal residence, generally through a second mortgage, as collateral to secure the loan. Commercial, commercial real estate, real estate construction and land development loans are referred to as the Corporation's commercial loan portfolio, while residential mortgage, consumer installment and home equity loans are referred to as the Corporation's consumer loan portfolio. A summary of the Corporation's loans follows: (Dollars in thousands) Originated Acquired (1) Total loans December 31, 2016 Commercial loan portfolio: Commercial $ 1,901,526 $ 1,315,774 $ 3,217,300 Commercial real estate 1,921,799 2,051,341 3,973,140 Real estate construction and land development 281,724 122,048 403,772 Subtotal 4,105,049 3,489,163 7,594,212 Consumer loan portfolio: Residential mortgage 1,475,342 1,611,132 3,086,474 Consumer installment 1,282,588 151,296 1,433,884 Home equity 595,422 280,787 876,209 Subtotal 3,353,352 2,043,215 5,396,567 Total loans $ 7,458,401 $ 5,532,378 $ 12,990,779 (2) December 31, 2015 Commercial loan portfolio: Commercial $ 1,521,515 $ 384,364 $ 1,905,879 Commercial real estate 1,424,059 688,103 2,112,162 Real estate construction and land development 185,147 46,929 232,076 Subtotal 3,130,721 1,119,396 4,250,117 Consumer loan portfolio: Residential mortgage 1,216,975 212,661 1,429,636 Consumer installment 869,426 8,031 877,457 Home equity 590,812 123,125 713,937 Subtotal 2,677,213 343,817 3,021,030 Total loans $ 5,807,934 $ 1,463,213 $ 7,271,147 (2) (1) Acquired loans are accounted for under ASC 310-30. (2) Reported net of deferred costs totaling $14.8 million and $10.7 million at December 31, 2016 and 2015 , respectively. Chemical Bank has extended loans to its directors, executive officers and their affiliates. These loans were made in the ordinary course of business upon normal terms, including collateralization and interest rates prevailing at the time, and did not involve more than the normal risk of repayment by the borrower. The aggregate loans outstanding to the directors, executive officers and their affiliates totaled $23.9 million at December 31, 2016 and $21.7 million at December 31, 2015 . During 2016 and 2015 , there were $33.8 million and $33.3 million , respectively, of new loans and other additions, while repayments and other reductions totaled $31.6 million and $42.8 million , respectively. Loans held-for-sale, comprised of fixed-rate residential mortgage loans, were $81.8 million at December 31, 2016 and $10.3 million at December 31, 2015 . The Corporation sold loans totaling $707.8 million in 2016 and $222.6 million in 2015 . Credit Quality Monitoring The Corporation maintains loan policies and credit underwriting standards as part of the process of managing credit risk. These standards include making loans generally only within the Corporation's market areas. The Corporation's lending markets generally consist of communities throughout Michigan and additional communities located within northwest Ohio and northern Indiana. The Corporation, through Chemical Bank, has a commercial loan portfolio approval process involving underwriting and individual and group loan approval authorities to consider credit quality and loss exposure at loan origination. The loans in the Corporation's commercial loan portfolio are risk rated at origination based on the grading system set forth below. The approval authority of relationship managers is established based on experience levels, with credit decisions greater than $2.0 million requiring group loan authority approval, except for six executive and senior officers who have varying loan limits exceeding $2.0 million and up to $3.5 million . With respect to the group loan authorities, Chemical Bank has various regional loan committees hat meet weekly to consider loan ranging in amounts from $2.0 million to $5.0 million , and a senior loan committee, consisting of certain executive and senior officers, that meets weekly to consider loans ranging in amounts from $5.0 million to $10.0 million , depending on risk rating and credit action required. A directors' loan committee of Chemical Bank, consisting of eight independent members of the board of directors of Chemical Bank, the chief executive officer of Chemical Bank and the chief 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 $25.0 million require the approval of the board of directors of Chemical Bank. The majority of the Corporation's consumer loan portfolio is comprised of secured loans that are relatively small. The Corporation's consumer loan portfolio has a centralized approval process which utilizes standardized underwriting criteria. The ongoing measurement of credit quality of the consumer loan portfolio is largely done on an exception basis. If payments are made on schedule, as agreed, then no further monitoring is performed. However, if delinquency occurs, the delinquent loans are turned over to the Corporation's collection department for resolution, resulting in repossession or foreclosure if payments are not brought current. Credit quality for the entire consumer loan portfolio is measured by the periodic delinquency rate, nonaccrual amounts and actual losses incurred. Loans in the commercial loan portfolio tend to be larger and more complex than those in the consumer loan portfolio, and therefore, are subject to more intensive monitoring. All loans in the commercial loan portfolio have an assigned relationship manager, and most borrowers provide periodic financial and operating information that allows the relationship managers to stay abreast of credit quality during the life of the loans. The risk ratings of loans in the commercial loan portfolio are reassessed at least annually, with loans below an acceptable risk rating reassessed more frequently and reviewed by various loan committees within the Corporation at least quarterly. The Corporation maintains a centralized independent loan review function that monitors the approval process and ongoing asset quality of the loan portfolio, including the accuracy of loan grades. The Corporation also maintains an independent appraisal review function that participates in the review of all appraisals obtained by the Corporation for loans in the commercial loan portfolio. Credit Quality Indicators Commercial Loan Portfolio Risk categories for the Corporation's commercial loan portfolio establish the credit quality of a borrower by measuring liquidity, debt capacity, coverage and payment behavior as shown in the borrower's financial statements. The risk categories also measure the quality of the borrower's management and the repayment support offered by any guarantors. Risk categories for the Corporation's commercial loan portfolio are described as follows: Pass: Includes all loans without weaknesses or potential weaknesses identified in the categories of special mention, substandard or doubtful. Special Mention: Loans with potential credit weakness or credit deficiency, which, if not corrected, pose an unwarranted financial risk that could weaken the loan by adversely impacting the future repayment ability of the borrower. Substandard: Loans with a well-defined weakness, or weaknesses, such as loans to borrowers who may be experiencing losses from operations or inadequate liquidity of a degree and duration that jeopardizes the orderly repayment of the loan. Substandard loans also are distinguished by the distinct possibility of loss in the future if these weaknesses are not corrected. Doubtful: Loans with all the characteristics of a loan classified as Substandard, with the added characteristic that credit weaknesses make collection in full highly questionable and improbable. The following schedule presents the recorded investment of loans in the commercial loan portfolio by credit risk categories at December 31, 2016 and 2015 : (Dollars in thousands) Pass Special Mention Substandard Doubtful Total December 31, 2016 Originated Portfolio: Commercial $ 1,803,750 $ 44,809 $ 51,898 $ 1,069 $ 1,901,526 Commercial real estate 1,849,315 36,981 35,502 1 1,921,799 Real estate construction and land development 280,968 157 599 — 281,724 Subtotal 3,934,033 81,947 87,999 1,070 4,105,049 Acquired Portfolio: Commercial 1,218,848 46,643 50,283 — 1,315,774 Commercial real estate 1,897,011 61,441 92,636 253 2,051,341 Real estate construction and land development 117,505 1,982 2,561 — 122,048 Subtotal 3,233,364 110,066 145,480 253 3,489,163 Total $ 7,167,397 $ 192,013 $ 233,479 $ 1,323 $ 7,594,212 December 31, 2015 Originated Portfolio: Commercial $ 1,418,301 $ 34,727 $ 66,392 $ 2,095 $ 1,521,515 Commercial real estate 1,341,202 31,036 51,821 — 1,424,059 Real estate construction and land development 183,323 180 1,644 — 185,147 Subtotal 2,942,826 65,943 119,857 2,095 3,130,721 Acquired Portfolio: Commercial 340,782 28,321 15,261 — 384,364 Commercial real estate 629,430 23,926 34,747 — 688,103 Real estate construction and land development 41,683 2,556 2,690 — 46,929 Subtotal 1,011,895 54,803 52,698 — 1,119,396 Total $ 3,954,721 $ 120,746 $ 172,555 $ 2,095 $ 4,250,117 Consumer Loan Portfolio The Corporation evaluates the credit quality of loans in the consumer loan portfolio based on the performing or nonperforming status of the loan. Loans in the consumer loan portfolio that are performing in accordance with original contractual terms and are less than 90 days past due and accruing interest are considered to be in a performing status, while those that are in nonaccrual status, contractually past due 90 days or more as to interest or principal payments are considered to be in a nonperforming status. Loans accounted for under ASC 310-30, "acquired loans", that are not performing in accordance with contractual terms are not reported as nonperforming because these loans are recorded in pools at their net realizable value based on the principal and interest the Corporation expects to collect on these loans. The following schedule presents the recorded investment of loans in the consumer loan portfolio based on loans in a performing status and loans in a nonperforming status at December 31, 2016 and 2015 : (Dollars in thousands) Residential mortgage Consumer installment Home equity Total consumer December 31, 2016 Originated Portfolio: Performing $ 1,468,373 $ 1,281,709 $ 592,071 $ 3,342,153 Nonperforming 6,969 879 3,351 11,199 Subtotal 1,475,342 1,282,588 595,422 3,353,352 Acquired Loans 1,611,132 151,296 280,787 2,043,215 Total $ 3,086,474 $ 1,433,884 $ 876,209 $ 5,396,567 December 31, 2015 Originated Portfolio: Performing $ 1,211,418 $ 868,975 $ 588,833 $ 2,669,226 Nonperforming 5,557 451 1,979 7,987 Subtotal 1,216,975 869,426 590,812 2,677,213 Acquired Loans 212,661 8,031 123,125 343,817 Total $ 1,429,636 $ 877,457 $ 713,937 $ 3,021,030 Nonperforming Assets and Past Due Loans Nonperforming assets consist of loans for which the accrual of interest has been discontinued, other real estate owned acquired through acquisitions, other real estate owned obtained through foreclosure and other repossessed assets. Loans are considered past due or delinquent when the contractual principal or interest due in accordance with the terms of the loan agreement or any portion thereof remains unpaid after the due date of the scheduled payments. Loans outside of those accounted for under ASC 310-30 are classified as nonaccrual when, in the opinion of management, collection of principal or interest is doubtful. The accrual of interest is discontinued when a loan is placed in nonaccrual status and any payments received reduce the carrying value of the loan. A loan may be placed back on accrual status if all contractual payments have been received and collection of future principal and interest payments are no longer doubtful. Acquired loans that are not performing in accordance with contractual terms are not reported as nonperforming because these loans are recorded in pools at their net realizable value based on the principal and interest the Corporation expects to collect on these loans. A summary of nonperforming assets follows: December 31, (Dollars in thousands) 2016 2015 Nonperforming assets Nonaccrual loans: Commercial $ 13,178 $ 28,554 Commercial real estate 19,877 25,163 Real estate construction and land development 80 521 Residential mortgage 6,969 5,557 Consumer installment 879 451 Home equity 3,351 1,979 Total nonaccrual loans 44,334 62,225 Other real estate owned and repossessed assets 17,187 9,935 Total nonperforming assets $ 61,521 $ 72,160 Accruing loans contractually past due 90 days or more as to interest or principal payments, excluding acquired loans accounted for under ASC 310-30 Commercial 11 364 Commercial real estate 277 254 Residential mortgage — 402 Home equity 995 1,267 Total accruing loans contractually past due 90 days or more as to interest or principal payments, excluding acquired loans accounted for under ASC 310-30 $ 1,283 $ 2,287 The Corporation's nonaccrual loans at December 31, 2016 and 2015 included $30.5 million and $35.9 million , respectively, of nonaccrual TDRs. There was no interest income recognized on nonaccrual loans during 2016 , 2015 and 2014 while the loans were in nonaccrual status. During 2016 , 2015 and 2014 , the Corporation recognized $0.4 million , $0.9 million and $0.5 million , respectively, of interest income on these loans while they were in an accruing status. Additional interest income that would have been recorded on nonaccrual loans had they been current in accordance with their original terms was $2.9 million in 2016 , $3.2 million in 2015 and $3.3 million in 2014 . During 2016 , 2015 and 2014 , the Corporation recognized interest income of $3.9 million , $3.9 million and $3.6 million , respectively, on performing TDRs. The Corporation had $7.3 million of residential mortgage loans that were in the process of foreclosure at December 31, 2016 , compared to $2.9 million at December 31, 2015 . Loan delinquency, excluding acquired loans accounted for under ASC 310-30, was as follows: (Dollars in thousands) 30-59 days past due 60-89 days past due 90 days or more past due Total past due Current Total loans 90 days or more past due and still accruing December 31, 2016 Originated Portfolio: Commercial $ 10,421 $ 4,842 $ 3,641 $ 18,904 $ 1,882,622 $ 1,901,526 $ 11 Commercial real estate 6,551 1,589 5,165 13,305 1,908,494 1,921,799 277 Real estate construction and land development 2,721 499 — 3,220 278,504 281,724 — Residential mortgage 3,147 62 1,752 4,961 1,470,381 1,475,342 — Consumer installment 3,991 675 238 4,904 1,277,684 1,282,588 — Home equity 3,097 893 2,349 6,339 589,083 595,422 995 Total $ 29,928 $ 8,560 $ 13,145 $ 51,633 $ 7,406,768 $ 7,458,401 $ 1,283 December 31, 2015 Originated Portfolio: Commercial $ 9,393 $ 5,243 $ 364 $ 15,000 $ 1,506,515 $ 1,521,515 $ 364 Commercial real estate 6,941 2,262 254 9,457 1,414,602 1,424,059 254 Real estate construction and land development 596 — — 596 184,551 185,147 — Residential mortgage 7,475 1,170 402 9,047 1,207,928 1,216,975 402 Consumer installment 3,347 741 — 4,088 865,338 869,426 — Home equity 2,075 1,113 1,267 4,455 586,357 590,812 1,267 Total $ 29,827 $ 10,529 $ 2,287 $ 42,643 $ 5,765,291 $ 5,807,934 $ 2,287 Impaired Loans A loan is impaired when, based on current information and events, it is probable that the Corporation will be unable to collect all amounts due according to the contractual terms of the loan agreement. Impaired loans include nonperforming loans and all TDRs. Impaired loans are accounted for at the lower of the present value of expected cash flows or the estimated fair value of the collateral. When the present value of expected cash flows or the fair value of the collateral of an impaired loan not accounted for under ASC 310-30 is less than the amount of unpaid principal outstanding on the loan, the recorded principal balance of the loan is reduced to its carrying value through either a specific allowance for loan loss or a partial charge-off of the loan balance. The following schedules present impaired loans by classes of loans at December 31, 2016 and December 31, 2015 : (Dollars in thousands) Recorded investment Unpaid principal balance Related valuation allowance December 31, 2016 Impaired loans with a valuation allowance: Commercial $ 28,925 $ 33,209 $ 3,128 Commercial real estate 21,318 27,558 2,102 Real estate construction and land development 177 177 4 Residential mortgage 20,864 20,864 3,528 Consumer installment 879 879 240 Home equity 2,577 2,577 390 Subtotal 71,284 81,808 8,762 Impaired loans with no related valuation allowance: Commercial 7,435 11,153 — Commercial real estate 20,588 23,535 — Real estate construction and land development 80 80 — Residential mortgage 3,252 3,252 — Consumer installment — — — Home equity 774 774 — Subtotal 32,129 38,794 — Total impaired loans: Commercial 36,360 44,362 3,128 Commercial real estate 41,906 51,093 2,102 Real estate construction and land development 257 257 4 Residential mortgage 24,116 24,116 3,528 Consumer installment 879 879 — Home equity 3,351 3,351 — Total $ 106,869 $ 124,058 $ 8,762 (Dollars in thousands) Recorded investment Unpaid principal balance Related valuation allowance December 31, 2015 Impaired loans with a valuation allowance: Commercial $ 18,898 $ 19,426 $ 5,700 Commercial real estate 4,448 4,688 497 Residential mortgage 21,037 21,037 192 Subtotal 44,383 45,151 6,389 Impaired loans with no related valuation allowance: Commercial 27,304 32,395 — Commercial real estate 48,747 59,949 — Real estate construction and land development 982 1,062 — Residential mortgage 5,557 5,557 — Consumer installment 451 451 — Home equity 1,979 1,979 — Subtotal 85,020 101,393 — Total impaired loans: Commercial 46,202 51,821 5,700 Commercial real estate 53,195 64,637 497 Real estate construction and land development 982 1,062 — Residential mortgage 26,594 26,594 192 Consumer installment 451 451 — Home equity 1,979 1,979 — Total $ 129,403 $ 146,544 $ 6,389 The following schedule presents additional information regarding impaired loans by classes of loans segregated by those requiring a valuation allowance and those not requiring a valuation allowance at December 31, 2016 , 2015 and 2014 and the respective interest income amounts recognized: For the years ended December 31, 2016 2015 2014 (Dollars in thousands) Average annual recorded investment Interest income recognized while on impaired status Average annual recorded investment Interest income recognized while on impaired status Average annual recorded investment Interest income recognized while on impaired status Impaired loans with a valuation allowance: Commercial $ 7,829 $ — $ 9,511 $ — $ 2,117 $ — Commercial real estate 5,658 — 2,918 — 3,699 — Real estate construction and land development 19 — — — — — Residential mortgage 23,958 1,285 20,661 1,312 19,740 1,252 Consumer installment 359 — — — — — Home equity 1,759 — — — — — Subtotal 37,464 1,285 33,090 1,312 25,556 1,252 Impaired loans with no related valuation allowance: Commercial 29,559 1,343 27,778 1,005 32,895 961 Commercial real estate 41,646 1,236 50,079 1,547 46,344 1,342 Real estate construction and land development 585 22 889 25 1,831 3 Residential mortgage 1,519 — 6,027 — 6,783 — Consumer installment — — 448 — 592 — Home equity 555 — 1,872 — 2,118 — Subtotal 73,864 2,601 87,093 2,577 90,563 2,306 Total impaired loans: Commercial 37,388 1,343 37,289 1,005 35,012 961 Commercial real estate 47,304 1,236 52,997 1,547 50,043 1,342 Real estate construction and land development 604 22 889 25 1,831 3 Residential mortgage 25,477 1,285 26,688 1,312 26,523 1,252 Consumer installment 359 — 448 — 592 — Home equity 2,314 — 1,872 — 2,118 — Total $ 113,446 $ 3,886 $ 120,183 $ 3,889 $ 116,119 $ 3,558 The difference between an impaired loan's recorded investment and the unpaid principal balance for originated loans represents a partial charge-off resulting from a confirmed loss due to the value of the collateral securing the loan being below the loan balance and management's assessment that full collection of the loan balance is not likely. Impaired loans included $62.5 million and $67.2 million at December 31, 2016 and December 31, 2015 , respectively, of accruing TDRs. Loans Modified Under Troubled Debt Restructurings (TDRs) The following tables present the recorded investment of loans modified into TDRs during the years ended December 31, 2016 , 2015 and 2014 by type of concession granted. In cases where more than one type of concession was granted, the loans were categorized based on the most significant concession. Concession type (Dollars in thousands) Principal Principal A/B Note Restructure (1) Interest Forbearance Total Pre- modification recorded investment Post- modification recorded investment For the year ended December 31, 2016 Commercial loan portfolio: Commercial $ 11,533 $ 1,527 $ 43 $ — $ 1,750 54 $ 14,853 $ 14,853 Commercial real estate 2,993 1,866 — — — 16 4,859 4,859 Subtotal 14,526 3,393 43 — 1,750 70 19,712 19,712 Consumer loan portfolio: Residential mortgage 477 — — — — 4 477 477 Consumer installment 87 — — — — 14 87 87 Home equity 179 — — 364 — 10 543 543 Subtotal 743 — — 364 — 28 1,107 1,107 Total loans $ 15,269 $ 3,393 $ 43 $ 364 $ 1,750 98 $ 20,819 $ 20,819 (1) Loan restructurings whereby the original loan is restructured into two notes: an "A" note, which generally reflects the portion of the modified loans which is expected to be collected: and a "B" note, which is fully charged off. Concession type (Dollars in thousands) Principal Principal A/B Note Restructure (1) Interest Forbearance Total Pre- modification recorded investment Post- modification recorded investment For the year ended December 31, 2015 Commercial loan portfolio: Commercial $ 6,031 $ — $ — $ 117 $ 5,298 53 $ 11,446 $ 11,446 Commercial real estate 5,904 450 — 102 740 21 7,196 7,196 Real estate construction and land development 705 — — — — 3 705 705 Subtotal 12,640 450 — 219 6,038 77 19,347 19,347 Consumer loan portfolio: Residential mortgage 1,246 — — 635 — 20 1,881 1,881 Consumer installment 210 — — — — 19 210 210 Home equity 1,110 — — 46 — 26 1,158 1,156 Subtotal 2,566 — — 681 — 65 3,249 3,247 Total loans $ 15,206 $ 450 $ — $ 900 $ 6,038 142 $ 22,596 $ 22,594 (1) Loan restructurings whereby the original loan is restructured into two notes: an "A" note, which generally reflects the portion of the modified loans which is expected to be collected: and a "B" note, which is fully charged off. Concession type (Dollars in thousands) Principal Principal A/B Note Restructure (1) Interest Forbearance Total Pre- modification recorded investment Post- modification recorded investment For the year ended December 31, 2014 Commercial loan portfolio: Commercial $ 12,657 $ 112 $ 111 $ 901 $ — 53 $ 13,781 $ 13,781 Commercial real estate 10,713 154 223 671 314 46 12,075 12,075 Real estate construction and land development 72 — — — — 1 72 72 Subtotal 23,442 266 334 1,572 314 100 25,928 25,928 Consumer loan portfolio: Residential mortgage 1,832 — — 991 — 36 2,847 2,823 Consumer installment 572 — — — — 52 572 572 Home equity 606 — — 157 — 31 765 763 Subtotal 3,010 — — 1,148 — 119 4,184 4,158 Total loans $ 26,452 $ 266 $ 334 $ 2,720 $ 314 219 $ 30,112 $ 30,086 (1) Loan restructurings whereby the original loan is restructured into two notes: an "A" note, which generally reflects the portion of the modified loans which is expected to be collected: and a "B" note, which is fully charged off. The pre-modification and post-modification 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 presents the Corporation's TDRs at December 31, 2016 and 2015 : (Dollars in thousands) Accruing TDRs Nonaccrual TDRs Total December 31, 2016 Commercial loan portfolio $ 45,388 $ 25,397 $ 70,785 Consumer loan portfolio 17,147 5,134 22,281 Total $ 62,535 $ 30,531 $ 93,066 December 31, 2015 Commercial loan portfolio $ 46,141 $ 32,682 $ 78,823 Consumer loan portfolio 21,037 3,251 24,288 Total $ 67,178 $ 35,933 $ 103,111 The following schedule includes TDRs for which there was a payment default during the years ended December 31, 2016 , 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: For the years ended December 31, 2016 2015 2014 Number of loans Principal balance at year end Number of loans Principal balance at year end Number of loans Principal balance at year end (Dollars in thousands) Commercial loan portfolio: Commercial — $ — 1 $ 1,206 7 $ 885 Commercial real estate 2 1,721 5 1,016 6 2,352 Subtotal — commercial loan portfolio 2 1,721 6 2,222 13 3,237 Consumer loan portfolio (residential mortgage) 14 259 3 65 12 259 Total 16 $ 1,980 9 $ 2,287 25 $ 3,496 At December 31, 2016 , commitments to lend additional funds to borrowers whose terms have been modified in TDRs totaled $1.5 million Allowance for Loan Losses The following schedule presents, by loan portfolio segment, the changes in the allowance for the years ended December 31, 2016 , 2015 and 2014 , and details regarding the balance in the allowance and the recorded investment in loans at December 31, 2016 and 2015 by impairment evaluation method. (Dollars in thousands) Commercial loan portfolio Consumer loan portfolio Unallocated Total Changes in allowance for loan losses for the year ended December 31, 2016: Beginning balance $ 47,234 $ 26,094 $ — $ 73,328 Provision for loan losses 9,788 5,087 — 14,875 Charge-offs (8,906 ) (6,396 ) — (15,302 ) Recoveries 3,085 2,282 — 5,367 Ending balance $ 51,201 $ 27,067 $ — $ 78,268 Allowance for loan losses balance at December 31, 2016 attributable to: Loans individually evaluated for impairment $ 5,234 $ 3,528 $ — $ 8,762 Loans collectively evaluated for impairment 45,967 23,539 — 69,506 Loans accounted for under ASC 310-30 — — — — Total $ 51,201 $ 27,067 $ — $ 78,268 Recorded investment (loan balance) at December 31, 2016: Loans individually evaluated for impairment $ 78,523 $ 28,346 $ — $ 106,869 Loans collectively evaluated for impairment 4,026,526 3,325,006 — 7,351,532 Loans accounted for under ASC 310-30 3,489,163 2,043,215 — 5,532,378 Total $ 7,594,212 $ 5,396,567 $ — $ 12,990,779 Changes in allowance for loan losses for the year ended December 31, 2015: Beginning balance $ 44,156 $ 28,803 $ 2,724 $ 75,683 Provision (benefit) for loan losses 7,275 1,949 (2,724 ) 6,500 Charge-offs (6,385 ) (7,116 ) — (13,501 ) Recoveries 2,188 2,458 — 4,646 Ending balance $ 47,234 $ 26,094 $ — $ 73,328 Allowance for loan losses balance at December 31, 2015 attributable to: Loans individually evaluated for impairment $ 6,197 $ 192 $ — $ 6,389 Loans collectively evaluated for impairment 41,037 25,902 — 66,939 Loans accounted for under ASC 310-30 — — — — Total $ 47,234 $ 26,094 $ — $ 73,328 Recorded investment (loan balance) at December 31, 2015: Loans individually evaluated for impairment $ 100,379 $ 29,024 $ — $ 129,403 Loans collectively evaluated for impairment 3,030,342 2,648,189 — 5,678,531 Loans accounted for under ASC 310-30 1,119,396 343,817 — 1,463,213 Total $ 4,250,117 $ 3,021,030 $ — $ 7,271,147 Changes in allowance for loan losses for the year ended December 31, 2014: Beginning balance $ 44,482 $ 30,145 $ 4,445 $ 79,072 Provision (benefit) for loan losses 3,464 4,357 (1,721 ) 6,100 Charge-offs (6,399 ) (7,830 ) — (14,229 ) Recoveries 2,609 2,131 — 4,740 Ending balance $ 44,156 $ 28,803 $ 2,724 $ 75,683

Premises and Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Premises and Equipment	Premises and Equipment The following table summarizes premises and equipment: December 31, (Dollars in thousands) 2016 2015 Land and land improvements $ 36,185 $ 28,447 Buildings 144,155 120,370 Furniture and equipment 91,963 77,882 Total 272,303 226,699 Less accumulated depreciation (127,291 ) (120,382 ) Premises and equipment, net $ 145,012 $ 106,317 The Corporation leases certain branch properties and equipment under operating leases. Net rent expense was $3.3 million , $1.7 million and $1.2 million for the years ended December 31, 2016 , 2015 and 2014 , respectively. During the years ended December 31, 2016 and 2015 the Corporation transferred $4.8 million and $2.7 million from premises and equipment to other assets, respectively, due to branch or building operation closings/consolidations.

Other Real Estate Owned and Rep

Other Real Estate Owned and Repossessed Assets	12 Months Ended
	Dec. 31, 2016
Other Real Estate [Abstract]
Other Real Estate Owned and Repossessed Assets	Other Real Estate Owned and Repossessed Assets Changes in other real estate owned and repossessed assets were as follows: (Dollars in thousands) Other real estate Repossessed Balance at January 1, 2014 $ 9,518 $ 258 Additions due to acquisitions 3,721 — Other additions (1) 8,986 2,322 Net payments received (264 ) (30 ) Disposals (7,360 ) (2,298 ) Write-downs (648 ) — Balance at December 31, 2014 $ 13,953 $ 252 Additions due to acquisitions 440 — Other additions (1) 6,957 2,372 Net payments received (45 ) (22 ) Disposals (10,168 ) (2,383 ) Write-downs (1,421 ) — Balance at December 31, 2015 $ 9,716 $ 219 Additions due to acquisitions 13,227 313 Other additions (1) 9,938 3,032 Net payments received (1,560 ) (763 ) Disposals (13,873 ) (2,426 ) Write-downs (636 ) — Balance at December 31, 2016 $ 16,812 $ 375 (1) Includes loans transferred to other real estate owned and other repossessed assets. At December 31, 2016 the Corporation had $1.0 million of other real estate owned and repossessed assets as a result of obtaining physical possession in accordance with ASU No. 2014-04, Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans Upon Foreclosure. In addition, there were $7.3 million of consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings are in process, as of December 31, 2016 . Income and expenses related to other real estate owned and repossessed assets, recorded as a component of “Other expense” in the Consolidated Statements of Income, were as follows: (Dollars in thousands) Other real estate owned Repossessed assets For the year ended December 31, 2016 Net gain (loss) on sale $ 5,325 $ 523 Write-downs (636 ) — Net operating expenses (740 ) (60 ) Total $ 3,949 $ 463 For the year ended December 31, 2015 Net gain (loss) on sale $ 4,128 $ (26 ) Write-downs (1,421 ) — Net operating expenses (1,604 ) (19 ) Total $ 1,103 $ (45 ) For the year ended December 31, 2014 Net gain (loss) on sale $ 2,545 $ (11 ) Write-downs (648 ) — Net operating expenses (1,242 ) (53 ) Total $ 655 $ (64 )

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill Goodwill was $1.13 billion and $287.4 million for the periods ended December 31, 2016 and 2015 , respectively. Goodwill recorded is primarily attributable to the synergies and economies of scale expected from combining the operations of the Corporation and other acquisitions. The Corporation recorded goodwill in the amount of $846.7 million related to the merger with Talmer completed on August 31, 2016. During 2015, the Corporation acquired Lake Michigan and Monarch, which resulted in the recognition of goodwill for each transaction of $101.1 million and $5.3 million , respectively. Goodwill is subject to impairment testing annually as of October 31 and on an interim basis if events or changes in circumstances indicate assets might be impaired. Impairment exists when the carrying value of goodwill exceeds its fair value. At December 31, 2016 , the Corporation had positive equity and the Corporation elected to perform a qualitative assessment to determine if it was more likely than not that the fair value exceeded its carrying value, including goodwill. The qualitative assessment indicated that it was more likely than not that the fair value exceeded its carrying value, resulting in no impairment.

Loan Servicing Rights

Loan Servicing Rights	12 Months Ended
	Dec. 31, 2016
Transfers and Servicing [Abstract]
Loan Servicing Rights	Loan Servicing Rights Loan servicing rights (LSRs) are created as a result of selling residential mortgage and commercial real estate loans in the secondary market while retaining the right to service these loans and receive servicing income over the life of the loan, and from acquisitions of other banks that had LSRs. Loans serviced for others are not reported as assets in the Consolidated Statements of Financial Position. Amortization is recorded on LSRs where there has not been an accounting election to account for under the fair value method. The Corporation elected to account for LSRs acquired related to the merger with Talmer effective August 31, 2016 under the fair value method. Loan servicing rights are established and recorded at the estimated fair value by calculating the present value of estimated future net servicing cash flows, taking into consideration actual and expected mortgage loan prepayment rates, discount rates, servicing costs, and other economic factors, which are determined based on current market conditions. The following table represents the activity for LSRs accounted for under the fair value method and the related fair value changes: For the year ended December 31, 2016 (Dollars in thousands) Commercial Real Estate Mortgage Total Fair value, beginning of period $ — $ — $ — Acquired in Talmer Bancorp, Inc. merger 365 42,097 42,462 Additions from loans sold with servicing retained — 1,030 1,030 Changes in fair value due to: Reductions from pay downs (17 ) (502 ) (519 ) Changes in estimates of fair value (1) (4 ) 5,116 5,112 Fair value, end of period $ 344 $ 47,741 $ 48,085 Principal balance of loans serviced for others that have servicing capitalized $ 64,756 $ 5,235,415 $ 5,300,171 (1) Represents estimated LSR value change resulting primarily from market-driven changes in interest rates and prepayments. The Corporation continues to account for all other LSRs using the amortization method. The following shows the net carrying value and fair value of LSRs and the total loans that the Corporation is servicing for others accounted for under the amortization method: December 31, (Dollars in thousands) 2016 2015 Net carrying value of LSRs $ 10,230 $ 11,122 Fair value of LSRs $ 15,891 $ 15,542 Valuation allowance $ 8 $ — Loans serviced for others that have servicing rights capitalized $ 2,074,057 $ 2,082,899 LSRs accounted for under the amortization method 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 $8 thousand as of December 31, 2016 related to impairment within certain pools attributable to the Corporation's servicing portfolios. There was no impairment valuation allowance recorded on the Corporation's LSRs at December 31, 2015. The following table shows the activity for capitalized LSRs accounted for under the amortization method: Years Ended December 31, (Dollars in thousands) 2016 2015 2014 Balance at beginning of period $ 11,122 $ 12,217 $ 3,423 Acquired through acquisitions — 1,284 9,235 Additions 3,303 1,476 1,075 Amortization (4,187 ) (4,055 ) (1,316 ) Change in valuation allowance (8 ) 200 (200 ) Balance at end of period $ 10,230 $ 11,122 $ 12,217 The Corporation realized total loan servicing fee income of $8.7 million , $5.4 million and $2.9 million for the years ended December 31, 2016 , 2015 and 2014 , respectively, recorded as a component of "Mortgage banking revenue" in the Consolidated Statements of Income. Expected and actual loan prepayment speeds are the most significant factors driving the fair value of loan servicing rights. The following table presents assumptions utilized in determining the fair value of loan servicing rights as of December 31, 2016 and 2015 . Commercial Real Estate Mortgage As of December 31, 2016 Prepayment speed 0.00 - 22.47% 0.00 - 99.75% Weighted average (“WA”) discount rate 16.46 % 10.09 % Cost to service/per year $467-$500 $65-$90 WA Ancillary income/per year N/A $ 28 WA float range 0.53 % 1.01 % As of December 31, 2015 Prepayment speed N/A 6.96 - 17.65% WA discount rate N/A 10.04 % Cost to service/per year N/A $70-$85 Ancillary income/per year N/A $ 20 WA float range N/A 1.72 %

Other Intangible Assets

Other Intangible Assets	12 Months Ended
	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Other Intangible Assets	Other Intangible Assets The following table shows the net carrying value of the Corporation's other intangible assets: December 31, (Dollars in thousands) 2016 2015 Core deposit intangible assets $ 40,211 $ 26,654 Non-compete intangible assets — 328 Total other intangible assets $ 40,211 $ 26,982 Core Deposit Intangible Assets The Corporation recorded core deposit intangibles (CDIs) associated with each of its acquisitions. CDIs are amortized on an accelerated basis over their estimated useful lives and have an estimated remaining weighted-average useful life of 8.4 years as of December 31, 2016. The following table presents the Corporation's carrying amount and accumulated amortization of CDIs: December 31, (Dollars in thousands) 2016 2015 Gross carrying amount $ 59,143 $ 40,055 Accumulated amortization 18,932 13,401 Net carrying amount $ 40,211 $ 26,654 Amortization expense recognized on CDIs was $5.2 million , $4.1 million and $2.0 million for the years ended December 31, 2016 , 2015 and 2014 , respectively. The estimated future amortization expense on CDIs for the next five years is as follows: (Dollars in thousands) Estimated amortization expense 2017 $ 5,952 2018 5,703 2019 5,441 2020 4,850 2021 4,471 Non-compete Intangible Assets 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 . Amortization expense on non-competes for the years ended December 31, 2016 and 2015 was $328 thousand and $248 thousand , respectively.

Derivative Instruments and Bala

Derivative Instruments and Balance Sheet Offsetting	12 Months Ended
	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Balance Sheet Offsetting	Derivative Instruments and Balance Sheet Offsetting In the normal course of business, the Corporation enters into various transactions involving derivative instruments to manage exposure to fluctuations in interest rates and to meet the financing needs of customers (customer-initiated derivatives). These financial instruments involve, to varying degrees, elements of market and credit risk. Market and credit risk are included in the determination of fair value. Commitments to fund mortgage loans (interest rate locks) to be sold into the secondary market and forward commitments for the future delivery of mortgage loans to third party investors are considered derivatives. It is the Corporation’s practice to enter into forward commitments for the future delivery of mortgage loans when interest rate lock commitments are entered into in order to economically hedge the effect of changes in interest rates resulting from its commitments to fund the loans. The Corporation enters into interest rate derivatives to provide a service to certain qualifying customers to help facilitate their respective risk management strategies, customer-initiated derivatives, and, therefore, are not used for interest rate risk management purposes. The Corporation generally takes offsetting positions with dealer counterparts to mitigate the inherent risk. Income primarily results from the spread between the customer derivative and the offsetting dealer positions. The Corporation additionally has written and purchased option derivatives consisting of instruments to facilitate an equity-linked time deposit product (the “Power Equity CD”). The Power Equity CD is a time deposit that provides the purchaser a guaranteed return of principal at maturity plus a potential equity return (a written option), while the Corporation receives a known stream of funds based on the equity return (a purchased option). The written and purchased options are mirror derivative instruments which are carried at fair value on the Consolidated Statements of Financial Position. The following table presents the notional amount and fair value of the Corporation’s derivative instruments held or issued in connection with customer-initiated and mortgage banking activities. December 31, 2016 2015 Fair Value Fair Value (Dollars in thousands) Notional Amount (1) Gross Derivative Assets (2) Gross Derivative Liabilities (2) Notional Amount (1) Gross Derivative Assets (2) Gross Derivative Liabilities (2) Customer-initiated and mortgage banking derivatives: Customer-initiated derivatives $ 600,598 $ 4,406 $ 4,141 $ — $ — $ — Forward contracts related to mortgage loans to be delivered for sale 140,155 635 — 33,787 144 57 Interest rate lock commitments 76,034 956 — 23,421 42 90 Power Equity CD 36,807 2,218 2,218 33,703 1,832 1,832 Total gross derivatives $ 853,594 $ 8,215 $ 6,359 $ 90,911 $ 2,018 $ 1,979 (1) Notional or contract amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Statements of Financial Position. (2) Derivative assets are included within “Other assets” and derivative liabilities are included within “Other liabilities” on the Consolidated Statements of Financial Position. Included in the fair value of the derivative assets are credit valuation adjustments for counterparty credit risk totaling $99 thousand at December 31, 2016 and $0 at December 31, 2015. In the normal course of business, the Corporation may decide to settle a forward contract rather than fulfill the contract. Cash received or paid in this settlement manner is included in “Mortgage banking revenue” in the Consolidated Statements of Income and is considered a cost of executing a forward contract. The following table presents the net gains (losses) related to derivative instruments reflecting the changes in fair value. For the years ended December 31, (Dollars in thousands) Location of Gain (Loss) 2016 2015 2014 Forward contracts related to mortgage loans to be delivered for sale Mortgage banking revenue $ 692 $ 193 $ (267 ) Interest rate lock commitments Mortgage banking revenue (1,356 ) (132 ) 157 Power Equity CD Other noninterest income — — — Customer-initiated derivatives Other noninterest income 581 — — Total gain (loss) recognized in income $ (83 ) $ 61 $ (110 ) Methods and assumptions used by the Corporation in estimating the fair value of its forward contracts, interest rate lock commitments and customer-initiated derivatives are discussed in Note 3: Fair Value Measurements. Balance Sheet Offsetting Certain financial instruments, including customer-initiated derivatives, may be eligible for offset in the Consolidated Statements of Financial Position and/or subject to master netting arrangements or similar agreements. The Corporation is party to master netting arrangements with its financial institution counterparties; however, the Corporation does not offset assets and liabilities under these arrangements for financial statement presentation purposes based on an accounting policy election. The tables below present information about the Corporation’s financial instruments that are eligible for offset. There were no financial instruments eligible for offset as of December 31, 2015. Gross amounts not offset in the (Dollars in thousands) Gross Gross amounts Net amounts Financial Collateral Net December 31, 2016 Offsetting derivative assets Derivative assets $ 4,405 $ — $ 4,405 $ — $ — $ 4,405 Offsetting derivative liabilities Derivative liabilities 4,141 — 4,141 — 2,550 1,591

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments, Contingencies and Guarantees Commitments In the normal course of business, the Corporation offers a variety of financial instruments containing credit risk that are not required to be reflected in the Consolidated Statements of Financial Position. These financial instruments include outstanding commitments to extend credit, approved but undisbursed loans (undisbursed loan commitments), credit lines, commercial letters of credit and standby letters of credit. The Corporation has risk management policies to identify, monitor and limit exposure to credit risk. To mitigate credit risk for these financial guarantees, the Corporation generally determines the need for specific covenant, guarantee and collateral requirements on a case-by-case basis, depending on the nature of the financial instrument and the customer's creditworthiness. At December 31, 2016 and 2015 , the Corporation had $118.9 million and $38.8 million , respectively, of outstanding financial and performance standby letters of credit. The majority of these standby letters of credit are collateralized. The Corporation determined that there were no potential losses from standby letters of credit at December 31, 2016 and 2015 . Commitments to extend credit are agreements to lend to a customer provided there is no violation of any condition established in the commitment. Commitments generally have fixed expiration dates or other termination clauses and may not require payment of a fee. Since many commitments expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The Corporation evaluates each customer's creditworthiness on an individual basis. The amount of collateral obtained, if deemed necessary by the Corporation upon extension of credit, is based on management's credit evaluation of the counterparty. The collateral held varies, but may include securities, real estate, accounts receivable, inventory, plant or equipment. Unfunded commitments under commercial lines of credit , revolving credit lines and overdraft protection agreements are included in commitments to extend credit. These lines of credit are generally not collateralized, usually do not contain a specified maturity date and may be drawn upon only to the total extent to which the Corporation is committed. At December 31, 2016 and 2015 , the Corporation had $2.70 billion and $1.59 billion , respectively, of commitments to extend credit. The Corporation had undisbursed loan commitments of $578.2 million and $293.6 million at December 31, 2016 and 2015 , respectively. Undisbursed loan commitments are not included in loans on the Consolidated Statements of Financial Position. The majority of undisbursed loan commitments will be funded and convert to a portfolio loan within a one year period. The allowance for credit losses on lending-related commitments included $1.3 million and $0 at December 31, 2016 and 2015 , respectively, for probable credit losses inherent in the Corporation's unused commitments and was recorded in "Interest payable and other liabilities" in the Consolidated Statements of Financial Position. Contingencies and Guarantees The Corporation has originated and sold certain loans, and additionally acquired the potential liability for those historical originated and sold loans by Talmer, for which the buyer has limited recourse to us in the event the loans do not perform as specified in the agreements. These loans had an outstanding balance of $16.9 million and $1.5 million at December 31, 2016 and 2015 , respectively. The maximum potential amount of undiscounted future payments that the Corporation could be required to make in the event of nonperformance by the borrower totaled $16.1 million and $1.5 million at December 31, 2016 and 2015 , respectively. In the event of nonperformance, the Corporation has rights to the underlying collateral securing the loans. As of December 31, 2016 and 2015 , respectively, the Corporation had recorded a liability of $200 thousand and $100 thousand , respectively, in connection with the recourse agreements, recorded in "Interest payable and other liabilities" in the Consolidated Statements of Financial Position. Representations and Warranties In connection with the Corporation's mortgage banking loan sales, and the historical sales of Talmer, the Corporation makes certain representations and warranties that the loans meet certain criteria, such as collateral type and underwriting standards. The Corporation may be required to repurchase individual loans and/or indemnify the purchaser against losses if the loan fails to meet established criteria. At December 31, 2016 and 2015 , respectively, the liability recorded in connection with these representations and warranties totaled $6.5 million and $4.0 million , respectively. For the years ended December 31, (Dollars in thousands) 2016 2015 2014 Reserve balance at beginning of period $ 4,048 $ 3,000 $ 1,600 Addition of fair value of representations and warranties due to acquisitions 3,100 1,712 2,000 Reserve reduction (580 ) — (287 ) Charge-offs (109 ) (664 ) (313 ) Ending reserve balance $ 6,459 $ 4,048 $ 3,000 Reserve balance: Liability for specific claims 730 — 118 General allowance 5,729 4,048 2,882 Total reserve balance $ 6,459 $ 4,048 $ 3,000 Operating Leases and Other Noncancelable Contractual Obligations The Corporation has operating leases and other noncancelable contractual obligations on buildings, equipment, computer software and other expenses that will require annual payments through 2034, including renewal option periods for those building leases that the Corporation expects to renew. Future minimum lease payments for operating leases and other noncancelable contractual obligations are as follows: (Dollars in thousands) Future Minimum Lease Payments(1) Years ending December 31, 2017 $ 20,712 2018 18,000 2019 14,594 2020 11,362 2021 7,173 Thereafter 16,549 Total $ 88,390 (1) Future minimum lease payments are reduced by $312 thousand related to sublease income to be received within the next five years. Minimum payments include estimates, where applicable, of estimated usage and annual Consumer Price Index increases of approximately 2.1% . Total expense recorded under operating leases and other noncancelable contractual obligations was $20.4 million in 2016 , compared to $15.6 million in 2015 and $12.4 million in 2014 . Legal Proceedings The Corporation and Chemical Bank are subject to various pending or threatened legal proceedings arising out of the normal course of business. The Corporation assesses its liabilities and contingencies in connection with outstanding legal proceedings utilizing the latest information available. Where it is probable that the Corporation will incur a loss and the amount of the loss can be reasonably estimated, the Corporation records a liability in its consolidated financial statements. While the ultimate liability with respect to these litigation matters and claims cannot be determined at this time, in the opinion of management, the ultimate disposition of these matters is not expected to have a material adverse effect on the financial position or results of operations of the Corporation.

Deposits

Deposits	12 Months Ended
	Dec. 31, 2016
Deposits [Abstract]
Deposit Liabilities Disclosures	Deposits A summary of deposits follows: December 31, (Dollars in thousands) 2016 2015 Noninterest-bearing demand $ 3,341,520 $ 1,934,583 Interest-bearing demand 2,825,801 1,870,197 Savings and money market accounts 3,695,434 2,004,575 Time deposits over $100,000 1,682,986 701,830 Other time deposits 1,327,381 945,582 Total deposits $ 12,873,122 $ 7,456,767 Excluded from total deposits are demand deposit account overdrafts (overdrafts) which have been classified as loans. At December 31, 2016 and 2015 , overdrafts totaled $5.0 million and $3.0 million , respectively. Time deposits, including certificates of deposit and certain individual retirement account deposits, of $250 thousand or more totaled $975.4 million and $364.0 million at December 31, 2016 and 2015 , respectively. At December 31, 2016 , the scheduled maturities of time deposits for the next five years were as follows: (Dollars in thousands) 2017 $ 2,159,477 2018 393,811 2019 167,132 2020 139,555 2021 142,146 Thereafter 8,246 Total $ 3,010,367

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Borrowings	Borrowings A summary of the Corporation's short- and long-term borrowings follows: December 31, 2016 2015 (Dollars in thousands) Amount Weighted Average Rate (1) Amount Weighted Average Rate (1) Short-term borrowings: FHLB advances: 0.60% - 0.66% fixed-rate notes $ 825,000 0.65 % $ 100,000 0.34 % Long-term borrowings: FHLB advances: 0.81% - 7.44% fixed-rate notes due 2017 to 2020 (2) 438,538 1.24 181,394 1.41 Securities sold under agreements to repurchase: 1.48% - 4.11% fixed-rate notes due through 2017 (3) 19,144 3.17 17,453 0.27 Line-of-credit: floating-rate based on one-month LIBOR plus 1.75% 124,625 2.52 25,000 2.27 Subordinated debt obligations: floating-rate based on three-month LIBOR plus 1.45% - 2.85% due 2034 to 2035 (4) 11,285 3.14 — — Subordinated debt obligations: floating-rate based on three-month LIBOR plus 3.25% due in 2032 (5) 4,255 4.25 — — Subordinated debt obligations — — 18,544 3.99 Total long-term borrowings 597,847 1.63 242,391 1.61 Total short-term and long-term borrowings $ 1,422,847 1.06 % $ 342,391 1.24 % (1) Weighted average rate presented is the contractual rate which excludes premiums and discounts related to purchase accounting. (2) The December 31, 2016 balance includes advances payable of $437.8 million and purchase accounting premiums of $0.7 million . The December 31, 2015 balance includes advances payable of $181.0 million and purchase accounting premiums of $0.4 million . (3) The December 31, 2016 balance includes advances payable of $19.0 million and purchase accounting premiums of $0.1 million . The December 31, 2015 balance includes advance payable of $17.0 million and purchase accounting premiums of $0.5 million . (4) The December 31, 2016 balance includes advances payable of $15.0 million and purchase accounting discounts of $3.7 million . (5) The December 31, 2016 balance includes advances payable of $5.0 million and purchase accounting discounts of $0.7 million . Chemical Bank is a member of the FHLB, which provides short- and long-term funding collateralized by mortgage related assets to its members. Each advance is payable at its maturity date, with a prepayment penalty for fixed-rate advances. The Corporation's FHLB advances, including both short-term and long-term, require monthly interest payments and are collateralized by commercial and residential mortgage loans totaling $5.14 billion as of December 31, 2016 . The Corporation's additional borrowing availability through the FHLB, subject to the FHLB's credit requirements and policies and based on the amount of FHLB stock owned by the Corporation, was $7.0 million at December 31, 2016 . Securities sold under agreements to repurchase are with an unaffiliated financial institution and are secured by available for-sale-securities. The Corporation's securities sold under agreements to repurchase do not qualify as sales for accounting purposes. The remaining contract maturity, excluding purchase accounting adjustments, of long-term securities under agreement to repurchase, is as follows: December 31, 2016 Remaining Contractual Maturities of the Agreements (Dollars in thousands) Overnight and continuous Up to 30 Days 30-90 Days Greater than 90 Days Total Securities sold under agreements to repurchase $ — $ 10,000 $ — $ 9,000 $ 19,000 Total borrowings $ — $ 10,000 $ — $ 9,000 $ 19,000 Amounts related to securities sold under agreements to repurchase not included in offsetting disclosure in Footnote 11 $ 19,000 In conjunction with the merger with Talmer, the Corporation entered into a credit agreement of $145.0 million consisting of a $125.0 million term line-of credit and a $20.0 million revolving line-of-credit. The Corporation drew $125.0 million on the term line-of-credit to pay off the Corporation's prior $25.0 million line-of-credit and a $37.5 million line-of-credit acquired in the merger with Talmer, with the remaining proceeds used to partially fund the cash portion of the merger consideration. The line-of-credit agreement contains certain restrictive covenants. The Corporation was in compliance with all of the covenants at December 31, 2016. As a result of the Lake Michigan transaction on May 31, 2015, the Corporation acquired subordinated debt obligations in the amount of $18.6 million . The Corporation fully repaid these debt obligations during the first quarter of 2016. As a result of the merger with Talmer on August 31, 2016, the Corporation acquired $687.1 million in short and long-term debt obligations, of which $142.2 million was paid off prior to December 31, 2016. At December 31, 2016 , the contractual principal payments due and the amortization/accretion of purchase accounting adjustments for the remaining maturities of long-term debt over the next five years and thereafter are as follows: (Dollars in thousands) Long-term Debt by Maturity Years Ending December 31, 2017 $ 126,089 2018 159,207 2019 186,338 2020 110,673 2021 — Thereafter 15,540 Total $ 597,847

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The current and deferred components of the provision for income taxes were as follows: Years Ended December 31, (Dollars in thousands) 2016 2015 2014 Current income tax expense (benefit) Federal $ 19,144 $ 31,300 $ 29,200 State (423 ) — — Total current income tax expense 18,721 31,300 29,200 Deferred expense (benefit) Federal 23,649 5,700 (1,700 ) State 442 — — Total deferred income tax expense (benefit) 24,091 5,700 (1,700 ) Change in valuation allowance (706 ) — — Income tax provision $ 42,106 $ 37,000 $ 27,500 A reconciliation of expected income tax expense at the federal statutory income tax rate and the amounts recorded in the Consolidated Financial Statements were as follows: Years Ended December 31, 2016 2015 2014 (Dollars in thousands) Amount Rate Amount Rate Amount Rate Tax at statutory rate $ 52,548 35.0 % $ 43,341 35.0 % $ 31,367 35.0 % Changes resulting from: Tax-exempt interest income (5,320 ) (3.5 ) (3,943 ) (3.2 ) (3,142 ) (3.5 ) State taxes, net of federal benefit 13 — — — — — Change in valuation allowance (706 ) (0.5 ) — — — — Bank-owned life insurance adjustments (832 ) (0.6 ) (124 ) (0.1 ) (95 ) (0.1 ) Director plan change in control (508 ) (0.3 ) — — — — Income tax credits, net (2,454 ) (1.6 ) (2,557 ) (2.1 ) (1,624 ) (1.8 ) Nondeductible transaction expenses 2,100 1.4 411 0.3 403 0.4 Tax benefits in excess of compensation costs on share-based payments (1) (2,240 ) (1.5 ) — — — — Other, net (495 ) (0.4 ) (128 ) — 591 0.7 Income tax expense $ 42,106 28.0 % $ 37,000 29.9 % $ 27,500 30.7 % (1) The year ended December 31, 2016 reflects the impact of the early adoption of ASU 2016-09 which resulted in excess tax benefits recognized within "Income tax expense" rather than previously recognized directly into equity with "Additional paid-in-capital." Refer to Note 1, Summary of Significant Accounting Policies, for further details. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The significant components of the deferred tax assets and liabilities at December 31, 2016 and 2015 were as follows: December 31, (Dollars in thousands) 2016 2015 Deferred tax assets: Allowance for loan losses $ 45,763 $ 24,863 Acquisition-related fair value adjustments 62,078 29,280 Accrued stock-based compensation 18,891 3,240 Loss and tax credit carry forwards 47,977 7,235 Acquisition built in loss carry forward 28,469 — Depreciation 3,896 4,333 Nonaccrual loan interest 9,465 4,994 Accrued expense 20,858 13,296 Other 7,401 5,951 Total deferred tax assets 244,798 93,192 Deferred tax liabilities: Loan servicing rights 20,450 3,893 Core deposit intangible assets 11,844 7,379 Goodwill 6,373 5,808 Other (715 ) 4,742 Total deferred tax liabilities 37,952 21,822 Net deferred tax asset before valuation allowance 206,846 71,370 Valuation allowance (2,239 ) (1,180 ) Net deferred tax asset $ 204,607 $ 70,190 On August 31, 2016, the Corporation merged with Talmer and recorded $151.9 million in deferred tax assets, net of valuation allowance. In connection with the merger, Talmer incurred an ownership change within the meaning of Section 382 of the Internal Revenue Code (IRC). At August 31, 2016, Talmer had $102.8 million in gross federal net operating loss carry forwards, $88.7 million in gross realized built-in loss carry forwards, $1.0 million in federal tax credit carry forwards that expire from 2026 through 2035, and $14.9 million in federal alternative minimum tax credits with an indefinite life. Talmer’s acquisitions prior to its merger with the Corporation on August 31, 2016 resulted in ownership changes within the meaning of IRC Section 382. As such, the Corporation’s ability to benefit from the use of Talmer’s previously acquired entities’ pre-ownership change net operating loss and tax credit carry forwards, as well as the deductibility of certain built-in losses if realized during a five-year recognition period (one year with respect to bad debt deductions), is limited, putting at risk the utilization of associated deferred tax assets before they expire. At August 31, 2016, a valuation allowance of $1.8 million was established against the deferred tax assets associated with Talmer’s previously acquired entities’ pre-change net operating losses and tax credit carry forwards, realized built-in loss carry forwards and management's estimate of the amount and timing of built-in losses more likely than not to be realized over the remaining Section 382 recognition periods. The valuation allowance against the Corporation’s deferred tax assets at December 31, 2016 totaled $2.2 million and included $1.4 million due to IRC Section 382 limitations on the utilization of pre-ownership change loss and tax credit carry forwards associated with Talmer’s previously acquired entities and $0.8 million due to management’s estimate of capital loss carry forwards more likely than not to expire unutilized. Actual outcomes could vary from the Corporation's current estimates, resulting in future increases or decreases in the valuation allowance and corresponding future tax expense or benefit. Due to the substantial equity value of Talmer at the time of the ownership change, the entity was deemed to be in a net unrealized built-in gain position which allows for the utilization of certain carry forward attributes. Therefore, no additional valuation allowance was established against Talmer's net deferred tax assets. The following table is a summary of the loss attributes, Section 382 limitations, and tax expiration periods as of December 31, 2016 . From the Acquisition of: Talmer's Prior Ownership Changes (Dollars in thousands) Talmer Monarch First Place Holdings/First Place Bank Talmer West Bank First of Huron Corp./Signature Bank From 2009 Ownership change Not Limited by Section 382 Total Tax Loss and Credit Carryforwards as of 12/31/16: Years Expiring (except AMT Credits) 2032-2034 2026-2034 2026-2031 2030-2035 2031-2033 2027-2029 2033-2035 Annual Section 382 limitation-base (1) $ 34,668 $ 673 $ 6,650 $ 3,028 $ 365 $ 145 $ — N/A Gross Federal Net Operating Losses 17,723 17,744 1,222 50,086 1,014 1,885 — 89,674 Gross Capital Losses 797 — — — — — — 797 Realized Built-in Losses — — 71,805 8,936 — — — 80,741 Business Tax Credits 170 1,651 781 — — — 592 3,194 Less amounts not recorded due to Sec 382 Limitation — (1,738 ) — (2,992 ) — (145 ) — (4,875 ) Alternative Minimum Tax Credits - no expiration 12,473 106 2,115 — 303 — 730 15,727 Valuation Allowance — — (66 ) (1,287 ) — — — (1,353 ) (1) In respect to the Monarch and Talmer acquisitions, in addition to the statutory "base" Section 382 limitation, recognized built in gain increases the Section 382 limitation during the five year period beginning on the acquisition date. The Corporation estimates that the recognized built in gain will total $5.6 million and $322.3 million for the Monarch and Talmer acquisitions, respectively. Management concluded that no valuation allowance was necessary on the remainder of the Corporation's net deferred tax assets at December 31, 2016 and 2015 . This determination was based on the Corporation's history of pre-tax and taxable income over the prior three years, as well as management's expectations for sustainable profitability in the future. Management monitors deferred tax assets quarterly for changes affecting realizability and the valuation allowance could be adjusted in future periods. At December 31, 2016 , the Corporation had approximately $36.0 million of bad debt reserve in equity for which no provision for federal income taxes was recorded. This amount represents Talmer's qualifying thrift bad debt reserve at December 31, 1987 through its acquisition of First Place Bank, which is only required to be recaptured into taxable income if certain events occur. At December 31, 2016 , the potential tax on the above amount was approximately $13.0 million . The Corporation does not intend to take any action that would result in a recapture of any portion of its bad debt reserve. The Corporation's federal tax return for the years ended December 31, 2013 to present are open to potential examination. Talmer amended its four federal tax returns for the years 2011, 2012, 2013 and 2014 to reflect the impact of changes to First Place Bank due to an IRS settlement in January of 2016. These four amendments were selected for audit and are currently in the process of being finalized. The Corporation does not anticipate any changes as a result of the audit. The Corporation's most significant states of operation, Michigan and Ohio, do not impose income-based taxes on financial institutions. The Corporation and/or its subsidiaries are subject to immaterial amounts of income tax in various other states, with varying years open to potential examination. The Corporation is not aware of any pending income tax examinations by any state jurisdiction. The Corporation had no unrecognized tax benefits at December 31, 2016 or 2015 and does not expect to record unrecognized tax benefits of any significance during the next twelve months. The Corporation recognizes interest and/or penalties related to income tax matters in income tax expense, when applicable. There are no liabilities accrued for interest or penalties at December 31, 2016 or 2015 .

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	Shared-Based Compensation The Corporation maintains share-based compensation plans under which it periodically grants share-based awards for a fixed number of shares to certain officers of the Corporation. The fair value of share-based awards is recognized as compensation expense over the requisite service or performance period. During the years ended December 31, 2016 , 2015 and 2014 , share-based compensation expense related to share-based awards totaled $14.7 million , $3.7 million and $2.9 million , respectively. The excess tax benefit realized from shared-based compensation transactions during the years ended December 31, 2016 , 2015 and 2014 was $2.2 million , $0.5 million and $0.2 million , respectively. During the year ended December 31, 2016 , the Corporation granted options to purchase 441,167 shares of common stock, 165,876 restricted stock units and 6,381 shares of common stock to certain officers of the Corporation. In addition, the Corporation assumed options to purchase 1,466,408 shares of common stock and 484,892 restricted stock awards in connection with the Talmer merger. 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 December 31, 2016 , there were 626,353 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 from time to time. The exercise price on stock options equals the current market price of the Corporation's common stock on the date of grant and stock options expire ten years from the date of grant. Stock options granted after 2012 vest ratably over a five -year period. Stock options granted prior to 2013 generally vest ratably over a three -year period. Stock options granted prior to 2016 fully vested upon completion of the merger with Talmer. Stock options assumed by the Corporation in the merger with Talmer were fully vested prior to assumption. The following summarizes information about stock options outstanding and exercisable at December 31, 2016 : Options outstanding Options exercisable Range of exercise prices per share Number outstanding Weighted average exercise price per share Weighted average contractual term (in years) Number exercisable Weighted average exercise price per share Weighted average contractual term (in years) $10.56 - 12.80 289,512 $ 11.83 3.50 289,512 $ 11.83 3.50 $13.20 - 16.24 1,044,881 16.20 5.99 1,044,881 16.20 5.99 $19.97 - 21.10 62,422 20.49 3.39 62,422 20.49 3.39 $28.43 - 32.81 703,378 31.58 8.58 295,439 29.88 7.76 $23.78 - 25.14 353,202 24.60 4.49 353,202 24.60 4.49 $10.56 - 32.81 2,453,395 $ 21.41 6.16 2,045,456 $ 19.14 5.56 The intrinsic value of all outstanding in-the-money stock options and exercisable in-the-money stock options was $80.4 million and $71.7 million , respectively, at December 31, 2016 . The aggregate intrinsic values of outstanding and exercisable options at December 31, 2016 were calculated based on the closing market price of the Corporation's common stock on December 31, 2016 of $54.17 per share less the exercise price. Options with intrinsic values less than zero, or "out-of-the-money" options, are not included in the aggregate intrinsic value reported. The total intrinsic value of stock options for the years ended December 31, 2015 and 2014 was $7.6 million and $5.1 million , respectively. Total cash received from option exercises during the years ended December 31, 2016 , 2015 and 2014 was $2.7 million , $2.3 million and $1.0 million , respectively, resulting in the issuance of 229 thousand shares, 135 thousand shares and 45 thousand shares, respectively. At December 31, 2016 , unrecognized compensation expense related to stock options totaled $2.1 million and is expected to be recognized over a remaining weighted average period of 4.2 years. Stock options granted prior to 2016 contain change-of-control provisions that triggered full vesting upon completion of the merger with Talmer. As a result, unrecognized compensation expense related to these stock options was recognized by the Corporation during the year ended December 31, 2016 . A summary of activity for the Corporation's stock options as of and during the years ended December 31, 2016 , 2015 and 2014 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, 2013 414,080 $ 24.29 $ 7.19 1,073,990 $ 26.84 Granted 190,011 29.45 9.64 190,011 29.45 Exercised — — — (72,936 ) 24.67 Vested (148,016 ) 23.43 6.98 — — Expired or forfeited (23,876 ) 25.67 7.79 (153,754 ) 37.50 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 Acquired — — — 132,883 12.93 Exercised — — — (310,985 ) 25.10 Vested (150,224 ) 25.57 7.80 — — Expired or forfeited (46,385 ) 27.99 8.50 (48,635 ) 28.18 Outstanding at December 31, 2015 479,755 $ 28.75 $ 8.49 1,054,739 $ 25.38 Acquired — — — 1,466,408 15.08 Granted 441,167 32.81 6.15 441,167 32.81 Exercised — — — (450,296 ) 20.02 Vested (454,360 ) 28.74 8.49 — — Forfeited/expired (58,623 ) 31.10 7.17 (58,623 ) 31.10 Outstanding at December 31, 2016 407,939 $ 32.81 $ 6.15 2,453,395 $ 21.41 Exercisable/vested at December 31, 2016 2,045,456 $ 19.14 The fair value of the stock options granted during the years ended December 31, 2016 , 2015 and 2014 were estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions. 2016 2015 2014 Expected dividend yield 3.30 % 3.50 % 3.00 % Risk-free interest rate 1.39 % 1.78 % 2.16 % Expected stock price volatility 27.9 % 39.1 % 42.2 % Expected life of options — in years 6.5 7.0 7.0 Weighted average fair value of options granted $6.15 $8.40 $9.64 The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant and the expected life of the options granted. Expected stock volatility was based on historical volatility of the Corporation's common stock over a the expected life of the option. The expected life of options represents the period of time that options granted are expected to be outstanding and is based primarily upon historical experience, including option exercise behavior. Because of the unpredictability of the assumptions required, the Black-Scholes (or any other valuation) model is incapable of accurately predicting the Corporation's common stock price or of placing an accurate present value on options to purchase its stock. In addition, the Black-Scholes model was designed to approximate value for types of options that are very different from those issued by the Corporation. In spite of any theoretical value that may be placed on a stock option grant, no value is possible under options issued by the Corporation without an increase in the market price per share of the Corporation's common stock over the market price per share of the Corporation's common stock at the date of grant. Restricted Stock Units The Corporation grants restricted stock performance units and restricted stock service-based units (collectively referred to as restricted stock units) to certain officers from time to time. The restricted stock performance units vest based on the Corporation achieving certain performance target levels and the grantee completing the requisite service period. The restricted stock performance units are eligible to vest from 0.5 x to 1.5 x the number of units originally granted depending on which, if any, of the performance target levels are met. However, if the minimum performance target levels are not achieved, no shares will become vested or be issued for that respective year's restricted stock performance units. The restricted stock service-based units vest upon satisfaction of a service condition. Upon achievement of the performance target level and/or satisfaction of a service condition, as 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 during the year ended December 31, 2016 is presented below: Number of units Weighted-average grant date fair value per unit Outstanding at December 31, 2015 207,989 $ 26.41 Granted 165,876 37.41 Converted into shares of common stock (67,331 ) 24.54 Forfeited/expired (8,177 ) 31.19 Outstanding at December 31, 2016 298,357 $ 32.81 At December 31, 2016 , unrecognized compensation expense related to restricted stock units totaled $4.7 million and is expected to be recognized over a remaining weighted average period of 2.4 years . Certain restricted stock units granted prior to 2016 fully vested upon completion of the merger with Talmer. In addition, in consideration for the award of additional restricted stock units that the holder and the Corporation agreed was a material benefit to which the holder was not otherwise entitled, certain holders of restricted stock units agreed with the Corporation to amend the terms of their restricted stock units such that vesting did not occur upon completion of the merger with Talmer and remained subject to existing performance-based or time-based vesting schedules. As a result, unrecognized compensation expense related to the elected restricted stock units was recognized by the Corporation during the year ended December 31, 2016 . Restricted Stock Awards The Corporation assumed restricted stock awards in the merger with Talmer that vest upon completion of future service requirements . The fair value of these awards is equal to the market price of the Corporation's common stock at the date the awards were assumed with the portion of the fair value related to post-combination service. The Corporation recognizes stock-based compensation expense over the vesting period, using the straight-lined method, based upon the number of shares of restricted stock ultimately expected to vest. If an individual awarded restricted stock awards terminates employment prior to the end of the vesting period, the unvested portion of the stock is forfeited, with certain exceptions. The following table provides information regarding nonvested restricted stock awards: Nonvested restricted stock awards Number of awards Weighted-average acquisition-date fair value Nonvested at January 1, 2016 — $ — Acquired 484,892 46.23 Vested (118,493 ) 46.23 Forfeited (508 ) 46.23 Nonvested at December 31, 2016 365,891 $ 46.23 At December 31, 2016 , unrecognized compensation expense related to nonvested restricted stock awards totaled $9.0 million and is expected to be recognized over a remaining weighted average period of 1.4 years .

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Retirement Plans	Retirement Plans Defined Benefit Pension Plan The Corporation has a noncontributory defined benefit pension plan (Pension Plan) covering certain salaried employees. Benefits under the Pension Plan were frozen for approximately two-thirds of the Corporation's salaried employees effective June 30, 2006. Pension benefits continued unchanged for the remaining salaried employees. Normal retirement benefits under the Pension Plan are based on years of vested service, up to a maximum of thirty years , and the employee's average annual pay for the five highest consecutive years during the ten years preceding retirement, except for employees whose benefits were frozen. Benefits, for employees with less than 15 years of service or whose age plus years of service were less than 65 at June 30, 2006, will be based on years of vested service at June 30, 2006 and generally the average of the employee's salary for the five years ended June 30, 2006. At December 31, 2016 , the Corporation had 135 employees who were continuing to earn benefits under the Pension Plan. Pension Plan contributions are intended to provide not only for benefits attributed to service-to-date, but also for those benefits expected to be earned in the future for employees whose benefits were not frozen at June 30, 2006. Employees hired after June 30, 2006 and employees affected by the partial freeze of the Pension Plan began receiving 4.0% of their eligible pay as a contribution to their 401(k) Savings Plan accounts on July 1, 2006. Pension Plan expense was $0.1 million in 2016 , $1.6 million in 2015 and zero in 2014 . Supplemental Plan The Corporation has a supplemental defined benefit pension plan, the Chemical Financial Corporation Supplemental Pension Plan (Supplemental Plan). The Corporation established the Supplemental Plan to provide payments to certain executive officers of the Corporation, as determined by the Compensation and Pension Committee. At December 31, 2016 and 2015 , the only executive officer earning benefits under the Supplemental Plan was the Corporation's chief executive officer. Obligations earned as of August 31, 2016, totaling $1.9 million , became payable in a lump-sum payment as a result of the Corporation undergoing a change in control under the Supplemental Plan due to the Talmer merger. This payment has been delayed for the chief executive officer on the basis that payment would not be deductible under Section 162(m) of the Internal Revenue Code, with payment to be made during the period beginning with the date of the chief executive officer's separation from service and ending on the later of the last day of the taxable year in which the chief executive officer separates from service or the15th day of the third months following separation from service. The calculation of benefits earned following the merger with Talmer continue to accrue under the supplemental defined benefit pension plan's original terms. The Internal Revenue Code limits both the amount of eligible compensation for benefit calculation purposes and the amount of annual benefits that may be paid from a tax-qualified retirement plan. The Supplemental Plan is designed to provide benefits to which executive officers of the Corporation would have been entitled, calculated under the provisions of the Pension Plan, as if the limits imposed by the Internal Revenue Code did not apply. The Supplemental Plan is an unfunded plan and, therefore, has no assets. The Supplemental Plan's projected benefit obligation was $2.6 million and $2.2 million at December 31, 2016 and 2015 , respectively. The Supplemental Plan's accumulated benefit obligation was $2.2 million and $1.8 million at December 31, 2016 and 2015 , respectively. Supplemental Plan expense totaled $0.5 million in 2016 , $0.4 million in 2015 and $0.3 million in 2014 . Postretirement Plan The Corporation has a postretirement benefit plan (Postretirement Plan) that provides medical and dental benefits, upon retirement, to a limited number of active and retired employees. The majority of the retirees are required to make contributions toward the cost of their benefits based on their years of credited service and age at retirement. Beginning January 1, 2012, the Corporation amended the Postretirement Plan to extend coverage to employees who were at least age 50 as of January 1, 2012. These employees must also retire at age 60 or older, have at least twenty-five years of service with the Corporation and be participating in the active employee group health insurance plan in order to be eligible to participate in the Corporation's Postretirement Plan. Eligible employees may also cover their spouse until age 65 as long as the spouse is not offered health insurance coverage through his or her employer. Employees and their spouses eligible to participate in the Postretirement Plan will be required to make contributions toward the cost of their benefits upon retirement, with the contribution levels designed to cover the projected overall cost of these benefits over the long-term. Retiree contributions are generally adjusted annually. The accounting for these postretirement benefits anticipates changes in future cost-sharing features such as retiree contributions, deductibles, copayments and coinsurance. The Corporation reserves the right to amend, modify or terminate these benefits at any time. 401(k) Savings Plan The Corporation's 401(k) Savings Plan provides an employer match, in addition to a 4.0% contribution for employees who are not grandfathered under the Pension Plan discussed above. The 401(k) Savings Plan is available to all regular employees and provides employees with tax deferred salary deductions and alternative investment options. The Corporation matches 50.0% of the participants' elective deferrals on the first 4.0% of the participants' base compensation up to the maximum amount allowed under the Internal Revenue Code. The 401(k) Savings Plan provides employees with the option to invest in the Corporation's common stock. The Corporation's match under the 401(k) Savings Plan was $3.0 million in 2016 , $1.6 million in 2015 and $1.0 million in 2014 . Employer contributions to the 401(k) Savings Plan for the 4.0% benefit for employees who are not grandfathered under the Pension Plan totaled $3.5 million in 2016 , $3.1 million in 2015 and $2.3 million in 2014 . The combined amount of the employer match and 4.0% contribution to the 401(k) Savings Plan totaled $6.5 million in 2016 , $4.7 million in 2015 and $3.3 million in 2014 . Multi-Employer Defined Benefit Plan In conjunction with the April 1, 2015 acquisition of Monarch, the Corporation acquired a participation in the Pentegra Defined Benefit Plan for Financial Institutions (Pentegra DB plan), a qualified defined benefit plan. Employee benefits for Monarch employees under the Pentegra DB Plan were frozen effective April 1, 2004. The Pentegra DB Plan operates as a multi-employer plan for accounting purposes and as a multiple employer plan under the Employee Retirement Income Security Act of 1974 and the Internal Revenue Code (IRC). The Pentegra DB Plan is a single plan under IRC Section 413(c) and, as a result, all the plan's assets stand behind all of the plan's liabilities. Accordingly, contributions made by a participating employer may be used to provide benefits to participants of other participating employers. No contributions were made to the Pentegra DB Plan during the years ended December 31, 2016 and 2015. The Pentegra DB Plan's Employer Identification Number is 13-5645888 and the Plan Number is 333. Financial information for the Pentegra DB Plan, which maintains a June 30 year end, is made available through the public Form 5500 which is available by April 15th of the year following the plan year end. The Pentegra DB Plan was fully funded as of its most recent year end. The Corporation's allocation of assets and liabilities in the Pentegra DB Plan totaled $3.5 million and $2.6 million respectively, as of the plan's most recent year end, and the Corporation's allocation of assets comprised less than 5.0% of the plan's total assets at that date. Benefit Obligations and Plan Expenses The following schedule sets forth the changes in the projected benefit obligation and plan assets of the Corporation's Pension and Postretirement Plans: Pension Plan Postretirement Plan (Dollars in thousands) 2016 2015 2016 2015 Projected benefit obligation: Benefit obligation at beginning of year $ 119,873 $ 129,160 $ 3,247 $ 3,702 Service cost 1,041 1,021 9 16 Interest cost 5,335 5,242 132 133 Net actuarial loss (gain) 2,684 (10,837 ) (478 ) (363 ) Benefits paid (4,965 ) (4,713 ) (309 ) (241 ) Benefit obligation at end of year 123,968 119,873 2,601 3,247 Fair value of plan assets: Fair value of plan assets at beginning of year 126,930 130,775 — — Actual return on plan assets 10,786 868 — — Employer contributions — — 309 241 Benefits paid (4,965 ) (4,713 ) (309 ) (241 ) Fair value of plan assets at end of year 132,751 126,930 — — Funded (unfunded) status at December 31 $ 8,783 $ 7,057 $ (2,601 ) $ (3,247 ) Accumulated benefit obligation $ 115,418 $ 109,583 $ 2,601 $ 3,247 The increases in the projected and accumulated benefit obligations of the Pension Plan during 2016 were primarily attributable to a decrease in the discount rate used to value these benefit obligations. The Corporation did not make a contribution to the Pension Plan in either 2016 or 2015. The Corporation is not required to make a contribution to the Pension Plan in 2017 . Weighted-average rate assumptions of the Pension and Postretirement Plans follow: Pension Plan Postretirement Plan 2016 2015 2014 2016 2015 2014 Discount rate used in determining benefit obligation — December 31 4.22 % 4.55 % 4.15 % 3.79 % 4.23 % 3.75 % Discount rate used in determining expense 4.55 4.15 5.00 4.23 3.75 4.27 Expected long-term return on Pension Plan assets 6.75 6.75 7.00 — — — Rate of compensation increase used in determining benefit obligation — December 31 3.50 3.50 3.50 — — — Rate of compensation increase used in determining pension expense 3.50 3.50 3.50 — — — Year 1 increase in cost of postretirement benefits — — — 7.0 7.5 8.0 The weighted-average rate assumptions of the Supplemental Plan were the same as the Pension Plan for 2016 , 2015 and 2014 , for the rate of compensation increase used in determining the benefit obligation and expense. In addition, the discount rate for the Supplemental Plan obligation was 3.63% , 4.51% and 4.07% at December 31, 2016 , 2015 and 2014 , respectively and the rate used to determine expense was 4.51% , 4.07% and 4.87% , respectively. Net periodic pension cost (income) of the Pension and Postretirement Plans was as follows for the years ended December 31: Pension Plan Postretirement Plan (Dollars in thousands) 2016 2015 2014 2016 2015 2014 Service cost $ 1,041 $ 1,021 $ 944 $ 9 $ 16 $ 18 Interest cost 5,335 5,242 5,167 132 133 142 Expected return on plan assets (8,562 ) (8,645 ) (8,314 ) — — — Amortization of prior service credit — (5 ) (1 ) 117 130 130 Amortization of net actuarial loss (gain) 2,259 3,962 2,159 (100 ) (1 ) (104 ) Net cost (income) $ 73 $ 1,575 $ (45 ) $ 158 $ 278 $ 186 The following schedule presents estimated future benefit payments for the next 10 years under the Pension and Postretirement Plans for retirees already receiving benefits and future retirees, assuming they retire and begin receiving unreduced benefits as soon as they are eligible: (Dollars in thousands) Pension Plan Postretirement Plan 2017 $ 5,474 $ 243 2018 5,706 239 2019 6,083 240 2020 6,263 237 2021 6,626 234 2022 - 2026 36,438 1,028 Total $ 66,590 $ 2,221 For measurement purposes for the Postretirement Plan, the annual rates of increase in the per capita cost of covered health care benefits and dental benefits for 2017 were each assumed at 7.0% . These rates were assumed to decrease gradually to 5.0% in 2020 and remain at that level thereafter. The assumed health care and dental cost trend rates could have a significant effect on the amounts reported for the Postretirement Plan. A one percentage-point change in these rates would have the following effects: One Percentage-Point (Dollars in thousands) Increase Decrease Effect on total of service and interest cost components in 2016 $ 14 $ (13 ) Effect on postretirement benefit obligation as of December 31, 2016 204 (194 ) Pension Plan Assets The assets of the Pension Plan are invested by the Wealth Management department of Chemical Bank. The investment policy and allocation of the assets of the pension trust were approved by the Compensation and Pension Committee of the board of directors of the Corporation. The Pension Plan's primary investment objective is long-term growth coupled with income. In consideration of the Pension Plan's fiduciary responsibilities, emphasis is placed on quality investments with sufficient liquidity to meet benefit payments and plan expenses, as well as providing the flexibility to manage the investments to accommodate current economic and financial market conditions. To meet the Pension Plan's long-term objective within the constraints of prudent management, target ranges have been set for the three primary asset classes: an equity securities range from 40.0% to 70.0% , a debt securities range from 20.0% to 60.0% , and a cash and cash equivalents and other range from 0.0% to 10.0% . Modest asset positions outside of these targeted ranges may occur due to the repositioning of assets within industries or other activity in the financial markets. Equity securities are primarily comprised of both individual securities and equity-based mutual funds, invested in either domestic or international markets. The stocks are diversified among the major economic sectors of the market and are selected based on balance sheet strength, expected earnings growth, the management team and position within their industries, among other characteristics. Debt securities are comprised of U.S. dollar denominated bonds issued by the U.S. Treasury, U.S. government agencies and investment grade bonds issued by corporations. The notes and bonds purchased are primarily rated A or better by the major bond rating companies from diverse industries. The Pension Plan's asset allocation by asset category was as follows: December 31, Asset Category 2016 2015 Equity securities 69 % 68 % Debt securities 29 31 Other 2 1 Total 100 % 100 % The following schedule sets forth the fair value of the Pension Plan's assets and the level of the valuation inputs used to value those assets at December 31, 2016 and 2015 : (Dollars in thousands) Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total December 31, 2016 Cash $ 2,825 $ — $ — $ 2,825 Equity securities: U.S. large- and mid-cap stocks (1) 55,389 — — 55,389 U.S. small-cap mutual funds 5,687 — — 5,687 International large-cap mutual funds 13,701 — — 13,701 Emerging markets mutual funds 5,147 — — 5,147 Chemical Financial Corporation common stock 11,412 — — 11,412 Debt securities: U.S. Treasury and government sponsored agency bonds and notes — 806 — 806 Corporate bonds (2) — 1,503 — 1,503 Mutual funds (3) 36,220 — — 36,220 Other 61 — — 61 Total $ 130,442 $ 2,309 $ — $ 132,751 December 31, 2015 Cash $ 354 $ — $ — $ 354 Equity securities: U.S. large- and mid-cap stocks (1) 55,709 — — 55,709 U.S. small-cap mutual funds 4,749 — — 4,749 International large-cap mutual funds 14,124 — — 14,124 Emerging markets mutual funds 4,886 — — 4,886 Chemical Financial Corporation common stock 7,219 — — 7,219 Debt securities: U.S. Treasury and government sponsored agency bonds and notes — 2,815 — 2,815 Corporate bonds (2) — 3,554 — 3,554 Mutual funds (3) 33,424 — — 33,424 Other 96 — — 96 Total $ 120,561 $ 6,369 $ — $ 126,930 (1) Comprised of common stocks and mutual funds traded on U.S. Exchanges whose issuers had market capitalizations exceeding $3 billion . (2) Comprised of investment grade bonds of U.S. issuers from diverse industries. (3) Comprised primarily of fixed-income bonds issued by the U.S. Treasury and government sponsored agencies and bonds of U.S. and foreign issuers from diverse industries. At both December 31, 2016 and 2015 , equity securities included 210,663 shares of the Corporation's common stock. During each of 2016 and 2015 , cash dividends of $0.2 million were paid on the Corporation's common stock held by the Pension Plan. The fair value of the Corporation's common stock held in the Pension Plan was $11.4 million at December 31, 2016 and $7.2 million at December 31, 2015 , which represented 8.6% and 5.7% of Pension Plan assets at December 31, 2016 and 2015 , respectively. Accumulated Other Comprehensive Loss The following sets forth the changes in accumulated other comprehensive income (loss), net of tax, related to the Corporation's Pension, Postretirement and Supplemental Plans during 2016 : (Dollars in thousands) Pension Plan Postretirement Plan Supplemental Plan Total Accumulated other comprehensive income (loss) at beginning of year $ (27,291 ) $ 402 $ (255 ) $ (27,144 ) Comprehensive income (loss) adjustment: Prior service costs (credits) — 76 — 76 Net actuarial (income) loss 1,168 246 (240 ) 1,174 Comprehensive income (loss) adjustment 1,168 322 (240 ) 1,250 Accumulated other comprehensive income (loss) at end of year $ (26,123 ) $ 724 $ (495 ) $ (25,894 ) The estimated income (loss) that will be amortized from accumulated other comprehensive income (loss) into net periodic cost, net of tax, in 2017 is as follows: (Dollars in thousands) Pension Plan Postretirement Plan Supplemental Plan Total Prior service (costs) credits $ — $ — $ — $ — Net gain (loss) (1,436 ) 105 (67 ) (1,398 ) Total $ (1,436 ) $ 105 $ (67 ) $ (1,398 )

Equity

Equity	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Equity	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 December 31, 2016 , there were 500,000 remaining shares available for repurchase under the Corporation's stock repurchase programs. 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. As of December 31, 2016 , no shares of preferred stock were issued and outstanding. Common Stock On July 19, 2016, the shareholders of the Corporation approved an amendment to the restated articles of incorporation to increase the number of authorized shares of common stock from 60,000,000 to 100,000,000 in anticipation of the merger with Talmer.

Regulatory Capital and Reserve

Regulatory Capital and Reserve Requirements	12 Months Ended
	Dec. 31, 2016
Banking and Thrift [Abstract]
Regulatory Capital and Reserve Requirements	Regulatory Capital and Reserve Requirements Banking regulations require that banks maintain cash reserve balances in vault cash, with the Federal Reserve Bank, or with certain other qualifying banks. The aggregate average amount of the regulatory balances required to be maintained by Chemical Bank during 2016 and 2015 were $52.3 million and $65.3 million , respectively. During 2016 , Chemical Bank satisfied its regulatory reserve requirements by maintaining a combination of vault cash balances and cash held with the FRB in excess of regulatory reserve requirements. Chemical Bank was not required to maintain compensating balances with correspondent banks during 2016 or 2015 . The Corporation and Chemical Bank are subject to various regulatory capital requirements administered by federal banking agencies. Under these capital requirements, Chemical Bank must meet specific capital guidelines that involve quantitative measures of assets and certain off-balance sheet items as calculated under regulatory accounting practices. In addition, capital amounts and classifications are subject to qualitative judgments by regulators. Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on the Corporation's consolidated financial statements. Quantitative measures established by regulation to ensure capital adequacy require minimum ratios of Tier 1 capital to average assets (Leverage Ratio) and common equity tier 1, Tier 1 and Total capital to risk-weighted assets. These capital guidelines assign risk weights to on- and off- balance sheet items in arriving at total risk-weighted assets. Minimum capital levels are based upon the perceived risk of various asset categories and certain off-balance sheet instruments. Risk-weighted assets for the Corporation and Chemical Bank totaled $13.42 billion and $13.36 billion , respectively, at December 31, 2016 , compared to $7.14 billion and $7.13 billion at December 31, 2015 , respectively. Effective January 1, 2015, the Corporation adopted the Basel III regulatory capital framework as approved by federal banking agencies, which is subject to a multi-year phase-in period. The adoption of this new framework modified the calculation of the various capital ratios, added a new ratio, common equity tier 1, and revised the adequately and well capitalized thresholds. In addition, Basel III establishes a new capital conservation buffer of 2.5% of risk-weighted assets, which is phased-in over a four-year period beginning January 1, 2016. The capital conservation buffer for 2016 is .625%. The Corporation has elected to opt-out of including capital in accumulated other comprehensive income in common equity tier 1 capital. At December 31, 2016 and 2015 , Chemical Bank's capital ratios exceeded the quantitative capital ratios required for an institution to be considered "well-capitalized." Significant factors that may affect capital adequacy include, but are not limited to, a disproportionate growth in assets versus capital and a change in mix or credit quality of assets. There are no conditions or events since that notification that management believes have changed the institutions' category. The summary below compares the actual capital amounts and ratios with the quantitative measures established by regulation to ensure capital adequacy: Actual Minimum Required for Capital Adequacy Purposes Minimum Required for Capital Adequacy Purposes Plus Capital Conservation Buffer Required to be Well Capitalized Under Prompt Corrective Action Regulations (Dollars in thousands) Capital Amount Ratio Capital Amount Ratio Capital Amount Ratio Capital Amount Ratio December 31, 2016 Total Capital to Risk-Weighted Assets Corporation $ 1,543,018 11.5 % $ 1,073,431 8.0 % $ 1,157,293 8.6 % N/A N/A Chemical Bank 1,608,980 12.0 1,068,560 8.0 1,152,041 8.6 $ 1,335,700 10.0 % Tier 1 Capital to Risk-Weighted Assets Corporation 1,441,209 10.7 805,073 6.0 888,935 6.6 N/A N/A Chemical Bank 1,522,711 11.4 801,420 6.0 884,901 6.6 1,068,560 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets Corporation 1,441,209 10.7 603,805 4.5 687,667 5.1 N/A N/A Chemical Bank 1,522,711 11.4 601,065 4.5 684,546 5.1 868,205 6.5 Leverage Ratio Corporation 1,441,209 9.0 643,603 4.0 643,603 4.0 N/A N/A Chemical Bank 1,522,711 9.5 641,457 4.0 641,457 4.0 801,822 5.0 December 31, 2015 Total Capital to Risk-Weighted Assets Corporation $ 841,257 11.8 % $ 571,509 8.0 % N/A N/A N/A N/A Chemical Bank 830,294 11.7 570,073 8.0 N/A N/A $ 712,591 10.0 % Tier 1 Capital to Risk-Weighted Assets Corporation 767,929 10.7 428,631 6.0 N/A N/A N/A N/A Chemical Bank 756,966 10.6 427,555 6.0 N/A N/A 570,073 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets Corporation 753,815 10.6 321,474 4.5 N/A N/A N/A N/A Chemical Bank 756,966 10.6 320,666 4.5 N/A N/A 463,184 6.5 Leverage Ratio Corporation 767,929 8.6 356,396 4.0 N/A N/A N/A N/A Chemical Bank 756,966 8.5 355,911 4.0 N/A N/A 444,888 5.0 Federal and state banking regulations place certain restrictions on the transfer of assets, in the form of dividends, loans or advances, from Chemical Bank to the Corporation. At December 31, 2016 , substantially all of the assets of Chemical Bank were restricted from transfer to the Corporation in the form of loans or advances. Dividends from Chemical Bank are the principal source of funds for the Corporation. In addition to the statutory limits, the Corporation considers the overall financial and capital position of Chemical Bank prior to making any cash dividend decisions. During the years ended December 31, 2016 and 2015 , Chemical Bank paid dividends to the Corporation totaling $110.5 million and $56.9 million , respectively. On February 20, 2017 , a cash dividend on the Corporation's common stock of $0.27 per share was declared. The dividend will be paid on March 17, 2017 to shareholders of record as of March 3, 2017 .

Parent Company Only Financial S

Parent Company Only Financial Statements	12 Months Ended
	Dec. 31, 2016
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Parent Company Only Financial Statements	Parent Company Only Financial Statements Condensed financial statements of Chemical Financial Corporation (parent company) only follow: Condensed Statements of Financial Position December 31, (Dollars in thousands) 2016 2015 Assets Cash at subsidiary bank $ 16,851 $ 28,884 Investment in subsidiaries 2,654,458 1,023,285 Premises and equipment 4,051 3,632 Goodwill 1,092 1,092 Other assets 63,584 13,051 Total assets $ 2,740,036 $ 1,069,944 Liabilities Other liabilities $ 18,345 $ 10,426 Non-revolving line-of-credit 124,625 25,000 Subordinated debentures 15,540 18,544 Total liabilities 158,510 53,970 Shareholders' equity 2,581,526 1,015,974 Total liabilities and shareholders' equity $ 2,740,036 $ 1,069,944 Condensed Statements of Income Years Ended December 31, (Dollars in thousands) 2016 2015 2014 Income Cash dividends from subsidiaries $ 110,450 $ 56,860 $ 64,468 Other income 151 144 95 Total income 110,601 57,004 64,563 Expenses Interest expense 1,816 761 42 Operating expenses 30,589 7,794 7,200 Total expenses 32,405 8,555 7,242 Income before income taxes and equity in undistributed net income of subsidiaries 78,196 48,449 57,321 Income tax benefit 11,378 2,582 2,302 Equity in undistributed net income of subsidiaries 18,458 35,799 2,498 Net income $ 108,032 $ 86,830 $ 62,121 Condensed Statements of Cash Flows Years Ended December 31, (Dollars in thousands) 2016 2015 2014 Cash Flows From Operating Activities Net income $ 108,032 $ 86,830 $ 62,121 Adjustments to reconcile net income to net cash provided by operating activities: Share-based compensation expense 13,452 3,478 2,931 Depreciation of premises and equipment 355 318 327 Equity in undistributed net income of subsidiaries (18,458 ) (35,799 ) (2,498 ) Net decrease in other assets 9,752 2,873 1,101 Net decrease in other liabilities (11,830 ) (19,033 ) (2,519 ) Net cash provided by operating activities 101,303 38,667 61,463 Cash Flows From Investing Activities Cash paid, net of cash assumed, in business combinations (107,622 ) (45,267 ) (117,853 ) Purchases of premises and equipment, net (774 ) (320 ) (26 ) Net cash used in investing activities (108,396 ) (45,587 ) (117,879 ) Cash Flows From Financing Activities Cash dividends paid (49,389 ) (36,918 ) (29,528 ) Proceeds from issuance of common stock, net of issuance costs — — 76,175 Repayment of subordinated debt obligations (18,558 ) — (10,310 ) Repayments of other borrowings (62,500 ) — — Proceeds from issuance of other borrowings 125,000 25,000 — Proceeds from directors' stock purchase plan and exercise of stock options 1,572 2,473 1,242 Cash paid for payroll taxes upon conversion of restricted stock units (1,065 ) (571 ) (701 ) Net cash provided by (used in) financing activities (4,940 ) (10,016 ) 36,878 Net decrease in cash and cash equivalents (12,033 ) (16,936 ) (19,538 ) Cash and cash equivalents at beginning of year 28,884 45,820 65,358 Cash and cash equivalents at end of year $ 16,851 $ 28,884 $ 45,820 Business combinations: Fair value of assets acquired (noncash) $ 46,898 $ 10,304 $ 1,537 Liabilities assumed 58,309 42,019 13,010 Common stock and stock options issued 1,504,811 159,904 —

Earnings Per Common Share

Earnings Per Common Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Earnings Per Common Share	Earnings Per Common Share The two-class method is used in the calculation of basic and diluted earnings per share. Under the two-class method, earnings available to common shareholders for the period are allocated between common shareholders and participating securities according to dividends declared (or accumulated) and participating rights in undistributed earnings. Average shares of common stock for diluted net income per common share include shares to be issued upon the exercise of stock options, restricted stock units that may be converted to stock, restricted stock awards and stock to be issued under the deferred stock compensation plan for non-employee directors. The factors used in the earnings per share computation follow: For the years ended December 31, (In thousands, except per share data) 2016 2015 2014 Net income $ 108,032 $ 86,830 $ 62,121 Net income allocated to participating securities 166 — — Net income allocated to common shareholders (1) $ 107,866 $ 86,830 $ 62,121 Weighted average common shares - issued 49,091 36,081 31,367 Average unvested restricted share awards (139 ) — — Weighted average common shares outstanding - basic 48,952 36,081 31,367 Effect of dilutive securities Weighted average common stock equivalents 651 272 221 Weighted average common shares outstanding - diluted 49,603 36,353 31,588 EPS available to common shareholders Basic earnings per common share $ 2.21 $ 2.41 $ 1.98 Diluted earnings per common share $ 2.17 $ 2.39 $ 1.97 (1) Net income allocated to common shareholders for basic and diluted earnings per share may differ under the two-class method as a result of adding common share equivalents for options and warrants to dilutive shares outstanding, which alters the ratio used to allocate net income to common shareholders and participating securities for the purposes of calculating diluted earnings per share. For the effect of dilutive securities, the assumed average stock valuation is $40.58 per share, $32.17 per share and $29.11 per share for the years ended December 31, 2016 , 2015 and 2014 , respectively. The average number of exercisable employee stock option awards outstanding that were "out-of-the-money," whereby the option exercise price per share exceeded the market price per share and, therefore, were not included in the computation of diluted earnings per common share because they would have been anti-dilutive, totaled 0 for the year ended December 31, 2016 , 54,771 for the year ended December 31, 2015 and 240,165 for the year ended December 31, 2014 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss The following table summarizes the changes within each component of accumulated other comprehensive income (loss), net of related tax benefit/expense for the years ended December 31, 2016, 2015 and 2014: (Dollars in thousands) Unrealized gains Defined Benefit Pension Plans Total For the year ended December 31, 2016 Beginning balance $ (1,888 ) $ (27,144 ) $ (29,032 ) Other comprehensive loss before reclassifications (12,170 ) (229 ) (12,399 ) Amounts reclassified from accumulated other comprehensive income (84 ) 1,479 1,395 Net current period other comprehensive income (loss) (12,254 ) 1,250 (11,004 ) Ending balance $ (14,142 ) $ (25,894 ) $ (40,036 ) For the year ended December 31, 2015 Beginning balance $ (210 ) $ (32,243 ) $ (32,453 ) Other comprehensive income (loss) before reclassifications (1,269 ) 2,443 1,174 Amounts reclassified from accumulated other comprehensive income (409 ) 2,656 2,247 Net current period other comprehensive income (loss) (1,678 ) 5,099 3,421 Ending balance $ (1,888 ) $ (27,144 ) $ (29,032 ) For the year ended December 31, 2014 Beginning balance $ (2,480 ) $ (18,040 ) $ (20,520 ) Other comprehensive income (loss) before reclassifications 2,270 (15,623 ) (13,353 ) Amounts reclassified from accumulated other comprehensive income — 1,420 1,420 Net current period other comprehensive income (loss) 2,270 (14,203 ) (11,933 ) Ending balance $ (210 ) $ (32,243 ) $ (32,453 ) The following table summarizes the amounts reclassified out of each component of accumulated other comprehensive income (loss) for the years ended December 31, 2016, 2015 and 2014: (Dollars in thousands) Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Income Statement December 31, 2016 December 31, 2015 December 31, 2014 Gains and losses on available-for-sale securities $ 129 $ 630 $ — Net gain on sale of investment securities (noninterest income) (45 ) (221 ) — Income tax (expense)/benefit $ 84 $ 409 $ — Net Income Amortization of defined benefit pension plan items $ (2,276 ) $ (4,086 ) $ (2,184 ) Salaries, wages and employee benefits (operating expenses) 797 1,430 764 Income tax (expense)/benefit $ (1,479 ) $ (2,656 ) $ (1,420 ) Net Income

Noninterest Income

Noninterest Income	12 Months Ended
	Dec. 31, 2016
Noninterest Income [Abstract]
Noninterest Income	Noninterest Income The following schedule includes the major components of noninterest income during the past three years: Years Ended December 31, (Dollars in thousands) 2016 2015 2014 Service charges and fees on deposit accounts $ 28,136 $ 25,481 $ 22,414 Wealth management revenue 22,601 20,552 16,015 Electronic banking fees 23,433 19,119 13,480 Mortgage banking revenue 21,859 6,133 5,041 Other fees for customer services 4,939 4,428 3,539 Insurance commissions 1,874 1,966 1,559 Gain on sale of investment securities 129 630 — Bank owned life insurance 1,836 646 281 Rental income 592 466 145 Gain on sale of branch offices 7,391 — — Gain on sale of closed branch offices and other assets — 266 — Gain on sale of merchant card servicing business — — 400 Other 9,560 529 221 Total noninterest income $ 122,350 $ 80,216 $ 63,095

Operating Expenses

Operating Expenses	12 Months Ended
	Dec. 31, 2016
Operating Expenses [Abstract]
Operating Expenses	Operating Expenses The following schedule includes the major categories of operating expenses during the past three years: Years Ended December 31, (Dollars in thousands) 2016 2015 2014 Salaries and wages $ 135,407 $ 104,490 $ 83,229 Employee benefits 29,806 23,430 19,328 Occupancy 23,525 18,213 15,842 Equipment and software 24,408 18,569 14,737 Outside processing and service fees 21,199 15,207 11,586 FDIC insurance premiums 7,407 5,485 4,307 Professional fees 5,832 4,842 3,570 Intangible asset amortization 5,524 4,389 2,029 Postage and express mail 3,777 3,313 3,418 Advertising and marketing 3,740 3,288 3,051 Training, travel and other employee expenses 4,025 3,224 2,480 Telephone 2,964 2,608 1,966 Supplies 2,318 2,216 1,897 Donations 1,951 1,375 1,155 Credit-related expenses (2,701 ) 632 996 Merger and acquisition-related transaction expenses 61,134 7,804 6,388 Other 8,102 4,809 3,946 Total operating expenses $ 338,418 $ 223,894 $ 179,925

Summary of Quarterly Statements

Summary of Quarterly Statements of Income (Unaudited)	12 Months Ended
	Dec. 31, 2016
Selected Quarterly Financial Information [Abstract]
Summary of Quarterly Statements of Income (Unaudited)	Summary of Quarterly Statements of Income (Unaudited) The following is a summary of the unaudited quarterly results of operation for the years ended December 31, 2016 and 2015. In the opinion of management, the information reflects all adjustments that are necessary for the fair presentation of the results of operations for the periods presented. 2016 (Dollars in thousands, except per share data) First Quarter (1) Second Quarter (1) Third Quarter (1) Fourth Quarter Total Interest income $ 79,464 $ 82,937 $ 103,562 $ 144,416 $ 410,379 Interest expense 5,134 5,442 6,753 11,969 29,298 Net interest income 74,330 77,495 96,809 132,447 381,081 Provision for loan losses 1,500 3,000 4,103 6,272 14,875 Noninterest income 19,419 20,897 27,770 54,264 122,350 Operating expenses 58,887 59,085 106,144 114,302 338,418 Income before income taxes 33,362 36,307 14,332 66,137 150,138 Income tax expense 9,757 10,532 2,848 18,969 42,106 Net income $ 23,605 $ 25,775 $ 11,484 $ 47,168 $ 108,032 Net income per common share: Basic $ 0.61 $ 0.67 $ 0.23 $ 0.67 $ 2.21 Diluted 0.60 0.67 0.23 0.66 2.17 Cash dividends declared per common share 0.26 0.26 0.27 0.27 1.06 (1) First, second and third quarter 2016 information is revised to reflect the impact of the early adoption of ASU 2016-09, "Improvements to Employee Share-Based Payment Accounting." 2015 (Dollars in thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter Total Interest income $ 62,630 $ 69,679 $ 78,851 $ 80,629 $ 291,789 Interest expense 3,450 3,944 5,234 5,153 17,781 Net interest income 59,180 65,735 73,617 75,476 274,008 Provision for loan losses 1,500 1,500 1,500 2,000 6,500 Noninterest income 19,275 20,674 20,215 20,052 80,216 Operating expenses 51,020 56,785 58,265 57,824 223,894 Income before income taxes 25,935 28,124 34,067 35,704 123,830 Income tax expense 8,100 9,100 9,600 10,200 37,000 Net income $ 17,835 $ 19,024 $ 24,467 $ 25,504 $ 86,830 Net income per common share: Basic $ 0.54 $ 0.54 $ 0.64 $ 0.67 $ 2.41 Diluted 0.54 0.54 0.64 0.66 2.39 Cash dividends declared per common share 0.24 0.24 0.26 0.26 1.00

Summary of Significant Accoun34

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations Chemical Financial Corporation ("Corporation" or "Chemical") operates in a single operating segment — commercial banking. The Corporation is a financial holding company, headquartered in Midland, Michigan, that operates through one commercial bank, Chemical Bank. Chemical Bank operates within Michigan, Ohio and Indiana as a state-chartered commercial bank. Chemical Bank operates through an internal organizational structure of seven 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, wealth management revenue and mortgage banking revenue.
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accounting and reporting policies of the Corporation and its subsidiaries have been prepared in accordance with U.S.generally accepted accounting principles ("GAAP"), Securities and Exchange Commission ("SEC") rules and interpretive releases and prevailing practices within the banking industry. The consolidated financial statements of the Corporation include the accounts of the Corporation and its wholly owned subsidiaries. All significant income and expenses are recorded on the accrual basis. Intercompany accounts and transactions have been eliminated in preparing the consolidated financial statements.
Use of Estimates	Use of Estimates Management makes estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying footnotes. Estimates that are particularly susceptible to significant change include the determination of the allowance for loan losses, expected cash flows from acquired loans, 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	Business Combinations Pursuant to the guidance of the Financial Accounting Standards Board's ("FASB") Accounting Standards Codification ("ASC") Topic 805, Business Combinations ("ASC 805"), the Corporation recognizes assets acquired, including identified intangible assets, and the liabilities assumed in acquisitions at their fair values as of the acquisition date, with the acquisition-related transaction and restructuring costs expensed in the period incurred. On August 31, 2016, the Corporation acquired all the outstanding stock of Talmer Bancorp, Inc. ("Talmer") for total consideration of $1.61 billion , which included stock consideration of $1.50 billion and cash consideration of $107.6 million . The Corporation recorded $846.7 million of goodwill in conjunction with the merger, which represented the purchase price over the fair value of identifiable net assets acquired. Additionally, the Corporation recorded $19.1 million of core deposit intangible assets in conjunction with the acquisition related to total deposits acquired of $5.29 billion . ASC 805 affords a measurement period beyond the acquisition date that allows the Corporation the opportunity to finalize the acquisition accounting in the event that new information is identified that existed as of the acquisition date but was not known by the Corporation at that time. The Corporation anticipates that measurement period adjustments may arise from adjustments to the fair values of assets and liabilities recognized at the acquisition date for its August 31, 2016 merger with Talmer, as additional information is obtained, such as appraisals of collateral securing loans and other borrower information. In the event that a measurement period adjustment is identified, the Corporation will recognize the adjustment as part of its acquisition accounting, which may result in an adjustment to goodwill being recorded in the period the adjustment was identified. See Note 2 for further information regarding the Corporation's mergers and acquisitions.
Cash and Cash Equivalents	Cash and Cash Equivalents For purposes of reporting cash flows, cash and cash equivalents include cash on hand and interest-bearing deposits held at the Federal Reserve Bank ("FRB").
Investment Securities	Investment Securities Investment securities include investments in debt, trust preferred and preferred stock securities. Investment securities are accounted for in accordance with ASC Topic 320, Investments — Debt and Equity Securities ("ASC 320"), which requires investments to be classified within one of three categories (trading, held-to-maturity or available-for-sale). The Corporation held no trading investment securities at December 31, 2016 or 2015 . Designation as an investment security held-to-maturity is based on the Corporation's intent and ability to hold the security to maturity. Investment securities held-to-maturity are stated at cost, adjusted for purchase price premiums and discounts. Investment securities that are not held-to-maturity are accounted for as securities available-for-sale, and are stated at estimated fair value, with the aggregate unrealized gains and losses, not deemed other-than-temporary, classified as a component of accumulated other comprehensive income (loss), net of income taxes. Realized gains and losses on the sale of investment securities and other-than-temporary impairment ("OTTI") charges are determined using the specific identification method and are included within noninterest income in the consolidated statements of income. Premiums and discounts on investment securities are amortized over the estimated lives of the related investment securities based on the effective interest yield method and are included in interest income in the consolidated statements of income. The Corporation assesses equity and debt securities that have fair values below amortized cost basis to determine whether declines (impairment) are other-than-temporary. If the Corporation intends to sell an impaired security or it is more-likely-than-not that the Corporation will be required to sell an impaired security prior to the recovery of its amortized cost, an OTTI write-down is recognized in earnings equal to the entire difference between the security's amortized cost basis and its fair value. If the Corporation does not intend to sell an impaired security and it is not more-likely-than-not that the Corporation would be required to sell an impaired security before the recovery of its amortized cost basis, then the recognition of the impairment is bifurcated if a credit loss is deemed to have occurred. For a security where the impairment is bifurcated, the impairment is separated into an amount representing the credit loss, which is recognized in earnings, and an amount related to all other factors, which is recognized in other comprehensive income. In assessing whether OTTI exists, management considers, among other things, (i) the length of time and the extent to which the fair value has been less than cost, (ii) the financial condition and near-term prospects of the issuer, (iii) the potential for impairments in an entire industry or sub-sector and (iv) the potential for impairments in certain economically depressed geographical locations.
Nonmarketable Equity Securities	Nonmarketable Equity Securities The Corporation is required to hold non-marketable equity securities, comprised of Federal Home Loan Bank of Indianapolis ("FHLB") and FRB stock, as a condition of membership. These securities are accounted for at cost, which equals par or redemption value. These securities do not have a readily determinable fair value as their ownership is restricted and there is no market for these securities. These securities can only be redeemed or sold at their par value and only to the respective issuing government supported institution or to another member institution. FHLB stock can only be redeemed upon giving five -years written notice and FRB stock can only be redeemed upon giving six months written notice, with no more than 25.0% eligible for redemption in any calendar year. The Corporation records these non-marketable equity securities as a component of other assets and they are periodically evaluated for impairment. Management considers these non-marketable equity securities to be long-term investments. Accordingly, when evaluating these securities for impairment, management considers the ultimate recoverability of the par value rather than recognizing temporary declines in value, if applicable. The Corporation's ownership of FHLB stock totaled $58.0 million at December 31, 2016 and $23.9 million at December 31, 2015 . The Corporation's ownership of FRB stock totaled $39.4 million at December 31, 2016 and $13.0 million at December 31, 2015 .
Loans Held for Sale	Loans Held for Sale Mortgage and construction loans intended for sale in the secondary market are carried at fair value based on the Corporation's election of the fair value option. The fair value includes the servicing value of the loans as well as any accrued interest. These loans are sold both with servicing rights retained and with servicing rights released.
Originated Loans	Originated Loans Originated loans include all of the Corporation's portfolio loans, excluding loans acquired in business combinations, as further discussed below. Originated loans are stated at their principal amount outstanding, net of unearned income, charge-offs and unamortized deferred fees and costs. Loan interest income is recognized on the accrual basis. Deferred loan fees and costs are amortized over the loan term based on the level-yield method. Net loan commitment fees are deferred and amortized into fee income on a straight-line basis over the commitment period. The past due status of a loan is based on the loan's contractual terms. A loan is placed in nonaccrual status (accrual of interest is discontinued) when principal or interest is past due 90 days or more, 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 August 31, 2016 in the merger with Talmer, on May 31, 2015 in the acquisition of Lake Michigan Financial Corporation ("Lake Michigan"), on April 1, 2015 in the acquisition of Monarch Community Bancorp, Inc. ("Monarch"), on October 31, 2014 in the acquisition of Northwestern Bancorp, Inc. ("Northwestern"), and on April 30, 2010 in the acquisition of O.A.K. Financial Corporation ("OAK"). Acquired loans were recorded at fair value at the date of acquisition, without a carryover of the associated allowance for loan losses related to these loans. The Corporation accounts for acquired loans, which are recorded at fair value at acquisition, in accordance with ASC Topic 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality ("ASC 310-30"). ASC 310-30 allows investors to aggregate loans acquired into loan pools that have common risk characteristics and thereby use a composite interest rate and expectation of cash flows expected to be collected for the loan pools. Under the provisions of ASC 310-30, the Corporation aggregated acquired loans into pools within each merger or acquisition based upon common risk characteristics, including types of loans, commercial type loans with similar risk grades and whether loans were performing or nonperforming. A pool is considered a single unit of accounting for the purposes of applying the guidance prescribed in ASC 310-30. A loan will be removed from a pool of acquired loans only if the loan is sold, foreclosed, paid off or written off, and will be removed from the pool at the carrying value. 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 estimate of expected credit losses was determined based on due diligence performed by executive and senior officers of the Corporation, with assistance from third-party consultants. The Corporation estimated the cash flows expected to be collected over the life of the pools of loans at acquisition and estimates expected cash flows quarterly thereafter, based on a set of assumptions including expectations as to default rates, prepayment rates and loss severities. The Corporation must make numerous assumptions, interpretations and judgments using internal and third-party credit quality information to determine whether it is probable that the Corporation will be able to collect all contractually required payments. This is a point in time assessment and inherently subjective due to the nature of the available information and judgment involved. The calculation of the fair value of the acquired loan pools entails estimating the amount and timing of cash flows attributable to both principal and interest expected to be collected on such loan pools and then discounting those cash flows at market interest rates. The excess of a loan pool's expected cash flows at the acquisition date over its estimated fair value is referred to as the "accretable yield," which is recognized into interest income over the estimated remaining life of the loan pool on a level-yield basis. The difference between a loan pool's contractually required principal and interest payments at the acquisition date and the cash flows expected to be collected at the acquisition date is referred to as the "nonaccretable difference," which includes an estimate of future credit losses expected to be incurred over the estimated life of the loan pool and interest payments that are not expected to be collected. Decreases to the expected cash flows in each loan pool in subsequent periods will require the Corporation to record a provision for loan losses and establish an allowance for loan loss. 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 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 accruing TDRs, which consist of originated loans that continue to accrue interest as the Corporation expects to collect the remaining principal and interest on the loan, and nonaccrual TDRs, which include originated loans that are in a nonaccrual status and are no longer accruing interest, as the Corporation does not expect to collect the full amount of principal and interest owed from the borrower on these loans. All TDRs are accounted for as impaired loans and are included in the Corporation's analysis of the allowance for loan losses. A TDR that has been renewed by a borrower who is no longer experiencing financial difficulty and which yields a market rate of interest at the time of a renewal is no longer reported as a TDR. 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 current and a six-month payment history has been sustained, the loan is classified as an accruing TDR. Since no loss is expected to be incurred on these loans, no additional provision for loan losses has been recognized for these loans and they continue to accrue interest at their contractual interest rate. Accruing TDRs are transferred to nonaccrual status if they become 90 days past due as to principal or interest payments or if it is probable that any remaining principal and interest payments due on the loan will not be collected in accordance with the modified terms of the loan. Loans in the Corporation's consumer loan portfolio (comprised of residential mortgage, consumer installment and home equity loans) that meet the definition of a TDR 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. TDRs are placed on nonaccrual status if they become 90 days past due as to principal or interest payments, or sooner if conditions warrant.
Impaired Loans	Impaired Loans Impaired loans include loans on nonaccrual status and TDRs. Loans are considered impaired when based on current information and events it is probable the Corporation will be unable to collect all amounts due in accordance with the original contractual terms of the loan agreements. Impaired loans are accounted for at the lower of the present value of expected cash flows discounted at the loan's original effective interest rate or the estimated fair value of the collateral, if the loan is collateral dependent. When the present value of expected cash flows or the fair value of collateral of an impaired loan in the originated loan portfolio is less than the amount of unpaid principal outstanding on the loan, the principal balance of the loan is reduced to its carrying value through either a specific allowance for loan losses or a partial charge-off of the loan balance.
Nonperforming Loans	Nonperforming Loans Nonperforming loans are comprised of loans for which the accrual of interest has been discontinued (nonaccrual loans, including nonaccrual TDRs). Acquired loans that were classified as nonperforming loans prior to being acquired and acquired loans that are not performing in accordance with contractual terms subsequent to acquisition are not classified as nonperforming loans subsequent to acquisition because the loans are recorded in pools at net realizable value based on the principal and interest the Corporation expects to collect on such loans.
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 originated loan portfolio. Management's evaluation of the adequacy of the allowance is based on a continuing review of the originated 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 originated 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 credit quality review quarterly on impaired loans, and may establish 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 historical experience and other 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 consumer 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 look-back period, with equal weighting placed on all of the years and giving consideration to estimated loss emergence periods, and (iv) a reserve for qualitative factors that take into consideration risks inherent in the originated loan portfolio that differ from historical loan loss experience. The first element reflects the Corporation's estimate of probable losses based upon the systematic review of individually impaired loans in the originated loan portfolio. These estimates are based upon a number of objective factors, such as payment history, financial condition of the borrower and discounted collateral exposure. The Corporation measures the investment in an impaired loan based on one of three methods: the loan's observable market price; the fair value of the collateral; or the present value of expected future cash flows discounted at the loan's effective interest rate. Loans in the commercial loan portfolio that were in nonaccrual status (including nonaccrual TDRs) were valued based on the fair value of the collateral securing the loan, while accruing TDRs in the commercial loan portfolio and consumer loans were valued based on the present value of expected future cash flows discounted at the loan's effective interest rate. It is the Corporation's general policy to obtain new appraisals at least annually on nonaccrual loans in the commercial loan portfolio. Appraisals on nonaccrual loans in the consumer loan portfolio are generally updated annually where there is a delay in the foreclosure process. When the Corporation determines that the fair value of the collateral is less than the carrying value of an impaired loan and a portion is deemed not collectible, the portion of the impairment that is deemed not collectible is charged off (confirmed loss) and deducted from the allowance. The remaining carrying value of the impaired loan is classified as a nonperforming loan. When the Corporation determines that the fair value of the collateral is less than the carrying value of an impaired loan but believes it is probable it will recover this impairment, the Corporation establishes a valuation allowance for such impairment. The second element reflects the application of the Corporation's loan grade risk rating system. This risk rating system is similar to those employed by state and federal banking regulators. Loans in the commercial loan portfolio that are risk rated below a certain predetermined risk grade are assigned a loss allocation factor that is based upon a historical analysis of actual loan losses incurred and a valuation of the type of collateral securing the loans. The third element is determined by assigning allocations based principally upon a five -year average of loss experience for each class of loan. Average losses may be adjusted based on current loan loss experience, delinquency trends, estimated loss emergence periods and other industry specific environmental factors. This component considers the lagging impact of historical charge-off ratios in periods where future loan charge-offs are expected to increase or decrease, trends in delinquencies and nonaccrual loans, the changing portfolio mix in terms of collateral, average loan balance, loan growth and the degree of seasoning in the various loan portfolios. Loan loss analyses are performed quarterly and certain inputs and parameters are updated as necessary to reflect the current credit environment. The fourth element is based on qualitative factors that cannot be associated with a specific credit or loan class and reflects an attempt to ensure that the overall allowance appropriately reflects additional losses that are inherent in the Corporation's loan portfolio. Determination of the probable losses inherent in the portfolio, which are not necessarily captured by the allocation methodology discussed above, involves the exercise of judgment. This qualitative portion of the allowance is judgmentally determined and generally serves to compensate for the uncertainty in estimating inherent losses, particularly in times of changing economic conditions, and also considers the inherent judgment associated with risk rating commercial loans. The qualitative portion of the allowance also takes into consideration, among other things, economic conditions within our geographic areas and nationwide, including unemployment levels, industry-wide and Corporation specific loan delinquency rates, changes in composition of and growth in the Corporation's loan portfolio and changing commercial and residential real estate values. Although the Corporation allocates portions of the allowance to specific loans and loan types, the entire allowance attributable to originated loans is available for any loan losses that occur in the originated portfolio. Loans that are deemed not collectible are charged off and reduce the allowance. The provision for loan losses and recoveries on loans previously charged off increase the allowance. Collection efforts may continue and recoveries may occur after a loan is charged off. Acquired loans are aggregated into pools based upon common risk characteristics. An allowance may be recorded related to an acquired loan pool if it experiences a decrease in expected cash flows, as compared to those projected at the acquisition date. On a quarterly basis, the expected future cash flow of each pool is estimated based on various factors, including changes in property values of collateral dependent loans, default rates, loss severities and prepayment speeds. Decreases in estimates of expected cash flows within a pool generally result in a charge to the provision for loan losses and a corresponding increase in the allowance allocated to acquired loans for the particular pool. Increases in estimates of expected cash flows within a pool generally result in a reduction in the allowance allocated to acquired loans for the particular pool, if applicable, and then an adjustment to the accretable yield for the pool, which will increase amounts recognized in interest income in subsequent periods. Various regulatory agencies, as an integral part of their examination processes, periodically review the allowance. Such agencies may require additions to the allowance, based on their judgment, reflecting information available to them at the time of their examinations.
Mortgage Banking Operations	Mortgage Banking Operations The origination of residential mortgage loans is a large component of the business of the Corporation. The Corporation generally sells conforming long-term fixed interest rate mortgage loans it originates in the secondary market. Gains on the sales of these loans are determined using the specific identification method. The Corporation sells residential mortgage loans in the secondary market on either a servicing retained or released basis. The Corporation elected the fair value measurement option, as prescribed by ASC Topic 820, Fair Value Measurements and Disclosures ("ASC 820"), for all residential mortgage loans held-for-sale originated on or after July 1, 2012. This election allows for a more effective offset of the changes in fair value of residential mortgage loans held-for-sale and the derivative instruments used to economically hedge them without having to apply complex hedge accounting provisions. Residential mortgage loans held-for-sale are carried at fair value, with changes in fair value recorded through earnings. Residential mortgage loan commitments, forward commitments, are generally entered into at the time customer applications are accepted to protect the value of the mortgage loans from increases in market interest rates during the period held and are generally settled with the investor in the secondary market within 90 days after entering into the forward commitment. Forward loan commitments are accounted for as derivatives and recorded at fair value, with changes in fair value recorded through earnings. The Corporation recognizes revenue associated with the expected future cash flows of servicing loans for loans held-for-sale at the time a forward loan commitment is made to originate a held-for-sale loan, as required under SEC Staff Accounting Bulletin No. 109, Written Loan Commitments Recorded at Fair Value Through Earnings. The Corporation accounts for loan servicing rights ("LSRs") by separately recognizing servicing assets at the date of sale. An asset is recognized for the rights to service mortgage loans that are created by the origination of mortgage loans that are sold with the servicing retained by the Corporation. The Corporation elected to account for LSRs acquired related to the merger with Talmer under the fair value measurement method. Loan servicing rights are established and recorded at the estimated fair value by calculating the present fair value of estimated future net servicing cash flows, taking into consideration actual and expected mortgage loan prepayment rates, discount rates, servicing costs, and other economic factors, which are determined based on current market conditions. The Corporation continues to account for all other LSRs at the lower of amortized cost or fair value ("Amortized LSRs") and amortizes LSRs in proportion to and over the period of net servicing income. Unexpected prepayments of mortgage loans result in increased amortization of Amortized LSRs, as the remaining book value of the LSRs is expensed at the time of prepayment. The Corporation assesses Amortized LSRs for impairment on a quarterly basis based on fair value measurements. For purposes of measuring impairment, Amortized LSRs are stratified into relatively homogeneous pools based on characteristics such as period of origination, maturity date and interest rates. Amortized LSRs are also stratified between servicing assets originated by the Corporation and those acquired in acquisitions of other institutions. Any temporary impairment of Amortized LSRs is recognized as a valuation allowance, resulting in a reduction of mortgage banking revenue. The valuation allowance is recovered when impairment that is believed to be temporary no longer exists. Other-than-temporary impairments are recognized if the recoverability of the carrying value is determined to be remote. When this occurs, the unrecoverable portion of the valuation allowance is recorded as a direct write-down to the carrying value of Amortized LSRs. This direct write-down permanently reduces the carrying value of the Amortized LSRs, precluding recognition of subsequent recoveries, and results in a reduction of mortgage banking revenue. For purposes of measuring the fair value of LSRs, the Corporation utilizes a third-party modeling software program which is periodically validated by using valuations received from third-party valuation specialists. Servicing income is recognized when earned and is offset by the amortization of LSRs. Effective January 1, 2017, the Corporation elected to account for all previously Amortized LSRs under the fair value method. The guidance in ASC Subtopic 860-50, "Transfers and Servicing-Servicing Assets and Liabilities" provides that an entity may make an irrevocable decision to subsequently measure a class of servicing assets and servicing liabilities at fair value at the beginning of any fiscal year. The guidance allows for the Corporation to apply this election prospectively to all new and existing servicing assets and servicing liabilities. Management believes this election will provide more comparable results to peers as many of those within our industry group account for loans servicing rights under the fair value method. The change in accounting policy in the first quarter of 2017 results in a cumulative adjustment to increase retained earnings in the amount of approximately $5.7 million .
Customer-Initiated Derivatives	Customer-Initiated Derivatives The Corporation enters into interest rate derivatives to provide a service to certain qualifying customers to help facilitate their respective risk management strategies ("customer-initiated derivatives"). Therefore, these derivatives are not used to manage interest rate risk in the Corporation's assets or liabilities. The Corporation generally takes offsetting positions with dealer counterparties to mitigate the valuation risk of the customer-initiated derivatives. Income primarily results in the spread between the customer derivatives and offsetting dealer positions. The gain or loss derived from changes in fair value are recognized in current earnings during the period of change.
Premises and Equipment	Premises and Equipment Land is carried at cost. Premises and equipment are stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method with useful lives ranging from 25 to 40 years for buildings and three to ten years for all other depreciable assets. Maintenance and repairs are charged to expense as incurred.
Other Real Estate Owned and Repossessed Assets	Other Real Estate Owned and Repossessed Assets Other real estate owned ("ORE") and repossessed assets represent property acquired by the Corporation as part of an acquisition or subsequently through the loan foreclosure or repossession process, or any other resolution activity that results in partial or total satisfaction of problem loans. ORE is primarily comprised of commercial and residential real estate properties, including vacant land and development properties, obtained in partial or total satisfaction of loan obligations.. The acquired properties are recorded at fair value at the date of acquisition. Losses arising at the time of acquisition of properties not acquired as part of an acquisition are charged against the allowance for loan and lease losses. Foreclosed properties are initially recorded at the lower of cost, or the estimated fair value of the property, less estimated costs to sell, based upon the property's appraised value at the date of transfer to ORE and management's estimate of the fair value of the collateral, establishing a new cost basis. Any difference between the net realizable value of the property and the carrying value of the loan is charged to the allowance for loan losses. Subsequently, all other real estate owned is valued at the lower of cost or fair value, less estimated costs to sell, based on periodic valuations performed by management, with any difference between the net realizable value of the property and the carrying value of the loan charged to the allowance for loan losses. If fair value declines subsequent to foreclosure, a valuation allowance is recorded through expense. Subsequent write-downs, for amounts not expected to be recovered, in the carrying value of other real estate owned and repossessed asset properties that may be required are expensed as incurred. Improvements to the properties may be capitalized if the improvements contribute to the overall value of the property. Improvement amounts may not be capitalized in excess of the net realizable value of the property. Any gains or losses realized at the time of disposal are reflected in the Consolidated Statements of Income. Other real estate owned and repossessed assets totaling $16.8 million and $12.7 million at December 31, 2016 and 2015 , respectively, was included in "Interest receivable and other assets" in the Consolidated Statements of Financial Position.
Goodwill	Goodwill Goodwill is not amortized, but rather is subject to impairment tests annually, or more frequently if triggering events occur and indicate potential impairment. The Corporation's annual goodwill impairment assessment was performed as of October 31, 2016 . The Corporation elected to utilize the qualitative assessment of goodwill impairment allowed under ASC Topic 350-20, Goodwill ("ASC 350-20") that became acceptable as a result of FASB Accounting Standards Update ("ASU") 2011-08, Testing Goodwill for Impairment. In accordance with ASC 350-20, the Corporation assessed qualitative factors to determine whether it is more likely than not that the fair value of its reporting units were less than their carrying amounts. In evaluating whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount, the Corporation assesses relevant events and circumstances, including macroeconomic conditions, industry and market considerations, overall financial performance, changes in the composition or carrying amount of assets and liabilities, the market price of the Corporation's common stock, and other relevant factors. Based on the qualitative assessment performed, the Corporation determined that no goodwill impairment was evident as of the October 31, 2016 assessment date. The Corporation also determined that no triggering events occurred that indicated impairment from the most recent assessment date through December 31, 2016 and that the Corporation's goodwill was not impaired at December 31, 2016 .
Other Intangible Assets	Other Intangible Assets Intangible assets consist of core deposit intangible assets and non-compete intangible assets. Core deposit intangible assets arose as the result of business combinations or other acquisitions and are amortized over periods ranging from 10 to 15 years , primarily on an accelerated basis, as applicable. Non-compete intangible assets arose as the result of business combinations and are amortized over the period of the non-compete agreements. Intangible assets are tested for impairment on an annual basis in accordance with ASC Topic 350. Intangibles-Goodwill and Other.
Share-based Compensation	Share-based Compensation The Corporation grants stock options, restricted stock service-based units, restricted stock performance units, and other stock awards to certain executive and senior management employees. The Corporation accounts for share-based compensation expense using the modified-prospective transition method. Under that method, compensation expense is recognized for stock options based on the estimated grant date fair value as computed using the Black-Scholes option pricing model and the probability of issuance. The Corporation accounts for stock awards based on the closing stock price of the Corporation's common stock on the date the award is granted. The fair values of stock options, stock awards and restricted stock awards are recognized as compensation expense on a straight-line basis over the requisite service period. The Corporation accounts for 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.
Bank-Owned Life Insurance	Bank-Owned Life Insurance The Corporation has life insurance policies on certain key officers of Chemical Bank. The majority of the bank-owned life insurance policies of the Corporation were obtained through its acquisition of Lake Michigan and the merger with Talmer. Bank-owned life insurance is recorded at the cash surrender value, net of surrender charges, and is included within "Interest receivable and other assets" on the Consolidated Statements of Financial Position and changes in the cash surrender values are recorded as "Other noninterest income" on the Consolidated Statements of Income.
Securities Sold Under Agreements to Repurchase with Customers	Securities Sold Under Agreements to Repurchase with Customers Securities sold under agreements to repurchase with customers are collateralized financing transactions and the obligations to repurchase securities sold are reflected as a liability in the accompanying Consolidated Statements of Financial Position. The dollar amount of the securities underlying the agreements remain in the Corporation's investment securities portfolio. The Corporation's securities sold under agreements to repurchase with customers are considered a stable source of liquidity, much like its core deposit base, and are generally only provided to customers that have an established banking relationship with Chemical Bank.
Short-term Borrowings	Short-term Borrowings Short-term borrowings are comprised of federal funds purchased and short-term FHLB advances with original scheduled maturities of one year or less. Federal funds purchased represent unsecured borrowings from nonaffiliated third-party financial institutions, generally on an overnight basis, to cover short-term liquidity needs.
Long-term Borrowings	Long-term Borrowings Long-term borrowings are comprised of securities sold under agreements with an unaffiliated third-party financial institution, a secured non-revolving line-of-credit with an unaffiliated third-party financial institution, subordinated debentures and long-term FHLB advances. Securities sold under agreements to repurchase are collateralized financing transactions and the obligations to repurchase securities sold are reflected as a liability in the accompanying Consolidated Statements of Financial Position. The dollar amount of the securities underlying the agreements remain in the Corporation's investment securities portfolio. FHLB advances, both short-term and long-term, are borrowings from the FHLB to fund short-term liquidity needs as well as a portion of the loan and investment securities portfolios. These advances are secured, under a blanket security agreement, by first lien residential mortgage loans with an aggregate book value equal to at least 140.0% of the FHLB advances and the FHLB stock owned by the Corporation. FHLB advances with an original maturity of one year or less are classified as short-term and FHLB advances with an original maturity of more than one year are classified as long-term.
Fair Value Measurements	Fair Value Measurements Fair value for assets and liabilities measured at fair value on a recurring or nonrecurring basis refers to the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants in the market in which the reporting entity transacts such sales or transfers based on the assumptions market participants would use when pricing an asset or liability. Assumptions are developed based on prioritizing information within a fair value hierarchy that gives the highest priority to quoted prices in active markets and the lowest priority to unobservable data, such as the reporting entity's own data. The Corporation may choose to measure eligible items at fair value at specified election dates. Unrealized gains and losses on items for which the fair value measurement option has been elected are reported in earnings at each subsequent reporting date. At December 31, 2016 and 2015 , the Corporation had elected the fair value option on all of its residential mortgage loans held-for-sale. In addition, the Corporation elected to account for loan servicing rights acquired in the merger with Talmer effective August 31, 2016 under the fair value method. The Corporation has not elected the fair value option for any other financial assets or liabilities as of December 31, 2016.
Pension and Postretirement Benefit Plan Actuarial Assumptions	Pension and Postretirement Benefit Plan Actuarial Assumptions The Corporation's defined benefit pension, supplemental pension and postretirement benefit obligations and related costs are calculated using actuarial concepts and measurements. Two critical assumptions, the discount rate and the expected long-term rate of return on plan assets, are important elements of expense and/or benefit obligation measurements. Other assumptions involve employee demographic factors such as retirement patterns, mortality, turnover and the rate of future compensation increases, as well as future health care costs. The Corporation evaluates all assumptions annually. Mortality assumptions at December 31, 2016 were based on the RP-2014 mortality tables, as prescribed by the Pension Protection Act of 2006, using the MP-2016 mortality improvement scale. Mortality assumptions at December 31, 2015 were based on the RP-2014 mortality tables using the MP-2015 mortality improvement scale. The discount rate enables the Corporation to state expected future benefit payments as a present value on the measurement date. The Corporation determined the discount rate at December 31, 2016 and 2015 by utilizing the results from a discount rate model that involves selecting a portfolio of bonds to settle the projected benefit payments of each plan. The selected bond portfolios are derived from a universe of corporate bonds rated at Aa quality. After a bond portfolio is selected, a single rate is determined that equates the market value of the bonds purchased to the discounted value of the plan's benefit payments which represents the discount rate. A lower discount rate increases the present value of benefit obligations and increases pension, supplemental pension and postretirement benefit expenses. To determine the expected long-term rate of return on defined benefit pension plan assets, the Corporation considers the current asset allocation of the defined benefit pension plan, as well as historical and expected returns on each asset class. A lower expected rate of return on defined benefit pension plan assets will increase pension expense. The Corporation recognizes the over- or under-funded status of a plan as an other asset or other liability in the Consolidated Statements of Financial Position as measured by the difference between the fair value of the plan assets and the projected benefit obligation. Unrecognized prior service costs and actuarial gains and losses are recognized as a component of accumulated other comprehensive income (loss). The Corporation measures defined benefit plan assets and obligations as of December 31.
Advertising Costs	Advertising Costs Advertising costs are expensed as incurred.
Income and Other Taxes	Income and Other Taxes The Corporation is subject to the income and other tax laws of the United States, the States of Michigan, Ohio and Indiana and other states where nexus has been created. These laws are complex and are subject to different interpretations by the taxpayer and the various taxing authorities. In determining the provision for income and other taxes, management must make judgments and estimates about the application of these inherently complex laws, related regulations and case law. In the process of preparing the Corporation's tax returns, management attempts to make reasonable interpretations of enacted tax laws. These interpretations are subject to challenge by the tax authorities upon audit or to reinterpretation based on management's ongoing assessment of facts and evolving case law. The Corporation and its subsidiaries file a consolidated federal income tax return. The provision for federal income taxes is based on income and expenses, as reported in the consolidated financial statements, rather than amounts reported on the Corporation's federal income tax return. The difference between the federal statutory income tax rate and the Corporation's effective federal income tax rate is primarily a function of the proportion of the Corporation's interest income exempt from federal taxation, nondeductible interest expense and other nondeductible expenses relative to pretax income and tax credits. When income and expenses are recognized in different periods for tax purposes than for book purposes, deferred tax assets and liabilities are recognized for the future tax consequences attributable to the temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Differences in the tax and book carrying amounts of assets and liabilities can also be generated when the Corporation acquires other banks or bank branches. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized as income or expense in the period that includes the enactment date of the change. On a quarterly basis, management assesses the reasonableness of its effective federal tax rate based upon its estimate of taxable income and the applicable taxes expected for the full year. Deferred tax assets and liabilities are reassessed on a quarterly basis, including the need for a valuation allowance for deferred tax assets. Uncertain income tax positions are evaluated to determine whether it is more-likely-than-not that a tax position will be sustained upon examination based on the technical merits of the tax position. If a tax position is more-likely-than-not to be sustained, a tax benefit is recognized for the amount that is greater than 50.0% 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 December 31, 2016 and 2015 .
Investments in Qualified Affordable Housing Projects, Federal Historic Projects and New Market Tax Credits	Investments in Qualified Affordable Housing Projects, Federal Historic Projects and New Market Tax Credits The Corporation invests in qualified affordable housing projects, federal historic projects, and new market projects for the purpose of community reinvestment and obtaining tax credits. Return on the Corporation's investment in these projects comes in the form of the tax credits and tax losses that pass through to the Corporation. The carrying value of the investments are reflected in "Interest receivable and other assets" on the Consolidated Statements of Financial Position. The Corporation utilizes the proportional amortization method to account for investments in qualified affordable housing projects and the equity method to account for investments in other tax credit projects. Under the proportional amortization method, the Corporation amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits. The Corporation recognized additional income tax expense attributable to the amortization of investments in qualified affordable housing projects of $2.6 million and $1.3 million during the years ended December 31, 2016 and 2015 , respectively. The Corporation's remaining investment in qualified affordable housing projects accounted for under the proportional amortization method totaled $29.5 million at December 31, 2016 and $21.7 million at December 31, 2015 . Under the equity method, the Corporation's share of the earnings or losses are included in "Other operating expenses" on the Consolidated Statements of Income. The Corporation's remaining investment in new market projects accounted for under the equity method totaled $10.9 million and $1.7 million at December 31, 2016 and 2015 , respectively. The Corporation's unfunded equity contributions relating to investments in qualified affordable housing projects, federal historic tax projects and new market projects is recorded in "Interest payable and other liabilities" on the Consolidated Statements of Financial Position. The Corporation's remaining unfunded equity contributions totaled $16.0 million at December 31, 2016 . 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 December 31, 2016 or 2015 . 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 variable interest entities ("VIEs"). 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 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.
Earnings Per Share	Earnings Per Share The Corporation applies the two-class method of computing earnings per share as the Corporation has unvested restricted stock awards which qualify as participating securities. Under this calculation, all outstanding unvested share-based payment awards that contain rights to nonforfeitable dividends are considered participating securities and earnings per share is determined according to dividends declared and participating right in undistributed earnings.
Comprehensive Income	Comprehensive Income Comprehensive income of the Corporation includes net income and adjustments to shareholders' equity for changes in unrealized gains and losses on investment securities available-for-sale and changes in the net actuarial gain/loss for the Corporation's defined benefit pension and postretirement plans, net of income taxes. The Corporation presents "Comprehensive income" as a component in the Consolidated Statements of Changes in Shareholders' Equity and the components of other comprehensive income separately in the Consolidated Statements of Comprehensive Income.
Reclassifications	Reclassifications Certain amounts appearing in the consolidated financial statements and notes thereto for prior periods have been reclassified to conform with the current presentation. The reclassification had no effect on net income or shareholders’ equity as previously reported.
Adopted Accounting Pronouncements	Adopted Accounting Pronouncements Consolidation of Variable Interest Entities In February 2015, the FASB issued ASU No. 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis ("ASU 2015-02"). ASU 2015-02 is applicable to reporting entities that are required to evaluate whether they should consolidate certain legal entities. Specifically, ASU 2015-02 (i) modifies the evaluation of whether limited partnerships and similar legal entities are VIEs, (ii) eliminates the presumption that a general partner should consolidate a limited partnership, (iii) affects the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships and (iv) provides a scope exception from consolidation guidance for reporting entities with interests in legal entities that are required to comply with or operate in accordance with requirements that are similar to those in Rule 2a-7 of the Investment Company Act of 1940 for registered money market funds. The adoption of ASU 2015-02 effective January 1, 2016 did not have a material impact on the Corporation's consolidated financial condition or results of operations. Customer's Accounting for Cloud Computing Fees In April 2015, the FASB issued ASU No. 2015-05, Intangibles - Goodwill and Other - Internal Use Software (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement ("ASU 2015-05"). ASU 2015-05 provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. ASU 2015-05 does not change the accounting for a customer’s accounting for service contracts. The purpose of ASU 2015-05 is to clarify which fees paid in a cloud computing arrangement should be capitalized and which fees should be expensed as incurred. The adoption of ASU 2015-05 prospectively effective January 1, 2016 did not have a material impact on the Corporation's consolidated financial condition or results of operations. Stock Compensation In March 2016, the FASB issued ASU No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting ("ASU 2016-09"), which simplifies the accounting for employee share-based payment transactions including the accounting for income taxes, forfeitures and statutory holding requirements, as well as classification on the statement of cash flows. ASU 2016-09 is effective for public companies for interim and annual periods beginning after December 15, 2016 with early adoption permitted for any interim or annual period. If an entity early adopts the amendments, any adjustment should be reflected as of the beginning of the fiscal year. The Corporation has elected to early adopt ASU 2016-09 during the fourth quarter of 2016. Prior to adoption of ASU 2016-09, all excess tax benefits resulting from the exercise or settlement of share-based payment transactions were recognized in additional-paid-in-capital ("APIC") and accumulated in an APIC pool, while tax deficiencies were either offset against the APIC pool or recognized in the income statement if no APIC pool was available. The new guidance eliminates additions to the APIC pool and all excess tax benefits and deficiencies are recognized as an income tax benefit or expense in the income statement prospectively. Accordingly, periods prior to January 1, 2016 have not been adjusted. During the year ended December 31, 2016, $2.2 million of excess tax benefits were recognized as income tax benefit.

Mergers and Acquisitions (Table

Mergers and Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2016
Business Combinations [Abstract]
Summary of assets acquired and liabilities assumed	A summary of the purchase price and the excess of the purchase price over the fair value of adjusted net assets acquired (goodwill) follows: (Dollars in thousands) Stock $ 26,988 Cash 203 Total consideration $ 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 1,826 Premises and equipment (415 ) Core deposit intangibles 1,930 Mortgage servicing rights 315 Other assets and other liabilities 48 Fair value of adjusted net assets acquired 21,852 Goodwill recognized as a result of the Monarch transaction $ 5,339 The following schedule summarizes the revised acquisition date estimated fair values, including the adjustments to the fair values identified and recorded from the acquisition date through December 31, 2015, of assets acquired and liabilities assumed from Monarch. (Dollars in thousands) Assets Cash and cash equivalents $ 32,171 Loans 121,783 Premises and equipment 3,019 Deferred tax assets, net Net operating loss carryforward 7,900 Other 2,392 Interest receivable and other assets 6,972 Goodwill 5,339 Core deposit intangibles 1,930 Mortgage servicing rights 1,284 Assets acquired, at fair value 182,790 Liabilities Deposits 144,300 FHLB advances 8,000 Interest payable and other liabilities 3,299 Total liabilities acquired, at fair value 155,599 Total purchase price $ 27,191 (Dollars in thousands) Consideration paid: Stock $ 1,504,811 Cash 107,638 Total consideration 1,612,449 Fair value of identifiable assets acquired (1) : Cash and cash equivalents 433,352 Investment securities: Available-for-sale 808,894 Held-to-maturity 1,657 Loans held-for-sale 244,916 Loans (2) 4,882,402 Premises and equipment 38,793 Loan servicing rights 42,462 Other intangible assets (2) 19,088 Interest receivable and other assets (2) 395,119 Total identifiable assets acquired 6,866,683 Fair value of liabilities assumed (1) : Noninterest-bearing deposits 1,236,902 Interest-bearing deposits 4,057,716 Interest payable and other liabilities (2) 99,482 Securities sold under agreements to repurchase with customers 19,704 Short-term borrowings 387,500 Long-term borrowings 299,597 Total liabilities assumed 6,100,901 Fair value of net identifiable assets acquired 765,782 Goodwill resulting from acquisition $ 846,667 (1) All amounts were previously reported in the Corporation's Quarterly Report on Form 10-Q for the three- and nine-month periods ended September 30, 2016, with the exception of loans, other intangible assets, interest receivable and other assets and interest payable and other liabilities. (2) Includes adjustments to the fair value as a result of additional valuation information obtained during the fourth quarter of 2016, including the corresponding tax effects. A summary of the purchase price and the excess of the purchase price over the fair value of adjusted net assets acquired (goodwill) follows: (Dollars in thousands) Stock $ 132,916 Cash 54,478 Total consideration 187,394 Net assets acquired (1) : 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 (5,031 ) Core deposit intangibles 8,003 Deferred tax assets, net (2) 4,096 Deposits and borrowings, net (3,182 ) Other assets and other liabilities (2) (121 ) Fair value of adjusted net assets acquired 86,333 Goodwill recognized as a result of the Lake Michigan transaction $ 101,061 (1) All amounts were previously reported in the Corporation's Annual Report on Form 10-K for the year ended December 31, 2015, with the exception of deferred tax assets, net and other assets and other liabilities. (2) Includes adjustments to the fair value as a result of additional valuation information obtained during the first quarter of 2016, including the corresponding tax effects. The following schedule summarizes the revised acquisition date estimated fair values, including the adjustments to the fair values identified and recorded from the acquisition date through December 31, 2016, of assets acquired and liabilities assumed from Lake Michigan (in thousands): (Dollars in thousands) Assets Cash and cash equivalents $ 39,301 Investment securities 66,699 Loans 985,542 Premises and equipment 10,975 Deferred tax asset, net 16,715 Goodwill 101,061 Core deposit intangible asset 8,003 Bank-owned life insurance 23,844 Other assets 37,695 Assets acquired, at fair value 1,289,835 Liabilities Deposits 924,697 Short-term borrowings 30,000 Other borrowings 124,857 Other liabilities 22,887 Total liabilities acquired, at fair value 1,102,441 Total purchase price $ 187,394
Information regarding acquired loans accounted for under ASC 310-30	Information regarding loans accounted for under ASC 310-30 at the merger date is as follows: (Dollars in thousands) Accounted for under ASC 310-30: Contractual cash flows $ 1,198,388 Contractual cash flows not expected to be collected (nonaccretable difference) 22,600 Expected cash flows 1,175,788 Interest component of expected cash flows (accretable yield) 190,246 Fair value at acquisition $ 985,542 Information regarding loans accounted for under ASC 310-30 at the merger date is as follows: (Dollars in thousands) Accounted for under ASC 310-30: Contractual cash flows $ 5,968,488 Contractual cash flows not expected to be collected (nonaccretable difference) 223,959 Expected cash flows 5,744,529 Interest component of expected cash flows (accretable yield) 862,127 Fair value at acquisition $ 4,882,402 Information regarding loans accounted for under ASC 310-30 at the merger date is as follows: (Dollars in thousands) Accounted for under ASC 310-30: Contractual cash flows $ 166,797 Contractual cash flows not expected to be collected (nonaccretable difference) 7,100 Expected cash flows 159,697 Interest component of expected cash flows (accretable yield) 37,914 Fair value at acquisition $ 121,783 Information regarding loans accounted for under ASC 310-30 at the merger date is as follows: (Dollars in thousands) Accounted for under ASC 310-30: Contractual cash flows $ 618,788 Contractual cash flows not expected to be collected (nonaccretable difference) 33,500 Expected cash flows 585,288 Interest component of expected cash flows (accretable yield) 110,003 Fair value at acquisition $ 475,285
Pro forma financial information	The following unaudited pro forma financial information presents the consolidated results of operation of the Corporation and Talmer as if the merger had occurred as of January 1, 2015, Lake Michigan and Monarch as if the acquisitions had occurred as of January 1, 2014 and Northwestern as if the acquisition had occurred as of January 1, 2013. The unaudited pro forma combined results of operations are presented solely for information purposes and are not intended to represent or be indicative of the consolidated results of operations that Chemical would have reported had these transactions been completed as of the dates and for the periods presented, nor are they necessarily indicative of future results. In particular, no adjustments have been made to eliminate the amount of Talmer, 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 accordance with Article 11 of SEC Regulation S-X, transaction costs directly attributable to the acquisitions have been excluded. Years ended December 31, (In thousands, except per share data) 2016 2015 2014 Net interest and other income $ 492,323 $ 654,962 $ 361,695 Net Income 115,847 142,504 79,455 Earnings per share: Basic $ 1.65 $ 2.03 $ 2.17 Diluted $ 1.62 $ 2.01 $ 2.16
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: (Dollars in thousands) Talmer Lake Michigan Monarch Northwestern OAK Total Year Ended December 31, 2016 Balance at beginning of period $ — $ 152,999 $ 34,558 $ 82,623 $ 28,077 $ 298,257 Addition attributable to acquisitions 862,127 — — — — 862,127 Additions, net of reductions* — (3,552 ) (1,908 ) (6,985 ) 1,091 (11,354 ) Accretion recognized in interest income (63,917 ) (33,031 ) (5,468 ) (15,791 ) (13,352 ) (131,559 ) Reclassification from nonaccretable difference — 5,000 — 10,000 7,500 22,500 Balance at end of period $ 798,210 $ 121,416 $ 27,182 $ 69,847 $ 23,316 $ 1,039,971 Year Ended December 31, 2015 Balance at beginning of period $ — $ — $ — $ 104,675 $ 33,286 $ 137,961 Addition attributable to acquisitions — 190,246 37,914 — — 228,160 Additions, net of reductions* — (12,991 ) 1,336 (3,396 ) 6,601 (8,450 ) Accretion recognized in interest income — (24,256 ) (4,692 ) (18,656 ) (11,810 ) (59,414 ) Balance at end of period $ — $ 152,999 $ 34,558 $ 82,623 $ 28,077 $ 298,257 * Represents additions in 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.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Summary of assets measured at fair value on a recurring basis	For assets measured at fair value on a recurring basis, quantitative disclosures about the fair value measurements for each major category of assets follow: (Dollars in thousands) Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total December 31, 2016 Investment securities — available-for-sale: U.S. Treasury securities $ 5,793 $ — $ — $ 5,793 Government sponsored agencies — 215,011 — 215,011 State and political subdivisions — 300,088 — 300,088 Residential mortgage-backed securities — 272,282 — 272,282 Collateralized mortgage obligations — 320,025 — 320,025 Corporate bonds — 89,474 — 89,474 Preferred stock and trust preferred securities — 32,291 — 32,291 Total investment securities — available-for-sale 5,793 1,229,171 — 1,234,964 Loans held-for-sale — 81,830 — 81,830 Loan servicing rights — — 48,085 48,085 Derivative assets: Customer-initiated derivatives — 4,406 — 4,406 Forward contracts related to mortgage loans to be delivered for sale — 635 — 635 Interest rate lock commitments — 956 — 956 Power Equity CD — 2,218 — 2,218 Total derivatives — 8,215 — 8,215 Total assets at fair value $ 5,793 $ 1,319,216 $ 48,085 $ 1,373,094 Derivative liabilities: Customer-initiated derivatives — 4,141 — 4,141 Power Equity CD — 2,218 — 2,218 Total derivatives — 6,359 — 6,359 Total liabilities at fair value $ — $ 6,359 $ — $ 6,359 (Dollars in thousands) Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total December 31, 2015 Investment securities — available-for-sale: U.S. Treasury securities $ 5,765 $ — $ — $ 5,765 Government sponsored agencies — 194,989 — 194,989 State and political subdivisions — 15,120 — 15,120 Residential mortgage-backed securities — 187,768 — 187,768 Collateralized mortgage obligations — 132,230 — 132,230 Corporate bonds — 14,627 — 14,627 Preferred stock and trust preferred securities — 3,232 — 3,232 Total investment securities — available-for-sale 5,765 547,966 — 553,731 Loans held-for-sale — 10,327 — 10,327 Derivative assets: Forward contracts related to mortgage loans to be delivered for sale — 144 — 144 Interest rate lock commitments — 42 — 42 Power Equity CD — 1,832 — 1,832 Total derivatives — 2,018 — 2,018 Total assets at fair value $ 5,765 $ 560,311 $ — $ 566,076 Derivative liabilities: Forward contracts related to mortgage loans to be delivered for sale — 57 — 57 Interest rate lock commitments — 90 — 90 Power Equity CD — 1,832 — 1,832 Total derivatives — 1,979 — 1,979 Total liabilities at fair value $ — $ 1,979 $ — $ 1,979
Summary of changes in Level 3 assets measured at fair value on a recurring basis	The following table summarizes the changes in Level 3 assets measured at fair value on a recurring basis. Year ended December 31, 2016 (Dollars in thousands) Loan servicing rights Balance, beginning of period $ — Additions due to acquisition 42,462 Gains (losses): Recorded in earnings (realized): Recorded in “Mortgage banking revenue” 4,593 New originations 1,030 Balance, end of period $ 48,085
Schedule of aggregate fair value contractual balance and gain (loss) for loans held-for-sale	The aggregate fair value, contractual balance (including accrued interest), and gain or loss for loans held-for-sale carried at fair value was as follows: December 31, (Dollars in thousands) 2016 2015 Aggregate fair value $ 81,830 $ 10,327 Contractual balance 81,009 10,366 Unrealized gain (loss) 821 (39 )
Amount of gains (losses) from loans held for sale included in the Consolidated Statements of Income	The total amount of gains (losses) from loans held for sale included in the Consolidated Statements of Income were as follows: For the years ended December 31, (Dollars in thousands) 2016 2015 2014 Interest income (1) $ 1,606 $ 83 $ 66 Change in fair value (2) 39 (61 ) 110 Total included in earnings $ 1,645 $ 22 $ 176 (1) Included in "Interest and fees on loans" in the Consolidated Statements of Income. (2) Included in "Mortgage banking revenue" in the Consolidated Statements of Income.
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 follow: (Dollars in thousands) Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total December 31, 2016 Impaired originated loans $ — $ — $ 62,184 $ 62,184 Other real estate/repossessed assets — — 1,386 1,386 Loan servicing rights — — 2 2 Total $ — $ — $ 63,572 $ 63,572 December 31, 2015 Impaired originated loans $ — $ — $ 42,065 $ 42,065 Other real estate/repossessed assets — — 3,068 3,068 Total $ — $ — $ 45,133 $ 45,133
Additional information about significant unobservable inputs used in the fair value measurement of financial assets	The following table presents additional information about the significant unobservable inputs used in the fair value measurement of financial assets measured on a nonrecurring basis that were categorized within the Level 3 of the fair value hierarchy: (Dollars in thousands) Fair Value at December 31, 2016 Valuation Technique Significant Unobservable Inputs Range Impaired originated loans $ 62,184 Appraisal of collateral Discount for type of collateral and age of appraisal 10%-25% Other real estate/repossessed assets 1,386 Appraisal of property Discount for type of property and age of appraisal 10%-25% Loan servicing rights 2 Discounted cash flow Constant prepayment rate 9%-18% Discount rate 10%-11%
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 not recorded at fair value in their entirety on a recurring basis on the Consolidated Statements of Financial Position was as follows: December 31, Level in Fair Value Measurement Hierarchy 2016 2015 (Dollars in thousands) Carrying Amount Fair Value Carrying Amount Fair Value Financial assets: Cash and cash equivalents Level 1 $ 474,402 $ 474,402 $ 238,789 $ 238,789 Investment securities: Held-to-maturity Level 2 622,927 608,221 509,471 512,405 Held-to-maturity Level 3 500 310 500 7,090 Nonmarketable equity securities NA 97,350 97,350 36,907 36,907 Net loans (1) Level 3 12,912,511 13,069,315 7,197,819 7,201,994 Interest receivable Level 2 42,235 42,235 21,953 21,953 Financial liabilities: Deposits: Deposits without defined maturities Level 2 $ 9,862,755 $ 9,862,755 $ 5,809,355 $ 5,809,355 Time deposits Level 2 3,010,367 3,010,048 1,647,412 1,647,412 Total deposits 12,873,122 12,872,803 7,456,767 7,456,767 Interest payable Level 2 5,415 5,415 1,578 1,578 Securities sold under agreements to repurchase with customers Level 2 343,047 343,047 297,199 297,199 Short-term borrowings Level 2 825,000 825,000 100,000 100,000 Long-term borrowings Level 2 597,847 591,227 242,391 242,391 (1) Included $62.2 million and $42.1 million of impaired loans recorded at fair value on a nonrecurring basis at December 31, 2016 and 2015 , respectively.

Investment Securities (Tables)

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Available-for-sale Securities	The following is a summary of the amortized cost and fair value of investment securities available-for-sale and investment securities held-to-maturity at December 31, 2016 and 2015 : Investment Securities Available-for-Sale (Dollars in thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2016 U.S. Treasury securities $ 5,788 $ 5 $ — $ 5,793 Government sponsored agencies 216,890 189 2,068 215,011 State and political subdivisions 311,704 163 11,779 300,088 Residential mortgage-backed securities 276,162 112 3,992 272,282 Collateralized mortgage obligations 323,965 63 4,003 320,025 Corporate bonds 90,859 16 1,401 89,474 Preferred stock and trust preferred securities 31,353 1,018 80 32,291 Total $ 1,256,721 $ 1,566 $ 23,323 $ 1,234,964 December 31, 2015 U.S. Treasury securities $ 5,773 $ — $ 8 $ 5,765 Government sponsored agencies 195,711 78 800 194,989 State and political subdivisions 14,731 395 6 15,120 Residential mortgage-backed securities 189,452 538 2,222 187,768 Collateralized mortgage obligations 133,256 111 1,137 132,230 Corporate bonds 14,825 2 200 14,627 Preferred stock and trust preferred securities 2,888 344 — 3,232 Total $ 556,636 $ 1,468 $ 4,373 $ 553,731
Held-to-maturity Securities	Investment Securities Held-to-Maturity (Dollars in thousands) Amortized Cost Unrecognized Gains Unrecognized Losses Fair Value December 31, 2016 State and political subdivisions $ 622,927 $ 2,648 $ 17,354 $ 608,221 Trust preferred securities 500 — 190 310 Total $ 623,427 $ 2,648 $ 17,544 $ 608,531 December 31, 2015 State and political subdivisions $ 509,471 $ 7,446 $ 4,512 $ 512,405 Trust preferred securities 500 — 200 300 Total $ 509,971 $ 7,446 $ 4,712 $ 512,705
Proceeds from sales of securities and the associated gains and losses recorded in earnings	Proceeds from sales of securities and the associated gains and losses recorded in earnings are listed below: For the years ended December 31, (Dollars in thousands) 2016 2015 2014 Proceeds $ 41,446 $ 40,301 $ — Gross gains 325 631 — Gross losses (196 ) (1 ) —
Amortized cost and fair value of debt securities by contractual maturity	The following is a summary of the amortized cost and fair value of investment securities at December 31, 2016 , by maturity, for both available-for-sale and held-to-maturity investment securities. The maturities of residential mortgage-backed securities and collateralized mortgage obligations are based on scheduled principal payments. The maturities of all other debt securities are based on final contractual maturity. December 31, 2016 (Dollars in thousands) Amortized Cost Fair Value Investment Securities Available-for-Sale: Due in one year or less $ 237,047 $ 235,845 Due after one year through five years 490,634 485,221 Due after five years through ten years 339,222 329,879 Due after ten years 188,429 182,281 Preferred stock 1,389 1,738 Total $ 1,256,721 $ 1,234,964 Investment Securities Held-to-Maturity: Due in one year or less $ 66,090 $ 65,954 Due after one year through five years 262,136 257,936 Due after five years through ten years 145,225 139,320 Due after ten years 149,976 145,321 Total $ 623,427 $ 608,531
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 December 31, 2016 and 2015 , aggregated by category and length of time that individual securities have been in a continuous unrealized loss position. As of December 31, 2016 , the Corporation's securities portfolio consisted of 2,504 securities, 1,563 of which were in an unrealized loss position. Less Than 12 Months 12 Months or More Total (Dollars in thousands) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses December 31, 2016 Government sponsored agencies $ 105,702 $ 1,707 $ 15,023 $ 361 $ 120,725 $ 2,068 State and political subdivisions 758,063 28,158 26,810 975 784,873 29,133 Residential mortgage-backed securities 244,239 3,992 — — 244,239 3,992 Collateralized mortgage obligations 279,001 3,778 14,754 225 293,755 4,003 Corporate bonds 80,536 1,401 — — 80,536 1,401 Trust preferred securities 10,699 80 310 190 11,009 270 Total $ 1,478,240 $ 39,116 $ 56,897 $ 1,751 $ 1,535,137 $ 40,867 December 31, 2015 U.S. Treasury securities $ 5,765 $ 8 $ — $ — $ 5,765 $ 8 Government sponsored agencies 114,640 292 21,681 508 136,321 800 State and political subdivisions 195,285 2,891 68,361 1,627 263,646 4,518 Residential mortgage-backed securities 169,226 2,146 3,435 76 172,661 2,222 Collateralized mortgage obligations 60,459 408 39,382 729 99,841 1,137 Corporate bonds 9,532 200 — — 9,532 200 Trust preferred securities — — 300 200 300 200 Total $ 554,907 $ 5,945 $ 133,159 $ 3,140 $ 688,066 $ 9,085

Loans (Tables)

Loans (Tables)	12 Months Ended
	Dec. 31, 2016
Receivables [Abstract]
Summary of loans under portfolio	A summary of the Corporation's loans follows: (Dollars in thousands) Originated Acquired (1) Total loans December 31, 2016 Commercial loan portfolio: Commercial $ 1,901,526 $ 1,315,774 $ 3,217,300 Commercial real estate 1,921,799 2,051,341 3,973,140 Real estate construction and land development 281,724 122,048 403,772 Subtotal 4,105,049 3,489,163 7,594,212 Consumer loan portfolio: Residential mortgage 1,475,342 1,611,132 3,086,474 Consumer installment 1,282,588 151,296 1,433,884 Home equity 595,422 280,787 876,209 Subtotal 3,353,352 2,043,215 5,396,567 Total loans $ 7,458,401 $ 5,532,378 $ 12,990,779 (2) December 31, 2015 Commercial loan portfolio: Commercial $ 1,521,515 $ 384,364 $ 1,905,879 Commercial real estate 1,424,059 688,103 2,112,162 Real estate construction and land development 185,147 46,929 232,076 Subtotal 3,130,721 1,119,396 4,250,117 Consumer loan portfolio: Residential mortgage 1,216,975 212,661 1,429,636 Consumer installment 869,426 8,031 877,457 Home equity 590,812 123,125 713,937 Subtotal 2,677,213 343,817 3,021,030 Total loans $ 5,807,934 $ 1,463,213 $ 7,271,147 (2) (1) Acquired loans are accounted for under ASC 310-30. (2) Reported net of deferred costs totaling $14.8 million and $10.7 million at December 31, 2016 and 2015 , respectively.
Recorded investment of loans in the commercial loan portfolio by risk rating categories	The following schedule presents the recorded investment of loans in the commercial loan portfolio by credit risk categories at December 31, 2016 and 2015 : (Dollars in thousands) Pass Special Mention Substandard Doubtful Total December 31, 2016 Originated Portfolio: Commercial $ 1,803,750 $ 44,809 $ 51,898 $ 1,069 $ 1,901,526 Commercial real estate 1,849,315 36,981 35,502 1 1,921,799 Real estate construction and land development 280,968 157 599 — 281,724 Subtotal 3,934,033 81,947 87,999 1,070 4,105,049 Acquired Portfolio: Commercial 1,218,848 46,643 50,283 — 1,315,774 Commercial real estate 1,897,011 61,441 92,636 253 2,051,341 Real estate construction and land development 117,505 1,982 2,561 — 122,048 Subtotal 3,233,364 110,066 145,480 253 3,489,163 Total $ 7,167,397 $ 192,013 $ 233,479 $ 1,323 $ 7,594,212 December 31, 2015 Originated Portfolio: Commercial $ 1,418,301 $ 34,727 $ 66,392 $ 2,095 $ 1,521,515 Commercial real estate 1,341,202 31,036 51,821 — 1,424,059 Real estate construction and land development 183,323 180 1,644 — 185,147 Subtotal 2,942,826 65,943 119,857 2,095 3,130,721 Acquired Portfolio: Commercial 340,782 28,321 15,261 — 384,364 Commercial real estate 629,430 23,926 34,747 — 688,103 Real estate construction and land development 41,683 2,556 2,690 — 46,929 Subtotal 1,011,895 54,803 52,698 — 1,119,396 Total $ 3,954,721 $ 120,746 $ 172,555 $ 2,095 $ 4,250,117
Recorded investment of loans in the consumer loan portfolio based on the credit risk profile of loans in a performing and nonperforming status	The following schedule presents the recorded investment of loans in the consumer loan portfolio based on loans in a performing status and loans in a nonperforming status at December 31, 2016 and 2015 : (Dollars in thousands) Residential mortgage Consumer installment Home equity Total consumer December 31, 2016 Originated Portfolio: Performing $ 1,468,373 $ 1,281,709 $ 592,071 $ 3,342,153 Nonperforming 6,969 879 3,351 11,199 Subtotal 1,475,342 1,282,588 595,422 3,353,352 Acquired Loans 1,611,132 151,296 280,787 2,043,215 Total $ 3,086,474 $ 1,433,884 $ 876,209 $ 5,396,567 December 31, 2015 Originated Portfolio: Performing $ 1,211,418 $ 868,975 $ 588,833 $ 2,669,226 Nonperforming 5,557 451 1,979 7,987 Subtotal 1,216,975 869,426 590,812 2,677,213 Acquired Loans 212,661 8,031 123,125 343,817 Total $ 1,429,636 $ 877,457 $ 713,937 $ 3,021,030
Summary of nonperforming loans	A summary of nonperforming assets follows: December 31, (Dollars in thousands) 2016 2015 Nonperforming assets Nonaccrual loans: Commercial $ 13,178 $ 28,554 Commercial real estate 19,877 25,163 Real estate construction and land development 80 521 Residential mortgage 6,969 5,557 Consumer installment 879 451 Home equity 3,351 1,979 Total nonaccrual loans 44,334 62,225 Other real estate owned and repossessed assets 17,187 9,935 Total nonperforming assets $ 61,521 $ 72,160 Accruing loans contractually past due 90 days or more as to interest or principal payments, excluding acquired loans accounted for under ASC 310-30 Commercial 11 364 Commercial real estate 277 254 Residential mortgage — 402 Home equity 995 1,267 Total accruing loans contractually past due 90 days or more as to interest or principal payments, excluding acquired loans accounted for under ASC 310-30 $ 1,283 $ 2,287
Schedule representing the aging status of the recorded investment in loans by classes	Loan delinquency, excluding acquired loans accounted for under ASC 310-30, was as follows: (Dollars in thousands) 30-59 days past due 60-89 days past due 90 days or more past due Total past due Current Total loans 90 days or more past due and still accruing December 31, 2016 Originated Portfolio: Commercial $ 10,421 $ 4,842 $ 3,641 $ 18,904 $ 1,882,622 $ 1,901,526 $ 11 Commercial real estate 6,551 1,589 5,165 13,305 1,908,494 1,921,799 277 Real estate construction and land development 2,721 499 — 3,220 278,504 281,724 — Residential mortgage 3,147 62 1,752 4,961 1,470,381 1,475,342 — Consumer installment 3,991 675 238 4,904 1,277,684 1,282,588 — Home equity 3,097 893 2,349 6,339 589,083 595,422 995 Total $ 29,928 $ 8,560 $ 13,145 $ 51,633 $ 7,406,768 $ 7,458,401 $ 1,283 December 31, 2015 Originated Portfolio: Commercial $ 9,393 $ 5,243 $ 364 $ 15,000 $ 1,506,515 $ 1,521,515 $ 364 Commercial real estate 6,941 2,262 254 9,457 1,414,602 1,424,059 254 Real estate construction and land development 596 — — 596 184,551 185,147 — Residential mortgage 7,475 1,170 402 9,047 1,207,928 1,216,975 402 Consumer installment 3,347 741 — 4,088 865,338 869,426 — Home equity 2,075 1,113 1,267 4,455 586,357 590,812 1,267 Total $ 29,827 $ 10,529 $ 2,287 $ 42,643 $ 5,765,291 $ 5,807,934 $ 2,287
Schedule of Impaired loans by classes	The following schedules present impaired loans by classes of loans at December 31, 2016 and December 31, 2015 : (Dollars in thousands) Recorded investment Unpaid principal balance Related valuation allowance December 31, 2016 Impaired loans with a valuation allowance: Commercial $ 28,925 $ 33,209 $ 3,128 Commercial real estate 21,318 27,558 2,102 Real estate construction and land development 177 177 4 Residential mortgage 20,864 20,864 3,528 Consumer installment 879 879 240 Home equity 2,577 2,577 390 Subtotal 71,284 81,808 8,762 Impaired loans with no related valuation allowance: Commercial 7,435 11,153 — Commercial real estate 20,588 23,535 — Real estate construction and land development 80 80 — Residential mortgage 3,252 3,252 — Consumer installment — — — Home equity 774 774 — Subtotal 32,129 38,794 — Total impaired loans: Commercial 36,360 44,362 3,128 Commercial real estate 41,906 51,093 2,102 Real estate construction and land development 257 257 4 Residential mortgage 24,116 24,116 3,528 Consumer installment 879 879 — Home equity 3,351 3,351 — Total $ 106,869 $ 124,058 $ 8,762 (Dollars in thousands) Recorded investment Unpaid principal balance Related valuation allowance December 31, 2015 Impaired loans with a valuation allowance: Commercial $ 18,898 $ 19,426 $ 5,700 Commercial real estate 4,448 4,688 497 Residential mortgage 21,037 21,037 192 Subtotal 44,383 45,151 6,389 Impaired loans with no related valuation allowance: Commercial 27,304 32,395 — Commercial real estate 48,747 59,949 — Real estate construction and land development 982 1,062 — Residential mortgage 5,557 5,557 — Consumer installment 451 451 — Home equity 1,979 1,979 — Subtotal 85,020 101,393 — Total impaired loans: Commercial 46,202 51,821 5,700 Commercial real estate 53,195 64,637 497 Real estate construction and land development 982 1,062 — Residential mortgage 26,594 26,594 192 Consumer installment 451 451 — Home equity 1,979 1,979 — Total $ 129,403 $ 146,544 $ 6,389 The following schedule presents additional information regarding impaired loans by classes of loans segregated by those requiring a valuation allowance and those not requiring a valuation allowance at December 31, 2016 , 2015 and 2014 and the respective interest income amounts recognized: For the years ended December 31, 2016 2015 2014 (Dollars in thousands) Average annual recorded investment Interest income recognized while on impaired status Average annual recorded investment Interest income recognized while on impaired status Average annual recorded investment Interest income recognized while on impaired status Impaired loans with a valuation allowance: Commercial $ 7,829 $ — $ 9,511 $ — $ 2,117 $ — Commercial real estate 5,658 — 2,918 — 3,699 — Real estate construction and land development 19 — — — — — Residential mortgage 23,958 1,285 20,661 1,312 19,740 1,252 Consumer installment 359 — — — — — Home equity 1,759 — — — — — Subtotal 37,464 1,285 33,090 1,312 25,556 1,252 Impaired loans with no related valuation allowance: Commercial 29,559 1,343 27,778 1,005 32,895 961 Commercial real estate 41,646 1,236 50,079 1,547 46,344 1,342 Real estate construction and land development 585 22 889 25 1,831 3 Residential mortgage 1,519 — 6,027 — 6,783 — Consumer installment — — 448 — 592 — Home equity 555 — 1,872 — 2,118 — Subtotal 73,864 2,601 87,093 2,577 90,563 2,306 Total impaired loans: Commercial 37,388 1,343 37,289 1,005 35,012 961 Commercial real estate 47,304 1,236 52,997 1,547 50,043 1,342 Real estate construction and land development 604 22 889 25 1,831 3 Residential mortgage 25,477 1,285 26,688 1,312 26,523 1,252 Consumer installment 359 — 448 — 592 — Home equity 2,314 — 1,872 — 2,118 — Total $ 113,446 $ 3,886 $ 120,183 $ 3,889 $ 116,119 $ 3,558
Schedule providing information on performing and nonperforming TDRs	The following tables present the recorded investment of loans modified into TDRs during the years ended December 31, 2016 , 2015 and 2014 by type of concession granted. In cases where more than one type of concession was granted, the loans were categorized based on the most significant concession. Concession type (Dollars in thousands) Principal Principal A/B Note Restructure (1) Interest Forbearance Total Pre- modification recorded investment Post- modification recorded investment For the year ended December 31, 2016 Commercial loan portfolio: Commercial $ 11,533 $ 1,527 $ 43 $ — $ 1,750 54 $ 14,853 $ 14,853 Commercial real estate 2,993 1,866 — — — 16 4,859 4,859 Subtotal 14,526 3,393 43 — 1,750 70 19,712 19,712 Consumer loan portfolio: Residential mortgage 477 — — — — 4 477 477 Consumer installment 87 — — — — 14 87 87 Home equity 179 — — 364 — 10 543 543 Subtotal 743 — — 364 — 28 1,107 1,107 Total loans $ 15,269 $ 3,393 $ 43 $ 364 $ 1,750 98 $ 20,819 $ 20,819 (1) Loan restructurings whereby the original loan is restructured into two notes: an "A" note, which generally reflects the portion of the modified loans which is expected to be collected: and a "B" note, which is fully charged off. Concession type (Dollars in thousands) Principal Principal A/B Note Restructure (1) Interest Forbearance Total Pre- modification recorded investment Post- modification recorded investment For the year ended December 31, 2015 Commercial loan portfolio: Commercial $ 6,031 $ — $ — $ 117 $ 5,298 53 $ 11,446 $ 11,446 Commercial real estate 5,904 450 — 102 740 21 7,196 7,196 Real estate construction and land development 705 — — — — 3 705 705 Subtotal 12,640 450 — 219 6,038 77 19,347 19,347 Consumer loan portfolio: Residential mortgage 1,246 — — 635 — 20 1,881 1,881 Consumer installment 210 — — — — 19 210 210 Home equity 1,110 — — 46 — 26 1,158 1,156 Subtotal 2,566 — — 681 — 65 3,249 3,247 Total loans $ 15,206 $ 450 $ — $ 900 $ 6,038 142 $ 22,596 $ 22,594 (1) Loan restructurings whereby the original loan is restructured into two notes: an "A" note, which generally reflects the portion of the modified loans which is expected to be collected: and a "B" note, which is fully charged off. Concession type (Dollars in thousands) Principal Principal A/B Note Restructure (1) Interest Forbearance Total Pre- modification recorded investment Post- modification recorded investment For the year ended December 31, 2014 Commercial loan portfolio: Commercial $ 12,657 $ 112 $ 111 $ 901 $ — 53 $ 13,781 $ 13,781 Commercial real estate 10,713 154 223 671 314 46 12,075 12,075 Real estate construction and land development 72 — — — — 1 72 72 Subtotal 23,442 266 334 1,572 314 100 25,928 25,928 Consumer loan portfolio: Residential mortgage 1,832 — — 991 — 36 2,847 2,823 Consumer installment 572 — — — — 52 572 572 Home equity 606 — — 157 — 31 765 763 Subtotal 3,010 — — 1,148 — 119 4,184 4,158 Total loans $ 26,452 $ 266 $ 334 $ 2,720 $ 314 219 $ 30,112 $ 30,086 (1) Loan restructurings whereby the original loan is restructured into two notes: an "A" note, which generally reflects the portion of the modified loans which is expected to be collected: and a "B" note, which is fully charged off.
Schedule of Corporation's TDRs	The following schedule presents the Corporation's TDRs at December 31, 2016 and 2015 : (Dollars in thousands) Accruing TDRs Nonaccrual TDRs Total December 31, 2016 Commercial loan portfolio $ 45,388 $ 25,397 $ 70,785 Consumer loan portfolio 17,147 5,134 22,281 Total $ 62,535 $ 30,531 $ 93,066 December 31, 2015 Commercial loan portfolio $ 46,141 $ 32,682 $ 78,823 Consumer loan portfolio 21,037 3,251 24,288 Total $ 67,178 $ 35,933 $ 103,111
Troubled debt restructurings on financing receivables with defaults payment	The following schedule includes TDRs for which there was a payment default during the years ended December 31, 2016 , 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: For the years ended December 31, 2016 2015 2014 Number of loans Principal balance at year end Number of loans Principal balance at year end Number of loans Principal balance at year end (Dollars in thousands) Commercial loan portfolio: Commercial — $ — 1 $ 1,206 7 $ 885 Commercial real estate 2 1,721 5 1,016 6 2,352 Subtotal — commercial loan portfolio 2 1,721 6 2,222 13 3,237 Consumer loan portfolio (residential mortgage) 14 259 3 65 12 259 Total 16 $ 1,980 9 $ 2,287 25 $ 3,496
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 years ended December 31, 2016 , 2015 and 2014 , and details regarding the balance in the allowance and the recorded investment in loans at December 31, 2016 and 2015 by impairment evaluation method. (Dollars in thousands) Commercial loan portfolio Consumer loan portfolio Unallocated Total Changes in allowance for loan losses for the year ended December 31, 2016: Beginning balance $ 47,234 $ 26,094 $ — $ 73,328 Provision for loan losses 9,788 5,087 — 14,875 Charge-offs (8,906 ) (6,396 ) — (15,302 ) Recoveries 3,085 2,282 — 5,367 Ending balance $ 51,201 $ 27,067 $ — $ 78,268 Allowance for loan losses balance at December 31, 2016 attributable to: Loans individually evaluated for impairment $ 5,234 $ 3,528 $ — $ 8,762 Loans collectively evaluated for impairment 45,967 23,539 — 69,506 Loans accounted for under ASC 310-30 — — — — Total $ 51,201 $ 27,067 $ — $ 78,268 Recorded investment (loan balance) at December 31, 2016: Loans individually evaluated for impairment $ 78,523 $ 28,346 $ — $ 106,869 Loans collectively evaluated for impairment 4,026,526 3,325,006 — 7,351,532 Loans accounted for under ASC 310-30 3,489,163 2,043,215 — 5,532,378 Total $ 7,594,212 $ 5,396,567 $ — $ 12,990,779 Changes in allowance for loan losses for the year ended December 31, 2015: Beginning balance $ 44,156 $ 28,803 $ 2,724 $ 75,683 Provision (benefit) for loan losses 7,275 1,949 (2,724 ) 6,500 Charge-offs (6,385 ) (7,116 ) — (13,501 ) Recoveries 2,188 2,458 — 4,646 Ending balance $ 47,234 $ 26,094 $ — $ 73,328 Allowance for loan losses balance at December 31, 2015 attributable to: Loans individually evaluated for impairment $ 6,197 $ 192 $ — $ 6,389 Loans collectively evaluated for impairment 41,037 25,902 — 66,939 Loans accounted for under ASC 310-30 — — — — Total $ 47,234 $ 26,094 $ — $ 73,328 Recorded investment (loan balance) at December 31, 2015: Loans individually evaluated for impairment $ 100,379 $ 29,024 $ — $ 129,403 Loans collectively evaluated for impairment 3,030,342 2,648,189 — 5,678,531 Loans accounted for under ASC 310-30 1,119,396 343,817 — 1,463,213 Total $ 4,250,117 $ 3,021,030 $ — $ 7,271,147 Changes in allowance for loan losses for the year ended December 31, 2014: Beginning balance $ 44,482 $ 30,145 $ 4,445 $ 79,072 Provision (benefit) for loan losses 3,464 4,357 (1,721 ) 6,100 Charge-offs (6,399 ) (7,830 ) — (14,229 ) Recoveries 2,609 2,131 — 4,740 Ending balance $ 44,156 $ 28,803 $ 2,724 $ 75,683

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Summary of premises and equipment	The following table summarizes premises and equipment: December 31, (Dollars in thousands) 2016 2015 Land and land improvements $ 36,185 $ 28,447 Buildings 144,155 120,370 Furniture and equipment 91,963 77,882 Total 272,303 226,699 Less accumulated depreciation (127,291 ) (120,382 ) Premises and equipment, net $ 145,012 $ 106,317

Other Real Estate Owned and R40

Other Real Estate Owned and Repossessed Assets (Tables)	12 Months Ended
	Dec. 31, 2016
Other Real Estate [Abstract]
Tabular disclosure of the changes in non-covered and covered other real estate on properties owned	Changes in other real estate owned and repossessed assets were as follows: (Dollars in thousands) Other real estate Repossessed Balance at January 1, 2014 $ 9,518 $ 258 Additions due to acquisitions 3,721 — Other additions (1) 8,986 2,322 Net payments received (264 ) (30 ) Disposals (7,360 ) (2,298 ) Write-downs (648 ) — Balance at December 31, 2014 $ 13,953 $ 252 Additions due to acquisitions 440 — Other additions (1) 6,957 2,372 Net payments received (45 ) (22 ) Disposals (10,168 ) (2,383 ) Write-downs (1,421 ) — Balance at December 31, 2015 $ 9,716 $ 219 Additions due to acquisitions 13,227 313 Other additions (1) 9,938 3,032 Net payments received (1,560 ) (763 ) Disposals (13,873 ) (2,426 ) Write-downs (636 ) — Balance at December 31, 2016 $ 16,812 $ 375 (1) Includes loans transferred to other real estate owned and other repossessed assets.
Schedule of income and expenses related to other real estate owned	Income and expenses related to other real estate owned and repossessed assets, recorded as a component of “Other expense” in the Consolidated Statements of Income, were as follows: (Dollars in thousands) Other real estate owned Repossessed assets For the year ended December 31, 2016 Net gain (loss) on sale $ 5,325 $ 523 Write-downs (636 ) — Net operating expenses (740 ) (60 ) Total $ 3,949 $ 463 For the year ended December 31, 2015 Net gain (loss) on sale $ 4,128 $ (26 ) Write-downs (1,421 ) — Net operating expenses (1,604 ) (19 ) Total $ 1,103 $ (45 ) For the year ended December 31, 2014 Net gain (loss) on sale $ 2,545 $ (11 ) Write-downs (648 ) — Net operating expenses (1,242 ) (53 ) Total $ 655 $ (64 )

Loan Servicing Rights (Tables)

Loan Servicing Rights (Tables)	12 Months Ended
	Dec. 31, 2016
Transfers and Servicing [Abstract]
Schedule of activity for loan servicing rights and the related fair value changes	The following table represents the activity for LSRs accounted for under the fair value method and the related fair value changes: For the year ended December 31, 2016 (Dollars in thousands) Commercial Real Estate Mortgage Total Fair value, beginning of period $ — $ — $ — Acquired in Talmer Bancorp, Inc. merger 365 42,097 42,462 Additions from loans sold with servicing retained — 1,030 1,030 Changes in fair value due to: Reductions from pay downs (17 ) (502 ) (519 ) Changes in estimates of fair value (1) (4 ) 5,116 5,112 Fair value, end of period $ 344 $ 47,741 $ 48,085 Principal balance of loans serviced for others that have servicing capitalized $ 64,756 $ 5,235,415 $ 5,300,171 (1) Represents estimated LSR value change resulting primarily from market-driven changes in interest rates and prepayments.
Net carrying value, fair value of mortgage servicing rights and loans Corporation servicing for others	The Corporation continues to account for all other LSRs using the amortization method. The following shows the net carrying value and fair value of LSRs and the total loans that the Corporation is servicing for others accounted for under the amortization method: December 31, (Dollars in thousands) 2016 2015 Net carrying value of LSRs $ 10,230 $ 11,122 Fair value of LSRs $ 15,891 $ 15,542 Valuation allowance $ 8 $ — Loans serviced for others that have servicing rights capitalized $ 2,074,057 $ 2,082,899
Activity for capitalized loan servicing rights	The following table shows the activity for capitalized LSRs accounted for under the amortization method: Years Ended December 31, (Dollars in thousands) 2016 2015 2014 Balance at beginning of period $ 11,122 $ 12,217 $ 3,423 Acquired through acquisitions — 1,284 9,235 Additions 3,303 1,476 1,075 Amortization (4,187 ) (4,055 ) (1,316 ) Change in valuation allowance (8 ) 200 (200 ) Balance at end of period $ 10,230 $ 11,122 $ 12,217
Schedule of assumptions included in loan servicing rights	Expected and actual loan prepayment speeds are the most significant factors driving the fair value of loan servicing rights. The following table presents assumptions utilized in determining the fair value of loan servicing rights as of December 31, 2016 and 2015 . Commercial Real Estate Mortgage As of December 31, 2016 Prepayment speed 0.00 - 22.47% 0.00 - 99.75% Weighted average (“WA”) discount rate 16.46 % 10.09 % Cost to service/per year $467-$500 $65-$90 WA Ancillary income/per year N/A $ 28 WA float range 0.53 % 1.01 % As of December 31, 2015 Prepayment speed N/A 6.96 - 17.65% WA discount rate N/A 10.04 % Cost to service/per year N/A $70-$85 Ancillary income/per year N/A $ 20 WA float range N/A 1.72 %

Other Intangible Assets (Tables

Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Net carrying value of other intangible assets	The following table shows the net carrying value of the Corporation's other intangible assets: December 31, (Dollars in thousands) 2016 2015 Core deposit intangible assets $ 40,211 $ 26,654 Non-compete intangible assets — 328 Total other intangible assets $ 40,211 $ 26,982
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets	The following table presents the Corporation's carrying amount and accumulated amortization of CDIs: December 31, (Dollars in thousands) 2016 2015 Gross carrying amount $ 59,143 $ 40,055 Accumulated amortization 18,932 13,401 Net carrying amount $ 40,211 $ 26,654
Estimated future amortization expense on CDIs	The estimated future amortization expense on CDIs for the next five years is as follows: (Dollars in thousands) Estimated amortization expense 2017 $ 5,952 2018 5,703 2019 5,441 2020 4,850 2021 4,471

Derivative Instruments and Ba43

Derivative Instruments and Balance Sheet Offsetting (Tables)	12 Months Ended
	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule reflecting the amount and fair value of risk management derivatives and mortgage banking and customer initiated derivatives	The following table presents the notional amount and fair value of the Corporation’s derivative instruments held or issued in connection with customer-initiated and mortgage banking activities. December 31, 2016 2015 Fair Value Fair Value (Dollars in thousands) Notional Amount (1) Gross Derivative Assets (2) Gross Derivative Liabilities (2) Notional Amount (1) Gross Derivative Assets (2) Gross Derivative Liabilities (2) Customer-initiated and mortgage banking derivatives: Customer-initiated derivatives $ 600,598 $ 4,406 $ 4,141 $ — $ — $ — Forward contracts related to mortgage loans to be delivered for sale 140,155 635 — 33,787 144 57 Interest rate lock commitments 76,034 956 — 23,421 42 90 Power Equity CD 36,807 2,218 2,218 33,703 1,832 1,832 Total gross derivatives $ 853,594 $ 8,215 $ 6,359 $ 90,911 $ 2,018 $ 1,979 (1) Notional or contract amounts, which represent the extent of involvement in the derivatives market, are used to determine the contractual cash flows required in accordance with the terms of the agreement. These amounts are typically not exchanged, significantly exceed amounts subject to credit or market risk and are not reflected in the Consolidated Statements of Financial Position. (2) Derivative assets are included within “Other assets” and derivative liabilities are included within “Other liabilities” on the Consolidated Statements of Financial Position. Included in the fair value of the derivative assets are credit valuation adjustments for counterparty credit risk totaling $99 thousand at December 31, 2016 and $0 at December 31, 2015.
Schedule reflecting the net gains (losses) relating to derivative instruments related to the changes in fair value	The following table presents the net gains (losses) related to derivative instruments reflecting the changes in fair value. For the years ended December 31, (Dollars in thousands) Location of Gain (Loss) 2016 2015 2014 Forward contracts related to mortgage loans to be delivered for sale Mortgage banking revenue $ 692 $ 193 $ (267 ) Interest rate lock commitments Mortgage banking revenue (1,356 ) (132 ) 157 Power Equity CD Other noninterest income — — — Customer-initiated derivatives Other noninterest income 581 — — Total gain (loss) recognized in income $ (83 ) $ 61 $ (110 )
Schedule of the Company's financial instruments eligible for offset, offsetting assets	The tables below present information about the Corporation’s financial instruments that are eligible for offset. There were no financial instruments eligible for offset as of December 31, 2015. Gross amounts not offset in the (Dollars in thousands) Gross Gross amounts Net amounts Financial Collateral Net December 31, 2016 Offsetting derivative assets Derivative assets $ 4,405 $ — $ 4,405 $ — $ — $ 4,405 Offsetting derivative liabilities Derivative liabilities 4,141 — 4,141 — 2,550 1,591
Schedule of the Company's financial instruments eligible for offset, offsetting liabilities	The tables below present information about the Corporation’s financial instruments that are eligible for offset. There were no financial instruments eligible for offset as of December 31, 2015. Gross amounts not offset in the (Dollars in thousands) Gross Gross amounts Net amounts Financial Collateral Net December 31, 2016 Offsetting derivative assets Derivative assets $ 4,405 $ — $ 4,405 $ — $ — $ 4,405 Offsetting derivative liabilities Derivative liabilities 4,141 — 4,141 — 2,550 1,591

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Schedule of activity related to liability recorded in connection with representation and warranties	For the years ended December 31, (Dollars in thousands) 2016 2015 2014 Reserve balance at beginning of period $ 4,048 $ 3,000 $ 1,600 Addition of fair value of representations and warranties due to acquisitions 3,100 1,712 2,000 Reserve reduction (580 ) — (287 ) Charge-offs (109 ) (664 ) (313 ) Ending reserve balance $ 6,459 $ 4,048 $ 3,000 Reserve balance: Liability for specific claims 730 — 118 General allowance 5,729 4,048 2,882 Total reserve balance $ 6,459 $ 4,048 $ 3,000
Schedule of future minimum lease payments for operating leases	Future minimum lease payments for operating leases and other noncancelable contractual obligations are as follows: (Dollars in thousands) Future Minimum Lease Payments(1) Years ending December 31, 2017 $ 20,712 2018 18,000 2019 14,594 2020 11,362 2021 7,173 Thereafter 16,549 Total $ 88,390 (1) Future minimum lease payments are reduced by $312 thousand related to sublease income to be received within the next five years.

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2016
Deposits [Abstract]
Schedule of Deposits	A summary of deposits follows: December 31, (Dollars in thousands) 2016 2015 Noninterest-bearing demand $ 3,341,520 $ 1,934,583 Interest-bearing demand 2,825,801 1,870,197 Savings and money market accounts 3,695,434 2,004,575 Time deposits over $100,000 1,682,986 701,830 Other time deposits 1,327,381 945,582 Total deposits $ 12,873,122 $ 7,456,767 At December 31, 2016 , the scheduled maturities of time deposits for the next five years were as follows: (Dollars in thousands) 2017 $ 2,159,477 2018 393,811 2019 167,132 2020 139,555 2021 142,146 Thereafter 8,246 Total $ 3,010,367

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Schedule of Other Borrowings	A summary of the Corporation's short- and long-term borrowings follows: December 31, 2016 2015 (Dollars in thousands) Amount Weighted Average Rate (1) Amount Weighted Average Rate (1) Short-term borrowings: FHLB advances: 0.60% - 0.66% fixed-rate notes $ 825,000 0.65 % $ 100,000 0.34 % Long-term borrowings: FHLB advances: 0.81% - 7.44% fixed-rate notes due 2017 to 2020 (2) 438,538 1.24 181,394 1.41 Securities sold under agreements to repurchase: 1.48% - 4.11% fixed-rate notes due through 2017 (3) 19,144 3.17 17,453 0.27 Line-of-credit: floating-rate based on one-month LIBOR plus 1.75% 124,625 2.52 25,000 2.27 Subordinated debt obligations: floating-rate based on three-month LIBOR plus 1.45% - 2.85% due 2034 to 2035 (4) 11,285 3.14 — — Subordinated debt obligations: floating-rate based on three-month LIBOR plus 3.25% due in 2032 (5) 4,255 4.25 — — Subordinated debt obligations — — 18,544 3.99 Total long-term borrowings 597,847 1.63 242,391 1.61 Total short-term and long-term borrowings $ 1,422,847 1.06 % $ 342,391 1.24 % (1) Weighted average rate presented is the contractual rate which excludes premiums and discounts related to purchase accounting. (2) The December 31, 2016 balance includes advances payable of $437.8 million and purchase accounting premiums of $0.7 million . The December 31, 2015 balance includes advances payable of $181.0 million and purchase accounting premiums of $0.4 million . (3) The December 31, 2016 balance includes advances payable of $19.0 million and purchase accounting premiums of $0.1 million . The December 31, 2015 balance includes advance payable of $17.0 million and purchase accounting premiums of $0.5 million . (4) The December 31, 2016 balance includes advances payable of $15.0 million and purchase accounting discounts of $3.7 million . (5) The December 31, 2016 balance includes advances payable of $5.0 million and purchase accounting discounts of $0.7 million .
Schedule of Securities Sold Under Agreements to Repurchase	The remaining contract maturity, excluding purchase accounting adjustments, of long-term securities under agreement to repurchase, is as follows: December 31, 2016 Remaining Contractual Maturities of the Agreements (Dollars in thousands) Overnight and continuous Up to 30 Days 30-90 Days Greater than 90 Days Total Securities sold under agreements to repurchase $ — $ 10,000 $ — $ 9,000 $ 19,000 Total borrowings $ — $ 10,000 $ — $ 9,000 $ 19,000 Amounts related to securities sold under agreements to repurchase not included in offsetting disclosure in Footnote 11 $ 19,000
Long-term Debt by Maturity	At December 31, 2016 , the contractual principal payments due and the amortization/accretion of purchase accounting adjustments for the remaining maturities of long-term debt over the next five years and thereafter are as follows: (Dollars in thousands) Long-term Debt by Maturity Years Ending December 31, 2017 $ 126,089 2018 159,207 2019 186,338 2020 110,673 2021 — Thereafter 15,540 Total $ 597,847

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Provision for Federal Income Taxes Components	The current and deferred components of the provision for income taxes were as follows: Years Ended December 31, (Dollars in thousands) 2016 2015 2014 Current income tax expense (benefit) Federal $ 19,144 $ 31,300 $ 29,200 State (423 ) — — Total current income tax expense 18,721 31,300 29,200 Deferred expense (benefit) Federal 23,649 5,700 (1,700 ) State 442 — — Total deferred income tax expense (benefit) 24,091 5,700 (1,700 ) Change in valuation allowance (706 ) — — Income tax provision $ 42,106 $ 37,000 $ 27,500
Schedule of Federal Effective Income Tax Rate Reconciliation	A reconciliation of expected income tax expense at the federal statutory income tax rate and the amounts recorded in the Consolidated Financial Statements were as follows: Years Ended December 31, 2016 2015 2014 (Dollars in thousands) Amount Rate Amount Rate Amount Rate Tax at statutory rate $ 52,548 35.0 % $ 43,341 35.0 % $ 31,367 35.0 % Changes resulting from: Tax-exempt interest income (5,320 ) (3.5 ) (3,943 ) (3.2 ) (3,142 ) (3.5 ) State taxes, net of federal benefit 13 — — — — — Change in valuation allowance (706 ) (0.5 ) — — — — Bank-owned life insurance adjustments (832 ) (0.6 ) (124 ) (0.1 ) (95 ) (0.1 ) Director plan change in control (508 ) (0.3 ) — — — — Income tax credits, net (2,454 ) (1.6 ) (2,557 ) (2.1 ) (1,624 ) (1.8 ) Nondeductible transaction expenses 2,100 1.4 411 0.3 403 0.4 Tax benefits in excess of compensation costs on share-based payments (1) (2,240 ) (1.5 ) — — — — Other, net (495 ) (0.4 ) (128 ) — 591 0.7 Income tax expense $ 42,106 28.0 % $ 37,000 29.9 % $ 27,500 30.7 % (1) The year ended December 31, 2016 reflects the impact of the early adoption of ASU 2016-09 which resulted in excess tax benefits recognized within "Income tax expense" rather than previously recognized directly into equity with "Additional paid-in-capital." Refer to Note 1, Summary of Significant Accounting Policies, for further details.
Schedule of Deferred Tax Assets and Liabilities	The significant components of the deferred tax assets and liabilities at December 31, 2016 and 2015 were as follows: December 31, (Dollars in thousands) 2016 2015 Deferred tax assets: Allowance for loan losses $ 45,763 $ 24,863 Acquisition-related fair value adjustments 62,078 29,280 Accrued stock-based compensation 18,891 3,240 Loss and tax credit carry forwards 47,977 7,235 Acquisition built in loss carry forward 28,469 — Depreciation 3,896 4,333 Nonaccrual loan interest 9,465 4,994 Accrued expense 20,858 13,296 Other 7,401 5,951 Total deferred tax assets 244,798 93,192 Deferred tax liabilities: Loan servicing rights 20,450 3,893 Core deposit intangible assets 11,844 7,379 Goodwill 6,373 5,808 Other (715 ) 4,742 Total deferred tax liabilities 37,952 21,822 Net deferred tax asset before valuation allowance 206,846 71,370 Valuation allowance (2,239 ) (1,180 ) Net deferred tax asset $ 204,607 $ 70,190
Summary of the loss attributes, Section 382 limitations, and tax expiration periods	The following table is a summary of the loss attributes, Section 382 limitations, and tax expiration periods as of December 31, 2016 . From the Acquisition of: Talmer's Prior Ownership Changes (Dollars in thousands) Talmer Monarch First Place Holdings/First Place Bank Talmer West Bank First of Huron Corp./Signature Bank From 2009 Ownership change Not Limited by Section 382 Total Tax Loss and Credit Carryforwards as of 12/31/16: Years Expiring (except AMT Credits) 2032-2034 2026-2034 2026-2031 2030-2035 2031-2033 2027-2029 2033-2035 Annual Section 382 limitation-base (1) $ 34,668 $ 673 $ 6,650 $ 3,028 $ 365 $ 145 $ — N/A Gross Federal Net Operating Losses 17,723 17,744 1,222 50,086 1,014 1,885 — 89,674 Gross Capital Losses 797 — — — — — — 797 Realized Built-in Losses — — 71,805 8,936 — — — 80,741 Business Tax Credits 170 1,651 781 — — — 592 3,194 Less amounts not recorded due to Sec 382 Limitation — (1,738 ) — (2,992 ) — (145 ) — (4,875 ) Alternative Minimum Tax Credits - no expiration 12,473 106 2,115 — 303 — 730 15,727 Valuation Allowance — — (66 ) (1,287 ) — — — (1,353 ) (1) In respect to the Monarch and Talmer acquisitions, in addition to the statutory "base" Section 382 limitation, recognized built in gain increases the Section 382 limitation during the five year period beginning on the acquisition date. The Corporation estimates that the recognized built in gain will total $5.6 million and $322.3 million for the Monarch and Talmer acquisitions, respectively.

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of stock options outstanding by exercise price range	The following summarizes information about stock options outstanding and exercisable at December 31, 2016 : Options outstanding Options exercisable Range of exercise prices per share Number outstanding Weighted average exercise price per share Weighted average contractual term (in years) Number exercisable Weighted average exercise price per share Weighted average contractual term (in years) $10.56 - 12.80 289,512 $ 11.83 3.50 289,512 $ 11.83 3.50 $13.20 - 16.24 1,044,881 16.20 5.99 1,044,881 16.20 5.99 $19.97 - 21.10 62,422 20.49 3.39 62,422 20.49 3.39 $28.43 - 32.81 703,378 31.58 8.58 295,439 29.88 7.76 $23.78 - 25.14 353,202 24.60 4.49 353,202 24.60 4.49 $10.56 - 32.81 2,453,395 $ 21.41 6.16 2,045,456 $ 19.14 5.56
Summary of activity for Corporation's stock options	A summary of activity for the Corporation's stock options as of and during the years ended December 31, 2016 , 2015 and 2014 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, 2013 414,080 $ 24.29 $ 7.19 1,073,990 $ 26.84 Granted 190,011 29.45 9.64 190,011 29.45 Exercised — — — (72,936 ) 24.67 Vested (148,016 ) 23.43 6.98 — — Expired or forfeited (23,876 ) 25.67 7.79 (153,754 ) 37.50 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 Acquired — — — 132,883 12.93 Exercised — — — (310,985 ) 25.10 Vested (150,224 ) 25.57 7.80 — — Expired or forfeited (46,385 ) 27.99 8.50 (48,635 ) 28.18 Outstanding at December 31, 2015 479,755 $ 28.75 $ 8.49 1,054,739 $ 25.38 Acquired — — — 1,466,408 15.08 Granted 441,167 32.81 6.15 441,167 32.81 Exercised — — — (450,296 ) 20.02 Vested (454,360 ) 28.74 8.49 — — Forfeited/expired (58,623 ) 31.10 7.17 (58,623 ) 31.10 Outstanding at December 31, 2016 407,939 $ 32.81 $ 6.15 2,453,395 $ 21.41 Exercisable/vested at December 31, 2016 2,045,456 $ 19.14
Assumptions of Black-Scholes option pricing model	The fair value of the stock options granted during the years ended December 31, 2016 , 2015 and 2014 were estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions. 2016 2015 2014 Expected dividend yield 3.30 % 3.50 % 3.00 % Risk-free interest rate 1.39 % 1.78 % 2.16 % Expected stock price volatility 27.9 % 39.1 % 42.2 % Expected life of options — in years 6.5 7.0 7.0 Weighted average fair value of options granted $6.15 $8.40 $9.64
Summary of activity for restricted stock units and awards	A summary of the activity for restricted stock units during the year ended December 31, 2016 is presented below: Number of units Weighted-average grant date fair value per unit Outstanding at December 31, 2015 207,989 $ 26.41 Granted 165,876 37.41 Converted into shares of common stock (67,331 ) 24.54 Forfeited/expired (8,177 ) 31.19 Outstanding at December 31, 2016 298,357 $ 32.81 The following table provides information regarding nonvested restricted stock awards: Nonvested restricted stock awards Number of awards Weighted-average acquisition-date fair value Nonvested at January 1, 2016 — $ — Acquired 484,892 46.23 Vested (118,493 ) 46.23 Forfeited (508 ) 46.23 Nonvested at December 31, 2016 365,891 $ 46.23

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Schedule of Changes in the Projected Benefit Obligation and Plan Assets of the Corporation’s Pension and Postretirement Plans	The following schedule sets forth the changes in the projected benefit obligation and plan assets of the Corporation's Pension and Postretirement Plans: Pension Plan Postretirement Plan (Dollars in thousands) 2016 2015 2016 2015 Projected benefit obligation: Benefit obligation at beginning of year $ 119,873 $ 129,160 $ 3,247 $ 3,702 Service cost 1,041 1,021 9 16 Interest cost 5,335 5,242 132 133 Net actuarial loss (gain) 2,684 (10,837 ) (478 ) (363 ) Benefits paid (4,965 ) (4,713 ) (309 ) (241 ) Benefit obligation at end of year 123,968 119,873 2,601 3,247 Fair value of plan assets: Fair value of plan assets at beginning of year 126,930 130,775 — — Actual return on plan assets 10,786 868 — — Employer contributions — — 309 241 Benefits paid (4,965 ) (4,713 ) (309 ) (241 ) Fair value of plan assets at end of year 132,751 126,930 — — Funded (unfunded) status at December 31 $ 8,783 $ 7,057 $ (2,601 ) $ (3,247 ) Accumulated benefit obligation $ 115,418 $ 109,583 $ 2,601 $ 3,247
Schedule of Weighted-average rate assumptions of the Pension and Postretirement Plans	Weighted-average rate assumptions of the Pension and Postretirement Plans follow: Pension Plan Postretirement Plan 2016 2015 2014 2016 2015 2014 Discount rate used in determining benefit obligation — December 31 4.22 % 4.55 % 4.15 % 3.79 % 4.23 % 3.75 % Discount rate used in determining expense 4.55 4.15 5.00 4.23 3.75 4.27 Expected long-term return on Pension Plan assets 6.75 6.75 7.00 — — — Rate of compensation increase used in determining benefit obligation — December 31 3.50 3.50 3.50 — — — Rate of compensation increase used in determining pension expense 3.50 3.50 3.50 — — — Year 1 increase in cost of postretirement benefits — — — 7.0 7.5 8.0
Schedule of Net periodic Pension Cost (Income) of the Pension and Postretirement Plans	Net periodic pension cost (income) of the Pension and Postretirement Plans was as follows for the years ended December 31: Pension Plan Postretirement Plan (Dollars in thousands) 2016 2015 2014 2016 2015 2014 Service cost $ 1,041 $ 1,021 $ 944 $ 9 $ 16 $ 18 Interest cost 5,335 5,242 5,167 132 133 142 Expected return on plan assets (8,562 ) (8,645 ) (8,314 ) — — — Amortization of prior service credit — (5 ) (1 ) 117 130 130 Amortization of net actuarial loss (gain) 2,259 3,962 2,159 (100 ) (1 ) (104 ) Net cost (income) $ 73 $ 1,575 $ (45 ) $ 158 $ 278 $ 186
Schedule of Estimated Future Benefit Payments Under the Pension and Postretirement Plans	The following schedule presents estimated future benefit payments for the next 10 years under the Pension and Postretirement Plans for retirees already receiving benefits and future retirees, assuming they retire and begin receiving unreduced benefits as soon as they are eligible: (Dollars in thousands) Pension Plan Postretirement Plan 2017 $ 5,474 $ 243 2018 5,706 239 2019 6,083 240 2020 6,263 237 2021 6,626 234 2022 - 2026 36,438 1,028 Total $ 66,590 $ 2,221
Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates	A one percentage-point change in these rates would have the following effects: One Percentage-Point (Dollars in thousands) Increase Decrease Effect on total of service and interest cost components in 2016 $ 14 $ (13 ) Effect on postretirement benefit obligation as of December 31, 2016 204 (194 )
Schedule of Allocation of Plan Assets	The Pension Plan's asset allocation by asset category was as follows: December 31, Asset Category 2016 2015 Equity securities 69 % 68 % Debt securities 29 31 Other 2 1 Total 100 % 100 % The following schedule sets forth the fair value of the Pension Plan's assets and the level of the valuation inputs used to value those assets at December 31, 2016 and 2015 : (Dollars in thousands) Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total December 31, 2016 Cash $ 2,825 $ — $ — $ 2,825 Equity securities: U.S. large- and mid-cap stocks (1) 55,389 — — 55,389 U.S. small-cap mutual funds 5,687 — — 5,687 International large-cap mutual funds 13,701 — — 13,701 Emerging markets mutual funds 5,147 — — 5,147 Chemical Financial Corporation common stock 11,412 — — 11,412 Debt securities: U.S. Treasury and government sponsored agency bonds and notes — 806 — 806 Corporate bonds (2) — 1,503 — 1,503 Mutual funds (3) 36,220 — — 36,220 Other 61 — — 61 Total $ 130,442 $ 2,309 $ — $ 132,751 December 31, 2015 Cash $ 354 $ — $ — $ 354 Equity securities: U.S. large- and mid-cap stocks (1) 55,709 — — 55,709 U.S. small-cap mutual funds 4,749 — — 4,749 International large-cap mutual funds 14,124 — — 14,124 Emerging markets mutual funds 4,886 — — 4,886 Chemical Financial Corporation common stock 7,219 — — 7,219 Debt securities: U.S. Treasury and government sponsored agency bonds and notes — 2,815 — 2,815 Corporate bonds (2) — 3,554 — 3,554 Mutual funds (3) 33,424 — — 33,424 Other 96 — — 96 Total $ 120,561 $ 6,369 $ — $ 126,930 (1) Comprised of common stocks and mutual funds traded on U.S. Exchanges whose issuers had market capitalizations exceeding $3 billion . (2) Comprised of investment grade bonds of U.S. issuers from diverse industries. (3) Comprised primarily of fixed-income bonds issued by the U.S. Treasury and government sponsored agencies and bonds of U.S. and foreign issuers from diverse industries.
Schedule of Changes in Accumulated Other Comprehensive Income (Loss), Net of Tax, Related to the Corporation’s Pension, Postretirement and Supplemental Plans	The following sets forth the changes in accumulated other comprehensive income (loss), net of tax, related to the Corporation's Pension, Postretirement and Supplemental Plans during 2016 : (Dollars in thousands) Pension Plan Postretirement Plan Supplemental Plan Total Accumulated other comprehensive income (loss) at beginning of year $ (27,291 ) $ 402 $ (255 ) $ (27,144 ) Comprehensive income (loss) adjustment: Prior service costs (credits) — 76 — 76 Net actuarial (income) loss 1,168 246 (240 ) 1,174 Comprehensive income (loss) adjustment 1,168 322 (240 ) 1,250 Accumulated other comprehensive income (loss) at end of year $ (26,123 ) $ 724 $ (495 ) $ (25,894 )
Schedule of Estimated Income (Loss) That Will Be Amortized From Accumulated Other Comprehensive Income (Loss) Into Net Periodic Cost	The estimated income (loss) that will be amortized from accumulated other comprehensive income (loss) into net periodic cost, net of tax, in 2017 is as follows: (Dollars in thousands) Pension Plan Postretirement Plan Supplemental Plan Total Prior service (costs) credits $ — $ — $ — $ — Net gain (loss) (1,436 ) 105 (67 ) (1,398 ) Total $ (1,436 ) $ 105 $ (67 ) $ (1,398 )

Regulatory Capital and Reserv50

Regulatory Capital and Reserve Requirements (Tables)	12 Months Ended
	Dec. 31, 2016
Banking and Thrift [Abstract]
Corporation's and Chemical Bank's actual capital amounts and ratios with the quantitative measures established by regulation to ensure capital adequacy	The summary below compares the actual capital amounts and ratios with the quantitative measures established by regulation to ensure capital adequacy: Actual Minimum Required for Capital Adequacy Purposes Minimum Required for Capital Adequacy Purposes Plus Capital Conservation Buffer Required to be Well Capitalized Under Prompt Corrective Action Regulations (Dollars in thousands) Capital Amount Ratio Capital Amount Ratio Capital Amount Ratio Capital Amount Ratio December 31, 2016 Total Capital to Risk-Weighted Assets Corporation $ 1,543,018 11.5 % $ 1,073,431 8.0 % $ 1,157,293 8.6 % N/A N/A Chemical Bank 1,608,980 12.0 1,068,560 8.0 1,152,041 8.6 $ 1,335,700 10.0 % Tier 1 Capital to Risk-Weighted Assets Corporation 1,441,209 10.7 805,073 6.0 888,935 6.6 N/A N/A Chemical Bank 1,522,711 11.4 801,420 6.0 884,901 6.6 1,068,560 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets Corporation 1,441,209 10.7 603,805 4.5 687,667 5.1 N/A N/A Chemical Bank 1,522,711 11.4 601,065 4.5 684,546 5.1 868,205 6.5 Leverage Ratio Corporation 1,441,209 9.0 643,603 4.0 643,603 4.0 N/A N/A Chemical Bank 1,522,711 9.5 641,457 4.0 641,457 4.0 801,822 5.0 December 31, 2015 Total Capital to Risk-Weighted Assets Corporation $ 841,257 11.8 % $ 571,509 8.0 % N/A N/A N/A N/A Chemical Bank 830,294 11.7 570,073 8.0 N/A N/A $ 712,591 10.0 % Tier 1 Capital to Risk-Weighted Assets Corporation 767,929 10.7 428,631 6.0 N/A N/A N/A N/A Chemical Bank 756,966 10.6 427,555 6.0 N/A N/A 570,073 8.0 Common Equity Tier 1 Capital to Risk-Weighted Assets Corporation 753,815 10.6 321,474 4.5 N/A N/A N/A N/A Chemical Bank 756,966 10.6 320,666 4.5 N/A N/A 463,184 6.5 Leverage Ratio Corporation 767,929 8.6 356,396 4.0 N/A N/A N/A N/A Chemical Bank 756,966 8.5 355,911 4.0 N/A N/A 444,888 5.0

Parent Company Only Financial51

Parent Company Only Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2016
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Parent Company Condensed Statement of Financial Position	Condensed financial statements of Chemical Financial Corporation (parent company) only follow: Condensed Statements of Financial Position December 31, (Dollars in thousands) 2016 2015 Assets Cash at subsidiary bank $ 16,851 $ 28,884 Investment in subsidiaries 2,654,458 1,023,285 Premises and equipment 4,051 3,632 Goodwill 1,092 1,092 Other assets 63,584 13,051 Total assets $ 2,740,036 $ 1,069,944 Liabilities Other liabilities $ 18,345 $ 10,426 Non-revolving line-of-credit 124,625 25,000 Subordinated debentures 15,540 18,544 Total liabilities 158,510 53,970 Shareholders' equity 2,581,526 1,015,974 Total liabilities and shareholders' equity $ 2,740,036 $ 1,069,944
Parent Company Condensed Statement of Income	Condensed Statements of Income Years Ended December 31, (Dollars in thousands) 2016 2015 2014 Income Cash dividends from subsidiaries $ 110,450 $ 56,860 $ 64,468 Other income 151 144 95 Total income 110,601 57,004 64,563 Expenses Interest expense 1,816 761 42 Operating expenses 30,589 7,794 7,200 Total expenses 32,405 8,555 7,242 Income before income taxes and equity in undistributed net income of subsidiaries 78,196 48,449 57,321 Income tax benefit 11,378 2,582 2,302 Equity in undistributed net income of subsidiaries 18,458 35,799 2,498 Net income $ 108,032 $ 86,830 $ 62,121
Parent Company Condensed Statement of Cash Flows	Condensed Statements of Cash Flows Years Ended December 31, (Dollars in thousands) 2016 2015 2014 Cash Flows From Operating Activities Net income $ 108,032 $ 86,830 $ 62,121 Adjustments to reconcile net income to net cash provided by operating activities: Share-based compensation expense 13,452 3,478 2,931 Depreciation of premises and equipment 355 318 327 Equity in undistributed net income of subsidiaries (18,458 ) (35,799 ) (2,498 ) Net decrease in other assets 9,752 2,873 1,101 Net decrease in other liabilities (11,830 ) (19,033 ) (2,519 ) Net cash provided by operating activities 101,303 38,667 61,463 Cash Flows From Investing Activities Cash paid, net of cash assumed, in business combinations (107,622 ) (45,267 ) (117,853 ) Purchases of premises and equipment, net (774 ) (320 ) (26 ) Net cash used in investing activities (108,396 ) (45,587 ) (117,879 ) Cash Flows From Financing Activities Cash dividends paid (49,389 ) (36,918 ) (29,528 ) Proceeds from issuance of common stock, net of issuance costs — — 76,175 Repayment of subordinated debt obligations (18,558 ) — (10,310 ) Repayments of other borrowings (62,500 ) — — Proceeds from issuance of other borrowings 125,000 25,000 — Proceeds from directors' stock purchase plan and exercise of stock options 1,572 2,473 1,242 Cash paid for payroll taxes upon conversion of restricted stock units (1,065 ) (571 ) (701 ) Net cash provided by (used in) financing activities (4,940 ) (10,016 ) 36,878 Net decrease in cash and cash equivalents (12,033 ) (16,936 ) (19,538 ) Cash and cash equivalents at beginning of year 28,884 45,820 65,358 Cash and cash equivalents at end of year $ 16,851 $ 28,884 $ 45,820 Business combinations: Fair value of assets acquired (noncash) $ 46,898 $ 10,304 $ 1,537 Liabilities assumed 58,309 42,019 13,010 Common stock and stock options issued 1,504,811 159,904 —

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Numerator and denominator of the basic and diluted earnings per common share computations	The factors used in the earnings per share computation follow: For the years ended December 31, (In thousands, except per share data) 2016 2015 2014 Net income $ 108,032 $ 86,830 $ 62,121 Net income allocated to participating securities 166 — — Net income allocated to common shareholders (1) $ 107,866 $ 86,830 $ 62,121 Weighted average common shares - issued 49,091 36,081 31,367 Average unvested restricted share awards (139 ) — — Weighted average common shares outstanding - basic 48,952 36,081 31,367 Effect of dilutive securities Weighted average common stock equivalents 651 272 221 Weighted average common shares outstanding - diluted 49,603 36,353 31,588 EPS available to common shareholders Basic earnings per common share $ 2.21 $ 2.41 $ 1.98 Diluted earnings per common share $ 2.17 $ 2.39 $ 1.97 (1) Net income allocated to common shareholders for basic and diluted earnings per share may differ under the two-class method as a result of adding common share equivalents for options and warrants to dilutive shares outstanding, which alters the ratio used to allocate net income to common shareholders and participating securities for the purposes of calculating diluted earnings per share.

Accumulated Other Comprehensi53

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Components of accumulated other comprehensive loss, net of related tax benefit/expense	The following table summarizes the changes within each component of accumulated other comprehensive income (loss), net of related tax benefit/expense for the years ended December 31, 2016, 2015 and 2014: (Dollars in thousands) Unrealized gains Defined Benefit Pension Plans Total For the year ended December 31, 2016 Beginning balance $ (1,888 ) $ (27,144 ) $ (29,032 ) Other comprehensive loss before reclassifications (12,170 ) (229 ) (12,399 ) Amounts reclassified from accumulated other comprehensive income (84 ) 1,479 1,395 Net current period other comprehensive income (loss) (12,254 ) 1,250 (11,004 ) Ending balance $ (14,142 ) $ (25,894 ) $ (40,036 ) For the year ended December 31, 2015 Beginning balance $ (210 ) $ (32,243 ) $ (32,453 ) Other comprehensive income (loss) before reclassifications (1,269 ) 2,443 1,174 Amounts reclassified from accumulated other comprehensive income (409 ) 2,656 2,247 Net current period other comprehensive income (loss) (1,678 ) 5,099 3,421 Ending balance $ (1,888 ) $ (27,144 ) $ (29,032 ) For the year ended December 31, 2014 Beginning balance $ (2,480 ) $ (18,040 ) $ (20,520 ) Other comprehensive income (loss) before reclassifications 2,270 (15,623 ) (13,353 ) Amounts reclassified from accumulated other comprehensive income — 1,420 1,420 Net current period other comprehensive income (loss) 2,270 (14,203 ) (11,933 ) Ending balance $ (210 ) $ (32,243 ) $ (32,453 )
Summary of amounts reclassified out of accumulated other comprehensive income (loss)	The following table summarizes the amounts reclassified out of each component of accumulated other comprehensive income (loss) for the years ended December 31, 2016, 2015 and 2014: (Dollars in thousands) Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in the Income Statement December 31, 2016 December 31, 2015 December 31, 2014 Gains and losses on available-for-sale securities $ 129 $ 630 $ — Net gain on sale of investment securities (noninterest income) (45 ) (221 ) — Income tax (expense)/benefit $ 84 $ 409 $ — Net Income Amortization of defined benefit pension plan items $ (2,276 ) $ (4,086 ) $ (2,184 ) Salaries, wages and employee benefits (operating expenses) 797 1,430 764 Income tax (expense)/benefit $ (1,479 ) $ (2,656 ) $ (1,420 ) Net Income

Noninterest Income (Tables)

Noninterest Income (Tables)	12 Months Ended
	Dec. 31, 2016
Noninterest Income [Abstract]
Schedule of major components of noninterest Income	The following schedule includes the major components of noninterest income during the past three years: Years Ended December 31, (Dollars in thousands) 2016 2015 2014 Service charges and fees on deposit accounts $ 28,136 $ 25,481 $ 22,414 Wealth management revenue 22,601 20,552 16,015 Electronic banking fees 23,433 19,119 13,480 Mortgage banking revenue 21,859 6,133 5,041 Other fees for customer services 4,939 4,428 3,539 Insurance commissions 1,874 1,966 1,559 Gain on sale of investment securities 129 630 — Bank owned life insurance 1,836 646 281 Rental income 592 466 145 Gain on sale of branch offices 7,391 — — Gain on sale of closed branch offices and other assets — 266 — Gain on sale of merchant card servicing business — — 400 Other 9,560 529 221 Total noninterest income $ 122,350 $ 80,216 $ 63,095

Operating Expenses (Tables)

Operating Expenses (Tables)	12 Months Ended
	Dec. 31, 2016
Operating Expenses [Abstract]
Schedule of major categories of operating expenses	The following schedule includes the major categories of operating expenses during the past three years: Years Ended December 31, (Dollars in thousands) 2016 2015 2014 Salaries and wages $ 135,407 $ 104,490 $ 83,229 Employee benefits 29,806 23,430 19,328 Occupancy 23,525 18,213 15,842 Equipment and software 24,408 18,569 14,737 Outside processing and service fees 21,199 15,207 11,586 FDIC insurance premiums 7,407 5,485 4,307 Professional fees 5,832 4,842 3,570 Intangible asset amortization 5,524 4,389 2,029 Postage and express mail 3,777 3,313 3,418 Advertising and marketing 3,740 3,288 3,051 Training, travel and other employee expenses 4,025 3,224 2,480 Telephone 2,964 2,608 1,966 Supplies 2,318 2,216 1,897 Donations 1,951 1,375 1,155 Credit-related expenses (2,701 ) 632 996 Merger and acquisition-related transaction expenses 61,134 7,804 6,388 Other 8,102 4,809 3,946 Total operating expenses $ 338,418 $ 223,894 $ 179,925

Summary of Quarterly Statemen56

Summary of Quarterly Statements of Income (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2016
Selected Quarterly Financial Information [Abstract]
Schedule of Quarterly Financial Information	The following is a summary of the unaudited quarterly results of operation for the years ended December 31, 2016 and 2015. In the opinion of management, the information reflects all adjustments that are necessary for the fair presentation of the results of operations for the periods presented. 2016 (Dollars in thousands, except per share data) First Quarter (1) Second Quarter (1) Third Quarter (1) Fourth Quarter Total Interest income $ 79,464 $ 82,937 $ 103,562 $ 144,416 $ 410,379 Interest expense 5,134 5,442 6,753 11,969 29,298 Net interest income 74,330 77,495 96,809 132,447 381,081 Provision for loan losses 1,500 3,000 4,103 6,272 14,875 Noninterest income 19,419 20,897 27,770 54,264 122,350 Operating expenses 58,887 59,085 106,144 114,302 338,418 Income before income taxes 33,362 36,307 14,332 66,137 150,138 Income tax expense 9,757 10,532 2,848 18,969 42,106 Net income $ 23,605 $ 25,775 $ 11,484 $ 47,168 $ 108,032 Net income per common share: Basic $ 0.61 $ 0.67 $ 0.23 $ 0.67 $ 2.21 Diluted 0.60 0.67 0.23 0.66 2.17 Cash dividends declared per common share 0.26 0.26 0.27 0.27 1.06 (1) First, second and third quarter 2016 information is revised to reflect the impact of the early adoption of ASU 2016-09, "Improvements to Employee Share-Based Payment Accounting." 2015 (Dollars in thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter Total Interest income $ 62,630 $ 69,679 $ 78,851 $ 80,629 $ 291,789 Interest expense 3,450 3,944 5,234 5,153 17,781 Net interest income 59,180 65,735 73,617 75,476 274,008 Provision for loan losses 1,500 1,500 1,500 2,000 6,500 Noninterest income 19,275 20,674 20,215 20,052 80,216 Operating expenses 51,020 56,785 58,265 57,824 223,894 Income before income taxes 25,935 28,124 34,067 35,704 123,830 Income tax expense 8,100 9,100 9,600 10,200 37,000 Net income $ 17,835 $ 19,024 $ 24,467 $ 25,504 $ 86,830 Net income per common share: Basic $ 0.54 $ 0.54 $ 0.64 $ 0.67 $ 2.41 Diluted 0.54 0.54 0.64 0.66 2.39 Cash dividends declared per common share 0.24 0.24 0.26 0.26 1.00

Summary of Significant Accoun57

Summary of Significant Accounting Policies (Nature of Operations) (Details)	12 Months Ended
	Dec. 31, 2016Bank
Nature of Operations
Number of banks through which company operates (in bank)	1
Number of regional banking units Chemical Bank operates through (in bank)	7

Summary of Significant Accoun58

Summary of Significant Accounting Policies (Business Combinations) (Details) - USD ($) $ in Thousands	Aug. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition
Goodwill acquired		$ 1,133,534	$ 287,393
Talmer
Business Acquisition
Acquisition purchase price	$ 1,612,449
Stock consideration	1,504,811
Cash paid	107,638
Goodwill acquired	846,667
Intangibles acquired	19,088
Deposits acquired	$ 5,290,000

Summary of Significant Accoun59

Summary of Significant Accounting Policies (Nonmarketable Equity Securities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
FHLB Stock Minimum Redemption Period	5 years
FRB Stock Minimum Redemption Period	6 months
FRB Stock Minimum Annual Amount Redeemable	25.00%
Corporation's ownership in FHLB stock	$ 58	$ 23.9
Corporation's ownership in FRB stock	$ 39.4	$ 13

Summary of Significant Accoun60

Summary of Significant Accounting Policies (Originated Loans) (Details)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Number of minimum days when principal or interest is past due is placed in nonaccrual category	90 days
Time period in which payments receive consistently and loans are returned to accrual status	6 months

Summary of Significant Accoun61

Summary of Significant Accounting Policies (Loans Modified Under Troubled Debt Restructuring) (Details)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Number of minimum days when principal or interest is past due is placed in nonaccrual category	90 days
Time period of real estate residential troubled debt restructurings reducing borrower's monthly payments by decreasing the interest rate charged on the loan	24 months

Summary of Significant Accoun62

Summary of Significant Accounting Policies (Allowance for Loan Losses) (Details)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Time period used for historical loan loss experience	5 years
Period of weighted average losses for the calculation of the allowance for loan losses	5 years

Summary of Significant Accoun63

Summary of Significant Accounting Policies (Mortgage Banking Operations) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Change in accounting policy for ASC Subtopic 860-50
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cumulative adjustment to retained earnings	$ 5.7
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Forward commitment term	90 days

Summary of Significant Accoun64

Summary of Significant Accounting Policies (Premises and Equipment) (Details)	12 Months Ended
	Dec. 31, 2016
Buildings | Minimum
Property, Plant and Equipment [Line Items]
Premises and equipment, estimated useful lives	25 years
Buildings | Maximum
Property, Plant and Equipment [Line Items]
Premises and equipment, estimated useful lives	40 years
All other depreciable assets | Minimum
Property, Plant and Equipment [Line Items]
Premises and equipment, estimated useful lives	3 years
All other depreciable assets | Maximum
Property, Plant and Equipment [Line Items]
Premises and equipment, estimated useful lives	10 years

Summary of Significant Accoun65

Summary of Significant Accounting Policies (Other Real Estate Owned and Repossessed Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Interest receivable and other assets
Other real estate owned and repossessed assets	$ 16.8	$ 12.7

Summary of Significant Accoun66

Summary of Significant Accounting Policies (Other Intangible Assets) (Details)	12 Months Ended
	Dec. 31, 2016
Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization period	10 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization period	15 years
Core deposit intangible assets | Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization period	10 years
Core deposit intangible assets | Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization period	15 years

Summary of Significant Accoun67

Summary of Significant Accounting Policies (Long-Term Borrowings) (Details)	Dec. 31, 2016
Accounting Policies [Abstract]
Percentage of FHLB advances secured by first lien real estate residential loans	140.00%

Summary of Significant Accoun68

Summary of Significant Accounting Policies (Income Taxes and Investment in Tax Credit Projects) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Contingent income tax liabilities recorded	$ 0	$ 0
Income tax expense attributable to qualified affordable housing projects	2,600,000	1,300,000
Investment in qualified affordable housing projects	29,500,000	21,700,000
Equity method investments	10,900,000	1,700,000
Remaining unfunded equity contributions	16,000,000
Tax benefits in excess of compensation costs on share-based payments	$ (2,240,000)	$ 0	$ 0

Mergers and Acquisitions (Textu

Mergers and Acquisitions (Textual) (Details) $ / shares in Units, $ in Thousands	Aug. 31, 2016USD ($)$ / sharesshares	May 31, 2015USD ($)office$ / sharesshares	Apr. 01, 2015USD ($)officeshares	Oct. 31, 2014USD ($)office	Dec. 31, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Business Acquisition
Credit facility drawn					$ 597,847		$ 597,847	$ 242,391
Merger and acquisition-related transaction expenses							61,134	7,804	$ 6,388
Goodwill					1,133,534		1,133,534	287,393
Talmer
Business Acquisition
Acquisition purchase price	$ 1,612,449
Stock consideration given (in shares) | shares	32,100,000
Exchange ratio of common stock issued	0.4725
Share price (in dollars per share) | $ / shares	$ 1.61
Repayments of lines of credit	$ 37,500
Decrease in goodwill recognized					3,600
Total assets acquired	765,782
Cash paid	107,638
Goodwill	846,667
Goodwill acquired during period							846,700
Contractual cash flows not expected to be collected (nonaccretable difference)	223,959
Outstanding contractual principal balance of acquired loan portfolio					4,500,000		4,500,000
Carrying amount of acquired loan portfolio					4,400,000		4,400,000
Intangibles acquired	19,088
Talmer | Other intangibles
Business Acquisition
Increase (decrease) in intangible assets					6,700
Talmer | Core deposit intangible assets
Business Acquisition
Increase (decrease) in intangible assets					(2,500)
Lake Michigan
Business Acquisition
Acquisition purchase price		$ 187,394						187,394
Stock consideration given (in shares) | shares		4,300,000
Exchange ratio of common stock issued		1.326
Share price (in dollars per share) | $ / shares		$ 16.64
Total assets acquired		$ 1,240,000
Loans		985,500						985,542
Total deposits acquired		$ 924,700						924,697
Service provided by acquiree bank through number of branches (in office) | office		5
Stock consideration given		$ 132,900
Cash paid		54,478
Goodwill		101,061						101,061
Core deposits and other intangible assets acquired		8,600
Goodwill acquired during period						$ 600
Contractual cash flows not expected to be collected (nonaccretable difference)		22,600
Outstanding contractual principal balance of acquired loan portfolio					656,100		656,100	864,400
Carrying amount of acquired loan portfolio					634,200		634,200	841,800
Purchase accounting fair value adjustment, core deposit intangibles		$ (8,003)
Intangibles acquired								8,003
Acquisition related expenses							5,500
Monarch
Business Acquisition
Acquisition purchase price			$ 27,191					27,191
Stock consideration given (in shares) | shares			860,575
Exchange ratio of common stock issued			0.0982
Total assets acquired			$ 182,800
Loans								121,783
Total deposits acquired			$ 144,300					144,300
Service provided by acquiree bank through number of branches (in office) | office			5
Cash paid			$ 203
Goodwill			5,339					5,339
Contractual cash flows not expected to be collected (nonaccretable difference)			7,100
Outstanding contractual principal balance of acquired loan portfolio					92,400		92,400	114,900
Carrying amount of acquired loan portfolio					86,400		86,400	108,300
Purchase accounting fair value adjustment, core deposit intangibles			$ (1,930)
Intangibles acquired								1,930
Acquisition related expenses							2,300
Northwestern Bancorp
Business Acquisition
Acquisition purchase price				$ 121,000
Total assets acquired				815,000
Loans				475,300
Total deposits acquired				$ 794,400
Service provided by acquiree bank through number of branches (in office) | office				25
Goodwill									60,300
Contractual cash flows not expected to be collected (nonaccretable difference)				$ 33,500
Outstanding contractual principal balance of acquired loan portfolio					283,100		283,100	361,300
Carrying amount of acquired loan portfolio					254,100		254,100	329,900
Intangibles acquired				$ 12,900
Acquisition related expenses									$ 5,800
Line of Credit
Business Acquisition
Credit facility drawn	125,000				$ 124,625		$ 124,625	$ 25,000
Repayments of lines of credit	$ 25,000

Mergers and Acquisitions (Asset

Mergers and Acquisitions (Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	Aug. 31, 2016	May 31, 2015	Apr. 01, 2015	Dec. 31, 2015	Dec. 31, 2016
Fair value of identifiable assets acquired:
Goodwill				$ 287,393	$ 1,133,534
Fair value of liabilities assumed:
Short-term borrowings				100,000	825,000
Long-term borrowings				242,391	$ 597,847
Talmer
Consideration paid:
Stock	$ 1,504,811
Cash	107,638
Total consideration	1,612,449
Fair value of identifiable assets acquired:
Cash and cash equivalents	433,352
Investment securities - AFS	808,894
Investment securities - HTM	1,657
Loans held-for-sale	244,916
Premises and equipment	38,793
Loan servicing rights	42,462
Other intangible assets	19,088
Interest receivable and other assets	395,119
Goodwill	846,667
Other assets	4,882,402
Total identifiable assets acquired	6,866,683
Fair value of liabilities assumed:
Noninterest-bearing deposits	1,236,902
Interest-bearing deposits	4,057,716
Interest payable and other liabilities	99,482
Securities sold under agreements to repurchase with customers	19,704
Short-term borrowings	387,500
Long-term borrowings	299,597
Total liabilities assumed	6,100,901
Fair value of net identifiable assets acquired	$ 765,782
Lake Michigan
Consideration paid:
Stock		$ 132,916
Cash		54,478
Total consideration		187,394		187,394
Fair value of identifiable assets acquired:
Cash and cash equivalents				39,301
Investment securities				66,699
Loans		985,500		985,542
Premises and equipment				10,975
Other intangible assets				8,003
Deferred tax asset, net				16,715
Goodwill		101,061		101,061
Bank-owned life insurance				23,844
Other assets				37,695
Total identifiable assets acquired				1,289,835
Fair value of liabilities assumed:
Deposits		924,700		924,697
Short-term borrowings				30,000
Long-term borrowings				124,857
Other liabilities				22,887
Total liabilities assumed				1,102,441
Fair value of net identifiable assets acquired		1,240,000
Shareholders' equity		89,280
Loans		(22,600)
Allowance for loan losses		15,888
Deferred tax assets, net		4,096
Premises and equipment		(5,031)
Core deposit intangibles		8,003
Deposits and borrowings, net		(3,182)
Other assets and other liabilities		(121)
Fair value of adjusted net assets acquired		$ 86,333
Monarch
Consideration paid:
Stock			$ 26,988
Cash			203
Total consideration			27,191	27,191
Fair value of identifiable assets acquired:
Cash and cash equivalents				32,171
Loans				121,783
Premises and equipment				3,019
Other intangible assets				1,930
Net operating loss carryforward				7,900
Deferred tax asset, net				2,392
Goodwill			5,339	5,339
Mortgage servicing rights				1,284
Other assets				6,972
Total identifiable assets acquired				182,790
Fair value of liabilities assumed:
Deposits			144,300	144,300
Long-term borrowings				8,000
Other liabilities				3,299
Total liabilities assumed				$ 155,599
Fair value of net identifiable assets acquired			182,800
Shareholders' equity			15,270
Loans			(7,150)
Allowance for loan losses			2,128
Deferred tax asset, net operating loss carryforward			7,900
Deferred tax assets, other			1,826
Premises and equipment			(415)
Core deposit intangibles			1,930
Mortgage servicing rights			315
Other assets and other liabilities			48
Fair value of adjusted net assets acquired			$ 21,852

Mergers and Acquisitions (Loans

Mergers and Acquisitions (Loans Accounted for Under ASC 310-30) (Details) - USD ($) $ in Thousands	Aug. 31, 2016	May 31, 2015	Apr. 01, 2015	Oct. 31, 2014
Talmer
Accounted for under ASC 310-30:
Contractual cash flows	$ 5,968,488
Contractual cash flows not expected to be collected (nonaccretable difference)	223,959
Expected cash flows	5,744,529
Interest component of expected cash flows (accretable yield)	862,127
Fair value at acquisition	$ 4,882,402
Lake Michigan
Accounted for under ASC 310-30:
Contractual cash flows		$ 1,198,388
Contractual cash flows not expected to be collected (nonaccretable difference)		22,600
Expected cash flows		1,175,788
Interest component of expected cash flows (accretable yield)		190,246
Fair value at acquisition		$ 985,542
Monarch
Accounted for under ASC 310-30:
Contractual cash flows			$ 166,797
Contractual cash flows not expected to be collected (nonaccretable difference)			7,100
Expected cash flows			159,697
Interest component of expected cash flows (accretable yield)			37,914
Fair value at acquisition			$ 121,783
Northwestern Bancorp
Accounted for under ASC 310-30:
Contractual cash flows				$ 618,788
Contractual cash flows not expected to be collected (nonaccretable difference)				33,500
Expected cash flows				585,288
Interest component of expected cash flows (accretable yield)				110,003
Fair value at acquisition				$ 475,285

Mergers and Acquisitions (Pro F

Mergers and Acquisitions (Pro Forma Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition
Net interest and other income	$ 492,323	$ 654,962	$ 361,695
Net income	$ 115,847	$ 142,504	$ 79,455
Earnings per share:
Basic (in dollars per share)	$ 1.65	$ 2.03	$ 2.17
Diluted (in dollars per share)	$ 1.62	$ 2.01	$ 2.16

Mergers and Acquisitions (Activ

Mergers and Acquisitions (Activity for Acquired Loans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period	$ 298,257	$ 137,961
Additions attributable to acquisitions	862,127	228,160
Additions (reductions)	(11,354)	(8,450)
Accretion recognized in interest income	(131,559)	(59,414)
Reclassification from nonaccretable difference	22,500
Balance at end of period	1,039,971	298,257
Talmer
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period	0	0
Additions attributable to acquisitions	862,127	0
Additions (reductions)	0	0
Accretion recognized in interest income	(63,917)	0
Reclassification from nonaccretable difference	0
Balance at end of period	798,210	0
Lake Michigan
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period	152,999	0
Additions attributable to acquisitions	0	190,246
Additions (reductions)	(3,552)	(12,991)
Accretion recognized in interest income	(33,031)	(24,256)
Reclassification from nonaccretable difference	5,000
Balance at end of period	121,416	152,999
Monarch
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period	34,558	0
Additions attributable to acquisitions	0	37,914
Additions (reductions)	(1,908)	1,336
Accretion recognized in interest income	(5,468)	(4,692)
Reclassification from nonaccretable difference	0
Balance at end of period	27,182	34,558
Northwestern
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period	82,623	104,675
Additions attributable to acquisitions	0	0
Additions (reductions)	(6,985)	(3,396)
Accretion recognized in interest income	(15,791)	(18,656)
Reclassification from nonaccretable difference	10,000
Balance at end of period	69,847	82,623
OAK
Activity for accretable yield includes contractually due interest of acquired loans
Balance at beginning of period	28,077	33,286
Additions attributable to acquisitions	0	0
Additions (reductions)	1,091	6,601
Accretion recognized in interest income	(13,352)	(11,810)
Reclassification from nonaccretable difference	7,500
Balance at end of period	$ 23,316	$ 28,077

Fair Value Measurements (Recurr

Fair Value Measurements (Recurring Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	$ 1,234,964	$ 553,731
Loan servicing rights	48,085	0
U.S. Treasury securities
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	5,793	5,765
Government sponsored agencies
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	215,011	194,989
State and political subdivisions
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	300,088	15,120
Residential mortgage-backed securities
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	272,282	187,768
Collateralized mortgage obligations
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	320,025	132,230
Corporate bonds
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	89,474	14,627
Preferred stock and trust preferred securities
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	32,291	3,232
Recurring
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	1,234,964	553,731
Loans held-for-sale	81,830	10,327
Loan servicing rights	48,085
Derivative assets	8,215	2,018
Total assets measured at fair value on a recurring basis	1,373,094	566,076
Derivative liabilities	6,359	1,979
Total liabilities at fair value	6,359	1,979
Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	5,793	5,765
Loans held-for-sale	0	0
Loan servicing rights	0
Derivative assets	0	0
Total assets measured at fair value on a recurring basis	5,793	5,765
Derivative liabilities	0	0
Total liabilities at fair value	0	0
Recurring | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	1,229,171	547,966
Loans held-for-sale	81,830	10,327
Loan servicing rights	0
Derivative assets	8,215	2,018
Total assets measured at fair value on a recurring basis	1,319,216	560,311
Derivative liabilities	6,359	1,979
Total liabilities at fair value	6,359	1,979
Recurring | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0
Loans held-for-sale	0	0
Loan servicing rights	48,085
Derivative assets	0	0
Total assets measured at fair value on a recurring basis	48,085	0
Derivative liabilities	0	0
Total liabilities at fair value	0	0
Recurring | Customer-initiated derivatives
Summary of assets measured at fair value on a recurring basis
Derivative assets	4,406
Derivative liabilities	4,141
Recurring | Customer-initiated derivatives | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0
Derivative liabilities	0
Recurring | Customer-initiated derivatives | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Derivative assets	4,406
Derivative liabilities	4,141
Recurring | Customer-initiated derivatives | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0
Derivative liabilities	0
Recurring | Forward contracts related to mortgage loans to be delivered for sale
Summary of assets measured at fair value on a recurring basis
Derivative assets	635	144
Derivative liabilities		57
Recurring | Forward contracts related to mortgage loans to be delivered for sale | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0	0
Derivative liabilities		0
Recurring | Forward contracts related to mortgage loans to be delivered for sale | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Derivative assets	635	144
Derivative liabilities		57
Recurring | Forward contracts related to mortgage loans to be delivered for sale | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0	0
Derivative liabilities		0
Recurring | Interest rate lock commitments
Summary of assets measured at fair value on a recurring basis
Derivative assets	956	42
Derivative liabilities		90
Recurring | Interest rate lock commitments | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0	0
Derivative liabilities		0
Recurring | Interest rate lock commitments | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Derivative assets	956	42
Derivative liabilities		90
Recurring | Interest rate lock commitments | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0	0
Derivative liabilities		0
Recurring | Power Equity CD
Summary of assets measured at fair value on a recurring basis
Derivative assets	2,218	1,832
Derivative liabilities	2,218	1,832
Recurring | Power Equity CD | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0	0
Derivative liabilities	0	0
Recurring | Power Equity CD | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Derivative assets	2,218	1,832
Derivative liabilities	2,218	1,832
Recurring | Power Equity CD | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Derivative assets	0	0
Derivative liabilities	0	0
Recurring | U.S. Treasury securities
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	5,793	5,765
Recurring | U.S. Treasury securities | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	5,793	5,765
Recurring | U.S. Treasury securities | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0
Recurring | U.S. Treasury securities | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0
Recurring | Government sponsored agencies
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	215,011	194,989
Recurring | Government sponsored agencies | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0
Recurring | Government sponsored agencies | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	215,011	194,989
Recurring | Government sponsored agencies | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0
Recurring | State and political subdivisions
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	300,088	15,120
Recurring | State and political subdivisions | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0
Recurring | State and political subdivisions | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	300,088	15,120
Recurring | State and political subdivisions | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0
Recurring | Residential mortgage-backed securities
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	272,282	187,768
Recurring | Residential mortgage-backed securities | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0
Recurring | Residential mortgage-backed securities | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	272,282	187,768
Recurring | Residential mortgage-backed securities | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0
Recurring | Collateralized mortgage obligations
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	320,025	132,230
Recurring | Collateralized mortgage obligations | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0
Recurring | Collateralized mortgage obligations | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	320,025	132,230
Recurring | Collateralized mortgage obligations | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0
Recurring | Corporate bonds
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	89,474	14,627
Recurring | Corporate bonds | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0
Recurring | Corporate bonds | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	89,474	14,627
Recurring | Corporate bonds | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0
Recurring | Preferred stock and trust preferred securities
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	32,291	3,232
Recurring | Preferred stock and trust preferred securities | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	0	0
Recurring | Preferred stock and trust preferred securities | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	32,291	3,232
Recurring | Preferred stock and trust preferred securities | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a recurring basis
Available-for-sale, at fair value	$ 0	$ 0

Fair Value Measurements (Change

Fair Value Measurements (Changes in Level 3 Assets) (Details) - Recurring - Loan servicing rights $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 0
Additions due to acquisition	42,462
Gains (losses): Recorded in earnings (realized)	4,593
New originations	1,030
Balance, end of period	$ 48,085

Fair Value Measurements (Aggreg

Fair Value Measurements (Aggregate Fair Value, Contractual Balance, and Gain or Loss for Loans Held-For-Sale) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Aggregate fair value	$ 81,830	$ 10,327
Contractual balance	81,009	10,366
Unrealized gain (loss)	$ 821	$ (39)

Fair Value Measurements (Gains

Fair Value Measurements (Gains (Losses) from Loans Held-for-Sale Included in the Consolidated Statements of Income) (Details) - Loans held for sale - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total included in earnings	$ 1,645	$ 22	$ 176
Interest income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total included in earnings	1,606	83	66
Mortgage banking revenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total included in earnings	$ 39	$ (61)	$ 110

Fair Value Measurements (Nonrec

Fair Value Measurements (Nonrecurring Basis) (Details) - Nonrecurring - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	$ 63,572	$ 45,133
Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	0	0
Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	0	0
Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	63,572	45,133
Impaired originated loans
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis		42,065
Impaired originated loans | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	0	0
Impaired originated loans | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	0	0
Impaired originated loans | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	62,184	42,065
Other real estate/repossessed assets
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	1,386	3,068
Other real estate/repossessed assets | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	0	0
Other real estate/repossessed assets | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	0	0
Other real estate/repossessed assets | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	1,386	$ 3,068
Loan Servicing Rights
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	2
Loan Servicing Rights | Quoted Prices In Active Markets for Identical Assets (Level 1)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	0
Loan Servicing Rights | Significant Other Observable Inputs (Level 2)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	0
Loan Servicing Rights | Significant Unobservable Inputs (Level 3)
Summary of assets measured at fair value on a nonrecurring basis
Total assets measured at fair value on a nonrecurring basis	$ 2

Fair Value Measurements (Textua

Fair Value Measurements (Textual) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for sale on nonaccrual status	$ 0	$ 0
Loans held for sale 90 days past due and on accrual status	0	0
Impairment of goodwill	0	0
Impairment identified for intangible assets	0	0
Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities recorded at fair value	6,359,000	1,979,000
Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities recorded at fair value	$ 0	0
Minimum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Discount factors used to determine fair value	75.00%
Finite-lived intangible assets amortization period	10 years
Minimum | Other Real Estate and Repossessed Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Discount factors used to determine fair value	75.00%
Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Discount factors used to determine fair value	90.00%
Finite-lived intangible assets amortization period	15 years
Maximum | Other Real Estate and Repossessed Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Discount factors used to determine fair value	90.00%
Loan Servicing Rights
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Valuation allowance related to impairment	$ 8,000	$ 0

Fair Value Measurements (Level

Fair Value Measurements (Level 3 Assets Measured on a Nonrecurring Basis) (Details) - Nonrecurring - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total assets measured at fair value on a nonrecurring basis	$ 63,572	$ 45,133
Impaired originated loans
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total assets measured at fair value on a nonrecurring basis		42,065
Other real estate/repossessed assets
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total assets measured at fair value on a nonrecurring basis	1,386	3,068
Loan Servicing Rights
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total assets measured at fair value on a nonrecurring basis	2
Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total assets measured at fair value on a nonrecurring basis	63,572	45,133
Level 3 | Impaired originated loans
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total assets measured at fair value on a nonrecurring basis	$ 62,184	42,065
Level 3 | Impaired originated loans | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate (as a percent)	10.00%
Level 3 | Impaired originated loans | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate (as a percent)	25.00%
Level 3 | Other real estate/repossessed assets
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total assets measured at fair value on a nonrecurring basis	$ 1,386	$ 3,068
Level 3 | Other real estate/repossessed assets | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate (as a percent)	10.00%
Level 3 | Other real estate/repossessed assets | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate (as a percent)	25.00%
Level 3 | Loan Servicing Rights
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total assets measured at fair value on a nonrecurring basis	$ 2
Level 3 | Loan Servicing Rights | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate (as a percent)	10.00%
Prepayment speed (as a percent)	9.00%
Level 3 | Loan Servicing Rights | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate (as a percent)	11.00%
Prepayment speed (as a percent)	18.00%

Fair Value Measurements (Carryi

Fair Value Measurements (Carrying Amounts and Estimated Fair Values) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets:
Held-to-maturity	$ 608,531	$ 512,705
Liabilities:
Short-term borrowings	825,000	100,000
Long-term borrowings	597,847	242,391
Nonrecurring
Liabilities:
Assets measured at fair value on a nonrecurring basis	63,572	45,133
Nonrecurring | Impaired originated loans
Liabilities:
Assets measured at fair value on a nonrecurring basis		42,065
Level 1 | Nonrecurring
Liabilities:
Assets measured at fair value on a nonrecurring basis	0	0
Level 1 | Nonrecurring | Impaired originated loans
Liabilities:
Assets measured at fair value on a nonrecurring basis	0	0
Level 2 | Nonrecurring
Liabilities:
Assets measured at fair value on a nonrecurring basis	0	0
Level 2 | Nonrecurring | Impaired originated loans
Liabilities:
Assets measured at fair value on a nonrecurring basis	0	0
Level 3 | Nonrecurring
Liabilities:
Assets measured at fair value on a nonrecurring basis	63,572	45,133
Level 3 | Nonrecurring | Impaired originated loans
Liabilities:
Assets measured at fair value on a nonrecurring basis	62,184	42,065
Carrying Amount
Assets:
Nonmarketable equity securities	97,350	36,907
Carrying Amount | Level 1
Assets:
Cash and cash equivalents	474,402	238,789
Carrying Amount | Level 2
Assets:
Held-to-maturity	622,927	509,471
Interest receivable	42,235	21,953
Liabilities:
Deposits without defined maturities	9,862,755	5,809,355
Time deposits	3,010,367	1,647,412
Total deposits	12,873,122	7,456,767
Interest payable	5,415	1,578
Securities sold under agreements to repurchase with customers	343,047	297,199
Short-term borrowings	825,000	100,000
Long-term borrowings	597,847	242,391
Carrying Amount | Level 3
Assets:
Held-to-maturity	500	500
Net loans	12,912,511	7,197,819
Fair Value
Assets:
Nonmarketable equity securities	97,350	36,907
Fair Value | Level 1
Assets:
Cash and cash equivalents	474,402	238,789
Fair Value | Level 2
Assets:
Held-to-maturity	608,221	512,405
Interest receivable	42,235	21,953
Liabilities:
Deposits without defined maturities	9,862,755	5,809,355
Time deposits	3,010,048	1,647,412
Total deposits	12,872,803	7,456,767
Interest payable	5,415	1,578
Securities sold under agreements to repurchase with customers	343,047	297,199
Short-term borrowings	825,000	100,000
Long-term borrowings	591,227	242,391
Fair Value | Level 3
Assets:
Held-to-maturity	310	7,090
Net loans	$ 13,069,315	$ 7,201,994

Investment Securities (Summary

Investment Securities (Summary of Amortized Cost and Fair Value of Available-for-Sale Investment Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Investment Securities Available-for-Sale
Amortized Cost	$ 1,256,721	$ 556,636
Unrealized Gains	1,566	1,468
Unrealized Losses	23,323	4,373
Available-for-sale, at fair value	1,234,964	553,731
U.S. Treasury securities
Investment Securities Available-for-Sale
Amortized Cost	5,788	5,773
Unrealized Gains	5	0
Unrealized Losses	0	8
Available-for-sale, at fair value	5,793	5,765
Government sponsored agencies
Investment Securities Available-for-Sale
Amortized Cost	216,890	195,711
Unrealized Gains	189	78
Unrealized Losses	2,068	800
Available-for-sale, at fair value	215,011	194,989
State and political subdivisions
Investment Securities Available-for-Sale
Amortized Cost	311,704	14,731
Unrealized Gains	163	395
Unrealized Losses	11,779	6
Available-for-sale, at fair value	300,088	15,120
Residential mortgage-backed securities
Investment Securities Available-for-Sale
Amortized Cost	276,162	189,452
Unrealized Gains	112	538
Unrealized Losses	3,992	2,222
Available-for-sale, at fair value	272,282	187,768
Collateralized mortgage obligations
Investment Securities Available-for-Sale
Amortized Cost	323,965	133,256
Unrealized Gains	63	111
Unrealized Losses	4,003	1,137
Available-for-sale, at fair value	320,025	132,230
Corporate bonds
Investment Securities Available-for-Sale
Amortized Cost	90,859	14,825
Unrealized Gains	16	2
Unrealized Losses	1,401	200
Available-for-sale, at fair value	89,474	14,627
Preferred stock and trust preferred securities
Investment Securities Available-for-Sale
Amortized Cost	31,353	2,888
Unrealized Gains	1,018	344
Unrealized Losses	80	0
Available-for-sale, at fair value	$ 32,291	$ 3,232

Investment Securities (Summar83

Investment Securities (Summary of Amortized Cost and Fair Value of Held-to-Maturity Investment Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Investment Securities Held-to-Maturity
Amortized Cost	$ 623,427	$ 509,971
Unrecognized Gains	2,648	7,446
Unrecognized Losses	17,544	4,712
Held-to-maturity, fair value	608,531	512,705
State and political subdivisions
Investment Securities Held-to-Maturity
Amortized Cost	622,927	509,471
Unrecognized Gains	2,648	7,446
Unrecognized Losses	17,354	4,512
Held-to-maturity, fair value	608,221	512,405
Trust preferred securities
Investment Securities Held-to-Maturity
Amortized Cost	500	500
Unrecognized Gains	0	0
Unrecognized Losses	190	200
Held-to-maturity, fair value	$ 310	$ 300

Investment Securities (Gains an

Investment Securities (Gains and (Losses) Recognized in Earnings) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Proceeds	$ 41,446	$ 40,301	$ 0
Gross gains	325	631	0
Gross losses	$ (196)	$ (1)	$ 0

Investment Securities (Summar85

Investment Securities (Summary of the Amortized Cost and Fair Value of Investment Securities by Maturity) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Investment Securities Available-for-Sale: Amortized Cost
Due in one year or less	$ 237,047
Due after one year through five years	490,634
Due after five years through ten years	339,222
Due after ten years	188,429
Preferred stock	1,389
Total	1,256,721
Investment Securities Available-for-Sale: Fair Value
Due in one year or less	235,845
Due after one year through five years	485,221
Due after five years through ten years	329,879
Due after ten years	182,281
Preferred stock	1,738
Total	1,234,964
Investment Securities Held-to-Maturity: Amortized Cost
Due in one year or less	66,090
Due after one year through five years	262,136
Due after five years through ten years	145,225
Due after ten years	149,976
Total	623,427	$ 509,971
Investment Securities Held-to-Maturity: Fair Value
Due in one year or less	65,954
Due after one year through five years	257,936
Due after five years through ten years	139,320
Due after ten years	145,321
Total	$ 608,531	$ 512,705

Investment Securities (Textual)

Investment Securities (Textual) (Details) $ in Millions	Dec. 31, 2016USD ($)security	Dec. 31, 2015USD ($)
Investments, Debt and Equity Securities [Abstract]
Securities pledged as collateral | $	$ 794	$ 530.8
Number of securities in portfolio (in security)	2,504
Number of securities in an unrealized loss position in portfolio (in security)	1,563

Investment Securities (Summar87

Investment Securities (Summary of Investment Securities with Gross Unrealized Losses) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	$ 1,478,240	$ 554,907
Less Than 12 Months, Gross Unrealized Losses	39,116	5,945
12 Months or More, Fair Value	56,897	133,159
12 Months or More, Gross Unrealized Losses	1,751	3,140
Total, Fair Value	1,535,137	688,066
Total, Gross Unrealized Losses	40,867	9,085
U.S. Treasury securities
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value		5,765
Less Than 12 Months, Gross Unrealized Losses		8
12 Months or More, Fair Value		0
12 Months or More, Gross Unrealized Losses		0
Total, Fair Value		5,765
Total, Gross Unrealized Losses		8
Government sponsored agencies
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	105,702	114,640
Less Than 12 Months, Gross Unrealized Losses	1,707	292
12 Months or More, Fair Value	15,023	21,681
12 Months or More, Gross Unrealized Losses	361	508
Total, Fair Value	120,725	136,321
Total, Gross Unrealized Losses	2,068	800
State and political subdivisions
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	758,063	195,285
Less Than 12 Months, Gross Unrealized Losses	28,158	2,891
12 Months or More, Fair Value	26,810	68,361
12 Months or More, Gross Unrealized Losses	975	1,627
Total, Fair Value	784,873	263,646
Total, Gross Unrealized Losses	29,133	4,518
Residential mortgage-backed securities
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	244,239	169,226
Less Than 12 Months, Gross Unrealized Losses	3,992	2,146
12 Months or More, Fair Value	0	3,435
12 Months or More, Gross Unrealized Losses	0	76
Total, Fair Value	244,239	172,661
Total, Gross Unrealized Losses	3,992	2,222
Collateralized mortgage obligations
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	279,001	60,459
Less Than 12 Months, Gross Unrealized Losses	3,778	408
12 Months or More, Fair Value	14,754	39,382
12 Months or More, Gross Unrealized Losses	225	729
Total, Fair Value	293,755	99,841
Total, Gross Unrealized Losses	4,003	1,137
Corporate bonds
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	80,536	9,532
Less Than 12 Months, Gross Unrealized Losses	1,401	200
12 Months or More, Fair Value	0	0
12 Months or More, Gross Unrealized Losses	0	0
Total, Fair Value	80,536	9,532
Total, Gross Unrealized Losses	1,401	200
Trust preferred securities
Summary of continuous unrealized loss position of securities
Less Than 12 Months, Fair Value	10,699	0
Less Than 12 Months, Gross Unrealized Losses	80	0
12 Months or More, Fair Value	310	300
12 Months or More, Gross Unrealized Losses	190	200
Total, Fair Value	11,009	300
Total, Gross Unrealized Losses	$ 270	$ 200

Loans (Textual) (Details)

Loans (Textual) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)loanSegmenttenantdirectoremployee	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of portfolio segment | Segment	2
Number of classes of loans | loan	6
Minimum number of tenants leased to for non-owner occupied real estate | tenant	1
Loans held-for-sale, at fair value	$ 81,830	$ 10,327
Loans held-for-sale, recorded investment sold	707,800	222,600
Nonaccrual TDRs Reported in Nonaccrual Loans	30,500	35,900
Minimum value of loan requires regional loan committee approval	2,000
Maximum value of loan requires regional loan committee approval	$ 5,000
Minimum due period of loans consider in a nonperforming status	90 days
Interest income recognized on nonaccrual loans while in accruing status	$ 400	900	$ 500
Interest lost on nonaccrual loans	2,900	3,200	3,300
Interest income recognized on TDRs	3,900	3,900	3,600
Real estate properties for which formal foreclosure proceedings are in process	7,300
Impaired Loans	93,066	103,111
Residential Mortgage Loans in Process of Foreclosure		2,900
Commitments to lend additional funds to borrowers whose terms have been modified in TDRs	1,500
Management
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to directors, executive officers and affiliates	23,900	21,700
Loans to directors, executive officers and affiliates, current year additions	33,800	33,300
Loans to directors, executive officers and affiliates, current year reductions	31,600	42,800
Fixed-Rate Real Estate Residential Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held-for-sale, at fair value		10,300
Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Loans	62,535	67,178
Total Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	113,446	120,183	116,119
Impaired Financing Receivable, Interest Income, Accrual Method	$ 3,886	3,889	3,558
Land Development Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Maximum period for payment of loan	12 months
Commercial Loan | Total Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	$ 37,388	37,289	35,012
Impaired Financing Receivable, Interest Income, Accrual Method	$ 1,343	1,005	961
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Period for loan secured under real estate residential security	15 years
Loan-to-value ratio at the time of origination	80.00%
Residential mortgage | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Upper limit of number of family residential properties | tenant	4
Residential mortgage | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Lower limit of number of family residential properties | tenant	1
Residential mortgage | Total Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Financing Receivable, Average Recorded Investment	$ 25,477	26,688	26,523
Impaired Financing Receivable, Interest Income, Accrual Method	$ 1,285	1,312	$ 1,252
Commercial Loan Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum due period of loans consider in a nonperforming status	90 days
Consumer Loan Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Original contractual terms	90 days
Minimum due period of loans consider in a nonperforming status	90 days
Commercial Loan Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Loans	$ 70,785	78,823
Commercial Loan Portfolio | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired Loans	45,388	$ 46,141
Commercial Loan Portfolio | Commercial Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum value of loan requires group loan authority approval	$ 2,000
Number of bank executives and senior officers with credit decision limits similar to group loan authorities | employee	6
Minimum value of loan requires executive and senior officer approval	$ 2,000
Maximum value of loan requires executive and senior officer approval	3,500
Minimum value of loan requires group loan authority approval	5,000
Maximum value of loan requires group loan authority approval	$ 10,000
Number of members of the board of directors in loan committee | director	8
Commercial Loan Portfolio | Commercial Loan | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other loans requiring director loan committee approval depending on risk rating and credit action required	$ 10,000
Commercial Loan Portfolio | Commercial Loan | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum value of loan requiring director loan committee approval	10,000
Minimum value of loans requiring board of directors approval	$ 25,000

Loans (Summary of Loans) (Detai

Loans (Summary of Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Summary of loans under portfolio
Loans	$ 12,990,779	$ 7,271,147
Deferred costs	14,800	10,700
Commercial
Summary of loans under portfolio
Loans		1,905,879
Commercial real estate
Summary of loans under portfolio
Loans		2,112,162
Real estate construction and land development
Summary of loans under portfolio
Loans		232,076
Residential mortgage
Summary of loans under portfolio
Loans		1,429,636
Consumer installment
Summary of loans under portfolio
Loans		877,457
Home equity
Summary of loans under portfolio
Loans		713,937
Commercial Originated Portfolio
Summary of loans under portfolio
Loans	4,105,049	3,130,721
Commercial Originated Portfolio | Commercial
Summary of loans under portfolio
Loans	1,901,526	1,521,515
Commercial Originated Portfolio | Commercial real estate
Summary of loans under portfolio
Loans	1,921,799	1,424,059
Commercial Originated Portfolio | Real estate construction and land development
Summary of loans under portfolio
Loans	281,724	185,147
Consumer Originated Portfolio
Summary of loans under portfolio
Loans	3,353,352	2,677,213
Consumer Originated Portfolio | Residential mortgage
Summary of loans under portfolio
Loans	1,475,342	1,216,975
Consumer Originated Portfolio | Consumer installment
Summary of loans under portfolio
Loans	1,282,588	869,426
Consumer Originated Portfolio | Home equity
Summary of loans under portfolio
Loans	595,422	590,812
Originated Portfolio
Summary of loans under portfolio
Loans	7,458,401	5,807,934
Originated Portfolio | Commercial
Summary of loans under portfolio
Loans	1,901,526	1,521,515
Originated Portfolio | Commercial real estate
Summary of loans under portfolio
Loans	1,921,799	1,424,059
Originated Portfolio | Real estate construction and land development
Summary of loans under portfolio
Loans	281,724	185,147
Originated Portfolio | Residential mortgage
Summary of loans under portfolio
Loans	1,475,342	1,216,975
Originated Portfolio | Consumer installment
Summary of loans under portfolio
Loans	1,282,588	869,426
Originated Portfolio | Home equity
Summary of loans under portfolio
Loans	595,422	590,812
Commercial Acquired Portfolio
Summary of loans under portfolio
Loans	3,489,163	1,119,396
Commercial Acquired Portfolio | Commercial
Summary of loans under portfolio
Loans	1,315,774	384,364
Commercial Acquired Portfolio | Commercial real estate
Summary of loans under portfolio
Loans	2,051,341	688,103
Commercial Acquired Portfolio | Real estate construction and land development
Summary of loans under portfolio
Loans	122,048	46,929
Consumer Acquired Portfolio
Summary of loans under portfolio
Loans	2,043,215	343,817
Consumer Acquired Portfolio | Residential mortgage
Summary of loans under portfolio
Loans	1,611,132	212,661
Consumer Acquired Portfolio | Consumer installment
Summary of loans under portfolio
Loans	151,296	8,031
Consumer Acquired Portfolio | Home equity
Summary of loans under portfolio
Loans	280,787	123,125
Acquired Portfolio
Summary of loans under portfolio
Loans	5,532,378	1,463,213
Commercial Loan Portfolio
Summary of loans under portfolio
Loans	7,594,212	4,250,117
Commercial Loan Portfolio | Commercial
Summary of loans under portfolio
Loans	3,217,300
Commercial Loan Portfolio | Commercial real estate
Summary of loans under portfolio
Loans	3,973,140
Commercial Loan Portfolio | Real estate construction and land development
Summary of loans under portfolio
Loans	403,772
Consumer Loan Portfolio
Summary of loans under portfolio
Loans	5,396,567	3,021,030
Consumer Loan Portfolio | Residential mortgage
Summary of loans under portfolio
Loans	3,086,474	1,429,636
Consumer Loan Portfolio | Consumer installment
Summary of loans under portfolio
Loans	1,433,884	877,457
Consumer Loan Portfolio | Home equity
Summary of loans under portfolio
Loans	$ 876,209	$ 713,937

Loans (Summary of Recorded Inve

Loans (Summary of Recorded Investment of Commercial Loans by Risk Rating Categories) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 12,990,779	$ 7,271,147
Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans		1,905,879
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans		2,112,162
Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans		232,076
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	7,594,212	4,250,117
Commercial Portfolio Segment [Member] | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	7,167,397	3,954,721
Commercial Portfolio Segment [Member] | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	192,013	120,746
Commercial Portfolio Segment [Member] | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	233,479	172,555
Commercial Portfolio Segment [Member] | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	1,323	2,095
Commercial Portfolio Segment [Member] | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	3,217,300
Commercial Portfolio Segment [Member] | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans	3,973,140
Commercial Portfolio Segment [Member] | Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans	403,772
Commercial Originated Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	4,105,049	3,130,721
Commercial Originated Portfolio | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	3,934,033	2,942,826
Commercial Originated Portfolio | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	81,947	65,943
Commercial Originated Portfolio | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	87,999	119,857
Commercial Originated Portfolio | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	1,070	2,095
Commercial Originated Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	1,901,526	1,521,515
Commercial Originated Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,803,750	1,418,301
Commercial Originated Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	44,809	34,727
Commercial Originated Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	51,898	66,392
Commercial Originated Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	1,069	2,095
Commercial Originated Portfolio | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans	1,921,799	1,424,059
Commercial Originated Portfolio | Commercial real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,849,315	1,341,202
Commercial Originated Portfolio | Commercial real estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	36,981	31,036
Commercial Originated Portfolio | Commercial real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	35,502	51,821
Commercial Originated Portfolio | Commercial real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	1	0
Commercial Originated Portfolio | Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans	281,724	185,147
Commercial Originated Portfolio | Real estate construction and land development | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	280,968	183,323
Commercial Originated Portfolio | Real estate construction and land development | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	157	180
Commercial Originated Portfolio | Real estate construction and land development | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	599	1,644
Commercial Originated Portfolio | Real estate construction and land development | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Commercial Acquired Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	3,489,163	1,119,396
Commercial Acquired Portfolio | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	3,233,364	1,011,895
Commercial Acquired Portfolio | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	110,066	54,803
Commercial Acquired Portfolio | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	145,480	52,698
Commercial Acquired Portfolio | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	253	0
Commercial Acquired Portfolio | Commercial
Financing Receivable, Recorded Investment [Line Items]
Loans	1,315,774	384,364
Commercial Acquired Portfolio | Commercial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,218,848	340,782
Commercial Acquired Portfolio | Commercial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	46,643	28,321
Commercial Acquired Portfolio | Commercial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	50,283	15,261
Commercial Acquired Portfolio | Commercial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Commercial Acquired Portfolio | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Loans	2,051,341	688,103
Commercial Acquired Portfolio | Commercial real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	1,897,011	629,430
Commercial Acquired Portfolio | Commercial real estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	61,441	23,926
Commercial Acquired Portfolio | Commercial real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	92,636	34,747
Commercial Acquired Portfolio | Commercial real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	253	0
Commercial Acquired Portfolio | Real estate construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans	122,048	46,929
Commercial Acquired Portfolio | Real estate construction and land development | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans	117,505	41,683
Commercial Acquired Portfolio | Real estate construction and land development | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans	1,982	2,556
Commercial Acquired Portfolio | Real estate construction and land development | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans	2,561	2,690
Commercial Acquired Portfolio | Real estate construction and land development | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 0	$ 0

Loans (Summary of Recorded In91

Loans (Summary of Recorded Investment of Consumer Loans by Risk Rating Categories) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 12,990,779	$ 7,271,147
Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans		1,429,636
Consumer installment
Financing Receivable, Recorded Investment [Line Items]
Loans		877,457
Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans		713,937
Consumer Loan Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	5,396,567	3,021,030
Consumer Loan Portfolio | Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans	3,086,474	1,429,636
Consumer Loan Portfolio | Consumer installment
Financing Receivable, Recorded Investment [Line Items]
Loans	1,433,884	877,457
Consumer Loan Portfolio | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	876,209	713,937
Consumer Originated Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	3,353,352	2,677,213
Consumer Originated Portfolio | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	3,342,153	2,669,226
Consumer Originated Portfolio | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans	11,199	7,987
Consumer Originated Portfolio | Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans	1,475,342	1,216,975
Consumer Originated Portfolio | Residential mortgage | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	1,468,373	1,211,418
Consumer Originated Portfolio | Residential mortgage | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans	6,969	5,557
Consumer Originated Portfolio | Consumer installment
Financing Receivable, Recorded Investment [Line Items]
Loans	1,282,588	869,426
Consumer Originated Portfolio | Consumer installment | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	1,281,709	868,975
Consumer Originated Portfolio | Consumer installment | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans	879	451
Consumer Originated Portfolio | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	595,422	590,812
Consumer Originated Portfolio | Home equity | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	592,071	588,833
Consumer Originated Portfolio | Home equity | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans	3,351	1,979
Consumer Acquired Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	2,043,215	343,817
Consumer Acquired Portfolio | Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans	1,611,132	212,661
Consumer Acquired Portfolio | Consumer installment
Financing Receivable, Recorded Investment [Line Items]
Loans	151,296	8,031
Consumer Acquired Portfolio | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 280,787	$ 123,125

Loans (Summary of Nonperforming

Loans (Summary of Nonperforming Loans) (Details) - Nonperforming - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Summary of nonperforming loans
Total nonaccrual loans	$ 44,334	$ 62,225
Other real estate owned and repossessed assets	17,187	9,935
Total nonperforming assets	61,521	72,160
Total accruing loans contractually past due 90 days or more as to interest or principal payments	1,283	2,287
Commercial Loan Portfolio | Commercial
Summary of nonperforming loans
Total nonaccrual loans	13,178	28,554
Total accruing loans contractually past due 90 days or more as to interest or principal payments	11	364
Commercial Loan Portfolio | Commercial real estate
Summary of nonperforming loans
Total nonaccrual loans	19,877	25,163
Total accruing loans contractually past due 90 days or more as to interest or principal payments	277	254
Commercial Loan Portfolio | Real estate construction and land development
Summary of nonperforming loans
Total nonaccrual loans	80	521
Consumer Loan Portfolio | Residential mortgage
Summary of nonperforming loans
Total nonaccrual loans	6,969	5,557
Total accruing loans contractually past due 90 days or more as to interest or principal payments	0	402
Consumer Loan Portfolio | Consumer installment
Summary of nonperforming loans
Total nonaccrual loans	879	451
Consumer Loan Portfolio | Home equity
Summary of nonperforming loans
Total nonaccrual loans	3,351	1,979
Total accruing loans contractually past due 90 days or more as to interest or principal payments	$ 995	$ 1,267

Loans (Summary of the Aging Sta

Loans (Summary of the Aging Status of the Recorded Investment in Loans by Portfolio Segment/Class) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule representing the aging status of the recorded investment in loans by classes
Total loans	$ 12,990,779	$ 7,271,147
Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Total loans		1,905,879
Commercial real estate
Schedule representing the aging status of the recorded investment in loans by classes
Total loans		2,112,162
Real estate construction and land development
Schedule representing the aging status of the recorded investment in loans by classes
Total loans		232,076
Residential mortgage
Schedule representing the aging status of the recorded investment in loans by classes
Total loans		1,429,636
Consumer installment
Schedule representing the aging status of the recorded investment in loans by classes
Total loans		877,457
Home equity
Schedule representing the aging status of the recorded investment in loans by classes
Total loans		713,937
Originated Portfolio
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	51,633	42,643
Current	7,406,768	5,765,291
Total loans	7,458,401	5,807,934
Financing receivable, recorded investment accruing loans past due 90 days or more	1,283	2,287
Originated Portfolio | 30-59 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	29,928	29,827
Originated Portfolio | 60-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	8,560	10,529
Originated Portfolio | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	13,145	2,287
Originated Portfolio | Commercial
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	18,904	15,000
Current	1,882,622	1,506,515
Total loans	1,901,526	1,521,515
Financing receivable, recorded investment accruing loans past due 90 days or more	11	364
Originated Portfolio | Commercial | 30-59 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	10,421	9,393
Originated Portfolio | Commercial | 60-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	4,842	5,243
Originated Portfolio | Commercial | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	3,641	364
Originated Portfolio | Commercial real estate
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	13,305	9,457
Current	1,908,494	1,414,602
Total loans	1,921,799	1,424,059
Financing receivable, recorded investment accruing loans past due 90 days or more	277	254
Originated Portfolio | Commercial real estate | 30-59 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	6,551	6,941
Originated Portfolio | Commercial real estate | 60-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	1,589	2,262
Originated Portfolio | Commercial real estate | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	5,165	254
Originated Portfolio | Real estate construction and land development
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	3,220	596
Current	278,504	184,551
Total loans	281,724	185,147
Financing receivable, recorded investment accruing loans past due 90 days or more	0	0
Originated Portfolio | Real estate construction and land development | 30-59 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	2,721	596
Originated Portfolio | Real estate construction and land development | 60-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	499	0
Originated Portfolio | Real estate construction and land development | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	0	0
Originated Portfolio | Residential mortgage
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	4,961	9,047
Current	1,470,381	1,207,928
Total loans	1,475,342	1,216,975
Financing receivable, recorded investment accruing loans past due 90 days or more	0	402
Originated Portfolio | Residential mortgage | 30-59 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	3,147	7,475
Originated Portfolio | Residential mortgage | 60-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	62	1,170
Originated Portfolio | Residential mortgage | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	1,752	402
Originated Portfolio | Consumer installment
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	4,904	4,088
Current	1,277,684	865,338
Total loans	1,282,588	869,426
Financing receivable, recorded investment accruing loans past due 90 days or more	0	0
Originated Portfolio | Consumer installment | 30-59 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	3,991	3,347
Originated Portfolio | Consumer installment | 60-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	675	741
Originated Portfolio | Consumer installment | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	238	0
Originated Portfolio | Home equity
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	6,339	4,455
Current	589,083	586,357
Total loans	595,422	590,812
Financing receivable, recorded investment accruing loans past due 90 days or more	995	1,267
Originated Portfolio | Home equity | 30-59 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	3,097	2,075
Originated Portfolio | Home equity | 60-89 days past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	893	1,113
Originated Portfolio | Home equity | 90 days or more past due
Schedule representing the aging status of the recorded investment in loans by classes
Total past due	$ 2,349	$ 1,267

Loans (Summary of Impaired Loan

Loans (Summary of Impaired Loans by Classes of Loans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Impaired loans with a valuation allowance
Schedule of Impaired loans by classes
Recorded Investment	$ 71,284	$ 44,383
Unpaid Principal Balance	81,808	45,151
Related Valuation Allowance	8,762	6,389
Average Annual Recorded Investment	37,464	33,090	$ 25,556
Interest Income Recognized While on Impaired Status	1,285	1,312	1,252
Impaired loans with no valuation allowance
Schedule of Impaired loans by classes
Recorded Investment	32,129	85,020
Unpaid Principal Balance	38,794	101,393
Related Valuation Allowance	0	0
Average Annual Recorded Investment	73,864	87,093	90,563
Interest Income Recognized While on Impaired Status	2,601	2,577	2,306
Total Impaired Loans
Schedule of Impaired loans by classes
Recorded Investment	106,869	129,403
Unpaid Principal Balance	124,058	146,544
Related Valuation Allowance	8,762	6,389
Average Annual Recorded Investment	113,446	120,183	116,119
Interest Income Recognized While on Impaired Status	3,886	3,889	3,558
Commercial Loan | Impaired loans with a valuation allowance
Schedule of Impaired loans by classes
Recorded Investment	28,925	18,898
Unpaid Principal Balance	33,209	19,426
Related Valuation Allowance	3,128	5,700
Average Annual Recorded Investment	7,829	9,511	2,117
Interest Income Recognized While on Impaired Status	0	0	0
Commercial Loan | Impaired loans with no valuation allowance
Schedule of Impaired loans by classes
Recorded Investment	7,435	27,304
Unpaid Principal Balance	11,153	32,395
Related Valuation Allowance	0	0
Average Annual Recorded Investment	29,559	27,778	32,895
Interest Income Recognized While on Impaired Status	1,343	1,005	961
Commercial Loan | Total Impaired Loans
Schedule of Impaired loans by classes
Recorded Investment	36,360	46,202
Unpaid Principal Balance	44,362	51,821
Related Valuation Allowance	3,128	5,700
Average Annual Recorded Investment	37,388	37,289	35,012
Interest Income Recognized While on Impaired Status	1,343	1,005	961
Commercial real estate | Impaired loans with a valuation allowance
Schedule of Impaired loans by classes
Recorded Investment	21,318	4,448
Unpaid Principal Balance	27,558	4,688
Related Valuation Allowance	2,102	497
Average Annual Recorded Investment	5,658	2,918	3,699
Interest Income Recognized While on Impaired Status	0	0	0
Commercial real estate | Impaired loans with no valuation allowance
Schedule of Impaired loans by classes
Recorded Investment	20,588	48,747
Unpaid Principal Balance	23,535	59,949
Related Valuation Allowance	0	0
Average Annual Recorded Investment	41,646	50,079	46,344
Interest Income Recognized While on Impaired Status	1,236	1,547	1,342
Commercial real estate | Total Impaired Loans
Schedule of Impaired loans by classes
Recorded Investment	41,906	53,195
Unpaid Principal Balance	51,093	64,637
Related Valuation Allowance	2,102	497
Average Annual Recorded Investment	47,304	52,997	50,043
Interest Income Recognized While on Impaired Status	1,236	1,547	1,342
Real estate construction and land development | Impaired loans with a valuation allowance
Schedule of Impaired loans by classes
Recorded Investment	177
Unpaid Principal Balance	177
Related Valuation Allowance	4
Average Annual Recorded Investment	19	0	0
Interest Income Recognized While on Impaired Status	0	0	0
Real estate construction and land development | Impaired loans with no valuation allowance
Schedule of Impaired loans by classes
Recorded Investment	80	982
Unpaid Principal Balance	80	1,062
Related Valuation Allowance	0	0
Average Annual Recorded Investment	585	889	1,831
Interest Income Recognized While on Impaired Status	22	25	3
Real estate construction and land development | Total Impaired Loans
Schedule of Impaired loans by classes
Recorded Investment	257	982
Unpaid Principal Balance	257	1,062
Related Valuation Allowance	4	0
Average Annual Recorded Investment	604	889	1,831
Interest Income Recognized While on Impaired Status	22	25	3
Residential mortgage | Impaired loans with a valuation allowance
Schedule of Impaired loans by classes
Recorded Investment	20,864	21,037
Unpaid Principal Balance	20,864	21,037
Related Valuation Allowance	3,528	192
Average Annual Recorded Investment	23,958	20,661	19,740
Interest Income Recognized While on Impaired Status	1,285	1,312	1,252
Residential mortgage | Impaired loans with no valuation allowance
Schedule of Impaired loans by classes
Recorded Investment	3,252	5,557
Unpaid Principal Balance	3,252	5,557
Related Valuation Allowance	0	0
Average Annual Recorded Investment	1,519	6,027	6,783
Interest Income Recognized While on Impaired Status	0	0	0
Residential mortgage | Total Impaired Loans
Schedule of Impaired loans by classes
Recorded Investment	24,116	26,594
Unpaid Principal Balance	24,116	26,594
Related Valuation Allowance	3,528	192
Average Annual Recorded Investment	25,477	26,688	26,523
Interest Income Recognized While on Impaired Status	1,285	1,312	1,252
Consumer installment | Impaired loans with a valuation allowance
Schedule of Impaired loans by classes
Recorded Investment	879
Unpaid Principal Balance	879
Related Valuation Allowance	240
Average Annual Recorded Investment	359	0	0
Interest Income Recognized While on Impaired Status	0	0	0
Consumer installment | Impaired loans with no valuation allowance
Schedule of Impaired loans by classes
Recorded Investment	0	451
Unpaid Principal Balance	0	451
Related Valuation Allowance	0	0
Average Annual Recorded Investment	0	448	592
Interest Income Recognized While on Impaired Status	0	0	0
Consumer installment | Total Impaired Loans
Schedule of Impaired loans by classes
Recorded Investment	879	451
Unpaid Principal Balance	879	451
Related Valuation Allowance	0	0
Average Annual Recorded Investment	359	448	592
Interest Income Recognized While on Impaired Status	0	0	0
Home equity | Impaired loans with a valuation allowance
Schedule of Impaired loans by classes
Recorded Investment	2,577
Unpaid Principal Balance	2,577
Related Valuation Allowance	390
Average Annual Recorded Investment	1,759	0	0
Interest Income Recognized While on Impaired Status	0	0	0
Home equity | Impaired loans with no valuation allowance
Schedule of Impaired loans by classes
Recorded Investment	774	1,979
Unpaid Principal Balance	774	1,979
Related Valuation Allowance	0	0
Average Annual Recorded Investment	555	1,872	2,118
Interest Income Recognized While on Impaired Status	0	0	0
Home equity | Total Impaired Loans
Schedule of Impaired loans by classes
Recorded Investment	3,351	1,979
Unpaid Principal Balance	3,351	1,979
Related Valuation Allowance	0	0
Average Annual Recorded Investment	2,314	1,872	2,118
Interest Income Recognized While on Impaired Status	$ 0	$ 0	$ 0

Loans (Summary of Loan Modifica

Loans (Summary of Loan Modifications by Concession Type) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)loan	Dec. 31, 2015USD ($)loan	Dec. 31, 2014USD ($)loan
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	98	142	219
Pre- modification recorded investment	$ 20,819	$ 22,596	$ 30,112
Post- modification recorded investment	20,819	22,594	30,086
Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	15,269	15,206	26,452
Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	3,393	450	266
A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	43	0	334
Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	364	900	2,720
Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 1,750	$ 6,038	$ 314
Commercial Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	70	77	100
Pre- modification recorded investment	$ 19,712	$ 19,347	$ 25,928
Post- modification recorded investment	19,712	19,347	25,928
Commercial Loan Portfolio | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	14,526	12,640	23,442
Commercial Loan Portfolio | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	3,393	450	266
Commercial Loan Portfolio | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	43	0	334
Commercial Loan Portfolio | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	219	1,572
Commercial Loan Portfolio | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 1,750	$ 6,038	$ 314
Commercial Loan Portfolio | Commercial
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	54	53	53
Pre- modification recorded investment	$ 14,853	$ 11,446	$ 13,781
Post- modification recorded investment	14,853	11,446	13,781
Commercial Loan Portfolio | Commercial | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	11,533	6,031	12,657
Commercial Loan Portfolio | Commercial | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	1,527	0	112
Commercial Loan Portfolio | Commercial | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	43	0	111
Commercial Loan Portfolio | Commercial | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	117	901
Commercial Loan Portfolio | Commercial | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 1,750	$ 5,298	$ 0
Commercial Loan Portfolio | Commercial real estate
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	16	21	46
Pre- modification recorded investment	$ 4,859	$ 7,196	$ 12,075
Post- modification recorded investment	4,859	7,196	12,075
Commercial Loan Portfolio | Commercial real estate | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	2,993	5,904	10,713
Commercial Loan Portfolio | Commercial real estate | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	1,866	450	154
Commercial Loan Portfolio | Commercial real estate | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	0	223
Commercial Loan Portfolio | Commercial real estate | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	102	671
Commercial Loan Portfolio | Commercial real estate | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 0	$ 740	$ 314
Commercial Loan Portfolio | Real estate construction and land development
Financing Receivable, Modifications [Line Items]
Total number of loans | loan		3	1
Pre- modification recorded investment		$ 705	$ 72
Post- modification recorded investment		705	72
Commercial Loan Portfolio | Real estate construction and land development | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment		705	72
Commercial Loan Portfolio | Real estate construction and land development | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment		0	0
Commercial Loan Portfolio | Real estate construction and land development | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment		0	0
Commercial Loan Portfolio | Real estate construction and land development | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment		0	0
Commercial Loan Portfolio | Real estate construction and land development | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment		$ 0	$ 0
Consumer Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	28	65	119
Pre- modification recorded investment	$ 1,107	$ 3,249	$ 4,184
Post- modification recorded investment	1,107	3,247	4,158
Consumer Loan Portfolio | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	743	2,566	3,010
Consumer Loan Portfolio | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	0	0
Consumer Loan Portfolio | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	0	0
Consumer Loan Portfolio | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	364	681	1,148
Consumer Loan Portfolio | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 0	$ 0	$ 0
Consumer Loan Portfolio | Residential mortgage
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	4	20	36
Pre- modification recorded investment	$ 477	$ 1,881	$ 2,847
Post- modification recorded investment	477	1,881	2,823
Consumer Loan Portfolio | Residential mortgage | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	477	1,246	1,832
Consumer Loan Portfolio | Residential mortgage | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	0	0
Consumer Loan Portfolio | Residential mortgage | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	0	0
Consumer Loan Portfolio | Residential mortgage | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	635	991
Consumer Loan Portfolio | Residential mortgage | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 0	$ 0	$ 0
Consumer Loan Portfolio | Consumer installment
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	14	19	52
Pre- modification recorded investment	$ 87	$ 210	$ 572
Post- modification recorded investment	87	210	572
Consumer Loan Portfolio | Consumer installment | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	87	210	572
Consumer Loan Portfolio | Consumer installment | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	0	0
Consumer Loan Portfolio | Consumer installment | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	0	0
Consumer Loan Portfolio | Consumer installment | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	0	0
Consumer Loan Portfolio | Consumer installment | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 0	$ 0	$ 0
Consumer Loan Portfolio | Home equity
Financing Receivable, Modifications [Line Items]
Total number of loans | loan	10	26	31
Pre- modification recorded investment	$ 543	$ 1,158	$ 765
Post- modification recorded investment	543	1,156	763
Consumer Loan Portfolio | Home equity | Principal deferral
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	179	1,110	606
Consumer Loan Portfolio | Home equity | Principal reduction
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	0	0
Consumer Loan Portfolio | Home equity | A/B Note Restructure
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	0	0	0
Consumer Loan Portfolio | Home equity | Interest rate
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	364	46	157
Consumer Loan Portfolio | Home equity | Forbearance agreement
Financing Receivable, Modifications [Line Items]
Post- modification recorded investment	$ 0	$ 0	$ 0

Loans (Summary of TDRs) (Detail

Loans (Summary of TDRs) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Modifications [Line Items]
Total TDRs	$ 93,066	$ 103,111
Commercial Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total TDRs	70,785	78,823
Consumer Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total TDRs	22,281	24,288
Accruing TDRs
Financing Receivable, Modifications [Line Items]
Total TDRs	62,535	67,178
Accruing TDRs | Commercial Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total TDRs	45,388	46,141
Accruing TDRs | Consumer Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total TDRs	17,147	21,037
Nonaccrual TDRs
Financing Receivable, Modifications [Line Items]
Total TDRs	30,531	35,933
Nonaccrual TDRs | Commercial Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total TDRs	25,397	32,682
Nonaccrual TDRs | Consumer Loan Portfolio
Financing Receivable, Modifications [Line Items]
Total TDRs	$ 5,134	$ 3,251

Loans (Summary of TDRs with a P

Loans (Summary of TDRs with a Payment Default During the Period) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)loan	Dec. 31, 2015USD ($)loan	Dec. 31, 2014USD ($)loan
Troubled debt restructurings on financing receivables with defaults payment
Number of loans (in loan) | loan	16	9	25
Principal balance at year end | $	$ 1,980	$ 2,287	$ 3,496
Commercial Loan Portfolio
Troubled debt restructurings on financing receivables with defaults payment
Number of loans (in loan) | loan	2	6	13
Principal balance at year end | $	$ 1,721	$ 2,222	$ 3,237
Consumer Loan Portfolio
Troubled debt restructurings on financing receivables with defaults payment
Number of loans (in loan) | loan	14	3	12
Principal balance at year end | $	$ 259	$ 65	$ 259
Commercial | Commercial Loan Portfolio
Troubled debt restructurings on financing receivables with defaults payment
Number of loans (in loan) | loan	0	1	7
Principal balance at year end | $	$ 0	$ 1,206	$ 885
Commercial real estate | Commercial Loan Portfolio
Troubled debt restructurings on financing receivables with defaults payment
Number of loans (in loan) | loan	2	5	6
Principal balance at year end | $	$ 1,721	$ 1,016	$ 2,352

Loans (Schedule of the Allowanc

Loans (Schedule of the Allowance for Loan Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	$ 73,328	$ 75,683	$ 79,072
Provision (benefit) for loan losses	14,875	6,500	6,100
Charge-offs	(15,302)	(13,501)	(14,229)
Recoveries	5,367	4,646	4,740
Ending balance	78,268	73,328	75,683
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses				$ 8,762	$ 6,389
Loans collectively evaluated for impairment related to allowance for loan losses				69,506	66,939
Total	73,328	75,683	79,072	78,268	73,328
Loans individually evaluated for impairment related to recorded investment (loan balance)				106,869	129,403
Loans collectively evaluated for impairment related to recorded investment (loan balance)				7,351,532	5,678,531
Total loans				12,990,779	7,271,147
Commercial Loan Portfolio
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	47,234	44,156	44,482
Provision (benefit) for loan losses	9,788	7,275	3,464
Charge-offs	(8,906)	(6,385)	(6,399)
Recoveries	3,085	2,188	2,609
Ending balance	51,201	47,234	44,156
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses				5,234	6,197
Loans collectively evaluated for impairment related to allowance for loan losses				45,967	41,037
Total	47,234	44,156	44,482	51,201	47,234
Loans individually evaluated for impairment related to recorded investment (loan balance)				78,523	100,379
Loans collectively evaluated for impairment related to recorded investment (loan balance)				4,026,526	3,030,342
Total loans				7,594,212	4,250,117
Consumer Loan Portfolio
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	26,094	28,803	30,145
Provision (benefit) for loan losses	5,087	1,949	4,357
Charge-offs	(6,396)	(7,116)	(7,830)
Recoveries	2,282	2,458	2,131
Ending balance	27,067	26,094	28,803
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses				3,528	192
Loans collectively evaluated for impairment related to allowance for loan losses				23,539	25,902
Total	26,094	28,803	30,145	27,067	26,094
Loans individually evaluated for impairment related to recorded investment (loan balance)				28,346	29,024
Loans collectively evaluated for impairment related to recorded investment (loan balance)				3,325,006	2,648,189
Total loans				5,396,567	3,021,030
Unallocated
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	0	2,724	4,445
Provision (benefit) for loan losses	0	(2,724)	(1,721)
Charge-offs	0	0	0
Recoveries	0	0	0
Ending balance	0	0	2,724
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses				0	0
Loans collectively evaluated for impairment related to allowance for loan losses				0	0
Total	$ 0	$ 2,724	$ 4,445	0	0
Loans individually evaluated for impairment related to recorded investment (loan balance)				0	0
Loans collectively evaluated for impairment related to recorded investment (loan balance)				0	0
Total loans				0	0
Receivables Acquired with Deteriorated Credit Quality
Allowance for loan losses
Allowance for loan losses related to loans acquired with deteriorated credit quality				0	0
Loans acquired with deteriorated credit quality related to recorded investment (loan balance)				5,532,378	1,463,213
Receivables Acquired with Deteriorated Credit Quality | Commercial Loan Portfolio
Allowance for loan losses
Allowance for loan losses related to loans acquired with deteriorated credit quality				0	0
Loans acquired with deteriorated credit quality related to recorded investment (loan balance)				3,489,163	1,119,396
Receivables Acquired with Deteriorated Credit Quality | Consumer Loan Portfolio
Allowance for loan losses
Allowance for loan losses related to loans acquired with deteriorated credit quality				0	0
Loans acquired with deteriorated credit quality related to recorded investment (loan balance)				2,043,215	343,817
Receivables Acquired with Deteriorated Credit Quality | Unallocated
Allowance for loan losses
Allowance for loan losses related to loans acquired with deteriorated credit quality				0	0
Loans acquired with deteriorated credit quality related to recorded investment (loan balance)				$ 0	$ 0

Premises and Equipment (Details

Premises and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 272,303	$ 226,699
Less accumulated depreciation	(127,291)	(120,382)
Premises and equipment, net	145,012	106,317
Net rent expense under operating leases	3,300	1,700	$ 1,200
Closed branch offices transferred to other assets	4,846	2,692	$ 841
Land and land improvements
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	36,185	28,447
Buildings
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	144,155	120,370
Furniture and equipment
Property, Plant and Equipment [Line Items]
Total premises and equipment, gross	$ 91,963	$ 77,882

Other Real Estate Owned and 100

Other Real Estate Owned and Repossessed Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Changes in other real estate owned
Balance at the beginning of the period	$ 9,716	$ 13,953	$ 9,518
Additions due to acquisitions	13,227	440	3,721
Other additions	9,938	6,957	8,986
Net payments received	(1,560)	(45)	(264)
Disposals	(13,873)	(10,168)	(7,360)
Write-downs	(636)	(1,421)	(648)
Balance at the end of the period	16,812	9,716	13,953
Changes in repossessed assets
Balance at the beginning of the period	219	252	258
Additions due to acquisitions	313	0	0
Other additions	3,032	2,372	2,322
Net payments received	(763)	(22)	(30)
Disposals	(2,426)	(2,383)	(2,298)
Write-downs	0	0	0
Balance at the end of the period	$ 375	$ 219	$ 252

Other Real Estate Owned and 101

Other Real Estate Owned and Repossessed Assets (Textuals) (Details) $ in Millions	Dec. 31, 2016USD ($)
Other Real Estate [Abstract]
Other real estate owned and repossessed assets acquired in accordance with ASU 2014-04	$ 1
Real estate properties for which formal foreclosure proceedings are in process	$ 7.3

Other Real Estate Owned and 102

Other Real Estate Owned and Repossessed Assets (Income and Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income and expenses related to other real estate owned
Net gain (loss) on sale	$ 5,325	$ 4,128	$ 2,545
Write-downs	(636)	(1,421)	(648)
Net operating expenses	(740)	(1,604)	(1,242)
Total	3,949	1,103	655
Income and expenses related to repossessed assets
Net gain (loss) on sale	523	(26)	(11)
Write-downs	0	0	0
Net operating expenses	(60)	(19)	(53)
Total	$ 463	$ (45)	$ (64)

Goodwill (Details)

Goodwill (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Aug. 31, 2016	May 31, 2015	Apr. 01, 2015
Goodwill [Line Items]
Goodwill		$ 1,133,534,000	$ 287,393,000
Goodwill impairment		0	0
Talmer
Goodwill [Line Items]
Goodwill				$ 846,667,000
Goodwill acquired during period		$ 846,700,000
Lake Michigan
Goodwill [Line Items]
Goodwill			101,061,000		$ 101,061,000
Goodwill acquired during period	$ 600,000
Monarch
Goodwill [Line Items]
Goodwill			$ 5,339,000			$ 5,339,000

Loan Servicing Rights (LSRs Act

Loan Servicing Rights (LSRs Activity) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Activity for loan servicing rights and the related fair value changes
Fair value, beginning of period	$ 0
Acquired in Talmer Bancorp, Inc. merger	42,462
Additions from loans sold with servicing retained	1,030
Changes in fair value due to reductions from pay downs	(519)
Changes in estimates of fair value	5,112
Fair value, end of period	48,085
Principal balance of loans serviced for others that have servicing capitalized	5,300,171
Commercial real estate
Activity for loan servicing rights and the related fair value changes
Fair value, beginning of period	0
Acquired in Talmer Bancorp, Inc. merger	365
Additions from loans sold with servicing retained	0
Changes in fair value due to reductions from pay downs	(17)
Changes in estimates of fair value	(4)
Fair value, end of period	344
Principal balance of loans serviced for others that have servicing capitalized	64,756
Residential mortgage
Activity for loan servicing rights and the related fair value changes
Fair value, beginning of period	0
Acquired in Talmer Bancorp, Inc. merger	42,097
Additions from loans sold with servicing retained	1,030
Changes in fair value due to reductions from pay downs	(502)
Changes in estimates of fair value	5,116
Fair value, end of period	47,741
Principal balance of loans serviced for others that have servicing capitalized	$ 5,235,415

Other Intangible Assets (Net Ca

Other Intangible Assets (Net Carrying Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Other intangible assets:
Total other intangible assets	$ 40,211	$ 26,982
Core deposit intangible assets
Other intangible assets:
Total other intangible assets	40,211	26,654
Non-compete intangible assets
Other intangible assets:
Total other intangible assets	$ 0	$ 328

Loan Servicing Rights (Carrying

Loan Servicing Rights (Carrying and Fair Value of LSRs) (Details) - Loan Servicing Rights - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Net carrying value of LSRs	$ 10,230,000	$ 11,122,000
Fair value of LSRs	15,891,000	15,542,000
Valuation allowance	8,000	0
Loans serviced for others that have servicing rights capitalized	$ 2,074,057,000	$ 2,082,899,000

Other Intangible Assets (Textua

Other Intangible Assets (Textual) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	May 31, 2015
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 10,046	$ 8,444	$ 3,345
Lake Michigan
Finite-Lived Intangible Assets [Line Items]
Non-compete agreements recorded in acquisition				$ 600
Core deposit intangible assets
Finite-Lived Intangible Assets [Line Items]
Remaining weighted-average useful life of intangible assets acquired	8 years 5 months
Amortization of intangible assets	$ 5,200	4,100	$ 2,000
Non-compete intangible assets
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 328	$ 248
Non-compete intangible assets | Lake Michigan
Finite-Lived Intangible Assets [Line Items]
Remaining weighted-average useful life of intangible assets acquired		1 year

Loan Servicing Rights (Activity

Loan Servicing Rights (Activity for Capitalized LSRs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Activity for Capitalized LSRs
Balance at beginning of period	$ 26,982
Amortization	(10,046)	$ (8,444)	$ (3,345)
Balance at end of period	40,211	26,982
Loan Servicing Rights
Activity for Capitalized LSRs
Balance at beginning of period	11,122	12,217	3,423
Acquired through acquisitions	0	1,284	9,235
Additions	3,303	1,476	1,075
Amortization	(4,187)	(4,055)	(1,316)
Change in valuation allowance	(8)	200	(200)
Balance at end of period	$ 10,230	$ 11,122	$ 12,217

Other Intangible Assets (Amorti

Other Intangible Assets (Amortization Expense of Core Deposit Intangible Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Net carrying amount	$ 40,211	$ 26,982
Core deposit intangible assets
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Gross carrying amount	59,143	40,055
Accumulated amortization	18,932	13,401
Net carrying amount	$ 40,211	$ 26,654

Loan Servicing Rights (Assumpti

Loan Servicing Rights (Assumptions Used in Determining Fair Value) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Transfers and Servicing [Abstract]
Loan servicing fee income	$ 8,700,000	$ 5,400,000	$ 2,900,000
Commercial Real Estate
Loan servicing rights
WA float range (as a percent)	0.53%
Commercial Real Estate | Minimum
Loan servicing rights
Prepayment speed (as a percent)	0.00%
Cost to service/per year	$ 467
Commercial Real Estate | Maximum
Loan servicing rights
Prepayment speed (as a percent)	22.47%
Cost to service/per year	$ 500
Commercial Real Estate | Weighted Average
Loan servicing rights
Discount rate (as a percent)	16.46%
Mortgage
Loan servicing rights
WA Ancillary income/per year	$ 28	$ 20
WA float range (as a percent)	1.01%	1.72%
Mortgage | Minimum
Loan servicing rights
Prepayment speed (as a percent)	0.00%	6.96%
Cost to service/per year	$ 65	$ 70
Mortgage | Maximum
Loan servicing rights
Prepayment speed (as a percent)	99.75%	17.65%
Cost to service/per year	$ 90	$ 85
Mortgage | Weighted Average
Loan servicing rights
Discount rate (as a percent)	10.09%	10.04%

Other Intangible Assets (Estima

Other Intangible Assets (Estimated Future Amortization Expense) (Details) - Core deposit intangible assets $ in Thousands	Dec. 31, 2016USD ($)
Estimated Future Amortization Expense
2,017	$ 5,952
2,018	5,703
2,019	5,441
2,020	4,850
2,021	$ 4,471

Derivative Instruments and B112

Derivative Instruments and Balance Sheet Offsetting (Notional Amount and Fair Value) (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Derivative instruments
Notional Amount	$ 853,594,000	$ 90,911,000
Gross Derivative Assets	8,215,000	2,018,000
Gross Derivative Liabilities	6,359,000	1,979,000
Credit valuation adjustments for counterparty credit risk	99,000	0
Not designated as hedging | Customer-initiated derivatives
Derivative instruments
Notional Amount	600,598,000	0
Gross Derivative Assets	4,406,000	0
Gross Derivative Liabilities	4,141,000	0
Not designated as hedging | Forward contracts related to mortgage loans to be delivered for sale
Derivative instruments
Notional Amount	140,155,000	33,787,000
Gross Derivative Assets	635,000	144,000
Gross Derivative Liabilities	0	57,000
Not designated as hedging | Interest rate lock commitments
Derivative instruments
Notional Amount	76,034,000	23,421,000
Gross Derivative Assets	956,000	42,000
Gross Derivative Liabilities	0	90,000
Not designated as hedging | Power Equity CD
Derivative instruments
Notional Amount	36,807,000	33,703,000
Gross Derivative Assets	2,218,000	1,832,000
Gross Derivative Liabilities	$ 2,218,000	$ 1,832,000

Derivative Instruments and B113

Derivative Instruments and Balance Sheet Offsetting (Net Gains (Losses) Related to Changes in Fair Value) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative instruments
Net gains (losses) relating to derivative instruments	$ (83)	$ 61	$ (110)
Forward contracts related to mortgage loans to be delivered for sale | Mortgage banking revenue
Derivative instruments
Net gains (losses) relating to derivative instruments	692	193	(267)
Interest rate lock commitments | Mortgage banking revenue
Derivative instruments
Net gains (losses) relating to derivative instruments	(1,356)	(132)	157
Power Equity CD | Other noninterest income
Derivative instruments
Net gains (losses) relating to derivative instruments	0	0	0
Customer-initiated derivatives | Other noninterest income
Derivative instruments
Net gains (losses) relating to derivative instruments	$ 581	$ 0	$ 0

Derivative Instruments and B114

Derivative Instruments and Balance Sheet Offsetting (Balance Sheet Offsetting) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Offsetting derivative assets
Gross amounts recognized	$ 8,215	$ 2,018
Offsetting derivative liabilities
Gross amounts recognized	6,359	$ 1,979
Interest rate swaps and customer-initiated derivatives
Offsetting derivative assets
Gross amounts recognized	4,405
Gross amounts offset in the statements of financial condition	0
Net amounts presented in the statements of financial position	4,405
Gross amounts of assets not offset in the statement of financial position
Financial instruments	0
Collateral (received)/posted	0
Net Amount	4,405
Offsetting derivative liabilities
Gross amounts recognized	4,141
Gross amounts offset in the statements of financial condition	0
Net amounts presented in the statements of financial position	4,141
Gross amounts of liabilities not offset in the statement of financial position
Financial instruments	0
Collateral (received)/posted	2,550
Net Amount	$ 1,591

Commitments and Contingencie115

Commitments and Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Undisbursed loan commitments	$ 578,200	$ 293,600
Consumer Price Index increase	2.10%
Allowance for credit losses on lending-related commitments	$ 1,300	0
Commitments to Extend Credit
Loss Contingencies [Line Items]
Face amount of off-balance sheet liability	2,700,000	1,590,000
Standby Letters of Credit
Loss Contingencies [Line Items]
Face amount of off-balance sheet liability	118,900	38,800
Performance guarantee
Loss Contingencies [Line Items]
Outstanding balance of loans	16,900	1,500
Maximum potential amount of undiscounted future payments	16,100	1,500
Recourse liability	$ 200	$ 100

Commitments and Contingencie116

Commitments and Contingencies (Warranties) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Changes in the activity related to liability recorded in connection with representations and warranties
Beginning reserve balance	$ 4,048	$ 3,000	$ 1,600
Addition of fair value of representations and warranties due to acquisitions	3,100	1,712	2,000
Reserve reduction	(580)	0	(287)
Charge-offs	(109)	(664)	(313)
Ending reserve balance	6,459	4,048	3,000
Liability for specific claims				$ 730	$ 0	$ 118
General allowance				5,729	4,048	2,882
Total reserve balance	$ 4,048	$ 3,000	$ 1,600	$ 6,459	$ 4,048	$ 3,000

Commitments and Contingencie117

Commitments and Contingencies (Operating Leases and Other Noncancelable Contractual Obligations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Future Minimum Lease Payments
2,017	$ 20,712
2,018	18,000
2,019	14,594
2,020	11,362
2,021	7,173
Thereafter	16,549
Total	88,390
Future sublease income	312
Total expense recorded under operating leases and other noncancelable contractual obligations	$ 20,400	$ 15,600	$ 12,400

Deposits (Details)

Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Summary of Deposits
Noninterest-bearing demand	$ 3,341,520	$ 1,934,583
Interest-bearing demand	2,825,801	1,870,197
Savings and money market accounts	3,695,434	2,004,575
Time deposits over $100,000	1,682,986	701,830
Other time deposits	1,327,381	945,582
Total deposits	12,873,122	7,456,767
Demand deposit overdrafts	5,000	3,000
Time Deposits, $250,000 or More	975,400	$ 364,000
Maturities of Time Deposits
2,017	2,159,477
2,018	393,811
2,019	167,132
2,020	139,555
2,021	142,146
Thereafter	8,246
Total	$ 3,010,367

Borrowings (Schedule of Other B

Borrowings (Schedule of Other Borrowings) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Aug. 31, 2016	Dec. 31, 2015
Short Term Borrowings and Long Term Debt [Line Items]
Long-term borrowings, Amount	$ 597,847		$ 242,391
Long-term borrowings, Weighted Average Rate	1.63%		1.61%
Total short-term and long-term borrowings	$ 1,422,847		$ 342,391
Total short-term and long-term borrowings, Weighted Average Rate	1.06%		1.24%
FHLB advances: 0.60% - 0.66% fixed-rate notes | Minimum
Short Term Borrowings and Long Term Debt [Line Items]
Stated interest rate	0.60%
FHLB advances: 0.60% - 0.66% fixed-rate notes | Maximum
Short Term Borrowings and Long Term Debt [Line Items]
Stated interest rate	0.66%
Federal Home Loan Bank Advances | FHLB advances: 0.81% - 7.44% fixed-rate notes due 2017 to 2020
Short Term Borrowings and Long Term Debt [Line Items]
Long-term borrowings, Amount	$ 438,538		$ 181,394
Long-term borrowings, Weighted Average Rate	1.24%		1.41%
Advances payable from Federal Home Loan Banks	$ 437,800		$ 181,000
Purchase accounting premiums	$ 700		400
Federal Home Loan Bank Advances | FHLB advances: 0.81% - 7.44% fixed-rate notes due 2017 to 2020 | Minimum
Short Term Borrowings and Long Term Debt [Line Items]
Stated interest rate	0.81%
Federal Home Loan Bank Advances | FHLB advances: 0.81% - 7.44% fixed-rate notes due 2017 to 2020 | Maximum
Short Term Borrowings and Long Term Debt [Line Items]
Stated interest rate	7.44%
Securities sold under agreements to repurchase | Securities sold under agreements to repurchase: 1.48% - 4.11% fixed-rate notes due through 2017
Short Term Borrowings and Long Term Debt [Line Items]
Long-term borrowings, Amount	$ 19,144		$ 17,453
Long-term borrowings, Weighted Average Rate	3.17%		0.27%
Advances payable from Federal Home Loan Banks	$ 19,000		$ 17,000
Purchase accounting premiums	$ 100		500
Securities sold under agreements to repurchase | Securities sold under agreements to repurchase: 1.48% - 4.11% fixed-rate notes due through 2017 | Minimum
Short Term Borrowings and Long Term Debt [Line Items]
Stated interest rate	1.48%
Securities sold under agreements to repurchase | Securities sold under agreements to repurchase: 1.48% - 4.11% fixed-rate notes due through 2017 | Maximum
Short Term Borrowings and Long Term Debt [Line Items]
Stated interest rate	4.11%
Line of Credit
Short Term Borrowings and Long Term Debt [Line Items]
Long-term borrowings, Amount	$ 124,625	$ 125,000	$ 25,000
Long-term borrowings, Weighted Average Rate	2.52%		2.27%
Line of Credit | LIBOR
Short Term Borrowings and Long Term Debt [Line Items]
Basis spread on variable rate	1.75%
Subordinated Debt Obligations
Short Term Borrowings and Long Term Debt [Line Items]
Long-term borrowings, Amount	$ 0		$ 18,544
Long-term borrowings, Weighted Average Rate	0.00%		3.99%
Subordinated Debt Obligations | Subordinated debt obligations: floating-rate based on three-month LIBOR plus 1.45% - 2.85% due 2034 to 2035
Short Term Borrowings and Long Term Debt [Line Items]
Long-term borrowings, Amount	$ 11,285		$ 0
Long-term borrowings, Weighted Average Rate	3.14%		0.00%
Purchase accounting discounts	$ 3,700
Advances payable	$ 15,000
Subordinated Debt Obligations | Subordinated debt obligations: floating-rate based on three-month LIBOR plus 1.45% - 2.85% due 2034 to 2035 | Minimum | LIBOR
Short Term Borrowings and Long Term Debt [Line Items]
Basis spread on variable rate	1.45%
Subordinated Debt Obligations | Subordinated debt obligations: floating-rate based on three-month LIBOR plus 1.45% - 2.85% due 2034 to 2035 | Maximum | LIBOR
Short Term Borrowings and Long Term Debt [Line Items]
Basis spread on variable rate	2.85%
Subordinated Debt Obligations | Subordinated debt obligations: floating-rate based on three-month LIBOR plus 3.25% due in 2032
Short Term Borrowings and Long Term Debt [Line Items]
Long-term borrowings, Amount	$ 4,255		$ 0
Long-term borrowings, Weighted Average Rate	4.25%		0.00%
Purchase accounting discounts	$ 700
Advances payable	$ 5,000
Subordinated Debt Obligations | Subordinated debt obligations: floating-rate based on three-month LIBOR plus 3.25% due in 2032 | LIBOR
Short Term Borrowings and Long Term Debt [Line Items]
Basis spread on variable rate	3.25%
Federal Home Loan Bank Advances | FHLB advances: 0.60% - 0.66% fixed-rate notes
Short Term Borrowings and Long Term Debt [Line Items]
Short-term borrowings, Amount	$ 825,000		$ 100,000
Weighted average interest rate	0.65%		0.34%

Income Taxes (Provision for Fed

Income Taxes (Provision for Federal Income Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current income tax expense (benefit)
Federal									$ 19,144	$ 31,300	$ 29,200
State									(423)	0	0
Total current income tax expense									18,721	31,300	29,200
Deferred expense (benefit)
Federal									23,649	5,700	(1,700)
State									442	0	0
Total deferred income tax expense (benefit)									24,091	5,700	(1,700)
Change in valuation allowance									(706)	0	0
Income tax provision	$ 18,969	$ 2,848	$ 10,532	$ 9,757	$ 10,200	$ 9,600	$ 9,100	$ 8,100	$ 42,106	$ 37,000	$ 27,500

Borrowings (Additional Informat

Borrowings (Additional Information) (Details) - USD ($)	Aug. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	May 31, 2015
Debt Disclosure [Abstract]
FHLB advances		$ 5,140,000,000
Additional borrowing availability through the FHLB		7,000,000
Debt Instrument [Line Items]
Long-term borrowings, Amount		597,847,000	$ 242,391,000
Subordinated debt obligations: floating-rate based on three-month LIBOR plus 3.25 % due in 2032 (5)				$ 18,600,000
Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 145,000,000
Long-term borrowings, Amount	125,000,000	124,625,000	$ 25,000,000
Repayment of debt	25,000,000
Line of Credit | Term Line of Credit [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	125,000,000
Line of Credit | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	20,000,000
Line of Credit Acquired in Merger With Talmer [Member] | Line of Credit
Debt Instrument [Line Items]
Repayment of debt	37,500,000
Talmer
Debt Instrument [Line Items]
Debt assumed in acquisition	$ 687,100,000
Repayment of assumed debt		$ 142,200,000

Income Taxes (Effective Tax Rat

Income Taxes (Effective Tax Rate Reconciliation) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effective Income Tax Rate Reconciliation, Amount
Tax at statutory rate									$ 52,548	$ 43,341	$ 31,367
Tax-exempt interest income									(5,320)	(3,943)	(3,142)
State taxes, net of federal benefit									13	0	0
Change in valuation allowance									(706)	0	0
Bank-owned life insurance adjustments									(832)	(124)	(95)
Director plan change in control									(508)	0	0
Income tax credits, net									(2,454)	(2,557)	(1,624)
Nondeductible transaction expenses									$ 2,100	$ 411	$ 403
Nondeductible transaction expenses									1.40%	0.30%	0.40%
Tax benefits in excess of compensation costs on share-based payments									$ (2,240)	$ 0	$ 0
Other, net									(495)	(128)	591
Income tax provision	$ 18,969	$ 2,848	$ 10,532	$ 9,757	$ 10,200	$ 9,600	$ 9,100	$ 8,100	$ 42,106	$ 37,000	$ 27,500
Effective Income Tax Rate, Tax Rate Reconciliation, Percent
Tax at statutory rate									35.00%	35.00%	35.00%
Tax-exempt interest income									(3.50%)	(3.20%)	(3.50%)
State taxes, net of federal benefit									0.00%	0.00%	0.00%
Change in valuation allowance									(0.50%)	0.00%	0.00%
Bank-owned life insurance adjustments									(0.60%)	(0.10%)	(0.10%)
Director plan change in control									(0.30%)	0.00%	0.00%
Income tax credits, net									(1.60%)	(2.10%)	(1.80%)
Tax benefits in excess of compensation costs on share-based payments									(1.50%)	(0.00%)	(0.00%)
Other, net									(0.40%)	0.00%	0.70%
Income tax expense									28.00%	29.90%	30.70%

Borrowings (Securities Under Re

Borrowings (Securities Under Repurchase Agreements) (Details) $ in Thousands	Dec. 31, 2016USD ($)
Short-term borrowings [Line Items]
Amounts related to securities sold under agreements to repurchase not included in offsetting disclosure in Footnote 14	$ 19,000
Securities sold under agreements to repurchase
Short-term borrowings [Line Items]
Overnight and continuous	0
Up to 30 Days	10,000
30-90 Days	0
Greater than 90 Days	9,000
Total	$ 19,000

Income Taxes (Deferred Tax Asse

Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Allowance for loan losses	$ 45,763	$ 24,863
Acquisition-related fair value adjustments	62,078	29,280
Accrued stock-based compensation	18,891	3,240
Loss and tax credit carry forwards	47,977	7,235
Acquisition built in loss carry forward	28,469	0
Depreciation	3,896	4,333
Nonaccrual loan interest	9,465	4,994
Accrued expense	20,858	13,296
Other	7,401	5,951
Total deferred tax assets	244,798	93,192
Deferred tax liabilities:
Loan servicing rights	20,450	3,893
Core deposit intangible assets	11,844	7,379
Goodwill	6,373	5,808
Other	(715)	4,742
Total deferred tax liabilities	37,952	21,822
Net deferred tax asset before valuation allowance	206,846	71,370
Valuation allowance	(2,239)	(1,180)
Net deferred tax asset	$ 204,607	$ 70,190

Borrowings (Long-term Debt by M

Borrowings (Long-term Debt by Maturity) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Long-term Debt by Maturity
2,017	$ 126,089
2,018	159,207
2,019	186,338
2,020	110,673
2,021	0
Thereafter	15,540
Long-term Debt	$ 597,847	$ 242,391

Income Taxes (Textuals) (Detail

Income Taxes (Textuals) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Aug. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
Net deferred tax assets acquired	$ 151,900,000
Realized Built-in Losses	80,741,000
Valuation allowance for deferred tax assets	2,239,000		$ 1,180,000
Bad debt reserve	78,268,000		73,328,000	$ 75,683,000	$ 79,072,000
Unrecognized tax benefits	0		0
Liabilities accrued for interest or penalties	0		$ 0
Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	89,674,000
Alternative Minimum Tax Credits
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	15,727,000
Talmer
Operating Loss Carryforwards [Line Items]
Realized Built-in Losses		$ 88,700,000
Valuation allowance for deferred tax assets	2,200,000	1,800,000
Valuation allowance for tax credit carryforward	800,000
Talmer | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses		102,800,000
Tax credit carryforwards		1,000,000
Talmer | Subject to limitations under section 382
Operating Loss Carryforwards [Line Items]
Realized Built-in Losses	0
Valuation allowance for deferred tax assets	1,400,000
Talmer | Subject to limitations under section 382 | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	17,723,000
Talmer | Alternative Minimum Tax Credits
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards		$ 14,900,000
Talmer | Alternative Minimum Tax Credits | Subject to limitations under section 382
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	12,473,000
First Place Holdings/First Place Bank | Subject to limitations under section 382
Operating Loss Carryforwards [Line Items]
Realized Built-in Losses	71,805,000
Bad debt reserve	36,000,000
Potential unrecognized tax expense that would impact effective tax rate	13,000,000
First Place Holdings/First Place Bank | Subject to limitations under section 382 | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	1,222,000
First Place Holdings/First Place Bank | Alternative Minimum Tax Credits | Subject to limitations under section 382
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	$ 2,115,000

Income Taxes (Summary of Loss A

Income Taxes (Summary of Loss Attributes, Section 382 Limitations, and Tax Expiration Periods) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Aug. 31, 2016
Operating Loss Carryforwards [Line Items]
Realized Built-in Losses	$ 80,741
Less amounts not recorded due to Sec 382 Limitation	(4,875)
Valuation Allowance	(1,353)
Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	89,674
Gross Capital Losses
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	797
Business Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	3,194
Alternative Minimum Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	15,727
Talmer
Operating Loss Carryforwards [Line Items]
Realized Built-in Losses		$ 88,700
Estimated recognized built in gain	322,300
Talmer | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses		102,800
Tax Credit Carryforwards		1,000
Talmer | Alternative Minimum Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards		$ 14,900
Monarch
Operating Loss Carryforwards [Line Items]
Estimated recognized built in gain	5,600
Subject to limitations under section 382 | Talmer
Operating Loss Carryforwards [Line Items]
Annual Section 382 limitation-base	34,668
Realized Built-in Losses	0
Less amounts not recorded due to Sec 382 Limitation	0
Valuation Allowance	0
Subject to limitations under section 382 | Talmer | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	17,723
Subject to limitations under section 382 | Talmer | Gross Capital Losses
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	797
Subject to limitations under section 382 | Talmer | Business Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	170
Subject to limitations under section 382 | Talmer | Alternative Minimum Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	12,473
Subject to limitations under section 382 | Monarch
Operating Loss Carryforwards [Line Items]
Annual Section 382 limitation-base	673
Realized Built-in Losses	0
Less amounts not recorded due to Sec 382 Limitation	(1,738)
Valuation Allowance	0
Subject to limitations under section 382 | Monarch | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	17,744
Subject to limitations under section 382 | Monarch | Gross Capital Losses
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0
Subject to limitations under section 382 | Monarch | Business Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	1,651
Subject to limitations under section 382 | Monarch | Alternative Minimum Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	106
Subject to limitations under section 382 | First Place Holdings/First Place Bank
Operating Loss Carryforwards [Line Items]
Annual Section 382 limitation-base	6,650
Realized Built-in Losses	71,805
Less amounts not recorded due to Sec 382 Limitation	0
Valuation Allowance	(66)
Subject to limitations under section 382 | First Place Holdings/First Place Bank | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	1,222
Subject to limitations under section 382 | First Place Holdings/First Place Bank | Gross Capital Losses
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0
Subject to limitations under section 382 | First Place Holdings/First Place Bank | Business Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	781
Subject to limitations under section 382 | First Place Holdings/First Place Bank | Alternative Minimum Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	2,115
Subject to limitations under section 382 | Talmer West Bank
Operating Loss Carryforwards [Line Items]
Annual Section 382 limitation-base	3,028
Realized Built-in Losses	8,936
Less amounts not recorded due to Sec 382 Limitation	(2,992)
Valuation Allowance	(1,287)
Subject to limitations under section 382 | Talmer West Bank | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	50,086
Subject to limitations under section 382 | Talmer West Bank | Gross Capital Losses
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0
Subject to limitations under section 382 | Talmer West Bank | Business Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0
Subject to limitations under section 382 | Talmer West Bank | Alternative Minimum Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0
Subject to limitations under section 382 | First of Huron Corp./Signature Bank
Operating Loss Carryforwards [Line Items]
Annual Section 382 limitation-base	365
Realized Built-in Losses	0
Less amounts not recorded due to Sec 382 Limitation	0
Valuation Allowance	0
Subject to limitations under section 382 | First of Huron Corp./Signature Bank | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	1,014
Subject to limitations under section 382 | First of Huron Corp./Signature Bank | Gross Capital Losses
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0
Subject to limitations under section 382 | First of Huron Corp./Signature Bank | Business Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0
Subject to limitations under section 382 | First of Huron Corp./Signature Bank | Alternative Minimum Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	303
Subject to limitations under section 382 | From 2009 Ownership change
Operating Loss Carryforwards [Line Items]
Annual Section 382 limitation-base	145
Realized Built-in Losses	0
Less amounts not recorded due to Sec 382 Limitation	(145)
Valuation Allowance	0
Subject to limitations under section 382 | From 2009 Ownership change | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	1,885
Subject to limitations under section 382 | From 2009 Ownership change | Gross Capital Losses
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0
Subject to limitations under section 382 | From 2009 Ownership change | Business Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0
Subject to limitations under section 382 | From 2009 Ownership change | Alternative Minimum Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0
Not subject to limitations under section 382
Operating Loss Carryforwards [Line Items]
Realized Built-in Losses	0
Less amounts not recorded due to Sec 382 Limitation	0
Valuation Allowance	0
Not subject to limitations under section 382 | Federal
Operating Loss Carryforwards [Line Items]
Gross Federal Net Operating Losses	0
Not subject to limitations under section 382 | Gross Capital Losses
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	0
Not subject to limitations under section 382 | Business Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	592
Not subject to limitations under section 382 | Alternative Minimum Tax Credits
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforwards	$ 730

Share-Based Compensation (Textu

Share-Based Compensation (Textual) (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)shares	Dec. 31, 2014USD ($)shares	Apr. 20, 2015shares
Share-Based Compensation Plans (Textual) [Abstract]
Share-based compensation expense | $	$ 14.7	$ 3.7	$ 2.9
Excess tax benefit from share-based compensation | $	$ 2.2	0.5	0.2
Corporation granted shares of common stock (in shares) | shares	6,381
Common stock available for future grants under share-based compensation plans (in shares) | shares	626,353			1,300,000
Cash received from option exercises | $	$ 2.7	$ 2.3	$ 1
Shares issued from exercises (in shares) | shares	229,000	135,000	45,000
Granted after 2012
Share-Based Compensation Plans (Textual) [Abstract]
Stock option vesting period	5 years
Granted prior to 2013
Share-Based Compensation Plans (Textual) [Abstract]
Stock option vesting period	3 years
Stock Options
Share-Based Compensation Plans (Textual) [Abstract]
Stock option expiration period	10 years
Intrinsic value of outstanding in-the-money stock options | $	$ 80.4	$ 7.6	$ 5.1
Intrinsic value of exercisable in-the-money stock options | $	$ 71.7
Closing price of common stock (USD per share) | $ / shares	$ 54.17
Unrecognized compensation expense related to share-based compensation | $	$ 2.1
Unrecognized compensation expense related to share-based compensation, period for recognition	4 years 2 months 12 days
Stock Options | Talmer
Share-Based Compensation Plans (Textual) [Abstract]
Corporation granted options to purchase common stock (in shares) | shares	1,466,408
Stock Options | Non-vested stock options outstanding
Share-Based Compensation Plans (Textual) [Abstract]
Corporation granted options to purchase common stock (in shares) | shares	441,167	244,165	190,011
Restricted Stock Units
Share-Based Compensation Plans (Textual) [Abstract]
Corporation granted options to purchase restricted stock performance units (in shares) | shares	165,876
Shares issued from exercises (in shares) | shares	67,331
Unrecognized compensation expense related to share-based compensation | $	$ 4.7
Unrecognized compensation expense related to share-based compensation, period for recognition	2 years 5 months
Restricted Stock Units | Minimum
Share-Based Compensation Plans (Textual) [Abstract]
Restricted stock performance units eligible to vest as a multiple of number of units granted	0.5
Restricted Stock Units | Maximum
Share-Based Compensation Plans (Textual) [Abstract]
Restricted stock performance units eligible to vest as a multiple of number of units granted	1.5
Restricted Stock Units | Talmer
Share-Based Compensation Plans (Textual) [Abstract]
Corporation granted options to purchase restricted stock performance units (in shares) | shares	484,892
Restricted Stock Awards
Share-Based Compensation Plans (Textual) [Abstract]
Unrecognized compensation expense related to share-based compensation | $	$ 9
Unrecognized compensation expense related to share-based compensation, period for recognition	1 year 5 months

Share-Based Compensation (Stock

Share-Based Compensation (Stock Options Outstanding Per Range of Exercise Prices) (Details) - Stock Options	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number Outstanding (in shares) | shares	2,453,395
Options Outstanding, Weighted Average Exercise Price Per Share (USD per share)	$ 21.41
Options Outstanding, Weighted Average Contractual Term	6 years 1 month 28 days
Options Exercisable, Weighted Average Exercise Price Per Share (USD per share)	$ 19.14
Options Exercisable, Weighted Average Contractual Term	5 years 6 months 22 days
Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, lower price range limit (USD per share)	$ 10.56
Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, upper price range limit (USD per share)	$ 32.81
$10.56 - 12.80
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number Outstanding (in shares) | shares	289,512
Options Outstanding, Weighted Average Exercise Price Per Share (USD per share)	$ 11.83
Options Outstanding, Weighted Average Contractual Term	3 years 6 months
Options Exercisable, Number Exercisable (in shares) | shares	289,512
Options Exercisable, Weighted Average Exercise Price Per Share (USD per share)	$ 11.83
Options Exercisable, Weighted Average Contractual Term	3 years 6 months
$10.56 - 12.80 | Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, lower price range limit (USD per share)	$ 10.56
$10.56 - 12.80 | Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, upper price range limit (USD per share)	$ 12.80
$13.20 - 16.24
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number Outstanding (in shares) | shares	1,044,881
Options Outstanding, Weighted Average Exercise Price Per Share (USD per share)	$ 16.20
Options Outstanding, Weighted Average Contractual Term	5 years 11 months 27 days
Options Exercisable, Number Exercisable (in shares) | shares	1,044,881
Options Exercisable, Weighted Average Exercise Price Per Share (USD per share)	$ 16.20
Options Exercisable, Weighted Average Contractual Term	5 years 11 months 27 days
$13.20 - 16.24 | Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, lower price range limit (USD per share)	$ 13.20
$13.20 - 16.24 | Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, upper price range limit (USD per share)	$ 16.24
$19.97 - 21.10
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number Outstanding (in shares) | shares	62,422
Options Outstanding, Weighted Average Exercise Price Per Share (USD per share)	$ 20.49
Options Outstanding, Weighted Average Contractual Term	3 years 4 months 21 days
Options Exercisable, Number Exercisable (in shares) | shares	62,422
Options Exercisable, Weighted Average Exercise Price Per Share (USD per share)	$ 20.49
Options Exercisable, Weighted Average Contractual Term	3 years 4 months 21 days
$19.97 - 21.10 | Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, lower price range limit (USD per share)	$ 19.97
$19.97 - 21.10 | Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, upper price range limit (USD per share)	$ 21.10
$28.43 - 32.81
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number Outstanding (in shares) | shares	703,378
Options Outstanding, Weighted Average Exercise Price Per Share (USD per share)	$ 31.58
Options Outstanding, Weighted Average Contractual Term	8 years 6 months 29 days
Options Exercisable, Number Exercisable (in shares) | shares	295,439
Options Exercisable, Weighted Average Exercise Price Per Share (USD per share)	$ 29.88
Options Exercisable, Weighted Average Contractual Term	7 years 9 months 4 days
$28.43 - 32.81 | Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, lower price range limit (USD per share)	$ 28.43
$28.43 - 32.81 | Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, upper price range limit (USD per share)	$ 32.81
$23.78 - 25.14
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number Outstanding (in shares) | shares	353,202
Options Outstanding, Weighted Average Exercise Price Per Share (USD per share)	$ 24.60
Options Outstanding, Weighted Average Contractual Term	4 years 5 months 27 days
Options Exercisable, Number Exercisable (in shares) | shares	353,202
Options Exercisable, Weighted Average Exercise Price Per Share (USD per share)	$ 24.60
Options Exercisable, Weighted Average Contractual Term	4 years 5 months 27 days
$23.78 - 25.14 | Minimum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, lower price range limit (USD per share)	$ 23.78
$23.78 - 25.14 | Maximum
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price per share, upper price range limit (USD per share)	$ 25.14

Share-Based Compensation (St130

Share-Based Compensation (Stock Option Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Weighted- average grant date fair value per share
Granted, Weighted Average Grant Date Fair Value Per Share (USD per share)	$ 6.15	$ 8.40	$ 9.64
Stock Options | Non-vested stock options outstanding
Number of options
Beginning balance, Number of Options	479,755	432,199	414,080
Granted, Number of Options	441,167	244,165	190,011
Acquired, Number of Options	0	0
Exercised, , Number of Options	0	0	0
Vested, Number of Options	(454,360)	(150,224)	(148,016)
Forfeited/expired, Number of Options	(58,623)	(46,385)	(23,876)
Ending balance, Number of Options	407,939	479,755	432,199
Weighted- average exercise price per share
Beginning balance, Weighted Average Exercise Price Per Share (USD per share)	$ 28.75	$ 26.75	$ 24.29
Granted, Weighted Average Exercise Price Per Share (USD per share)	32.81	30.18	29.45
Acquired, Weighted Average Exercise Price Per Share (USD per share)	0	0
Exercised, Weighted Average Exercise Price Per Share (USD per share)	0	0	0
Vested, Weighted Average Exercise Price Per Share (USD per share)	28.74	25.57	23.43
Forfeited/expired, Weighted Average Exercise Price Per Share (USD per share)	31.10	27.99	25.67
Ending balance, Weighted Average Exercise Price Per Share (USD per share)	32.81	28.75	26.75
Weighted- average grant date fair value per share
Beginning balance, Weighted Average Grant Date Fair Value Per Share (USD per share)	8.49	8.30	7.19
Granted, Weighted Average Grant Date Fair Value Per Share (USD per share)	6.15	8.40	9.64
Acquired, Weighted Average Grant Date Fair Value Per Share (USD per share)	0	0
Exercised, Granted, Weighted Average Grant Date Fair Value Per Share (USD per share)	0	0	0
Vested, Granted, Weighted Average Grant Date Fair Value Per Share (USD per share)	8.49	7.80	6.98
Forfeited/expired, Granted, Weighted Average Grant Date Fair Value Per Share (USD per share)	7.17	8.50	7.79
Ending balance, Weighted Average Grant Date Fair Value Per Share (USD per share)	$ 6.15	$ 8.49	$ 8.30
Stock Options | Stock options outstanding
Number of options
Beginning balance, Number of Options	1,054,739	1,037,311	1,073,990
Granted, Number of Options	441,167	244,165	190,011
Acquired, Number of Options	1,466,408	132,883
Exercised, , Number of Options	(450,296)	(310,985)	(72,936)
Vested, Number of Options	0	0	0
Forfeited/expired, Number of Options	(58,623)	(48,635)	(153,754)
Ending balance, Number of Options	2,453,395	1,054,739	1,037,311
Weighted- average exercise price per share
Beginning balance, Weighted Average Exercise Price Per Share (USD per share)	$ 25.38	$ 25.90	$ 26.84
Granted, Weighted Average Exercise Price Per Share (USD per share)	32.81	30.18	29.45
Acquired, Weighted Average Exercise Price Per Share (USD per share)	15.08	12.93
Exercised, Weighted Average Exercise Price Per Share (USD per share)	20.02	25.10	24.67
Vested, Weighted Average Exercise Price Per Share (USD per share)	0	0	0
Forfeited/expired, Weighted Average Exercise Price Per Share (USD per share)	31.10	28.18	37.50
Ending balance, Weighted Average Exercise Price Per Share (USD per share)	$ 21.41	$ 25.38	$ 25.90
Weighted- average grant date fair value per share
Options Exercisable, Number Exercisable (in shares)	2,045,456
Exercisable/vested, Weighted Average Exercise Price Per Share (USD per share)	$ 19.14

Share-Based Compensation (Black

Share-Based Compensation (Black-Scholes Pricing Model Assumptions) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assumptions of Black-Scholes option pricing model
Expected dividend yield	3.30%	3.50%	3.00%
Risk-free interest rate	1.39%	1.78%	2.16%
Expected stock price volatility	27.90%	39.10%	42.20%
Expected life of options — in years	6 years 6 months	7 years	7 years
Weighted average fair value of options granted (USD per share)	$ 6.15	$ 8.40	$ 9.64

Share-Based Compensation (Restr

Share-Based Compensation (Restricted Stock Unit Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Number of units
Converted into shares of common stock, Number of Units	(229,000)	(135,000)	(45,000)
Restricted Stock Units
Number of units
Beginning balance, Number of Units	207,989
Granted, Number of Units	165,876
Converted into shares of common stock, Number of Units	(67,331)
Forfeited/expired, Number of Units	(8,177)
Ending balance, Number of Units	298,357	207,989
Weighted-average grant date fair value per unit
Beginning balance, Weighted Average Grant Date Fair Value Per Share (USD per share)	$ 26.41
Granted, Weighted Average Grant Date Fair Value Per Unit (USD per Unit)	37.41
Converted into shares of common stock, Weighted Average Grant Date Fair Value Per Unit (USD per Unit)	24.54
Forfeited/expired, Weighted Average Grant Date Fair Value Per Unit (USD per Unit)	31.19
Ending balance, Weighted Average Grant Date Fair Value Per Share (USD per share)	$ 32.81	$ 26.41

Share-Based Compensation (Re133

Share-Based Compensation (Restricted Stock Awards Activity) (Details) - Restricted Stock Awards	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Number of awards
Beginning balance, Number of Units | shares	0
Acquired, Number of Units | shares	484,892,000
Vested, Number of Units | shares	(118,493,000)
Forfeited, Number of Units | shares	(508,000)
Ending balance, Number of Units | shares	365,891,000
Weighted-average acquisition-date fair value
Beginning balance, Weighted Average Grant Date Fair Value Per Share (USD per share) | $ / shares	$ 0
Acquired (USD per share) | $ / shares	46.23
Vested (USD per share) | $ / shares	46.23
Forfeited (USD per share) | $ / shares	46.23
Ending balance, Weighted Average Grant Date Fair Value Per Share (USD per share) | $ / shares	$ 46.23

Retirement Plans (Textual) (Det

Retirement Plans (Textual) (Details) $ in Thousands	Aug. 31, 2016USD ($)	Dec. 31, 2016USD ($)employeeshares	Dec. 31, 2015USD ($)shares	Dec. 31, 2014USD ($)
Defined Benefit Plan Disclosure [Line Items]
Percentage of eligible pay contribution to certain employees		4.00%
Common Stock, Shares Held by Plan | shares		70,599,133	38,167,861
Dividends paid (in dollars per share)		$ 49,389	$ 36,918	$ 29,528
Multiemployer Plan, Period Contributions		0
Multiemployer Plan, Participating Company, Allocation of Plan Liabilities		$ 3,500	2,600
Multiemployer Plan, Company's Asset Participation Level		5.00%
Employer discretionary contribution percent		4.00%
Employer total contribution amount		$ 6,500	4,700	3,300
Contribution to 401(k) savings plan		$ 3,500	3,100	2,300
Maximum annual contribution per employee percent		50.00%
Employer matching contribution percent		4.00%
Employer matching contribution amount		$ 3,000	1,600	1,000
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Maximum years of vested service for calculation of retirement benefits		30 years
Years of employees highest average salary for calculation of retirement benefits		5 years
Number of years preceding retirement for calculation of retirement benefits		10 years
Maximum years of service for which pension benefits calculation is based upon vested service and average five years of salary		15 years
Number of Employees Covered (in employee) | employee		135
Maximum total years of age and years of service for which pension benefits calculation is based upon vested service and average five years of salary		65 years
Pension Plan expense		$ 73	1,575	$ (45)
Employer contributions		$ 0	$ 0
Discount rate used in determining benefit obligation		4.22%	4.55%	4.15%
Discount rate used in determining expense		4.55%	4.15%	5.00%
Pension plan actual asset allocations		100.00%	100.00%
Projected benefit obligation		$ 123,968	$ 119,873	$ 129,160
Accumulated benefit obligation		$ 115,418	$ 109,583
Pension Plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range - minimum		40.00%
Target plan asset allocations range - maximum		70.00%
Pension plan actual asset allocations		69.00%	68.00%
Pension Plan | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range - minimum		20.00%
Target plan asset allocations range - maximum		60.00%
Pension plan actual asset allocations		29.00%	31.00%
Pension Plan | Other
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range - minimum		0.00%
Target plan asset allocations range - maximum		10.00%
Pension plan actual asset allocations		2.00%	1.00%
Pension Plan | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Common Stock, Shares Held by Plan | shares		210,663	210,663
Fair value of common stock		$ 11,400	$ 7,200
Pension plan actual asset allocations		8.60%	5.70%
Supplemental Plan
Defined Benefit Plan Disclosure [Line Items]
Defined benefits owed related to change in control	$ 1,900
Discount rate used in determining benefit obligation		3.63%	4.51%	4.07%
Discount rate used in determining expense		4.51%	4.07%	4.87%
Number of employees covered by the pension plan | employee		1
Projected benefit obligation		$ 2,600	$ 2,200
Accumulated benefit obligation		2,200	1,800
Supplemental Plan expense		500	400	$ 300
Postretirement Plan
Defined Benefit Plan Disclosure [Line Items]
Pension Plan expense		158	278	$ 186
Employer contributions		$ 309	$ 241
Discount rate used in determining benefit obligation		3.79%	4.23%	3.75%
Discount rate used in determining expense		4.23%	3.75%	4.27%
Expected health care cost trend rate assumed for 2014		7.00%
Expected ultimate health care cost trend rate in 2020		5.00%
Projected benefit obligation		$ 2,601	$ 3,247	$ 3,702
Accumulated benefit obligation		$ 2,601	3,247
Minimum retirement age (years)		50 years
Maximum benefit age of spouse (years)		65 years
Minimum retirement age with twenty-five years of service to be eligible for postretirement benefits (years)		60 years
Minimum years of service for retirees at age sixty to be eligible for postretirement benefits (years)		25 years
Chemical Financial Corporation | Pension Plan | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Dividends paid (in dollars per share)		$ 200	$ 200

Retirement Plans (Changes in th

Retirement Plans (Changes in the Projected Benefit Obligation and Plan Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plan
Projected benefit obligation:
Benefit obligation at beginning of year	$ 119,873	$ 129,160
Service cost	1,041	1,021	$ 944
Interest cost	5,335	5,242	5,167
Net actuarial loss (gain)	2,684	(10,837)
Benefits paid	(4,965)	(4,713)
Benefit obligation at end of year	123,968	119,873	129,160
Fair value of plan assets:
Fair value of plan assets at beginning of year	126,930	130,775
Actual return on plan assets	10,786	868
Employer contributions	0	0
Benefits paid	(4,965)	(4,713)
Fair value of plan assets at end of year	132,751	126,930	130,775
Funded (unfunded) status at December 31	8,783	7,057
Accumulated benefit obligation	115,418	109,583
Postretirement Plan
Projected benefit obligation:
Benefit obligation at beginning of year	3,247	3,702
Service cost	9	16	18
Interest cost	132	133	142
Net actuarial loss (gain)	(478)	(363)
Benefits paid	(309)	(241)
Benefit obligation at end of year	2,601	3,247	3,702
Fair value of plan assets:
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	309	241
Benefits paid	(309)	(241)
Fair value of plan assets at end of year	0	0	$ 0
Funded (unfunded) status at December 31	(2,601)	(3,247)
Accumulated benefit obligation	$ 2,601	$ 3,247

Retirement Plans (Weighted-aver

Retirement Plans (Weighted-average rate assumptions of the Pension and Postretirement Plans) (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate used in determining benefit obligation — December 31	4.22%	4.55%	4.15%
Discount rate used in determining expense	4.55%	4.15%	5.00%
Expected long-term return on Pension Plan assets	6.75%	6.75%	7.00%
Rate of compensation increase used in determining benefit obligation — December 31	3.50%	3.50%	3.50%
Rate of compensation increase used in determining pension expense	3.50%	3.50%	3.50%
Year 1 increase in cost of postretirement benefits	0.00%	0.00%	0.00%
Postretirement Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate used in determining benefit obligation — December 31	3.79%	4.23%	3.75%
Discount rate used in determining expense	4.23%	3.75%	4.27%
Expected long-term return on Pension Plan assets	0.00%	0.00%	0.00%
Rate of compensation increase used in determining benefit obligation — December 31	0.00%	0.00%	0.00%
Rate of compensation increase used in determining pension expense	0.00%	0.00%	0.00%
Year 1 increase in cost of postretirement benefits	7.00%	7.50%	8.00%

Retirement Plans (Net Periodic

Retirement Plans (Net Periodic Pension Cost (Income)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plan
Components of net periodic benefit cost (income) for the Corporation's qualified and nonqualified pension plans and nonqualified postretirement benefits plan
Service cost	$ 1,041	$ 1,021	$ 944
Interest cost	5,335	5,242	5,167
Expected return on plan assets	(8,562)	(8,645)	(8,314)
Amortization of prior service credit	0	(5)	(1)
Amortization of net actuarial loss (gain)	2,259	3,962	2,159
Net cost (income)	73	1,575	(45)
Postretirement Plan
Components of net periodic benefit cost (income) for the Corporation's qualified and nonqualified pension plans and nonqualified postretirement benefits plan
Service cost	9	16	18
Interest cost	132	133	142
Expected return on plan assets	0	0	0
Amortization of prior service credit	117	130	130
Amortization of net actuarial loss (gain)	(100)	(1)	(104)
Net cost (income)	$ 158	$ 278	$ 186

Retirement Plans (Schedule of E

Retirement Plans (Schedule of Estimated Future Benefit Payments) (Details) $ in Thousands	Dec. 31, 2016USD ($)
Pension Plan
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,017	$ 5,474
2,018	5,706
2,019	6,083
2,020	6,263
2,021	6,626
2022 - 2026	36,438
Total	66,590
Postretirement Plan
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,017	243
2,018	239
2,019	240
2,020	237
2,021	234
2022 - 2026	1,028
Total	$ 2,221

Retirement Plans (Impact of One

Retirement Plans (Impact of One Percentage Point Change in Assumed Health Care and Dental Cost Trend Rates) (Details) - Postretirement Plan $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Effect of one percentage point increase on service and interest cost components	$ 14
Effect of one percentage point decrease on service and interest cost components	(13)
Effect of one percentage point increase on postretirement benefit obligation	204
Effect of one percentage point decrease on postretirement benefit obligation	$ (194)

Retirement Plans (Pension Plan

Retirement Plans (Pension Plan Asset Allocations) (Details) - Pension Plan	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension plan actual asset allocations	100.00%	100.00%
Equity securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension plan actual asset allocations	69.00%	68.00%
Debt securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension plan actual asset allocations	29.00%	31.00%
Other
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension plan actual asset allocations	2.00%	1.00%

Retirement Plans (Fair Value of

Retirement Plans (Fair Value of Plan Assets by Fair Value Level) (Details) - Pension Plan - USD ($)	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 132,751,000	$ 126,930,000	$ 130,775,000
Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	132,751,000	126,930,000
Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	130,442,000	120,561,000
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,309,000	6,369,000
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,825,000	354,000
Cash | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,825,000	354,000
Cash | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. large- and mid-cap stocks
Defined Benefit Plan Disclosure [Line Items]
Minimum market capitalization for investments	3,000,000,000
U.S. large- and mid-cap stocks | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	55,389,000	55,709,000
U.S. large- and mid-cap stocks | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	55,389,000	55,709,000
U.S. large- and mid-cap stocks | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. large- and mid-cap stocks | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. small-cap mutual funds | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,687,000	4,749,000
U.S. small-cap mutual funds | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,687,000	4,749,000
U.S. small-cap mutual funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. small-cap mutual funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International large-cap mutual funds | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13,701,000	14,124,000
International large-cap mutual funds | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13,701,000	14,124,000
International large-cap mutual funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International large-cap mutual funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Emerging markets mutual funds | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,147,000	4,886,000
Emerging markets mutual funds | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,147,000	4,886,000
Emerging markets mutual funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Emerging markets mutual funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Chemical Financial Corporation common stock | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11,412,000	7,219,000
Chemical Financial Corporation common stock | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11,412,000	7,219,000
Chemical Financial Corporation common stock | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Chemical Financial Corporation common stock | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. Treasury and government sponsored agency bonds and notes | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	806,000	2,815,000
U.S. Treasury and government sponsored agency bonds and notes | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. Treasury and government sponsored agency bonds and notes | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	806,000	2,815,000
U.S. Treasury and government sponsored agency bonds and notes | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Corporate bonds | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,503,000	3,554,000
Corporate bonds | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Corporate bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,503,000	3,554,000
Corporate bonds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mutual funds | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	36,220,000	33,424,000
Mutual funds | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	36,220,000	33,424,000
Mutual funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mutual funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other | Fair Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	61,000	96,000
Other | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	61,000	96,000
Other | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0

Retirement Plans (Changes in Ac

Retirement Plans (Changes in Accumulated Other Comprehensive Income (Loss) Related to Retirement Plans) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Accumulated Other Comprehensive Income (Loss), Net of Tax
Accumulated other comprehensive income (loss) at beginning of year	$ (27,144)
Prior service costs (credits)	76
Net actuarial (income) loss	1,174
Comprehensive income (loss) adjustment	1,250
Accumulated other comprehensive income (loss) at end of year	(25,894)
Pension Plan
Accumulated Other Comprehensive Income (Loss), Net of Tax
Accumulated other comprehensive income (loss) at beginning of year	(27,291)
Prior service costs (credits)	0
Net actuarial (income) loss	1,168
Comprehensive income (loss) adjustment	1,168
Accumulated other comprehensive income (loss) at end of year	(26,123)
Postretirement Plan
Accumulated Other Comprehensive Income (Loss), Net of Tax
Accumulated other comprehensive income (loss) at beginning of year	402
Prior service costs (credits)	76
Net actuarial (income) loss	246
Comprehensive income (loss) adjustment	322
Accumulated other comprehensive income (loss) at end of year	724
Supplemental Plan
Accumulated Other Comprehensive Income (Loss), Net of Tax
Accumulated other comprehensive income (loss) at beginning of year	(255)
Prior service costs (credits)	0
Net actuarial (income) loss	(240)
Comprehensive income (loss) adjustment	(240)
Accumulated other comprehensive income (loss) at end of year	$ (495)

Retirement Plans (Income (Loss)

Retirement Plans (Income (Loss) Estimated to be Amortized from Accumulated Other Comprehensive Income (Loss) into Net Periodic Cost) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Twelve Months
Prior service (costs) credits	$ 0
Net gain (loss)	(1,398)
Total	(1,398)
Pension Plan
Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Twelve Months
Prior service (costs) credits	0
Net gain (loss)	(1,436)
Total	(1,436)
Postretirement Plan
Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Twelve Months
Prior service (costs) credits	0
Net gain (loss)	105
Total	105
Supplemental Plan
Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Twelve Months
Prior service (costs) credits	0
Net gain (loss)	(67)
Total	$ (67)

Retirement Plans (401(k) Saving

Retirement Plans (401(k) Savings Plan) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Employer discretionary contribution percent	4.00%
Maximum annual contribution per employee percent	50.00%
Employer matching contribution percent	4.00%
Employer matching contribution amount	$ 3	$ 1.6	$ 1
Contribution to 401(k) savings plan	3.5	3.1	2.3
Employer total contribution amount	$ 6.5	$ 4.7	$ 3.3

Equity (Details)

Equity (Details) - shares	12 Months Ended
	Dec. 31, 2016	Jul. 19, 2016	Jul. 18, 2016	Dec. 31, 2015	Apr. 20, 2015	Apr. 20, 2009	Jan. 31, 2008
Class of Stock [Line Items]
Preferred stock, shares authorized	2,000,000			2,000,000	2,000,000	200,000
Preferred stock, shares issued	0			0
Preferred stock, shares outstanding	0
Common sock, shares authorized	100,000,000	100,000,000	60,000,000	60,000,000
Common Stock
Class of Stock [Line Items]
Stock repurchased during the period	0
Common Stock
Class of Stock [Line Items]
Number of shares authorized to be repurchased							500,000
Number of remaining shares authorized to be repurchased	500,000

Regulatory Capital and Reser146

Regulatory Capital and Reserve Requirements (Details) - USD ($) $ / shares in Units, $ in Thousands	Feb. 20, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Minimum average regulatory cash reserve balance		$ 52,300				$ 65,300				$ 52,300	$ 65,300
Leverage Ratio:
Cash dividends declared per share (in dollars per share)		$ 0.27	$ 0.27	$ 0.26	$ 0.26	$ 0.26	$ 0.26	$ 0.24	$ 0.24	$ 1.06	$ 1	$ 0.94
Subsequent Event
Leverage Ratio:
Cash dividends declared per share (in dollars per share)	$ 0.27
Chemical Financial Corporation
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Risk weighted assets		$ 13,420,000				$ 7,140,000				$ 13,420,000	$ 7,140,000
Total Capital to Risk-Weighted Assets:
Actual, Capital Amount		$ 1,543,018				$ 841,257				$ 1,543,018	$ 841,257
Actual, Ratio		11.50%				11.80%				11.50%	11.80%
Minimum Required for Capital Adequacy Purposes, Capital Amount		$ 1,073,431				$ 571,509				$ 1,073,431	$ 571,509
Minimum Required for Capital Adequacy Purposes, Ratio		8.00%				8.00%				8.00%	8.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 1,157,293								$ 1,157,293
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		8.60%								8.60%
Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount		$ 1,441,209				$ 767,929				$ 1,441,209	$ 767,929
Actual, Ratio		10.70%				10.70%				10.70%	10.70%
Minimum Required for Capital Adequacy Purposes, Capital Amount		$ 805,073				$ 428,631				$ 805,073	$ 428,631
Minimum Required for Capital Adequacy Purposes, Ratio		6.00%				6.00%				6.00%	6.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 888,935								$ 888,935
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		6.60%								6.60%
Common Equity Tier 1 Capital to Risk-Weighted Assets
Actual, Capital Amount		$ 1,441,209				$ 753,815				$ 1,441,209	$ 753,815
Minimum Required for Capital Adequacy Purposes, Capital Amount		10.70%				10.60%				10.70%	10.60%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount		$ 603,805				$ 321,474				$ 603,805	$ 321,474
Actual, Ratio		4.50%				4.50%				4.50%	4.50%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 687,667								$ 687,667
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		5.10%								5.10%
Leverage Ratio:
Actual, Capital Amount		$ 1,441,209				$ 767,929				$ 1,441,209	$ 767,929
Actual, Ratio		9.00%				8.60%				9.00%	8.60%
Minimum Required for Capital Adequacy Purposes, Capital Amount		$ 643,603				$ 356,396				$ 643,603	$ 356,396
Minimum Required for Capital Adequacy Purposes, Ratio		4.00%				4.00%				4.00%	4.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 643,603								$ 643,603
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		4.00%								4.00%
Cash dividends from subsidiaries										$ 110,450	$ 56,860	$ 64,468
Chemical Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Risk weighted assets		$ 13,360,000				$ 7,130,000				13,360,000	7,130,000
Total Capital to Risk-Weighted Assets:
Actual, Capital Amount		$ 1,608,980				$ 830,294				$ 1,608,980	$ 830,294
Actual, Ratio		12.00%				11.70%				12.00%	11.70%
Minimum Required for Capital Adequacy Purposes, Capital Amount		$ 1,068,560				$ 570,073				$ 1,068,560	$ 570,073
Minimum Required for Capital Adequacy Purposes, Ratio		8.00%				8.00%				8.00%	8.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 1,152,041								$ 1,152,041
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		8.60%								8.60%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount		$ 1,335,700				$ 712,591				$ 1,335,700	$ 712,591
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio		10.00%				10.00%				10.00%	10.00%
Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount		$ 1,522,711				$ 756,966				$ 1,522,711	$ 756,966
Actual, Ratio		11.40%				10.60%				11.40%	10.60%
Minimum Required for Capital Adequacy Purposes, Capital Amount		$ 801,420				$ 427,555				$ 801,420	$ 427,555
Minimum Required for Capital Adequacy Purposes, Ratio		6.00%				6.00%				6.00%	6.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 884,901								$ 884,901
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		6.60%								6.60%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount		$ 1,068,560				$ 570,073				$ 1,068,560	$ 570,073
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio		8.00%				8.00%				8.00%	8.00%
Common Equity Tier 1 Capital to Risk-Weighted Assets
Actual, Capital Amount		$ 1,522,711				$ 756,966				$ 1,522,711	$ 756,966
Minimum Required for Capital Adequacy Purposes, Capital Amount		11.40%				10.60%				11.40%	10.60%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount		$ 601,065				$ 320,666				$ 601,065	$ 320,666
Actual, Ratio		4.50%				4.50%				4.50%	4.50%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 684,546								$ 684,546
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		5.10%								5.10%
Minimum Required for Capital Adequacy Purposes, Ratio		$ 868,205				$ 463,184				$ 868,205	$ 463,184
Required to be Well Capital Under Prompt Corrective Action Regulations, Ratio		6.50%				6.50%				6.50%	6.50%
Leverage Ratio:
Actual, Capital Amount		$ 1,522,711				$ 756,966				$ 1,522,711	$ 756,966
Actual, Ratio		9.50%				8.50%				9.50%	8.50%
Minimum Required for Capital Adequacy Purposes, Capital Amount		$ 641,457				$ 355,911				$ 641,457	$ 355,911
Minimum Required for Capital Adequacy Purposes, Ratio		4.00%				4.00%				4.00%	4.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount		$ 641,457								$ 641,457
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio		4.00%								4.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount		$ 801,822				$ 444,888				$ 801,822	$ 444,888
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio		5.00%				5.00%				5.00%	5.00%

Parent Company Only Financia147

Parent Company Only Financial Statements (Financial Position) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	May 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets
Premises and equipment	$ 145,012	$ 106,317
Goodwill	1,133,534	287,393
Other assets	650,973	246,346
Total assets	17,355,179	9,188,797
Liabilities and Equity [Abstract]
Other liabilities	134,637	76,466
Subordinated debentures			$ 18,600
Total liabilities	14,773,653	8,172,823
Shareholders' equity	2,581,526	1,015,974		$ 797,133	$ 696,500
Total liabilities and shareholders' equity	17,355,179	9,188,797
Chemical Financial Corporation
Assets
Cash at subsidiary bank	16,851	28,884
Investment in subsidiaries	2,654,458	1,023,285
Premises and equipment	4,051	3,632
Goodwill	1,092	1,092
Other assets	63,584	13,051
Total assets	2,740,036	1,069,944
Liabilities and Equity [Abstract]
Other liabilities	18,345	10,426
Non-revolving line-of-credit	124,625	25,000
Subordinated debentures	15,540	18,544
Total liabilities	158,510	53,970
Shareholders' equity	2,581,526	1,015,974
Total liabilities and shareholders' equity	$ 2,740,036	$ 1,069,944

Parent Company Only Financia148

Parent Company Only Financial Statements (Statements of Income) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Other income									$ 11,988	$ 1,907	$ 697
Interest expense	$ 11,969	$ 6,753	$ 5,442	$ 5,134	$ 5,153	$ 5,234	$ 3,944	$ 3,450	29,298	17,781	14,710
Operating expenses	114,302	106,144	59,085	58,887	57,824	58,265	56,785	51,020	338,418	223,894	179,925
Income tax benefit	(18,969)	(2,848)	(10,532)	(9,757)	(10,200)	(9,600)	(9,100)	(8,100)	(42,106)	(37,000)	(27,500)
Net income	$ 47,168	$ 11,484	$ 25,775	$ 23,605	$ 25,504	$ 24,467	$ 19,024	$ 17,835	108,032	86,830	62,121
Chemical Financial Corporation
Condensed Financial Statements, Captions [Line Items]
Cash dividends from subsidiaries									110,450	56,860	64,468
Other income									151	144	95
Total income									110,601	57,004	64,563
Interest expense									1,816	761	42
Operating expenses									30,589	7,794	7,200
Total expenses									32,405	8,555	7,242
Income before income taxes and equity in undistributed net income of subsidiaries									78,196	48,449	57,321
Income tax benefit									11,378	2,582	2,302
Equity in undistributed net income of subsidiaries									18,458	35,799	2,498
Net income									$ 108,032	$ 86,830	$ 62,121

Parent Company Only Financia149

Parent Company Only Financial Statements (Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash Flows From Operating Activities
Net Income	$ 47,168	$ 11,484	$ 25,775	$ 23,605	$ 25,504	$ 24,467	$ 19,024	$ 17,835	$ 108,032	$ 86,830	$ 62,121
Share-based compensation expense									13,452	3,478	2,931
Depreciation									13,270	11,028	8,980
Net cash from operating activities									280,578	103,049	90,225
Cash Flows From Investing Activities
Net cash acquired (paid) in business combinations									325,714	16,551	(14,260)
Purchases of premises and equipment, net									(18,098)	(8,527)	(13,411)
Net cash used in investing activities									(542,946)	(408,784)	(479,049)
Cash Flows From Financing Activities
Cash dividends paid									(49,389)	(36,918)	(29,528)
Proceeds from issuance of common stock, net of issuance costs									0	0	76,175
Repayments of other borrowings									(351,018)	(6,000)	(10,310)
Proceeds from issuance of other borrowings									375,000	125,000	0
Proceeds from directors' stock purchase plan and exercise of stock options									1,572	2,473	1,242
Cash paid for payroll taxes upon conversion of restricted stock units									(1,065)	(571)	(701)
Net cash from financing activities									497,981	361,504	261,056
Net increase (decrease) in cash and cash equivalents									235,613	55,769	(127,768)
Cash and cash equivalents at beginning of year				238,789				183,020	238,789	183,020	310,788
Cash and cash equivalents at end of year	474,402				238,789				474,402	238,789	183,020
Business combinations:
Fair value of tangible assets acquired (noncash)									6,371,781	1,282,420	747,181
Liabilities assumed									6,100,901	1,258,051	815,011
Common stock and stock options issued									1,504,811	159,904	0
Chemical Financial Corporation
Cash Flows From Operating Activities
Net Income									108,032	86,830	62,121
Share-based compensation expense									13,452	3,478	2,931
Depreciation									355	318	327
Equity in undistributed net income of subsidiaries									(18,458)	(35,799)	(2,498)
Net decrease in other assets									9,752	2,873	1,101
Net decrease in other liabilities									(11,830)	(19,033)	(2,519)
Net cash from operating activities									101,303	38,667	61,463
Cash Flows From Investing Activities
Net cash acquired (paid) in business combinations									(107,622)	(45,267)	(117,853)
Purchases of premises and equipment, net									(774)	(320)	(26)
Net cash used in investing activities									(108,396)	(45,587)	(117,879)
Cash Flows From Financing Activities
Cash dividends paid									(49,389)	(36,918)	(29,528)
Proceeds from issuance of common stock, net of issuance costs									0	0	76,175
Repayment of subordinated debt obligations									(18,558)	0	(10,310)
Repayments of other borrowings									(62,500)	0	0
Proceeds from issuance of other borrowings									125,000	25,000	0
Proceeds from directors' stock purchase plan and exercise of stock options									1,572	2,473	1,242
Cash paid for payroll taxes upon conversion of restricted stock units									(1,065)	(571)	(701)
Net cash from financing activities									(4,940)	(10,016)	36,878
Net increase (decrease) in cash and cash equivalents									(12,033)	(16,936)	(19,538)
Cash and cash equivalents at beginning of year				$ 28,884				$ 45,820	28,884	45,820	65,358
Cash and cash equivalents at end of year	$ 16,851				$ 28,884				16,851	28,884	45,820
Business combinations:
Fair value of tangible assets acquired (noncash)									46,898	10,304	1,537
Liabilities assumed									58,309	42,019	13,010
Common stock and stock options issued									$ 1,504,811	$ 159,904	$ 0

Earnings Per Common Share (Deta

Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Net Income	$ 47,168	$ 11,484	$ 25,775	$ 23,605	$ 25,504	$ 24,467	$ 19,024	$ 17,835	$ 108,032	$ 86,830	$ 62,121
Net income allocated to participating securities									166	0	0
Net income allocated to common shareholders									$ 107,866	$ 86,830	$ 62,121
Weighted average common shares - issued (in shares)									49,091,000	36,081,000	31,367,000
Average unvested restricted share awards (in shares)									(139,000)	0	0
Weighted average common shares outstanding - basic (in shares)									48,952,000	36,081,000	31,367,000
Effect of dilutive securities
Weighted average common stock equivalents (in shares)									651,000	272,000	221,000
Weighted average common shares outstanding - diluted (in shares)									49,603,000	36,353,000	31,588,000
EPS available to common shareholders
Basic earnings per common share (usd per share)	$ 0.67	$ 0.23	$ 0.67	$ 0.61	$ 0.67	$ 0.64	$ 0.54	$ 0.54	$ 2.21	$ 2.41	$ 1.98
Diluted earnings per common share (usd per share)	$ 0.66	$ 0.23	$ 0.67	$ 0.60	$ 0.66	$ 0.64	$ 0.54	$ 0.54	2.17	2.39	1.97
Schedule Of Earnings Per Share By Common Class [Line Items]
Average stock valuation (usd per share)									$ 40.58	$ 32.17	$ 29.11
Stock Option
Schedule Of Earnings Per Share By Common Class [Line Items]
Average number of exercisable employee stock option awards that were not included in the computation of diluted earnings per common share (in shares)									0	54,771	240,165

Accumulated Other Comprehens151

Accumulated Other Comprehensive Loss (Changes in Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Components of accumulated other comprehensive income (loss), net of related tax benefit/expense
Beginning balance	$ 1,015,974	$ 797,133	$ 696,500
Other comprehensive loss before reclassifications	(12,399)	1,174	(13,353)
Amounts reclassified from accumulated other comprehensive income	1,395	2,247	1,420
Net current period other comprehensive income (loss)	(11,004)	3,421	(11,933)
Ending balance	2,581,526	1,015,974	797,133
Unrealized gains (losses) on securities available-for-sale, net of tax
Components of accumulated other comprehensive income (loss), net of related tax benefit/expense
Beginning balance	(1,888)	(210)	(2,480)
Other comprehensive loss before reclassifications	(12,170)	(1,269)	2,270
Amounts reclassified from accumulated other comprehensive income	(84)	(409)	0
Net current period other comprehensive income (loss)	(12,254)	(1,678)	2,270
Ending balance	(14,142)	(1,888)	(210)
Defined Benefit Pension Plans
Components of accumulated other comprehensive income (loss), net of related tax benefit/expense
Beginning balance	(27,144)	(32,243)	(18,040)
Other comprehensive loss before reclassifications	(229)	2,443	(15,623)
Amounts reclassified from accumulated other comprehensive income	1,479	2,656	1,420
Net current period other comprehensive income (loss)	1,250	5,099	(14,203)
Ending balance	(25,894)	(27,144)	(32,243)
Total
Components of accumulated other comprehensive income (loss), net of related tax benefit/expense
Beginning balance	(29,032)	(32,453)	(20,520)
Ending balance	$ (40,036)	$ (29,032)	$ (32,453)

Accumulated Other Comprehens152

Accumulated Other Comprehensive Loss (Reclassifications Out of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gross gains									$ 325	$ 631	$ 0
Income tax (expense)/benefit	$ (18,969)	$ (2,848)	$ (10,532)	$ (9,757)	$ (10,200)	$ (9,600)	$ (9,100)	$ (8,100)	(42,106)	(37,000)	(27,500)
Net gain on sale of investment securities									129	630	0
Net Income									(1,395)	(2,247)	(1,420)
Unrealized gains (losses) on securities available-for-sale, net of tax
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net Income									84	409	0
Unrealized gains (losses) on securities available-for-sale, net of tax | Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gross gains									129	630	0
Income tax (expense)/benefit									(45)	(221)	0
Net gain on sale of investment securities									84	409	0
Amortization of defined benefit pension plan items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Salaries, wages and employee benefits (operating expenses)									(2,276)	(4,086)	(2,184)
Income tax (expense)/benefit									797	1,430	764
Net Income									$ (1,479)	$ (2,656)	$ (1,420)

Noninterest Income (Details)

Noninterest Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Noninterest Income [Abstract]
Service charges and fees on deposit accounts									$ 28,136	$ 25,481	$ 22,414
Wealth management revenue									22,601	20,552	16,015
Electronic banking fees									23,433	19,119	13,480
Mortgage banking revenue									21,859	6,133	5,041
Other fees for customer services									4,939	4,428	3,539
Insurance commissions									1,874	1,966	1,559
Gain on sale of investment securities									129	630	0
Bank owned life insurance									1,836	646	281
Rental income									592	466	145
Gain on sale of branch offices									7,391	0	0
Gain on sale of closed branch offices and other assets									0	266	0
Gain on sale of merchant card servicing business									0	0	400
Other									9,560	529	221
Total noninterest income	$ 54,264	$ 27,770	$ 20,897	$ 19,419	$ 20,052	$ 20,215	$ 20,674	$ 19,275	$ 122,350	$ 80,216	$ 63,095

Operating Expenses (Details)

Operating Expenses (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Expenses [Abstract]
Salaries and wages									$ 135,407	$ 104,490	$ 83,229
Employee benefits									29,806	23,430	19,328
Occupancy									23,525	18,213	15,842
Equipment and software									24,408	18,569	14,737
Outside processing and service fees									21,199	15,207	11,586
FDIC insurance premiums									7,407	5,485	4,307
Professional fees									5,832	4,842	3,570
Intangible asset amortization									5,524	4,389	2,029
Postage and express mail									3,777	3,313	3,418
Advertising and marketing									3,740	3,288	3,051
Training, travel and other employee expenses									4,025	3,224	2,480
Telephone									2,964	2,608	1,966
Supplies									2,318	2,216	1,897
Donations									1,951	1,375	1,155
Credit-related expenses									(2,701)	632	996
Merger and acquisition-related transaction expenses									61,134	7,804	6,388
Other									8,102	4,809	3,946
Total operating expenses	$ 114,302	$ 106,144	$ 59,085	$ 58,887	$ 57,824	$ 58,265	$ 56,785	$ 51,020	$ 338,418	$ 223,894	$ 179,925

Summary of Quarterly Stateme155

Summary of Quarterly Statements of Income (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Selected Quarterly Financial Information [Abstract]
Interest income	$ 144,416	$ 103,562	$ 82,937	$ 79,464	$ 80,629	$ 78,851	$ 69,679	$ 62,630	$ 410,379	$ 291,789	$ 227,261
Interest expense	11,969	6,753	5,442	5,134	5,153	5,234	3,944	3,450	29,298	17,781	14,710
Net Interest Income	132,447	96,809	77,495	74,330	75,476	73,617	65,735	59,180	381,081	274,008	212,551
Provision for loan losses	6,272	4,103	3,000	1,500	2,000	1,500	1,500	1,500	14,875	6,500	6,100
Noninterest income	54,264	27,770	20,897	19,419	20,052	20,215	20,674	19,275	122,350	80,216	63,095
Operating expenses	114,302	106,144	59,085	58,887	57,824	58,265	56,785	51,020	338,418	223,894	179,925
Income before income taxes	66,137	14,332	36,307	33,362	35,704	34,067	28,124	25,935	150,138	123,830	89,621
Income tax expense	18,969	2,848	10,532	9,757	10,200	9,600	9,100	8,100	42,106	37,000	27,500
Net income	$ 47,168	$ 11,484	$ 25,775	$ 23,605	$ 25,504	$ 24,467	$ 19,024	$ 17,835	$ 108,032	$ 86,830	$ 62,121
Basic earnings per common share (usd per share)	$ 0.67	$ 0.23	$ 0.67	$ 0.61	$ 0.67	$ 0.64	$ 0.54	$ 0.54	$ 2.21	$ 2.41	$ 1.98
Diluted earnings per common share (usd per share)	0.66	0.23	0.67	0.60	0.66	0.64	0.54	0.54	2.17	2.39	1.97
Cash dividends declared per share (in dollars per share)	$ 0.27	$ 0.27	$ 0.26	$ 0.26	$ 0.26	$ 0.26	$ 0.24	$ 0.24	$ 1.06	$ 1	$ 0.94