Old National Bancorp (ONB) 10-K 12 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Jan. 31, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Trading Symbol	ONB
Entity Registrant Name	Old National Bancorp /IN/
Entity Central Index Key	707,179
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		175,163,000
Entity Public Float			$ 2,791,017,355

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets
Cash and due from banks	$ 284,003	$ 222,753
Money market and other interest-earning investments	33,162	67,679
Total cash and cash equivalents	317,165	290,432
Equity securities	5,582	5,584
Investment securities - available-for-sale, at fair value	4,123,416	3,196,207
Investment securities - held-to-maturity, at amortized cost (fair value $506,103 and $727,703, respectively)	506,334	684,063
Federal Home Loan Bank/Federal Reserve Bank stock, at cost	142,980	119,686
Loans held for sale, at fair value	14,911	17,930
Loans, net of unearned income	12,243,892	11,118,121
Allowance for loan losses	(55,461)	(50,381)
Net loans	12,188,431	11,067,740
Premises and equipment, net	485,912	458,074
Accrued interest receivable	89,464	87,102
Goodwill	1,036,258	828,051
Other intangible assets	77,016	53,096
Company-owned life insurance	444,224	403,753
Net deferred tax assets	87,048	110,857
Loan servicing rights	24,497	24,661
Assets held for sale	3,253	7,180
Other real estate owned and repossessed personal property	3,232	8,810
Other assets	178,712	155,066
Total assets	19,728,435	17,518,292
Deposits:
Noninterest-bearing demand	3,965,380	3,680,807
Interest-bearing:
Checking and NOW	3,788,339	3,115,822
Savings	2,944,092	3,035,622
Money market	1,627,882	1,139,077
Time	2,024,256	1,634,436
Total deposits	14,349,949	12,605,764
Federal funds purchased and interbank borrowings	270,135	335,033
Securities sold under agreements to repurchase	362,294	384,810
Federal Home Loan Bank advances	1,613,481	1,609,579
Other borrowings	247,883	248,782
Accrued expenses and other liabilities	195,123	179,927
Total liabilities	17,038,865	15,363,895
Commitments and contingencies (Note 22)
Shareholders' Equity
Preferred stock, series A, 2,000 shares authorized, no shares issued or outstanding
Common stock, $1.00 per share stated value, 300,000 shares authorized, 175,141 and 152,040 shares issued and outstanding, respectively	175,141	152,040
Capital surplus	2,031,695	1,639,499
Retained earnings	527,684	413,130
Accumulated other comprehensive income (loss), net of tax	(44,950)	(50,272)
Total shareholders' equity	2,689,570	2,154,397
Total liabilities and shareholders' equity	$ 19,728,435	$ 17,518,292

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Investment securities - held-to-maturity, fair value	$ 506,103	$ 727,703
Common stock, stated value	$ 1	$ 1
Authorized and unissued common shares reserved for issuance	300,000,000	300,000,000
Common stock, shares issued	175,141,000	152,040,000
Common stock, shares outstanding	175,141,000	152,040,000
Series A Preferred Stock [Member]
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Loans including fees:
Taxable	$ 508,293	$ 389,219	$ 349,095
Nontaxable	16,299	13,970	12,287
Investment securities:
Taxable	80,168	63,031	57,005
Nontaxable	26,655	28,858	28,617
Money market and other interest-earning investments	630	258	130
Total interest income	632,045	495,336	447,134
Interest Expense
Deposits	41,277	20,356	17,283
Federal funds purchased and interbank borrowings	4,793	1,966	673
Securities sold under agreements to repurchase	1,962	1,270	1,509
Federal Home Loan Bank advances	34,925	24,818	15,547
Other borrowings	11,486	9,758	9,419
Total interest expense	94,443	58,168	44,431
Net interest income	537,602	437,168	402,703
Provision for loan losses	6,966	3,050	960
Net interest income after provision for loan losses	530,636	434,118	401,743
Noninterest Income
Wealth management fees	36,863	37,316	34,641
Service charges on deposit accounts	44,026	41,331	41,578
Debit card and ATM fees	20,216	17,676	16,769
Mortgage banking revenue	17,657	18,449	20,240
Insurance premiums and commissions	399	617	20,527
Investment product fees	20,539	20,977	18,822
Capital markets income	4,934	6,544	3,227
Company-owned life insurance	10,584	8,654	8,479
Net securities gains (losses)	2,060	9,135	5,848
Recognition of deferred gain on sale leaseback transactions	1,577	2,080	16,057
Net gain on branch divestitures	13,989
Gain on sale of ONB Insurance Group, Inc.			41,864
Other income	22,461	20,603	24,778
Total noninterest income	195,305	183,382	252,830
Noninterest Expense
Salaries and employee benefits	281,275	246,738	252,892
Occupancy	51,941	46,511	50,947
Equipment	14,861	13,560	13,448
Marketing	15,847	13,172	14,620
Data processing	36,170	32,306	32,002
Communication	10,846	9,284	9,959
Professional fees	14,503	16,840	15,705
Loan expense	7,028	6,596	7,632
Supplies	3,037	2,406	2,865
FDIC assessment	10,638	9,480	8,681
Other real estate owned expense	878	3,376	4,195
Amortization of intangibles	14,442	11,841	12,486
Amortization of tax credit investments	22,949	11,733
Other expense	32,846	24,993	28,715
Total noninterest expense	517,261	448,836	454,147
Income before income taxes	208,680	168,664	200,426
Income tax expense	17,850	72,939	66,162
Net income	$ 190,830	$ 95,725	$ 134,264
Net income per common share - basic	$ 1.23	$ 0.69	$ 1.05
Net income per common share - diluted	$ 1.22	$ 0.69	$ 1.05
Weighted average number of common shares outstanding - basic	155,675	137,821	127,705
Weighted average number of common shares outstanding - diluted	156,539	138,513	128,301
Dividends per common share	$ 0.52	$ 0.52	$ 0.52

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 190,830	$ 95,725	$ 134,264
Change in debt securities available-for-sale:
Unrealized holding gains (losses) for the period	(4,769)	14,259	(49,813)
Reclassification for securities transferred to held-to-maturity	14,007	0	0
Reclassification adjustment for securities gains realized in income	(2,060)	(9,135)	(5,848)
Income tax effect	(1,386)	(1,669)	20,455
Unrealized gains (losses) on available-for-sale debt securities	5,792	3,455	(35,206)
Change in securities held-to-maturity:
Adjustment for securities transferred to available-for-sale	19,412	0	0
Adjustment for securities transferred from available-for-sale	(14,007)	0	0
Amortization of unrealized losses on securities transferred from available-for-sale	2,181	1,830	1,776
Income tax effect	(1,394)	(627)	(606)
Changes from securities held-to-maturity	6,192	1,203	1,170
Cash flow hedges:
Net unrealized derivative gains (losses) on cash flow hedges	5,145	927	(2,323)
Reclassification adjustment for (gains) losses realized in net income	150	6,135	6,453
Income tax effect	(1,298)	(2,684)	(1,569)
Changes from cash flow hedges	3,997	4,378	2,561
Defined benefit pension plans:
Amortization of net loss and settlement cost recognized in income	191	159	11,203
Income tax effect	(47)	(95)	(4,303)
Changes from defined benefit pension plans	144	64	6,900
Other comprehensive income (loss), net of tax	16,125	9,100	(24,575)
Comprehensive income	$ 206,955	$ 104,825	$ 109,689

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	AnchorBank WI [Member]	Minnesota-based Klein [Member]	Common Stock [Member]	Common Stock [Member]Minnesota-based Klein [Member]	Capital Surplus [Member]	Capital Surplus [Member]Minnesota-based Klein [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Other Comprehensive Income (Loss) [Member]AnchorBank WI [Member]
Beginning Balance at Dec. 31, 2015	$ 1,491,170			$ 114,297		$ 1,087,911		$ 323,759	$ (34,797)
Net income	134,264							134,264
Other comprehensive income (loss)	(24,575)	$ (24,575)								$ (24,575)
Acquisition	273,565	$ 273,565		20,415		253,150
Dividends - common stock	(67,536)							(67,536)
Common stock issued	388			32		356
Common stock repurchased	(2,044)			(154)		(1,890)
Share-based compensation expense	7,318					7,318
Stock activity under incentive compensation plans	1,867			569		1,493		(195)
Ending Balance at Dec. 31, 2016	1,814,417			135,159		1,348,338		390,292	(59,372)
Net income	95,725							95,725
Other comprehensive income (loss)	9,100								9,100
Acquisition	300,828			16,527		284,301
Dividends - common stock	(72,604)							(72,604)
Common stock issued	404			24		380
Common stock repurchased	(2,761)			(153)		(2,608)
Share-based compensation expense	6,275					6,275
Stock activity under incentive compensation plans	3,013			483		2,813		(283)
Ending Balance at Dec. 31, 2017	2,154,397			152,040		1,639,499		413,130	(50,272)
Cumulative effect of change in accounting principles (Note 1)	(4,179)							(4,127)	(52)
Balance, January 1, 2018	2,150,218			152,040		1,639,499		409,003	(50,324)
Reclassification of certain tax effects related to the Tax Cuts and Jobs Act of 2017 (Note 1)								10,751	(10,751)
Net income	190,830							190,830
Other comprehensive income (loss)	16,125								16,125
Acquisition			$ 406,474		$ 22,772		$ 383,702
Dividends - common stock	(82,161)							(82,161)
Common stock issued	497			29		468
Common stock repurchased	(1,805)			(104)		(1,701)
Share-based compensation expense	8,118					8,118
Stock activity under incentive compensation plans	1,274			404		1,609		(739)
Ending Balance at Dec. 31, 2018	$ 2,689,570			$ 175,141		$ 2,031,695		$ 527,684	(44,950)
Cumulative effect of change in accounting principles (Note 1)									$ (52)

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Stockholders Equity [Abstract]
Dividends per common share	$ 0.52	$ 0.52	$ 0.52

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows From Operating Activities
Net income	$ 190,830	$ 95,725	$ 134,264
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	23,773	22,183	16,558
Amortization of other intangible assets	14,442	11,841	12,486
Amortization of tax credit investments	22,949	11,733
Net premium amortization on investment securities	14,384	15,302	18,633
Accretion income related to acquired loans	(40,598)	(40,576)	(57,244)
Share-based compensation expense	8,118	6,275	7,318
Excess tax (benefit) expense on share-based compensation	401	79
Provision for loan losses	6,966	3,050	960
Net securities (gains) losses	(2,060)	(9,135)	(5,848)
Recognition of deferred gain on sale leaseback transactions	(1,577)	(2,080)	(16,057)
Gain on sale of ONB Insurance Group, Inc.			(41,864)
Net gain on branch divestitures	(13,989)
Net (gains) losses on sales of loans and other assets	(2,290)	(6,421)	(4,741)
Increase in cash surrender value of company-owned life insurance	(10,584)	(8,654)	(8,479)
Residential real estate loans originated for sale	(501,999)	(452,604)	(637,639)
Proceeds from sale of residential real estate loans	514,891	535,271	578,653
(Increase) decrease in interest receivable	2,038	151	(4,974)
(Increase) decrease in other real estate owned	6,532	10,794	11,301
(Increase) decrease in other assets	2,046	45,008	46,004
Increase (decrease) in accrued expenses and other liabilities	134	12,141	(24,524)
Total adjustments	43,577	154,358	(109,457)
Net cash flows provided by (used in) operating activities	234,407	250,083	24,807
Cash Flows From Investing Activities
Cash portion of bank purchase price, net of cash acquired	60,759	2,564	(62,532)
Payments related to branch divestitures	(210,659)
Proceeds from sale of ONB Insurance Group, Inc.			91,771
Purchases of investment securities available-for-sale	(663,338)	(874,555)	(1,625,746)
Purchases of Federal Home Loan Bank/Federal Reserve Bank stock	(23,066)	(17,979)	(10,974)
Proceeds from maturities, prepayments, and calls of investment securities available-for-sale	419,270	438,818	1,177,130
Proceeds from sales of investment securities available-for-sale	139,364	342,233	243,312
Proceeds from maturities, prepayments, and calls of investment securities held-to-maturity	55,520	57,682	120,954
Proceeds from sales of Federal Home Loan Bank/Federal Reserve Bank stock	2,409	6,594
Proceeds from sales of equity securities	128	127
Proceeds from sale of student loan portfolio	70,674
Reimbursements under FDIC loss share agreements			10,000
Net principal collected from (loans made to) loan customers	(102,928)	(475,519)	(370,442)
Proceeds from settlements on company-owned life insurance	6,501	2,347	4,095
Proceeds from sale of premises and equipment and other assets	7,341	18,592	6,332
Purchases of premises and equipment and other assets	(33,391)	(37,303)	(224,659)
Net cash flows provided by (used in) investing activities	(271,416)	(536,399)	(640,759)
Cash Flows From Financing Activities
Deposits	261,551	85,062	489,680
Federal funds purchased and interbank borrowings	(64,898)	76,430	(78,087)
Securities sold under agreements to repurchase	(41,997)	(5,207)	(23,489)
Other borrowings	(1,505)	(20,056)	(67)
Payments for maturities of Federal Home Loan Bank advances	(1,001,888)	(947,694)	(594,541)
Proceeds from Federal Home Loan Bank advances	995,000	1,205,000	925,000
Cash dividends paid on common stock	(82,161)	(72,604)	(67,536)
Common stock repurchased	(1,805)	(2,761)	(2,044)
Proceeds from exercise of stock options	948	2,655	2,349
Common stock issued	497	404	388
Net cash flows provided by (used in) financing activities	63,742	321,229	651,653
Net increase (decrease) in cash and cash equivalents	26,733	34,913	35,701
Cash and cash equivalents at beginning of period	290,432	255,519	219,818
Cash and cash equivalents at end of period	$ 317,165	$ 290,432	$ 255,519

Nature of Operations

Nature of Operations	12 Months Ended
	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Operations	NATURE OF OPERATIONS Old National Bancorp, a financial holding company headquartered in Evansville, Indiana, operates primarily in Indiana, Kentucky, Michigan, Wisconsin, and Minnesota. Its principal subsidiary is Old National Bank. Through its bank and non-bank affiliates, Old National Bancorp provides to its clients an array of financial services including loan, deposit, wealth management, investment consulting, and investment products.

Basis of Presentation and Signi

Basis of Presentation and Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	NOTE 1 – BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying consolidated financial statements include the accounts of Old National Bancorp and its wholly-owned affiliates (hereinafter collectively referred to as “Old National”) and have been prepared in conformity with accounting principles generally accepted in the United States of America and prevailing practices within the banking industry. Such principles require management to make estimates and assumptions that affect the reported amounts of assets, liabilities and the disclosures of contingent assets and liabilities at the date of the financial statements and amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. All significant intercompany transactions and balances have been eliminated. Certain prior year amounts have been reclassified to conform to the 2018 presentation. Such reclassifications had no effect on net income or shareholders’ equity and were insignificant amounts. Equity Securities Equity securities consist of mutual funds held in trusts associated with deferred compensation plans for former directors and executives. These mutual funds are recorded as equity securities at fair value. Gains and losses are included in net securities gains. Investment Securities Old National classifies debt investment securities as available-for-sale or held-to-maturity on the date of purchase. Debt securities classified as available-for-sale are recorded at fair value with the unrealized gains and losses, net of tax effect, recorded in other comprehensive income. Realized gains and losses affect income and the prior fair value adjustments are reclassified within shareholders’ equity. Debt securities classified as held-to-maturity, which management has the intent and ability to hold to maturity, are reported at amortized cost. Premiums and discounts are amortized on the level-yield method. Anticipated prepayments are considered when amortizing premiums and discounts on mortgage backed securities. Gains and losses on the sale of available-for-sale debt securities are determined using the specific-identification method. Equity investments are measured at fair value with changes in fair value recognized in net income. Other-Than-Temporary Impairment – Management evaluates debt securities for OTTI at least on a quarterly basis, and more frequently when economic or market conditions warrant such evaluation. Consideration is given to (1) the length of time and the extent to which the fair value has been less than cost, (2) the financial condition and near-term prospects of the issuer including an evaluation of credit ratings, (3) whether the market decline was affected by macroeconomic conditions, (4) the intent of Old National to sell a debt security, and (5) whether it is more likely than not Old National will have to sell the debt security before recovery of its cost basis. If Old National intends to sell an impaired debt security, Old National records an other-than-temporary loss in an amount equal to the entire difference between fair value and amortized cost. If a debt security is determined to be other-than-temporarily impaired, but Old National does not intend to sell the debt security and it is not more likely than not that it will be required to sell the debt security, only the credit portion of the estimated loss is recognized in earnings, with the other portion of the loss recognized in other comprehensive income. See Note 3 to the consolidated financial statements for a detailed description of the quarterly evaluation process. Federal Home Loan Bank Stock Old National is a member of the FHLB system. Members are required to own a certain amount of stock based on the level of borrowings and other factors and may invest in additional amounts. FHLB stock is carried at cost, classified as a restricted security, and periodically evaluated for impairment based on ultimate recovery of par value. Both cash and stock dividends are reported as income. Loans Held for Sale Loans that Old National has originated with an intent to sell are classified as loans held for sale and are recorded in accordance with FASB ASC 825-10 at fair value, determined individually, as of the balance sheet date. The loan’s fair value includes the servicing value of the loans as well as any accrued interest. Loans Loans that Old National intends to hold for investment purposes are classified as portfolio loans. Portfolio loans are carried at the principal balance outstanding, net of earned interest, purchase premiums or discounts, deferred loan fees and costs, and an allowance for loan losses. Interest income is accrued on the principal balances of loans outstanding. For all loan classes, a loan is generally placed on nonaccrual status when principal or interest becomes 90 days past due unless it is well secured and in the process of collection, or earlier when concern exists as to the ultimate collectibility of principal or interest. Interest accrued during the current year on such loans is reversed against earnings. Interest accrued in the prior year, if any, is charged to the allowance for loan losses. Cash interest received on these loans is applied to the principal balance until the principal is recovered or until the loan returns to accrual status. Loans may be returned to accrual status when all the principal and interest amounts contractually due are brought current, remain current for a prescribed period, and future payments are reasonably assured. Purchased loans acquired in a business combination are recorded at estimated fair value on their purchase date with no carryover of the related allowance for loan and lease losses. In determining the estimated fair value of purchased loans, management considers a number of factors including, among others, the remaining life of the acquired loans, estimated prepayments, estimated loss ratios, estimated value of the underlying collateral, and net present value of cash flows expected to be received. Purchased loans are accounted for in accordance with guidance for certain loans acquired in a transfer (ASC 310-30), when the loans have evidence of credit deterioration since origination and it is probable at the date of acquisition that the acquirer will not collect all contractually required principal and interest payments. The difference between contractually required payments and the cash flows expected to be collected at acquisition is referred to as the non-accretable difference. Subsequent decreases to the expected cash flows will generally result in a provision for loan and lease losses. Subsequent increases in expected cash flows will result in a reversal of the provision for loan losses to the extent of prior charges and then an adjustment to accretable yield, which would have a positive impact on interest income. Allowance for Loan Losses The allowance for loan losses is maintained at a level believed adequate by management to absorb probable losses incurred in the consolidated loan portfolio. Management’s evaluation of the adequacy of the allowance is an estimate based on reviews of individual loans, pools of homogeneous loans, assessments of the impact of current and anticipated economic conditions on the portfolio, and historical loss experience. The allowance is increased through a provision charged to operating expense. Loans deemed to be uncollectible are charged to the allowance. Recoveries of loans previously charged-off are added to the allowance. For all loan classes, a loan is considered impaired when it is probable that contractual interest and principal payments will not be collected either for the amounts or by the dates as scheduled in the loan agreement. If a loan is impaired, a portion of the allowance is allocated so that the loan is reported net, at the present value of estimated cash flows using the loan’s existing rate or at the fair value of collateral if repayment is expected solely from the collateral. Old National’s policy, for all but PCI loans, is to recognize interest income on impaired loans unless the loan is placed on nonaccrual status. Acquired loans accounted for under ASC Topic 310-30 accrue interest, even though they may be contractually past due, as any nonpayment of contractual principal or interest is considered in the periodic re-estimation of expected cash flows and is included in the resulting recognition of current period loan loss provision or prospective yield adjustments. Old National charges off small commercial loans scored through our small business credit center with contractual balances under $250,000 that are 90 days For all portfolio segments, the general component covers non-impaired loans and is based on historical loss experience adjusted for current factors. This actual loss experience is supplemented with other economic factors based on the risks present for each portfolio segment. These economic factors include consideration of the following: levels of and trends in delinquencies and impaired loans; levels of and trends in charge-offs and recoveries; trends in volume and terms of loans; effects of any changes in risk selection and underwriting standards; other changes in lending policies, procedures, and practices; experience, ability, and depth of lending management and other relevant staff; national and local economic trends and conditions; industry conditions; and effects of changes in credit concentrations. Further information regarding Old National’s policies and methodology used to estimate the allowance for loan losses is presented in Note 5. Premises and Equipment Premises and equipment are stated at cost less accumulated depreciation. Land is stated at cost. Depreciation is charged to operating expense over the useful lives of the assets, principally on the straight-line method. Useful lives for premises and equipment are as follows: buildings and building improvements – 15 to 39 years; and furniture and equipment – 3 to 7 years. Leasehold improvements are depreciated over the lesser of their useful lives or the term of the lease. Maintenance and repairs are expensed as incurred while major additions and improvements are capitalized. Interest costs on construction of qualifying assets are capitalized. Premises and equipment are reviewed for impairment when events indicate their carrying amount may not be recoverable from future undiscounted cash flows. If impaired, the assets are adjusted to fair value. Such impairments are included in other expense. Goodwill and Other Intangible Assets The excess of the cost of acquired entities over the fair value of identifiable assets acquired less liabilities assumed is recorded as goodwill. In accordance with FASB ASC 350, Intangibles – Goodwill and Other Company-Owned Life Insurance Old National has purchased, as well as obtained through acquisitions, life insurance policies on certain key executives. Old National records company-owned life insurance at the amount that can be realized under the insurance contract at the balance sheet date, which is the cash surrender value adjusted for other charges or other amounts due that are probable at settlement. Loan Servicing Rights When loans are sold with servicing retained, servicing rights are initially recorded at fair value with the income statement effect recorded in gain on sales of loans. Fair value is based on market prices for comparable servicing contracts, when available or alternatively, is based on a valuation model that calculates the present value of estimated future net servicing income. All classes of servicing assets are subsequently measured using the amortization method which requires servicing rights to be amortized into noninterest income in proportion to, and over the period of, the estimated future net servicing income of the underlying loans. Loan servicing rights are evaluated for impairment based upon the fair value of the rights as compared to carrying amount. Impairment is determined by stratifying rights into groupings based on predominant risk characteristics, such as interest rate, loan type, term, and investor type. Impairment is recognized through a valuation allowance for an individual grouping, to the extent that fair value is less than the carrying amount. If Old National later determines that all or a portion of the impairment no longer exists for a particular grouping, a reduction of the allowance may be recorded as an increase to income. Changes in valuation allowances are reported with mortgage banking revenue on the income statement. The fair values of servicing rights are subject to significant fluctuations as a result of changes in estimated and actual prepayment speeds and default rates and losses. Servicing fee income, which is reported on the income statement as mortgage banking revenue, is recorded for fees earned for servicing loans. The fees are based on a contractual percentage of the outstanding principal , or a fixed amount per loan and are recorded as income when earned. Derivative Financial Instruments As part of Old National’s overall interest rate risk management, Old National uses derivative instruments, including TBA The accrued net settlements on derivatives that qualify for hedge accounting are recorded in interest income or interest expense, consistent with the item being hedged. Old National formally documents all relationships between hedging instruments and hedged items, as well as its risk-management objective and strategy for undertaking various hedge transactions. This process includes linking all derivative instruments that are designated as fair-value or cash-flow hedges to specific assets and liabilities on the balance sheet or to specific firm commitments or forecasted transactions. Old National also formally assesses, both at the hedge’s inception and on an ongoing basis, whether the derivative instruments that are used in hedging transactions are highly effective in offsetting changes in fair values or cash flows of hedged items. Old National discontinues hedge accounting prospectively when it is determined that (1) the derivative is no longer effective in offsetting changes in the fair value or cash flows of the hedged item; (2) the derivative expires, is sold, or terminated; (3) the derivative instrument is de-designated as a hedge because the forecasted transaction is no longer probable of occurring; (4) a hedged firm commitment no longer meets the definition of a firm commitment; (5) or management otherwise determines that designation of the derivative as a hedging instrument is no longer appropriate. When hedge accounting is discontinued, the future changes in fair value of the derivative are recorded as noninterest income. When a fair value hedge is discontinued, the hedged asset or liability is no longer adjusted for changes in fair value and the existing basis adjustment is amortized or accreted over the remaining life of the asset or liability. When a cash flow hedge is discontinued but the hedged cash flows or forecasted transaction is still expected to occur, changes in value that were accumulated in other comprehensive income are amortized or accreted into earnings over the same periods which the hedged transactions will affect earnings. Old National enters into various stand-alone mortgage-banking derivatives in order to hedge the risk associated with the fluctuation of interest rates. Changes in fair value are recorded as mortgage banking revenue. Old National also enters into various stand-alone derivative contracts to provide derivative products to customers which are carried at fair value with changes in fair value recorded as other noninterest income. Old National is exposed to losses if a counterparty fails to make its payments under a contract in which Old National is in the net receiving position. Old National anticipates that the counterparties will be able to fully satisfy their obligations under the agreements. In addition, Old National obtains collateral above certain thresholds of the fair value of its hedges for each counterparty based upon their credit standing. All of the contracts to which Old National is a party settle monthly, quarterly, or semiannually. Further, Old National has netting agreements with the dealers with which it does business. Credit-Related Financial Instruments In the ordinary course of business, Old National’s affiliate bank has entered into credit-related financial instruments consisting of commitments to extend credit, commercial letters of credit, and standby letters of credit. The notional amount of these commitments is not reflected in the consolidated financial statements until they are funded. Repossessed Collateral Other real estate owned and repossessed personal property are initially recorded at the fair value of the property less estimated cost to sell. Physical possession of residential real estate property collateralizing a consumer mortgage loan occurs when legal title is obtained upon completion of foreclosure or when the borrower conveys all interest in the property to satisfy the loan through the completion of a deed in lieu of foreclosure or through a similar legal agreement Any excess recorded investment over the fair value of the property received is charged to the allowance for loan losses. Any subsequent write-downs are recorded in noninterest expense, as are the costs of operating the properties. Gains or losses resulting from the sale of collateral are recognized in noninterest expense at the date of sale. Securities Purchased Under Agreements to Resell and Securities Sold Under Agreements to Repurchase We purchase certain securities, generally U.S. government-sponsored entity and agency securities, under agreements to resell. The amounts advanced under these agreements represent short-term secured loans and are reflected as assets in the accompanying consolidated balance sheets. We also sell certain securities under agreements to repurchase. These agreements are treated as collateralized financing transactions. These secured borrowings are reflected as liabilities in the accompanying consolidated balance sheets and are recorded at the amount of cash received in connection with the transaction. Short-term securities sold under agreements to repurchase generally mature within one to four days from the transaction date. Securities, generally U.S. government and federal agency securities, pledged as collateral under these financing arrangements can be repledged by the secured party. Additional collateral may be required based on the fair value of the underlying securities. Net Income per Share Basic and diluted net income per share are calculated using the two-class method. Net income is divided by the weighted-average number of common shares outstanding during the period. Adjustments to the weighted average number of common shares outstanding are made only when such adjustments will dilute net income per common share. Net income is then divided by the weighted-average number of common shares and common share equivalents during the period. The following table reconciles basic and diluted net income per share for the years ended December 31. (dollars and shares in thousands, Years Ended December 31, except per share data) 2018 2017 2016 Basic Net Income Per Share Net income $ 190,830 $ 95,725 $ 134,264 Weighted average common shares outstanding 155,675 137,821 127,705 Basic Net Income Per Share $ 1.23 $ 0.69 $ 1.05 Diluted Net Income Per Share Net income $ 190,830 $ 95,725 $ 134,264 Weighted average common shares outstanding 155,675 137,821 127,705 Effect of dilutive securities: Restricted stock 796 599 543 Stock options (1) 68 93 53 Weighted average shares outstanding 156,539 138,513 128,301 Diluted Earnings Per Share $ 1.22 $ 0.69 $ 1.05 (1) Options to purchase 14 thousand shares, 0.1 million shares, and 0.5 million shares outstanding at December 31, 2018, 2017, and 2016, respectively, were not included in the computation of net income per diluted share because the exercise price of these options was greater than the average market price of the common shares and, therefore, the effect would be antidilutive. Share-Based Compensation Compensation cost is recognized for stock options and restricted stock awards and units issued to employees based on the fair value of these awards at the date of grant. A Black-Scholes model is utilized to estimate the fair value of stock options, while the market price of our Common Stock at the date of grant is used for restricted stock awards. A third party provider is used to value certain restricted stock units where the performance measure is based on total shareholder return. Compensation expense is recognized over the requisite service period. Forfeitures are recognized as they occur. Income Taxes Income tax expense is the total of the current year income tax due or refundable and the change in deferred tax assets and liabilities. Deferred tax assets and liabilities are the expected future tax amounts for the temporary differences between carrying amounts and tax bases of assets and liabilities, computed using enacted tax rates. A valuation allowance, if needed, reduces deferred tax assets to the amount expected to be realized. We recognize a tax position as a benefit only if it is “more likely than not” that the tax position would be sustained in a tax examination, with a tax examination being presumed to occur. The amount recognized is the largest amount of tax benefit that is greater than 50% likely of being realized on examination. For tax positions not meeting the “more likely than not” test, no tax benefit is recorded. We recognize interest and/or penalties related to income tax matters in income tax expense. Old National is a limited partner in several tax-advantaged limited partnerships whose purpose is to invest in approved qualified affordable housing, renewable energy, or other renovation or community revitalization projects. These investments are included in other assets on the balance sheet, with any unfunded commitments included with other liabilities. Certain of these assets qualify for the proportional amortization method and are amortized over the period that Old National expects to receive the tax credits, with the expense included within income tax expense on the consolidated statements of income. The other investments are accounted for under the equity method, with the expense included within pre-tax income on the consolidated statements of income. All of our tax credit investments are evaluated for impairment at the end of each reporting period. Loss Contingencies Loss contingencies, including claims and legal actions arising in the normal course of business, are recorded as liabilities when the likelihood of loss is probable and an amount or range of loss can be reasonably estimated. See Note 22 to the consolidated financial statements for further disclosure. Cash Equivalents and Cash Flows For the purpose of presentation in the accompanying consolidated statement of cash flows, cash and cash equivalents are defined as cash, due from banks, federal funds sold and resell agreements, and money market investments, which have maturities less than 90 days. Cash flows from loans, either originated or acquired, are classified at that time according to management’s intent to either sell or hold the loan for the foreseeable future. When management’s intent is to sell the loan, the cash flows of that loan are presented as operating cash flows. When management’s intent is to hold the loan for the foreseeable future, the cash flows of that loan are presented as investing cash flows. The following table summarizes the supplemental cash flow information for the years ended December 31: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Cash payments: Interest $ 91,813 $ 56,682 $ 43,698 Income taxes (net of refunds) (2,505 ) 4,326 23,636 Noncash Investing and Financing Activities: Securities transferred from held-to-maturity to available-for-sale 447,026 — — Securities transferred from available-for-sale to held-to-maturity 323,990 — — Transfer of premises and equipment to assets held for sale 9,634 16,617 4,620 The following table summarizes the common shares issued and resultant value of total shareholders’ equity associated with acquisitions for the years ended December 31: Total Shares of Shareholders' (dollars and shares in thousands) Common Stock Equity 2018 Acquisition of Klein 22,772 $ 406,474 2017 Acquisition of Anchor (MN) 16,527 $ 300,828 2016 Acquisition of Anchor (WI) 20,415 $ 273,565 Business Combinations Old National accounts for business combinations using the acquisition method of accounting. The accounts of an acquired entity are included as of the date of acquisition, and any excess of purchase price over the fair value of the net assets acquired is capitalized as goodwill. Old National typically issues common stock and/or pays cash for an acquisition, depending on the terms of the acquisition agreement. The value of common shares issued is determined based on the market price of the stock as of the closing of the acquisition. Impact of Accounting Changes Accounting Guidance Adopted in 2018 FASB ASC 606 – On January 1, 2018, Old National adopted ASU 2014-09, Revenue from Contracts with Customers and all subsequent amendments to the ASU (collectively, “Topic 606”), which creates a single framework for recognizing revenue from contracts with customers that fall within its scope. A significant majority of Old National’s revenues come from interest income and other sources, including loans, leases, securities and derivatives, that are not subject to Topic 606. Services within the scope of Topic 606 include wealth management fees, service charges on deposit accounts, debit card and ATM fees, and investment product fees, all of which are presented within noninterest income. Old National enters into various contracts with customers to provide these traditional banking services on a routine basis. Old National’s performance obligations are generally service-related and provided on a daily, monthly, or quarterly basis. The performance obligations are generally satisfied as services are rendered and the fees are collected at such time, or shortly thereafter. It is not typical for contracts to require significant judgment to determine the transaction price. See Note 24 for additional information. Old National adopted Topic 606 using the modified retrospective method applied to all contracts not completed as of January 1, 2018. Results for reporting periods beginning after adoption are presented under Topic 606. As allowed under the update, results for prior periods continue to be reported under the accounting standards in effect for those periods. The adoption of this update did not have a material impact on the measurement, timing, or recognition of revenue. Accordingly, no cumulative effect adjustment to opening retained earnings was deemed necessary. FASB ASC 825 – In January 2016, the FASB issued an update (ASU No. 2016-01, Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities) . The amendments in this update impact public business entities as follows: (1) require equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income; (2) simplify the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment; and when a qualitative assessment indicates that impairment exists, an entity is required to measure the investment at fair value; (3) eliminate the requirement to disclose the methods and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet; (4) require entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; (5) require an entity to present separately in other comprehensive income the portion of the total change in fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments; (6) require separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (that is, securities or loans and receivables) on the balance sheet or the accompanying notes to the financial statements; and (7) clarify that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity’s other deferred tax assets. The amendments in this update became effective for annual periods and interim periods within those annual periods beginning after December 15, 2017 and did not have a material impact on the consolidated financial statements. In February 2018, the FASB issued an update (ASU No. 2018-03, Technical Corrections and Improvements to Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities) FASB ASC 740 – In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory . Current guidance prohibits the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset has been sold to an outside party. This prohibition on recognition is an exception to the principle of comprehensive recognition of current and deferred income taxes in generally accepted accounting principles. The exception has led to diversity in practice and is a source of complexity in financial reporting. FASB decided that an entity should recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. Consequently, the amendments in this update eliminate the exception for an intra-entity transfer of an asset other than inventory. The amendments in this update do not include new disclosure requirements; however, existing disclosure requirements might be applicable when accounting for the current and deferred income taxes for an intra-entity transfer of an asset other than inventory. The amendments in this update became effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within those annual reporting periods. The amendments in this update were applied on a modified retrospective basis through a cumulative-effect reduction of $ 1.0 million directly to retained earnings as of the beginning of 2018. FASB ASC 805 – In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business . The amendments in this update provide a more robust framework to use in determining when a set of assets and activities is a business. Because the current definition of a business is interpreted broadly and can be difficult to apply, stakeholders indicated that analyzing transactions is inefficient and costly and that the definition does not permit the use of reasonable judgment. The amendments provide more consistency in applying the guidance, reduce the costs of application, and make the definition of a business more operable. The amendments in this update became effective for annual periods and interim periods within those annual periods beginning after December 15, 2017. Old National has completed its evaluation of adopting the new guidance on the consolidated financial statements and there is no impact. FASB ASC 610 – In February 2017, the FASB issued ASU No. 2017-05, Other Income – Gains and Losses from the Derecognition of Nonfinancial Assets (Topic 610): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets . Subtopic 610-20 was originally issued as part of ASU No. 2014-09 to provide guidance for recognizing gains and losses from the transfer of nonfinancial assets in contracts with noncustomers. This update was issued to help clarify uncertainties and complexities of ASU 2014-09. The amendments in this update define the term in substance nonfinancial asset, in part, as a financial asset promised to a counterparty in a contract if substantially all of its fair value of the assets (recognized and

Acquisition and Divestiture Act

Acquisition and Divestiture Activity	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Acquisition and Divestiture Activity	NOTE 2 – ACQUISITION AND DIVESTITURE ACTIVITY Acquisitions Anchor Bancorp, Inc. Effective November 1, 2017, Old National completed the acquisition of St. Paul, Minnesota-based Anchor (MN) through a stock and cash merger. Anchor (MN) was a bank holding company with Anchor Bank (MN) as its wholly-owned subsidiary. Founded in 1967 and with 17 total branches, Anchor Bank (MN) was one of the largest community banks headquartered in the Twin Cities, and also served Mankato, Minnesota. Anchor Bank (MN) has no affiliation with the former AnchorBank (WI) in Madison, Wisconsin, which Old National acquired in 2016. Old National achieved cost savings by integrating the two companies and combining accounting, data processing, retail and lending support, and other administrative functions, which enabled Old National to achieve economies of scale in these areas. Pursuant to the merger agreement, each holder of Anchor (MN) common stock received $2.625 in cash and 1.350 shares of Old National Common Stock per share of Anchor (MN) common stock such holder owned. The total fair value of consideration for Anchor (MN) was $332.8 million, consisting of $31.9 million of cash and the issuance of 16.5 million shares of Old National Common Stock valued at $300.8 million. Through December 31, 2018, transaction and integration costs of $19.2 million associated with this acquisition have been expensed and remaining integration costs will be expensed in future periods as incurred. We do not anticipate additional expenses related to this acquisition. As of June 30, 2018, Old National finalized its valuation of all assets acquired and liabilities assumed, resulting in immaterial change s to acquisition accounting adjustments. A summary of the fair values of the acquired assets, liabilities assumed, and resulting goodwill follows (in thousands) : Cash and cash equivalents $ 34,501 Investment securities 302,195 FHLB/Federal Reserve Bank stock 6,585 Loans held for sale 1,407 Loans 1,593,991 Premises and equipment 33,433 Accrued interest receivable 5,872 Other real estate owned 1,058 Company-owned life insurance 44,490 Other assets 30,036 Deposits (1,777,588 ) Federal funds purchased and interbank borrowings (45,600 ) Securities sold under agreements to repurchase (22,965 ) Other borrowings (49,257 ) Accrued expenses and other liabilities (25,784 ) Net tangible assets acquired 132,374 Definite-lived intangible assets acquired 26,606 Goodwill 173,785 Total consideration $ 332,765 Goodwill related to this acquisition will not be deductible for tax purposes. The estimated fair value of the core deposit intangible was $26.6 million and is being amortized over an estimated useful life of 10 years. Acquired loan data for Anchor (MN) can be found in the table below: (in thousands) Fair Value of Acquired Loans at Acquisition Date Gross Contractual Amounts Receivable at Acquisition Date Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected Acquired receivables subject to ASC 310-30 $ 10,555 $ 16,898 $ 4,787 Acquired receivables not subject to ASC 310-30 $ 1,583,436 $ 1,879,449 $ 87,767 Klein Financial, Inc. Effective November 1, 2018, Old National completed the acquisition of Minnesota-based Klein through a 100% stock merger. Klein was a bank holding company with KleinBank as its wholly-owned subsidiary. Founded in 1907 and headquartered in Chaska, Minnesota with 18 full-service branches, KleinBank was the largest family-owned community bank serving the Twin Cities and its western communities. Old National believes that it will be able to achieve cost savings by integrating the two companies and combining accounting, data processing, retail and lending support, and other administrative functions, which will enable Old National to achieve economies of scale in these areas. Pursuant to the merger agreement, each holder of Klein common stock received 7.92 shares of Old National Common Stock per share of Klein common stock such holder owned. The total fair value of consideration for Klein was $406.5 million, consisting of 22.8 million shares of Old National Common Stock valued at $406.5 million. Through December 31, 2018, transaction and integration costs of $14.3 million associated with this acquisition have been expensed and remaining integration costs will be expensed in future periods as incurred. The following table reflects management’s preliminary valuation of the assets acquired and liabilities assumed (in thousands): Cash and cash equivalents $ 60,759 Investment securities 697,951 FHLB/Federal Reserve Bank stock 2,637 Loans held for sale 3,371 Loans 1,049,073 Premises and equipment 33,391 Accrued interest receivable 7,896 Company-owned life insurance 36,380 Net deferred tax assets 6,500 Other real estate owned 954 Other assets 10,299 Deposits (1,713,086 ) Securities sold under agreements to repurchase (19,481 ) Accrued expenses and other liabilities (17,506 ) Net tangible assets acquired 159,138 Definite-lived intangible assets acquired 39,017 Loan servicing rights 285 Goodwill 208,034 Total consideration $ 406,474 Old National is in the process of finalizing Klein’s 2018 short-period tax return; thus, provisional measurements of goodwill, deferred income tax assets, and contingent consideration are subject to change during the measurement period. In addition, certain loan, intangible assets, and premises and equipment measurements have not been finalized and are subject to change. As Old National receives the information related to facts and circumstances that existed as of the acquisition date, we will finalize the provisional measurements recorded as of December 31, 2018. Such adjustments will be included in the allocation in the reporting period in which the final amounts are determined, not to exceed one year from the acquisition date. Goodwill related to this acquisition will not be deductible for tax purposes. The estimated fair value of the core deposit intangible was $39.0 million and is being amortized over an estimated useful life of 12 years. Acquired loan data for Klein can be found in the table below: (in thousands) Fair Value of Acquired Loans at Acquisition Date Gross Contractual Amounts Receivable at Acquisition Date Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected Acquired receivables subject to ASC 310-30 $ 11,663 $ 18,568 $ 4,521 Acquired receivables not subject to ASC 310-30 $ 1,037,410 $ 1,252,954 $ 76,534 Summary of Unaudited Pro-Forma Information The unaudited pro-forma information below for 2018 and 2017 gives effect to the Klein acquisition as if it had occurred on January 1, 2017. The pro-forma financial information is not necessarily indicative of the results of operations if the acquisition had been effective as of this date. (dollars in thousands) 2018 2017 Revenue (1) $ 819,777 $ 708,422 Income before income taxes $ 273,125 $ 183,494 (1) Net interest income plus noninterest income. Supplemental pro-forma earnings for 2018 were adjusted to exclude $14.3 million of acquisition-related costs incurred during 2018. Supplemental pro-forma earnings for 2017 were adjusted to include these charges. Divestitures On October 26, 2018, Old National in Wisconsin to Marine Credit Union of La Crosse, Wisconsin. At closing, the purchasers assumed $230.6 million in deposits and no loans. Old National recorded a net pre-tax gain of $14.0 million in the fourth quarter of 2018, which included a deposit premium of $15.0 million, . Based on an ongoing assessment of our service and delivery network, Old National consolidated 5 branches during 2016, 29 in 2017, and an additional 10 branches in 2018.

Investment Securities

Investment Securities	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Investment Securities	NOTE 3 – INVESTMENT SECURITIES The following table summarizes the amortized cost and fair value of the available-for-sale and held-to-maturity investment securities portfolio at December 31 and the corresponding amounts of unrealized gains and losses therein: Amortized Unrealized Unrealized Fair (dollars in thousands) Cost Gains Losses Value December 31, 2018 Available-for-Sale U.S. Treasury $ 5,332 $ — $ (31 ) $ 5,301 U.S. government-sponsored entities and agencies 639,458 35 (11,342 ) 628,151 Mortgage-backed securities - Agency 2,243,774 9,738 (44,217 ) 2,209,295 States and political subdivisions 932,757 11,113 (3,441 ) 940,429 Pooled trust preferred securities 13,861 — (5,366 ) 8,495 Other securities 337,435 486 (6,176 ) 331,745 Total available-for-sale securities $ 4,172,617 $ 21,372 $ (70,573 ) $ 4,123,416 Held-to-Maturity U.S. government-sponsored entities and agencies $ 73,986 $ — $ (1,627 ) $ 72,359 Mortgage-backed securities - Agency 127,120 39 (2,750 ) 124,409 States and political subdivisions 305,228 6,208 (2,101 ) 309,335 Total held-to-maturity securities $ 506,334 $ 6,247 $ (6,478 ) $ 506,103 December 31, 2017 Available-for-Sale U.S. Treasury $ 5,473 $ 83 $ (5 ) $ 5,551 U.S. government-sponsored entities and agencies 675,643 3 (11,360 ) 664,286 Mortgage-backed securities - Agency 1,704,014 1,600 (37,932 ) 1,667,682 States and political subdivisions 529,835 5,085 (4,727 ) 530,193 Pooled trust preferred securities 16,605 — (8,157 ) 8,448 Other securities 321,016 1,172 (2,141 ) 320,047 Total available-for-sale securities $ 3,252,586 $ 7,943 $ (64,322 ) $ 3,196,207 Held-to-Maturity Mortgage-backed securities - Agency $ 6,903 $ 153 $ — $ 7,056 States and political subdivisions 677,160 43,495 (8 ) 720,647 Total held-to-maturity securities $ 684,063 $ 43,648 $ (8 ) $ 727,703 As previously disclosed in Note 1, upon the early adoption of ASU No. 2017-12 on January 1, 2018, Old National reclassified $447.0 million in state and political subdivision securities from the held-to-maturity portfolio to the available-for-sale portfolio. Separately, on January 1, 2018, U.S. government-sponsored entities and agencies, agency mortgage-backed securities, and state and political subdivision securities with a fair value of $324.0 million were transferred from the available-for-sale portfolio to the held-to-maturity portfolio. The $10.8 million unrealized holding loss, net of tax, at the date of transfer shall continue to be reported as a separate component of shareholders’ equity and is being amortized over the remaining term of the securities as an adjustment to yield. The corresponding discount on these securities will offset this adjustment to yield as it is amortized. Proceeds from sales or calls of available-for-sale investment securities, the resulting realized gains and realized losses, and other securities gains or losses were as follows for the years ended December 31: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Proceeds from sales of available-for-sale securities $ 139,364 $ 342,233 $ 243,312 Proceeds from calls of available-for-sale securities 32,437 88,233 635,624 Total $ 171,801 $ 430,466 $ 878,936 Realized gains on sales of available-for-sale securities $ 3,259 $ 8,710 $ 5,423 Realized gains on calls of available-for-sale securities 283 29 922 Realized losses on sales of available-for-sale securities (1,469 ) (263 ) (450 ) Realized losses on calls of available-for-sale securities (63 ) (8 ) (147 ) Other securities gains (losses) (1) 50 667 100 Net securities gains $ 2,060 $ 9,135 $ 5,848 (1) Other securities gains (losses) includes net realized and unrealized gains or losses associated with equity securities and mutual funds. Investment securities pledged to secure public and other funds had a carrying value of $2.4 billion at December 31, 2018 and $1.8 billion at December 31, 2017. Equity securities, which consist of mutual funds held in trusts associated with deferred compensation plans for former directors and executives, are recorded at fair value and totaled $5.6 million at December 31, 2018 and December 31, 2017. At December 31, 2018, Old National had a concentration of investment securities issued by certain states and their political subdivisions with the following aggregate market values: $344.4 million by Indiana, which represented 12.8% of shareholders’ equity, and $176.0 million by Texas, which represented 6.5% of shareholders’ equity. Of the Indiana municipal bonds, 99% are rated “A” or better, and the remaining 1% generally represent non-rated local interest bonds where Old National has a market presence. All of the Texas municipal bonds are rated “A” or better, and the majority of issues are backed by the “AAA” rated State of Texas Permanent School Fund Guarantee Program. All of the mortgage-backed securities in the investment portfolio are residential mortgage-backed securities. The amortized cost and fair value of the investment securities portfolio are shown by expected maturity. Expected maturities may differ from contractual maturities if borrowers have the right to call or prepay obligations with or without call or prepayment penalties. Weighted average yield is based on amortized cost. At December 31, 2018 (dollars in thousands) Weighted Amortized Fair Average Maturity Cost Value Yield Available-for-Sale Within one year $ 101,077 $ 101,138 2.58 % One to five years 532,706 527,283 2.39 Five to ten years 483,510 482,231 3.22 Beyond ten years 3,055,324 3,012,764 2.94 Total $ 4,172,617 $ 4,123,416 2.89 % Held-to-Maturity Within one year $ 30,188 $ 30,352 3.96 % One to five years 34,511 35,246 3.93 Five to ten years 72,442 74,199 4.44 Beyond ten years 369,193 366,306 3.58 Total $ 506,334 $ 506,103 3.75 % The following table summarizes the available-for-sale investment securities with unrealized losses at December 31 by aggregated major security type and length of time in a continuous unrealized loss position: Less than 12 months 12 months or longer Total Fair Unrealized Fair Unrealized Fair Unrealized (dollars in thousands) Value Losses Value Losses Value Losses December 31, 2018 Available-for-Sale U.S. Treasury $ 3,829 $ (12 ) $ 1,472 $ (19 ) $ 5,301 $ (31 ) U.S. government-sponsored entities and agencies 54,701 (594 ) 519,911 (10,748 ) 574,612 (11,342 ) Mortgage-backed securities - Agency 82,289 (742 ) 1,172,984 (43,475 ) 1,255,273 (44,217 ) States and political subdivisions 99,162 (1,340 ) 151,097 (2,101 ) 250,259 (3,441 ) Pooled trust preferred securities — — 8,495 (5,366 ) 8,495 (5,366 ) Other securities 94,607 (1,965 ) 143,842 (4,211 ) 238,449 (6,176 ) Total available-for-sale $ 334,588 $ (4,653 ) $ 1,997,801 $ (65,920 ) $ 2,332,389 $ (70,573 ) December 31, 2017 Available-for-Sale U.S. Treasury $ 1,480 $ (5 ) $ — $ — $ 1,480 $ (5 ) U.S. government-sponsored entities and agencies 201,773 (1,333 ) 408,493 (10,027 ) 610,266 (11,360 ) Mortgage-backed securities - Agency 789,804 (8,692 ) 774,825 (29,240 ) 1,564,629 (37,932 ) States and political subdivisions 196,024 (1,899 ) 90,637 (2,828 ) 286,661 (4,727 ) Pooled trust preferred securities — — 8,448 (8,157 ) 8,448 (8,157 ) Other securities 61,260 (429 ) 125,517 (1,712 ) 186,777 (2,141 ) Total available-for-sale $ 1,250,341 $ (12,358 ) $ 1,407,920 $ (51,964 ) $ 2,658,261 $ (64,322 ) The following table summarizes the held-to-maturity investment securities with unrecognized losses at December 31 by aggregated major security type and length of time in a continuous unrecognized loss position: Less than 12 months 12 months or longer Total Fair Unrecognized Fair Unrecognized Fair Unrecognized (dollars in thousands) Value Losses Value Losses Value Losses December 31, 2018 Held-to-Maturity U.S. government-sponsored entities and agencies $ — $ — $ 72,359 $ (4,642 ) $ 72,359 $ (4,642 ) Mortgage-backed securities - Agency 4,335 (24 ) 119,207 (8,006 ) 123,542 (8,030 ) States and political subdivisions 24,533 (983 ) 70,022 (3,556 ) 94,555 (4,539 ) Total held-to-maturity $ 28,868 $ (1,007 ) $ 261,588 $ (16,204 ) $ 290,456 $ (17,211 ) December 31, 2017 Held-to-Maturity States and political subdivisions $ 2,309 $ (8 ) $ — $ — $ 2,309 $ (8 ) Total held-to-maturity $ 2,309 $ (8 ) $ — $ — $ 2,309 $ (8 ) The unrecognized losses on held-to-maturity investment securities presented in the table above include unrecognized losses on securities that were transferred from available-for-sale to held-to-maturity totaling $10.7 million at December 31, 2018. There were no unrecognized losses on securities that were transferred from available-for-sale to held-to-maturity at December 31, 2017. Management evaluates debt securities for OTTI at least on a quarterly basis, and more frequently when economic or market conditions warrant such an evaluation. Management considers many factors, including: (1) the length of time and the extent to which the fair value has been less than cost, (2) the financial condition and near-term prospects of the issuer, (3) whether the market decline was affected by macroeconomic conditions, and (4) whether the entity has the intent to sell the debt security or more likely than not will be required to sell the debt security before its anticipated recovery. The assessment of whether an other-than-temporary decline exists involves a high degree of subjectivity and judgment and is based on the information available to management at a point in time . When OTTI occurs, the amount of the OTTI recognized in earnings depends on whether an entity intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss. If an entity intends to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss, the OTTI shall be recognized in earnings equal to the entire difference between the investment’s amortized cost basis and its fair value at the balance sheet date. Otherwise, the OTTI shall be separated into the amount representing the credit loss and the amount related to all other factors. The amount of the total OTTI related to the credit loss is determined based on the present value of cash flows expected to be collected and is recognized in earnings. The amount of the total OTTI related to other factors shall be recognized in other comprehensive income, net of applicable taxes. The previous amortized cost basis less the OTTI recognized in earnings shall become the new amortized cost basis of the investment. We did not record OTTI in 2018, 2017, or 2016. As of December 31, 2018, Old National’s securities portfolio consisted of 2,100 securities, 791 of which were in an unrealized loss position. The unrealized losses attributable to our U.S. Treasury, U.S. government-sponsored entities and agencies, agency mortgage-backed securities, states and political subdivisions, and other securities are the result of fluctuations in interest rates. Our pooled trust preferred securities are discussed below. At December 31, 2018, we had no intent to sell any securities that were in an unrealized loss position nor is it expected that we would be required to sell any securities. Pooled Trust Preferred Securities At December 31, 2018, our securities portfolio contained two pooled trust preferred securities with a fair value of $8.5 million and unrealized losses of $5.4 million. These securities are not subject to FASB ASC 325-10 and are evaluated using collateral-specific assumptions to estimate the expected future interest and principal cash flows. For the years ended December 31, 2018 and 2017, our analysis indicated no OTTI on these securities. During the first quarter of 2018, Old National sold a pooled trust security that fell within the scope of FASB ASC 325-10 (EITF 99-20). Proceeds from the sale were $1.8 million, which resulted in a loss of $0.9 million. Although Old National typically does not sell securities in an unrealized loss position, this security was sold because the final liquidation value was significantly higher than our assessment of value for this position. The table below summarizes the relevant characteristics of our pooled trust preferred securities as well as our single issuer trust preferred securities that are included in the “other securities” category in this footnote. Each of the pooled trust preferred securities support a more senior tranche of security holders. Both pooled trust preferred securities have experienced credit defaults. However, these securities have excess subordination and are not other-than-temporarily impaired as a result of their class hierarchy, which provides more loss protection. Trust preferred securities Actual Expected Excess December 31, 2018 Deferrals Defaults as Subordination (dollars in thousands) # of Issuers and Defaults a % of as a % of Lowest Unrealized Realized Currently as a % of Remaining Current Credit Amortized Fair Gain/ Losses Performing/ Original Performing Performing Class Rating (1) Cost Value (Loss) 2018 Remaining Collateral Collateral Collateral Pooled trust preferred securities: Pretsl XXVII LTD B B 4,349 2,404 (1,945 ) $ — 33/43 17.3% 10.7% 38.8% Trapeza Ser 13A A2A BBB 9,512 6,091 (3,421 ) — 44/49 4.5% 7.2% 56.1% 13,861 8,495 (5,366 ) — Single Issuer trust preferred securities: JP Morgan Chase Cap XIII BBB- 4,788 4,500 (288 ) — 4,788 4,500 (288 ) — Total $ 18,649 $ 12,995 $ (5,654 ) $ — (1)

Loans Held for Sale

Loans Held for Sale	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Loans Held for Sale	NOTE 4 – LOANS HELD FOR SALE Mortgage loans held for immediate sale in the secondary market were $14.9 million at December 31, 2018, compared to $17.9 million at December 31, 2017. Residential loans that Old National has originated with the intent to sell are recorded at fair value in accordance with FASB ASC 825-10, Financial Instruments

Loans and Allowance for Loan Lo

Loans and Allowance for Loan Losses	12 Months Ended
	Dec. 31, 2018
Text Block [Abstract]
Loans and Allowance for Loan Losses	NOTE 5 – LOANS AND ALLOWANCE FOR LOAN LOSSES Old National’s loans consist primarily of loans made to consumers and commercial clients in various industries including manufacturing, agribusiness, transportation, mining, wholesaling, and retailing. Most of Old National’s lending activity occurs within our principal geographic markets of Indiana, Kentucky, Michigan, Wisconsin, and Minnesota. Old National manages concentrations of credit exposure by industry, product, geography, customer relationship, and loan size. While loans to lessors of both residential and non-residential real estate exceed 10% The composition of loans at December 31 by lending classification was as follows: December 31, (dollars in thousands) 2018 2017 Commercial (1) $ 3,232,970 $ 2,717,269 Commercial real estate: Construction 504,625 374,306 Other 4,454,226 3,980,246 Residential real estate 2,248,404 2,167,053 Consumer credit: Home equity 589,322 507,507 Auto 1,059,633 1,148,672 Other 154,712 223,068 Total loans 12,243,892 11,118,121 Allowance for loan losses (55,461 ) (50,381 ) Net loans $ 12,188,431 $ 11,067,740 (1) Includes direct finance leases of $60.0 million at December 31, 2018 and $29.5 million at December 31, 2017. The risk characteristics of each loan portfolio segment are as follows: Commercial Commercial loans are primarily based on the identified cash flows of the borrower and secondarily on the underlying collateral provided by the borrower. The cash flows of borrowers, however, may not be as expected and the collateral securing these loans may fluctuate in value. Most commercial loans are secured by the assets being financed or other business assets such as accounts receivable or inventory and may incorporate a personal guarantee; however, some loans may be made on an unsecured basis. In the case of loans secured by accounts receivable, the availability of funds for the repayment of these loans may be substantially dependent on the ability of the borrower to collect amounts due from its customers. Commercial Real Estate These loans are viewed primarily as cash flow loans and secondarily as loans secured by real estate. Commercial real estate lending typically involves higher loan principal amounts, and the repayment of these loans is generally dependent on the successful operation of the property securing the loan or the business conducted on the property securing the loan. Commercial real estate loans may be adversely affected by conditions in the real estate markets or in the general economy. The properties securing Old National’s commercial real estate portfolio are diverse in terms of type and geographic location. Management monitors and evaluates commercial real estate loans based on collateral, geography and risk grade criteria. In addition, management tracks the level of owner-occupied commercial real estate loans versus non-owner occupied loans. Included with commercial real estate are construction loans, which are underwritten utilizing independent appraisal reviews, sensitivity analysis of absorption and lease rates, financial analysis of the developers and property owners, and feasibility studies, if available. Construction loans are generally based on estimates of costs and value associated with the complete project. These estimates may be inaccurate. Construction loans often involve the disbursement of substantial funds with repayment substantially dependent on the success of the ultimate project. Sources of repayment for these types of loans may be pre-committed permanent loans from approved long-term lenders (including Old National), sales of developed property, or an interim loan commitment from Old National until permanent financing is obtained. These loans are closely monitored by on-site inspections and are considered to have higher risks than other real estate loans due to their ultimate repayment being sensitive to interest rate changes, governmental regulation of real property, general economic conditions, and the availability of long-term financing. The acquisition of Klein on November 1, 2018 added $559.5 million of commercial real estate loans to our portfolio. At 198%, Old National Bank’s commercial real estate loans as a percentage of its risk-based capital remained well below the regulatory guideline limit of 300% at December 31, 2018. Residential With respect to residential loans that are secured by 1-4 family residences and are generally owner occupied, Old National typically establishes a maximum loan-to-value ratio and generally requires private mortgage insurance if that ratio is exceeded. Repayment of these loans is primarily dependent on the personal income of the borrowers, which can be impacted by economic conditions in their market areas such as unemployment levels. Repayment can also be impacted by changes in residential property values. Risk is mitigated by the fact that the loans are of smaller individual amounts and spread over a large number of borrowers. Consumer Home equity loans are typically secured by a subordinate interest in 1-4 family residences, and consumer loans are secured by consumer assets such as automobiles or recreational vehicles. Some consumer loans are unsecured such as small installment loans and certain lines of credit. Repayment of these loans is primarily dependent on the personal income of the borrowers, which can be impacted by economic conditions in their market areas such as unemployment levels. Repayment can also be impacted by changes in residential property or other collateral values. Risk is mitigated by the fact that the loans are of smaller individual amounts and spread over a large number of borrowers. Old National assumed student loans in the acquisition of Anchor (WI) in May 2016. Student loans are guaranteed by the government from 97% to 100% and totaled $68.2 million at December 31, 2017. Old National sold the remaining student loan portfolio totaling $64.9 million during the second quarter of 2018, resulting in a $2.2 million gain that is included in other income on the income statement. Related Party Loans In the ordinary course of business, Old National grants loans to certain executive officers, directors, and significant subsidiaries (collectively referred to as “related parties”). Activity in related party loans during 2018 is presented in the following table: Year Ended (dollars in thousands) December 31, 2018 Balance at beginning of period $ 9,481 New loans 9,152 Repayments (8,721 ) Officer and director changes (602 ) Balance at end of period $ 9,310 Allowance for Loan Losses The allowance for loan losses is maintained at a level believed adequate by management to absorb probable losses incurred in the consolidated loan portfolio. Management’s evaluation of the adequacy of the allowance is an estimate based on reviews of individual loans, pools of homogeneous loans, assessments of the impact of current and anticipated economic conditions on the portfolio, and historical loss experience. The allowance is increased through a provision charged to operating expense. Loans deemed to be uncollectible are charged to the allowance. Recoveries of loans previously charged-off are added to the allowance. We utilize a PD and LGD model as a tool to determine the adequacy of the allowance for loan losses for performing commercial and commercial real estate loans. The PD is forecast using a transition matrix to determine the likelihood of a customer’s AQR migrating from its current AQR to any other status within the time horizon. Transition rates are measured using Old National’s own historical experience. The model assumes that recent historical transition rates will continue into the future. The LGD is defined as credit loss incurred when an obligor of the bank defaults. The sum of all net charge-offs for a particular portfolio segment are divided by all loans that have defaulted over a given period of time. The expected loss derived from the model considers the PD, LGD, and exposure at default. Additionally, qualitative factors, such as changes in lending policies or procedures, and economic business conditions are also considered. We use h istoric loss ratios adjusted for economic conditions to determine the appropriate level of allowance for residential real estate and consumer loans. No allowance was brought forward on any of the acquired loans as any credit deterioration evident in the loans was included in the determination of the fair value of the loans at the acquisition date. An allowance for loan losses will be established for any subsequent credit deterioration or adverse changes in expected cash flows. Old National’s activity in the allowance for loan losses for the years ended December 31, 2018, 2017, and 2016 was as follows: Commercial (dollars in thousands) Commercial Real Estate Residential Consumer Total 2018 Allowance for loan losses: Balance at beginning of period $ 19,246 $ 21,436 $ 1,763 $ 7,936 $ 50,381 Charge-offs (3,087 ) (879 ) (1,100 ) (7,903 ) (12,969 ) Recoveries 1,519 2,740 2,118 4,706 11,083 Provision 4,064 173 (504 ) 3,233 6,966 Balance at end of period $ 21,742 $ 23,470 $ 2,277 $ 7,972 $ 55,461 2017 Allowance for loan losses: Balance at beginning of period $ 21,481 $ 18,173 $ 1,643 $ 8,511 $ 49,808 Charge-offs (1,108 ) (3,700 ) (985 ) (6,924 ) (12,717 ) Recoveries 2,281 3,777 255 3,927 10,240 Provision (3,408 ) 3,186 850 2,422 3,050 Balance at end of period $ 19,246 $ 21,436 $ 1,763 $ 7,936 $ 50,381 2016 Allowance for loan losses: Balance at beginning of period $ 26,347 $ 15,993 $ 2,051 $ 7,842 $ 52,233 Charge-offs (5,047 ) (2,632 ) (800 ) (6,131 ) (14,610 ) Recoveries 3,102 4,763 174 3,186 11,225 Provision (2,921 ) 49 218 3,614 960 Balance at end of period $ 21,481 $ 18,173 $ 1,643 $ 8,511 $ 49,808 The following table provides Old National’s recorded investment in loans by portfolio segment at December 31, 2018 and 2017 and other information regarding the allowance: Commercial (dollars in thousands) Commercial Real Estate Residential Consumer Total December 31, 2018 Allowance for loan losses: Individually evaluated for impairment $ 6,035 $ 8,306 $ — $ — $ 14,341 Collectively evaluated for impairment 15,700 14,845 2,276 7,821 40,642 Loans acquired with deteriorated credit quality 7 319 1 151 478 Total allowance for loan losses $ 21,742 $ 23,470 $ 2,277 $ 7,972 $ 55,461 Loans and leases outstanding: Individually evaluated for impairment $ 35,410 $ 83,104 $ — $ — $ 118,514 Collectively evaluated for impairment 3,191,367 4,850,356 2,239,147 1,800,115 12,080,985 Loans acquired with deteriorated credit quality 6,193 25,391 9,257 3,552 44,393 Total loans and leases outstanding $ 3,232,970 $ 4,958,851 $ 2,248,404 $ 1,803,667 $ 12,243,892 December 31, 2017 Allowance for loan losses: Individually evaluated for impairment $ 3,424 $ 6,654 $ — $ — $ 10,078 Collectively evaluated for impairment 15,790 14,782 1,763 7,802 40,137 Loans acquired with deteriorated credit quality 32 — — 134 166 Total allowance for loan losses $ 19,246 $ 21,436 $ 1,763 $ 7,936 $ 50,381 Loans and leases outstanding: Individually evaluated for impairment $ 26,270 $ 66,061 $ — $ — $ 92,331 Collectively evaluated for impairment 2,685,847 4,266,665 2,155,750 1,874,002 10,982,264 Loans acquired with deteriorated credit quality 5,152 21,826 11,303 5,245 43,526 Total loans and leases outstanding $ 2,717,269 $ 4,354,552 $ 2,167,053 $ 1,879,247 $ 11,118,121 Credit Quality Old National’s management monitors the credit quality of its loans in an on-going manner. Internally, management assigns an AQR to each non-homogeneous commercial and commercial real estate loan in the portfolio, with the exception of certain FICO-scored small business loans. The primary determinants of the AQR are based upon the reliability of the primary source of repayment and the past, present, and projected financial condition of the borrower. The AQR will also consider current industry conditions. Major factors used in determining the AQR can vary based on the nature of the loan, but commonly include factors such as debt service coverage, internal cash flow, liquidity, leverage, operating performance, debt burden, FICO scores, occupancy, interest rate sensitivity, and expense burden. Old National uses the following definitions for risk ratings: Criticized . Special mention loans that have a potential weakness that deserves management’s close attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects for the loan or of the institution’s credit position at some future date. Classified – Substandard . Loans classified as substandard are inadequately protected by the current net worth and paying capacity of the obligor or of the collateral pledged, if any. Loans so classified have a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. They are characterized by the distinct possibility that the institution will sustain some loss if the deficiencies are not corrected. Classified – Nonaccrual . Loans classified as nonaccrual have all the weaknesses inherent in those classified as substandard, with the added characteristic that the weaknesses make collection in full, on the basis of currently existing facts, conditions, and values, in doubt. Classified – Doubtful . Loans classified as doubtful have all the weaknesses inherent in those classified as nonaccrual, with the added characteristic that the weaknesses make collection in full, on the basis of currently existing facts, conditions, and values, highly questionable and improbable. Pass rated loans are those loans that are other than criticized, classified – substandard, classified – nonaccrual, or classified – doubtful. The risk category of commercial and commercial real estate loans by class of loans at December 31, 2018 and 2017 was as follows: (dollars in thousands) Commercial Commercial Corporate Credit Exposure Real Estate - Real Estate - Credit Risk Profile by Commercial Construction Other Internally Assigned Grade 2018 2017 2018 2017 2018 2017 Grade: Pass $ 3,029,130 $ 2,577,824 $ 460,158 $ 357,438 $ 4,167,902 $ 3,762,896 Criticized 98,798 74,876 29,368 14,758 110,586 98,451 Classified - substandard 66,394 37,367 1,275 — 102,961 58,584 Classified - nonaccrual 29,003 24,798 13,824 2,110 37,441 30,108 Classified - doubtful 9,645 2,404 — — 35,336 30,207 Total $ 3,232,970 $ 2,717,269 $ 504,625 $ 374,306 $ 4,454,226 $ 3,980,246 Old National considers the performance of the loan portfolio and its impact on the allowance for loan losses. For residential and consumer loan classes, Old National also evaluates credit quality based on the aging status of the loan and by payment activity. The following table presents the recorded investment in residential and consumer loans based on payment activity at December 31, 2018 and 2017: (dollars in thousands) Consumer Home Residential Equity Auto Other December 31, 2018 Performing $ 2,223,450 $ 586,235 $ 1,057,038 $ 153,113 Nonperforming 24,954 3,087 2,595 1,599 Total $ 2,248,404 $ 589,322 $ 1,059,633 $ 154,712 December 31, 2017 Performing $ 2,144,882 $ 502,322 $ 1,145,977 $ 217,819 Nonperforming 22,171 5,185 2,695 5,249 Total $ 2,167,053 $ 507,507 $ 1,148,672 $ 223,068 Impaired Loans Large commercial credits are subject to individual evaluation for impairment. Retail credits and other small balance credits that are part of a homogeneous group are not tested for individual impairment unless they are modified as a TDR. A loan is considered impaired when it is probable that contractual interest and principal payments will not be collected either for the amounts or by the dates as scheduled in the loan agreement. If a loan is impaired, a portion of the allowance is allocated so that the loan is reported net, at the present value of estimated cash flows using the loan’s existing rate or at the fair value of collateral if repayment is expected solely from the collateral. Old National’s policy, for all but PCI loans, is to recognize interest income on impaired loans unless the loan is placed on nonaccrual status. The following table shows Old National’s impaired loans at December 31, 2018 and 2017, respectively. Only purchased loans that have experienced subsequent impairment since the date acquired (excluding loans acquired with deteriorated credit quality) are included in the table below. Unpaid Recorded Principal Related (dollars in thousands) Investment Balance Allowance December 31, 2018 With no related allowance recorded: Commercial $ 22,031 $ 22,292 $ — Commercial Real Estate - Other 41,126 41,914 — Residential 2,276 2,296 — Consumer 362 535 — With an allowance recorded: Commercial 13,379 13,432 6,035 Commercial Real Estate - Construction 13,824 13,824 1,830 Commercial Real Estate - Other 28,154 28,154 6,476 Residential 889 889 44 Consumer 2,013 2,013 101 Total $ 124,054 $ 125,349 $ 14,486 December 31, 2017 With no related allowance recorded: Commercial $ 20,557 $ 21,483 $ — Commercial Real Estate - Other 38,678 44,564 — Residential 2,443 2,464 — Consumer 1,685 2,105 — With an allowance recorded: Commercial 5,713 5,713 3,424 Commercial Real Estate - Construction 905 1,371 401 Commercial Real Estate - Other 26,478 26,902 6,253 Residential 870 870 44 Consumer 2,211 2,228 110 Total $ 99,540 $ 107,700 $ 10,232 The average balance of impaired loans for the years ended December 31, 2018, 2017, and 2016 are included in the table below. Years Ended December 31, (dollars in thousands) 2018 2017 2016 Average Recorded Investment With no related allowance recorded: Commercial $ 21,295 $ 24,780 $ 34,708 Commercial Real Estate - Other 39,902 34,632 28,793 Residential 2,305 2,415 1,355 Consumer 832 1,761 855 With an allowance recorded: Commercial 9,546 7,002 16,669 Commercial Real Estate - Construction 7,365 453 352 Commercial Real Estate - Other 27,317 26,562 20,465 Residential 840 1,012 1,074 Consumer 1,957 2,155 2,367 Total $ 111,359 $ 100,772 $ 106,638 Old National does not record interest on nonaccrual loans until principal is recovered. Interest income recognized on impaired loans during 2018, 2017, and 2016 was immaterial. For all loan classes, a loan is generally placed on nonaccrual status when principal or interest becomes 90 days past due unless it is well secured and in the process of collection, or earlier when concern exists as to the ultimate collectibility of principal or interest. Interest accrued during the current year on such loans is reversed against interest income. Interest accrued in the prior year, if any, is charged to the allowance for loan losses. Cash interest received on these loans is applied to the principal balance until the principal is recovered or until the loan returns to accrual status. Loans may be returned to accrual status when all the principal and interest amounts contractually due are brought current, remain current for a prescribed period, and future payments are reasonably assured. Loans accounted for under FASB ASC Topic 310-30 accrue interest, even though they may be contractually past due, as any nonpayment of contractual principal or interest is considered in the periodic re-estimation of expected cash flows and is included in the resulting recognition of current period loan loss provision or prospective yield adjustments. Old National’s past due loans as of December 31 were as follows: Past Due 90 Days or 30-59 Days 60-89 Days More and Total (dollars in thousands) Past Due Past Due Accruing Nonaccrual (1) Past Due Current December 31, 2018 Commercial $ 3,627 $ 279 $ 52 $ 38,648 $ 42,606 $ 3,190,364 Commercial Real Estate: Construction — — — 13,824 13,824 490,801 Other 1,633 500 40 72,777 74,950 4,379,276 Residential 25,947 3,437 258 24,954 54,596 2,193,808 Consumer: Home equity 1,434 960 456 3,087 5,937 583,385 Auto 7,091 1,903 377 2,595 11,966 1,047,667 Other 711 210 170 1,599 2,690 152,022 Total $ 40,443 $ 7,289 $ 1,353 $ 157,484 $ 206,569 $ 12,037,323 December 31, 2017 Commercial $ 986 $ 360 $ 144 $ 27,202 $ 28,692 $ 2,688,577 Commercial Real Estate: Construction — — — 2,110 2,110 372,196 Other 2,247 89 — 60,315 62,651 3,917,595 Residential 18,948 3,416 — 22,171 44,535 2,122,518 Consumer: Home equity 1,467 230 68 5,185 6,950 500,557 Auto 6,487 1,402 532 2,695 11,116 1,137,556 Other 3,967 1,514 150 5,249 10,880 212,188 Total $ 34,102 $ 7,011 $ 894 $ 124,927 $ 166,934 $ 10,951,187 (1) Includes purchased credit impaired loans of $20.5 million at December 31, 2018 and $12.6 million at December 31, 2017 that are categorized as nonaccrual for credit analysis purposes because the collection of principal or interest is doubtful. However, these loans are accounted for under FASB ASC 310-30 and accordingly treated as performing assets. Loan Participations Old National has loan participations, which qualify as participating interests, with other financial institutions. At December 31, 2018, these loans totaled $924.8 million, of which $461.7 million had been sold to other financial institutions and $463.1 million was retained by Old National. The loan participations convey proportionate ownership rights with equal priority to each participating interest holder; involve no recourse (other than ordinary representations and warranties) to, or subordination by, any participating interest holder; all cash flows are divided among the participating interest holders in proportion to each holder’s share of ownership; and no holder has the right to pledge the entire financial asset unless all participating interest holders agree. Troubled Debt Restructurings Old National may choose to restructure the contractual terms of certain loans. The decision to restructure a loan, versus aggressively enforcing the collection of the loan, may benefit Old National by increasing the ultimate probability of collection. Any loans that are modified are reviewed by Old National to identify if a TDR has occurred, which is when for economic or legal reasons related to a borrower’s financial difficulties, Old National Bank grants a concession to the borrower that it would not otherwise consider. Terms may be modified to fit the ability of the borrower to repay in line with its current financial status. The modification of the terms of such loans include one or a combination of the following: a reduction of the stated interest rate of the loan, an extension of the maturity date at a stated rate of interest lower than the current market rate of new debt with similar risk, or a permanent reduction of the recorded investment of the loan. Loans modified in a TDR are typically placed on nonaccrual status until we determine the future collection of principal and interest is reasonably assured, which generally requires that the borrower demonstrate a period of performance according to the restructured terms for six months. If we are unable to resolve a nonperforming loan issue, the credit will be charged off when it is apparent there will be a loss. For large commercial type loans, each relationship is individually analyzed for evidence of apparent loss based on quantitative benchmarks or subjectively based upon certain events or particular circumstances. Generally, Old National charges off small commercial loans scored through our small business credit center with contractual balances under $250,000 that are 90 days or more delinquent and do not have adequate collateral support. For residential and consumer loans, a charge off is recorded at the time foreclosure is initiated or when the loan becomes 120 to 180 days past due, whichever is earlier. For commercial TDRs, an allocated reserve is established within the allowance for loan losses for the difference between the carrying value of the loan and its computed value. To determine the value of the loan, one of the following methods is selected: (1) the present value of expected cash flows discounted at the loan’s original effective interest rate, (2) the loan’s observable market price, or (3) the fair value of the collateral value, if the loan is collateral dependent. The allocated reserve is established as the difference between the carrying value of the loan and the collectable value. If there are significant changes in the amount or timing of the loan’s expected future cash flows, impairment is recalculated and the valuation allowance is adjusted accordingly. When a residential or consumer loan is identified as a TDR, the loan is typically written down to its collateral value less selling costs. The following table presents activity in TDRs for the years ended December 31, 2018, 2017, and 2016: Commercial (dollars in thousands) Commercial Real Estate Residential Consumer Total 2018 Balance at beginning of period $ 12,088 $ 34,705 $ 3,315 $ 3,895 $ 54,003 (Charge-offs)/recoveries (169 ) 561 23 16 431 (Payments)/disbursements (5,188 ) (8,808 ) (450 ) (1,969 ) (16,415 ) Additions 3,544 1,213 502 432 5,691 Balance at end of period $ 10,275 $ 27,671 $ 3,390 $ 2,374 $ 43,710 2017 Balance at beginning of period $ 16,802 $ 18,327 $ 2,985 $ 2,602 $ 40,716 (Charge-offs)/recoveries 417 381 — (294 ) 504 (Payments)/disbursements (18,519 ) (11,752 ) (608 ) (981 ) (31,860 ) Additions 13,388 27,749 938 2,568 44,643 Balance at end of period $ 12,088 $ 34,705 $ 3,315 $ 3,895 $ 54,003 2016 Balance at beginning of period $ 23,354 $ 14,602 $ 2,693 $ 3,602 $ 44,251 (Charge-offs)/recoveries (1,982 ) 953 42 (6 ) (993 ) (Payments)/disbursements (19,566 ) (8,358 ) (511 ) (1,379 ) (29,814 ) Additions 14,996 11,130 761 385 27,272 Balance at end of period $ 16,802 $ 18,327 $ 2,985 $ 2,602 $ 40,716 Approximately $26.3 million of the TDRs at December 31, 2018 were included with nonaccrual loans, compared to $34.0 million at December 31, 2017. Old National has allocated specific reserves to customers whose loan terms have been modified in TDRs totaling $3.0 million at December 31, 2018 and $5.7 million at December 31, 2017. As of December 31, 2018, Old National had committed to lend an additional $4.4 million to customers with outstanding loans that are classified as TDRs. The pre-modification and post-modification outstanding recorded investments of loans modified as TDRs during t he years ended December 31, 201 8 , 201 7 , and 201 6 are the same except for when the loan modifications involve the forgiveness of principal. The following table presents loans by class modified as TDRs that occurred during the year s ended December 31, 201 8 , 201 7 , and 201 6 : Pre-modification Post-modification Number Outstanding Recorded Outstanding Recorded (dollars in thousands) of Loans Investment Investment 2018 Troubled Debt Restructuring: Commercial 6 $ 3,544 $ 3,544 Commercial Real Estate - Other 2 1,213 1,213 Residential 1 502 502 Consumer 1 432 432 Total 10 $ 5,691 $ 5,691 2017 Troubled Debt Restructuring: Commercial 11 $ 13,388 $ 13,388 Commercial Real Estate - Other 12 27,749 27,749 Residential 6 938 938 Consumer 7 2,568 2,568 Total 36 $ 44,643 $ 44,643 2016 Troubled Debt Restructuring: Commercial 20 $ 14,996 $ 14,996 Commercial Real Estate - Other 10 11,130 11,130 Residential 6 761 761 Consumer 8 385 385 Total 44 $ 27,272 $ 27,272 The TDRs that occurred during 2018 did not have a material impact on the allowance for loan losses and resulted in no charge-offs during 2018. The TDRs that occurred during 2017 increased the allowance for loan losses by $2.7 million and resulted in $0.2 million of charge-offs during 2017. The TDRs that occurred during 2016 decreased the allowance for loan losses by $2.3 million due to a change in collateral position on a large commercial loan and resulted in $0.8 million of charge-offs during 2016. A loan is considered to be in payment default once it is 90 days contractually past due under the modified terms. TDRs for which there was a payment default within twelve months following the modification during the year were insignificant in 2018, 2017, and 2016. The terms of certain other loans were modified during 2018 that did not meet the definition of a TDR. It is our process to review all classified and criticized loans that, during the period, have been renewed, have entered into a forbearance agreement, have gone from principal and interest to interest only, or have extended the maturity date. In order to determine whether a borrower is experiencing financial difficulty, an evaluation is performed of the probability that the borrower will be in payment default on its debt in the foreseeable future without the modification. The evaluation is performed under our internal underwriting policy. We also evaluate whether a concession has been granted or if we were adequately compensated through a market interest rate, additional collateral or a bona fide guarantee. We also consider whether the modification was insignificant relative to the other terms of the agreement or the delay in a payment. PCI loans are not considered impaired until after the point at which there has been a degradation of cash flows below our expected cash flows at acquisition. If a PCI loan is subsequently modified, and meets the definition of a TDR, it will be removed from PCI accounting and accounted for as a TDR only if the PCI loan was being accounted for individually. If the PCI loan is being accounted for as part of a pool, it will not be removed from the pool. As of December 31, 2018, it has not been necessary to remove any loans from PCI accounting . In general, once a modified loan is considered a TDR, the loan will always be considered a TDR, and therefore impaired, until it is paid in full, otherwise settled, sold or charged off. However, guidance also permits for loans to be removed from TDR status when subsequently restructured under these circumstances: (1) at the time of the subsequent restructuring, the borrower is not experiencing financial difficulties, and this is documented by a current credit evaluation at the time of the restructuring, (2) under the terms of the subsequent restructuring agreement, the institution has granted no concession to the borrower; and (3) the subsequent restructuring agreement includes market terms that are no less favorable than those that would be offered for a comparable new loan. For loans subsequently restructured that have cumulative principal forgiveness, the loan should continue to be measured in accordance with ASC 310-10, Receivables – Overall Troubled Debt Restructurings by Creditors, Creditor Disclosure of Troubled Debt Restructurings Purchased Credit Impaired Loans Purchased loans acquired in a business combination are recorded at estimated fair value on their purchase date with no carryover of the related allowance for loan and lease losses. In determining the estimated fair value of purchased loans, management considers a number of factors including, among others, the remaining life of the acquired loans, estimated prepayments, estimated loss ratios, estimated value of the underlying collateral, and net present value of cash flows expected to be received. Purchased loans are accounted for in accordance with guidance for certain loans acquired in a transfer (ASC 310-30), when the loans have evidence of credit deterioration since origination and it is probable at the date of acquisition that the acquirer will not collect all contractually required principal and interest payments. The difference between contractually required payments and the cash flows expected to be collected at acquisition is referred to as the non-accretable difference. Subsequent decreases to the expected cash flows will generally result in a provision for loan and lease losses. Subsequent increases in expected cash flows will result in a reversal of the provision for loan losses to the extent of prior charges and then an adjustment to accretable yield, which would have a positive impact on interest income prospectively. Old National has purchased loans for which there was, at acquisition, evidence of deterioration of credit quality since origination and it was probable, at acquisition, that all contractually required payments would not be collected. For these loans that meet the criteria of ASC 310-30 treatment, the carrying amount was as follows: December 31, (dollars in thousands) 2018 2017 Commercial $ 6,193 $ 5,152 Commercial real estate 25,391 21,826 Residential 9,257 11,303 Consumer 3,552 5,245 Carrying amount 44,393 43,526 Allowance for loan losses (478 ) (166 ) Carrying amount, net of allowance $ 43,915 $ 43,360 The outstanding balance of loans accounted for under ASC 310-30, including contractual principal, interest, fees and penalties, was $246.9 million at December 31, 2018 and $235.9 million at December 31, 2017. The accretable difference on PCI loans is the difference between the expected cash

Other Real Estate Owned

Other Real Estate Owned	12 Months Ended
	Dec. 31, 2018
Banking And Thrift [Abstract]
Other Real Estate Owned	NOTE 6 – OTHER REAL ESTATE OWNED The following table presents activity in other real estate owned for the years ended December 31, 2018 and 2017: Years Ended December 31, (dollars in thousands) 2018 2017 Balance at beginning of period $ 8,810 $ 18,546 Additions (1) 2,025 4,016 Sales (6,689 ) (11,160 ) Impairment (914 ) (2,592 ) Balance at end of period (2) $ 3,232 $ 8,810 (1) Additions in 2018 include other real estate owned of $1.0 million acquired from Klein in November 2018. Additions in 2017 include other real estate owned of $1.1 million acquired from Anchor (MN) in November 2017. (2) Includes repossessed personal property of $0.3 million at December 31, 2018 and 2017. Foreclosed residential real estate property included in the table above totaled $1.3 million at December 31, 2018 and $1.6 million at December 31, 2017. Consumer mortgage loans collateralized by residential real property that were in the process of foreclosure totaled $4.9 million at December 31, 2018 and $5.2 million at December 31, 2017.

Premises and Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Premises and Equipment	NOTE 7 – PREMISES AND EQUIPMENT The composition of premises and equipment was as follows at December 31: December 31, (dollars in thousands) 2018 2017 Land $ 79,231 $ 73,046 Buildings 365,102 343,833 Furniture, fixtures, and equipment 107,862 94,254 Leasehold improvements 42,288 38,918 Total 594,483 550,051 Accumulated depreciation (108,571 ) (91,977 ) Premises and equipment, net $ 485,912 $ 458,074 The increase in premises and equipment at December 31, 2018 was primarily due to $33.4 million of assets attributable to the Klein acquisition. Depreciation expense was $23.8 million in 2018, $22.2 million in 2017, and $16.6 million in 2016. Operating Leases Old National rents certain premises and equipment under operating leases, which expire at various dates. Many of these leases require the payment of property taxes, insurance premiums, maintenance, and other costs. In some cases, rentals are subject to increase in relation to a cost-of-living index. The leases have original terms ranging from one year and five months to twenty-five years, and Old National has the right, at its option, to extend the terms of certain leases for five additional successive terms of five years. Old National does not have any material sub-lease agreements. See Note 1 to the consolidated financial statements for details regarding new guidance in Topic 842 that will affect the accounting for these leases effective January 1, 2019. Rent expense was $17.9 million in 2018, $15.8 million in 2017, and $25.4 million in 2016. The following is a summary of future minimum lease commitments as of December 31, 2018: (dollars in thousands) 2019 $ 19,480 2020 18,416 2021 17,400 2022 15,169 2023 9,697 Thereafter 65,612 Total $ 145,774 Old National purchased 23 properties during 2016 that it had previously leased, 20 of which had deferred gains that were accelerated when the associated leases were terminated. These gains were partially offset by the recognition of deferred rent expense, cease-use liabilities, and other expense, resulting in a net gain of $12.0 million. Old National had deferred gains remaining associated with prior sale leaseback transactions totaling $6.5 million at December 31, 2018 and $8.2 million at December 31, 2017. The deferred gains were eliminated as a cumulative-effect adjustment upon adoption of the new accounting guidance in Topic 842 effective January 1, 2019. See Note 1 to the consolidated financial statements for details regarding new accounting guidance in Topic 842. Capital Leases Old National leases two branch buildings and certain equipment under capital leases. See Note 14 to the consolidated financial statements for detail regarding these leases.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	NOTE 8 – GOODWILL AND OTHER INTANGIBLE ASSETS The following table shows the changes in the carrying amount of goodwill for the years ended December 31, 2018 and 2017: Years Ended December 31, (dollars in thousands) 2018 2017 Balance at beginning of period $ 828,051 $ 655,018 Acquisitions 208,787 173,033 Divestitures (580 ) — Balance at end of period $ 1,036,258 $ 828,051 Goodwill is reviewed annually for impairment. No events or circumstances since the August 31, 2018 annual impairment test were noted that would indicate it was more likely than not a goodwill impairment exists. During 2018, Old National recorded $208.0 million of goodwill associated with the acquisition of Klein and increased goodwill associated with the acquisition of Anchor (MN) by $0.8 million. Also during 2018, Old National eliminated $0.6 million of goodwill associated with the sale of branches to Marine Credit Union. See Note 2 to the consolidated financial statements for detail regarding changes in goodwill recorded in 2017 associated with acquisitions and divestitures. The gross carrying amounts and accumulated amortization of other intangible assets at December 31, 2018 and 2017 were as follows: Gross Accumulated Net Carrying Amortization Carrying (dollars in thousands) Amount and Impairment Amount December 31, 2018 Core deposit $ 129,100 $ (57,524 ) $ 71,576 Customer trust relationships 16,547 (11,107 ) 5,440 Total intangible assets $ 145,647 $ (68,631 ) $ 77,016 December 31, 2017 Core deposit $ 108,923 $ (62,874 ) $ 46,049 Customer trust relationships 16,547 (9,533 ) 7,014 Customer loan relationships 4,413 (4,380 ) 33 Total intangible assets $ 129,883 $ (76,787 ) $ 53,096 Other intangible assets consist of core deposit intangibles and customer relationship intangibles and are being amortized primarily on an accelerated basis over their estimated useful lives, generally over a period of 5 to 15 years. During 2018, Old National increased core deposit intangibles by $39.0 million related to the Klein acquisition. Old National reviews other intangible assets for possible impairment whenever events or changes in circumstances indicate that carrying amounts may not be recoverable. No impairment charges were recorded in 2018, 2017, or 2016. Total amortization expense associated with intangible assets was $14.4 million in 2018, $11.8 million in 2017, and $12.5 million in 2016. Estimated amortization expense for future years is as follows: (dollars in thousands) 2019 $ 16,929 2020 14,091 2021 11,336 2022 9,014 2023 7,053 Thereafter 18,593 Total $ 77,016

Loan Servicing Rights

Loan Servicing Rights	12 Months Ended
	Dec. 31, 2018
Text Block [Abstract]
Loan Servicing Rights	NOTE 9 – LOAN SERVICING RIGHTS At December 31, 2018, loan servicing rights derived from loans sold with servicing retained totaled $24.5 million, compared to $24.7 million at December 31, 2017. Loans serviced for others are not reported as assets. The principal balance of loans serviced for others was $3.306 billion at December 31, 2018, compared to $3.321 billion at December 31, 2017. Approximately 99.7% of the loans serviced for others at December 31, 2018 were residential mortgage loans. Custodial escrow balances maintained in connection with serviced loans were $10.7 million at December 31, 2018 and $8.9 million at December 31, 2017. The following table summarizes the activity related to loan servicing rights and the related valuation allowance in 2018 and 2017: Years Ended December 31, (dollars in thousands) 2018 2017 Balance at beginning of period $ 24,690 $ 25,629 Additions (1) 4,264 4,206 Amortization (4,442 ) (5,145 ) Balance before valuation allowance at end of period 24,512 24,690 Valuation allowance: Balance at beginning of period (29 ) (68 ) (Additions)/recoveries 14 39 Balance at end of period (15 ) (29 ) Loan servicing rights, net $ 24,497 $ 24,661 (1) Additions in 2018 include loan servicing rights of $0.3 million acquired from Klein in November 2018. At December 31, 2018, the fair value of servicing rights was $27.4 million, which was determined using a discount rate of 12% and a weighted average prepayment speed of 119% PSA. At December 31, 2017, the fair value of servicing rights was $25.8 million, which was determined using a discount rate of 13% and a weighted average prepayment speed of 140% PSA.

Qualified Affordable Housing Pr

Qualified Affordable Housing Projects and Other Tax Credit Investments	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Qualified Affordable Housing Projects and Other Tax Credit Investments	NOTE 10 – QUALIFIED AFFORDABLE HOUSING PROJECTS AND OTHER TAX CREDIT INVESTMENTS Old National is a limited partner in several tax-advantaged limited partnerships whose purpose is to invest in approved qualified affordable housing, renewable energy, or other renovation or community revitalization projects. As of December 31, 2018, Old National expects to recover its remaining investments through the use of the tax credits that are generated by the investments. The following table summarizes Old National’s investments in qualified affordable housing projects and other tax credit investments at December 31, 2018 and 2017: (dollars in thousands) December 31, 2018 December 31, 2017 Unfunded Unfunded Investment Accounting Method Investment Commitment (1) Investment Commitment LIHTC Proportional amortization $ 28,396 $ 2,238 $ 31,183 $ 15,553 FHTC Equity 16,815 17,945 10,645 12,040 CReED Equity 17 538 704 1,502 Renewable Energy Equity 9,176 17,827 22,364 19,771 Total $ 54,404 $ 38,548 $ 64,896 $ 48,866 (1) All commitments will be paid by Old National by 2027. The following table summarizes the amortization expense and tax benefit recognized for Old National’s qualified affordable housing projects and other tax credit investments during 2018, 2017, and 2016: Tax Expense Amortization (Benefit) (dollars in thousands) Expense (1) Recognized (2) Year Ended December 31, 2018 LIHTC $ 2,585 $ (3,349 ) FHTC 9,206 (10,775 ) CReED (3) 687 (687 ) Renewable Energy 13,055 (14,566 ) Total $ 25,533 $ (29,377 ) Year Ended December 31, 2017 LIHTC $ 1,922 $ (2,666 ) FHTC 10,441 (11,348 ) CReED (3) 800 (1,074 ) Renewable Energy 492 (613 ) Total $ 13,655 $ (15,701 ) Year Ended December 31, 2016 LIHTC $ 804 $ (1,125 ) FHTC — — CReED (3) — — Total $ 804 $ (1,125 ) (1) The amortization expense for the LIHTC investments are included in our income tax expense. The amortization expense for the FHTC, CReED, and Renewable Energy tax credits are included in noninterest expense. (2) All of the tax benefits recognized are included in our income tax expense. The tax benefit recognized for the FHTC, CReED, and Renewable Energy investments primarily reflects the tax credits generated from the investments and excludes the net tax expense/benefit of the investments’ income (loss). (3) The CReED tax credit investment qualifies for an Indiana state tax credit.

Deposits

Deposits	12 Months Ended
	Dec. 31, 2018
Banking And Thrift [Abstract]
Deposits	NOTE 11 – DEPOSITS The aggregate amount of time deposits in denominations of $250,000 or more was $612.7 million at December 31, 2018 and $422.3 million at December 31, 2017. At December 31, 2018, the scheduled maturities of total time deposits were as follows: (dollars in thousands) Due in 2019 $ 1,505,694 Due in 2020 277,142 Due in 2021 109,890 Due in 2022 52,697 Due in 2023 54,637 Thereafter 24,196 Total $ 2,024,256

Securities Sold Under Agreement

Securities Sold Under Agreements to Repurchase	12 Months Ended
	Dec. 31, 2018
Transfers And Servicing [Abstract]
Securities Sold Under Agreements to Repurchase	NOTE 12 – SECURITES SOLD UNDER AGREEMENTS TO REPURCHASE Securities sold under agreements to repurchase are secured borrowings. Old National pledges investment securities to secure these borrowings. The following table presents securities sold under agreements to repurchase and related weighted-average interest rates for each of the years ended December 31: (dollars in thousands) 2018 2017 Outstanding at year-end $ 362,294 $ 384,810 Average amount outstanding 344,964 336,539 Maximum amount outstanding at any month-end 364,001 402,543 Weighted-average interest rate: During year 0.57 % 0.38 % End of year 0.75 0.49 The following table presents the contractual maturity of our secured borrowings and class of collateral pledged: At December 31, 2018 Remaining Contractual Maturity of the Agreements Overnight and Up to Greater Than (dollars in thousands) Continuous 30 Days 30-90 Days 90 days Total Repurchase Agreements: U.S. Treasury and agency securities $ 362,294 $ — $ — $ — $ 362,294 Total $ 362,294 $ — $ — $ — $ 362,294 The fair value of securities pledged to secure repurchase agreements may decline. Old National has pledged securities valued at 122% of the gross outstanding balance of repurchase agreements at December 31, 2018 to manage this risk.

Federal Home Loan Bank Advances

Federal Home Loan Bank Advances	12 Months Ended
	Dec. 31, 2018
Banking And Thrift [Abstract]
Federal Home Loan Bank Advances	NOTE 13 – FEDERAL HOME LOAN BANK ADVANCES The following table summarizes Old National Bank’s FHLB advances at December 31: December 31, (dollars in thousands) 2018 2017 FHLB advances (fixed rates 1.50% to 6.08% and variable rates 2.51% to 2.75%) maturing January 2019 to October 2028 $ 1,603,643 $ 1,610,531 ASC 815 fair value hedge and other basis adjustments 9,838 (952 ) Total other borrowings $ 1,613,481 $ 1,609,579 FHLB advances had weighted-average rates of 2.56% at December 31, 2018 and 1.55% at December 31, 2017. These borrowings are collateralized by investment securities and residential real estate loans up to 140% of outstanding debt. Contractual maturities of FHLB advances at December 31, 2018 were as follows: (dollars in thousands) Due in 2019 $ 326,474 Due in 2020 100,000 Due in 2021 20,000 Due in 2022 57,000 Due in 2023 169 Thereafter 1,100,000 ASC 815 fair value hedge and other basis adjustments 9,838 Total $ 1,613,481

Other Borrowings

Other Borrowings	12 Months Ended
	Dec. 31, 2018
Other Liabilities Disclosure [Abstract]
Other Borrowings	NOTE 14 – OTHER BORROWINGS The following table summarizes Old National’s other borrowings at December 31: December 31, (dollars in thousands) 2018 2017 Old National Bancorp: Senior unsecured notes (fixed rate 4.125%) maturing August 2024 $ 175,000 $ 175,000 Unamortized debt issuance costs related to senior unsecured bank notes (870 ) (1,026 ) Junior subordinated debentures (variable rates of 4.01% to 6.39%) maturing April 2032 to June 2037 60,310 60,310 Other basis adjustments (3,046 ) (3,585 ) Old National Bank: Capital lease obligations 5,262 5,389 Subordinated debentures (fixed rate 5.75%) 12,000 12,000 Other (773 ) 694 Total other borrowings $ 247,883 $ 248,782 Contractual maturities of other borrowings at December 31, 2018 were as follows: (dollars in thousands) Due in 2019 $ 137 Due in 2020 147 Due in 2021 160 Due in 2022 172 Due in 2023 196 Thereafter 250,382 Unamortized debt issuance costs and other basis adjustments (3,311 ) Total $ 247,883 Senior Notes In August 2014, Old National issued $175.0 million of senior unsecured notes with a 4.125% interest rate. These notes pay interest on February 15 and August 15. The notes mature on August 15, 2024. Junior Subordinated Debentures Junior subordinated debentures related to trust preferred securities are classified in “other borrowings.” With the addition of Anchor (MN) assets, these securities now qualify as Tier 2 capital for regulatory purposes, subject to certain limitations. Prior to the fourth quarter of 2017, these securities qualified as Tier 1 capital for regulatory purposes. Through various acquisitions, Old National assumed junior subordinated debenture obligations related to various trusts that issued trust preferred securities. Old National guarantees the payment of distributions on the trust preferred securities issued by the trusts. Proceeds from the issuance of each of these securities were used to purchase junior subordinated debentures with the same financial terms as the securities issued by the trusts. Old National, at any time, may redeem the junior subordinated debentures at par and, thereby cause a redemption of the trust preferred securities in whole or in part. The following table summarizes the terms of our outstanding junior subordinated debentures as of December 31, 2018: (dollars in thousands) Rate at Issuance December 31, Name of Trust Issuance Date Amount Rate 2018 Maturity Date VFSC Capital Trust I April 2002 $ 3,093 6-month LIBOR plus 3.70% 6.39% April 22, 2032 VFSC Capital Trust II October 2002 4,124 3-month LIBOR plus 3.45% 6.09% November 7, 2032 VFSC Capital Trust III April 2004 3,093 3-month LIBOR plus 2.80% 5.57% September 8, 2034 St. Joseph Capital Trust II March 2005 5,000 3-month LIBOR plus 1.75% 4.54% March 17, 2035 Anchor Capital Trust III August 2005 5,000 3-month LIBOR plus 1.55% 4.35% September 30, 2035 Tower Capital Trust 2 December 2005 8,000 3-month LIBOR plus 1.34% 4.14% December 30, 2035 Home Federal Statutory Trust I September 2006 15,000 3-month LIBOR plus 1.65% 4.44% September 15, 2036 Monroe Bancorp Capital Trust I July 2006 3,000 3-month LIBOR plus 1.60% 4.01% October 7, 2036 Tower Capital Trust 3 December 2006 9,000 3-month LIBOR plus 1.69% 4.43% March 1, 2037 Monroe Bancorp Statutory Trust II March 2007 5,000 3-month LIBOR plus 1.60% 4.39% June 15, 2037 Total $ 60,310 Subordinated Debentures On November 1, 2017, Old National assumed $12.0 million of subordinated fixed-to-floating notes related to the acquisition of Anchor (MN). The subordinated debentures have a 5.75% fixed rate of interest through October 29, 2020. From October 30, 2020 to the October 30, 2025 maturity date, the debentures have a floating rate of interest equal to the three-month LIBOR rate plus 4.356%. Capital Lease Obligations On January 1, 2004, Old National entered into a long-term capital lease obligation for a branch office building in Owensboro, Kentucky, which extends for 25 years with one renewal option for 10 years. The economic substance of this lease is that Old National is financing the acquisition of the building through the lease and accordingly, the building is recorded as an asset and the lease is recorded as a liability. The fair value of the capital lease obligation was estimated using a discounted cash flow analysis based on Old National’s current incremental borrowing rate for similar types of borrowing arrangements. On November 1, 2017, Old National assumed a capital lease obligation for a banking center in Arden Hills, Minnesota related to the acquisition of Anchor (MN). The remaining base term of the lease is five years with one renewal option of ten years. For purposes of measuring the lease obligation, we determined that we would be “reasonably assured” to exercise the renewal option. The fair value of the capital lease obligation was estimated using a discounted cash flow analysis based on a market rate for similar types of borrowing arrangements. Based on the above assumptions, Old National measured the capital lease obligation at $1.5 million as of the date of acquisition. At December 31, 2018, the future minimum lease payments under the capital lease arrangements were as follows: (dollars in thousands) 2019 $ 589 2020 589 2021 589 2022 589 2023 599 Thereafter 8,676 Total minimum lease payments 11,631 Less amounts representing interest (6,369 ) Present value of net minimum lease payments $ 5,262 See Note 1 to the consolidated financial statements for details regarding new guidance in Topic 842 that will affect the accounting for these leases effective January 1, 2019.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	NOTE 15 – ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The following table summarizes the changes within each classification of AOCI, net of tax, for the years ended December 31, 2018, 2017, and 2016: (dollars in thousands) Unrealized Gains and Losses on Available- for-Sale Debt Securities Unrealized Gains and Losses on Held-to- Maturity Securities Gains and Losses on Cash Flow Hedges Defined Benefit Pension Plans Total 2018 Balance at beginning of period $ (35,557 ) $ (12,107 ) $ (2,337 ) $ (271 ) $ (50,272 ) Other comprehensive income (loss) before reclassifications 7,454 4,514 3,884 — 15,852 Amounts reclassified from AOCI to income (1) (1,662 ) 1,678 113 144 273 Amount reclassified from AOCI to retained earnings for cumulative effect of change in accounting principle (2) — — (52 ) — (52 ) Amounts reclassified from AOCI to retained earnings related to the Tax Cuts and Jobs Act of 2017 (3) (7,583 ) (2,600 ) (509 ) (59 ) (10,751 ) Balance at end of period $ (37,348 ) $ (8,515 ) $ 1,099 $ (186 ) $ (44,950 ) 2017 Balance at beginning of period $ (39,012 ) $ (13,310 ) $ (6,715 ) $ (335 ) $ (59,372 ) Other comprehensive income (loss) before reclassifications 9,615 — 575 — 10,190 Amounts reclassified from AOCI (1) (6,160 ) 1,203 3,803 64 (1,090 ) Balance at end of period $ (35,557 ) $ (12,107 ) $ (2,337 ) $ (271 ) $ (50,272 ) 2016 Balance at beginning of period $ (3,806 ) $ (14,480 ) $ (9,276 ) $ (7,235 ) $ (34,797 ) Other comprehensive income (loss) before reclassifications (31,513 ) — (1,440 ) — (32,953 ) Amounts reclassified from AOCI (1) (3,693 ) 1,170 4,001 6,900 8,378 Balance at end of period $ (39,012 ) $ (13,310 ) $ (6,715 ) $ (335 ) $ (59,372 ) (1) See table below for details about reclassifications. (2) See Note 1 for details about reclassification from AOCI to beginning retained earnings resulting from the adoption of ASU 2017-12. (3) See Note 1 for details about reclassification from AOCI to beginning retained earnings resulting from the adoption of ASU 2018-02. The following tables summarize the significant amounts reclassified out of each component of AOCI for the years ended December 31, 2018, 2017, and 2016: Amount Reclassified Affected Line Item in the Details about AOCI Components from AOCI Statement of Income Years Ended December 31, (dollars in thousands) 2018 2017 2016 Unrealized gains and losses on available-for-sale debt securities $ 2,060 $ 9,135 $ 5,848 Net securities gains (398 ) (2,975 ) (2,155 ) Income tax (expense) benefit $ 1,662 $ 6,160 $ 3,693 Net income Unrealized gains and losses on held-to-maturity securities $ (2,181 ) $ (1,830 ) $ (1,776 ) Interest income (expense) 503 627 606 Income tax (expense) benefit $ (1,678 ) $ (1,203 ) $ (1,170 ) Net income Gains and losses on cash flow hedges Interest rate contracts $ (150 ) $ (6,135 ) $ (6,453 ) Interest income (expense) 37 2,332 2,452 Income tax (expense) benefit $ (113 ) $ (3,803 ) $ (4,001 ) Net income Amortization of defined benefit pension items Actuarial gains (losses) and settlement cost $ (191 ) $ (159 ) $ (11,203 ) Salaries and employee benefits 47 95 4,303 Income tax (expense) benefit $ (144 ) $ (64 ) $ (6,900 ) Net income Total reclassifications for the period $ (273 ) $ 1,090 $ (8,378 ) Net income

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	NOTE 16 – INCOME TAXES Following is a summary of the major items comprising the differences in taxes from continuing operations computed at the federal statutory rate and as recorded in the consolidated statement of income: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Provision at statutory rate (1) $ 43,823 $ 59,032 $ 70,149 Tax-exempt income: Tax-exempt interest (9,021 ) (15,026 ) (14,356 ) Section 291/265 interest disallowance 321 289 191 Company-owned life insurance income (2,223 ) (3,029 ) (2,968 ) Tax-exempt income (10,923 ) (17,766 ) (17,133 ) State income taxes 5,621 998 3,461 Tax credit investments - federal (21,576 ) (8,500 ) (321 ) Revaluation of deferred tax assets — 39,300 — ONB Insurance Group, Inc. nondeductible goodwill — — 8,328 Other, net 905 (125 ) 1,678 Income tax expense $ 17,850 $ 72,939 $ 66,162 Effective tax rate 8.6 % 43.3 % 33.0 % (1) The statutory rate in effect was 21% for 2018, compared to 35% for 2017 and 2016. The lower effective tax rate in 2018 when compared 2017 is primarily the result of the lowering of the federal corporate tax rate to 21% in 2018 and an increase in federal tax credits available. The higher effective tax rate in 2017 when compared to 2016 was the result of $39.3 million of additional tax expense in 2017 to estimate the revaluation of deferred tax assets due to the lowering of the federal corporate tax rate to 21%, partially offset by an increase in federal tax credits available. On December 22, 2017, the Tax Cuts and Jobs Act (“H.R. 1”) was enacted into legislation. Under ASC 740, the effects of changes in tax rates and laws are recognized in the period in which the new legislation is enacted. Accordingly, Old National recorded an estimated $39.3 million for the revaluation of Old National’s deferred tax assets. Shortly after the enactment date, the SEC issued Staff Accounting Bulletin (“SAB”) 118, which addresses the situations where the accounting for changes in tax laws is complete, incomplete but can be reasonably estimated, and incomplete and cannot be reasonably estimated. SAB 118 also permits a measurement period of up to one year from the date of enactment to refine the provisional accounting. Old National completed its analysis of H.R. 1 during the second quarter of 2018 and there were immaterial adjustments made to the revaluation of Old National’s deferred tax assets . The provision for income taxes consisted of the following components for the years ended December 31: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Income taxes currently payable: Federal $ 12,256 $ — $ 23,735 State 4,601 — 2,242 Deferred income taxes related to: Federal (1,513 ) 31,915 35,955 Revaluation of deferred tax assets — 39,300 — State 2,506 1,724 4,230 Deferred income tax expense 993 72,939 40,185 Income tax expense $ 17,850 $ 72,939 $ 66,162 Net Deferred Tax Assets Significant components of net deferred tax assets (liabilities) were as follows at December 31: (dollars in thousands) 2018 2017 Deferred Tax Assets Allowance for loan losses, net of recapture $ 14,514 $ 12,958 Benefit plan accruals 21,694 11,080 Alternative minimum tax credit 2,545 25,084 Unrealized losses on benefit plans 61 108 Net operating loss carryforwards 31,765 39,631 Federal tax credits 1,779 5,516 Deferred gain on securities 1,976 — Other-than-temporary impairment 37 1,424 Acquired loans 26,956 29,669 Lease exit obligation 1,025 1,337 Unrealized losses on available-for-sale investment securities 11,853 14,011 Unrealized losses on held-to-maturity investment securities 2,497 3,630 Unrealized losses on hedges — 923 Tax credit investments 662 — Other real estate owned 144 369 Other, net 5,471 829 Total deferred tax assets 122,979 146,569 Deferred Tax Liabilities Accretion on investment securities (595 ) (493 ) Purchase accounting (18,100 ) (16,718 ) Loan servicing rights (6,141 ) (6,058 ) Premises and equipment (8,507 ) (10,052 ) Prepaid expenses (681 ) (1,277 ) Tax credit investments — (168 ) Unrealized gains on hedges (358 ) — Other, net (1,549 ) (946 ) Total deferred tax liabilities (35,931 ) (35,712 ) Net deferred tax assets $ 87,048 $ 110,857 Through the acquisition of Anchor (WI) in the second quarter of 2016 and Lafayette Savings Bank in the fourth quarter of 2014, both former thrifts, Old National Bank’s retained earnings at December 31, 2018 include base-year bad debt reserves, created for tax purposes prior to 1988, totaling $ 52.8 million. Of this total, $ 50.9 million was acquired from Anchor (WI) , and $ 1.9 million was acquired from Lafayette Savings Bank. Base-year reserves are subject to recapture in the unlikely event that Old National Bank (1) makes distributions in excess of current and accumulated earnings and profits, as calculated for federal income tax purposes, (2) redeems its stock, or (3) liquidates. Old National Bank has no intention of making such a nondividend distribution. Accordingly, under current accounting principles, a related deferred income tax liability of $ million has not been recognized. No valuation allowance was recorded at December 31, 2018 or 2017 because, based on current expectations, Old National believes it will generate sufficient income in future years to realize deferred tax assets. Old National has federal net operating loss carryforwards totaling $104.5 million at December 31, 2018 and $130.7 million at December 31, 2017. This federal net operating loss was acquired from the acquisition of Anchor (WI) in 2016. If not used, the federal net operating loss carryforwards will expire from 2028 to 2033. Old National has alternative minimum tax credit carryforwards totaling $10.1 million at December 31, 2018 and $25.1 million at December 31, 2017. The enactment of H.R.1 eliminates the parallel tax system known as the alternative minimum tax and allows any existing alternative minimum tax credits to be used to reduce regular tax or be refunded from 2018 to 2021. ASC 740 allows for the reclassification of the alternative minimum tax credit from a deferred tax asset to a current tax asset, except for the amount limited by section 382. Old National has $2.5 million of alternative minimum tax credit carryforward subject to section 382 limitations. The $2.5 million is maintained in deferred tax assets and the remaining $21.5 million has been reclassified to a current tax asset. Old National has federal tax credit carryforwards of $1.8 million at December 31, 2018 and $5.5 million at December 31, 2017. The federal tax credits consist mainly of energy efficient home credits, low income housing credits, and research and development credits that, if not used, will expire from 2025 to 2038. Old National has recorded state net operating loss carryforwards totaling $165.6 million at December 31, 2018 and $203.6 million at December 31, 2017. If not used, the state net operating loss carryforwards will expire from 2024 to 2033. The federal and recorded state net operating loss carryforwards are subject to an annual limitation under Internal Revenue Code section 382. Old National believes that all of the recorded net operating loss carryforwards will be used prior to expiration. Unrecognized Tax Benefits Unrecognized state income tax benefits are reported net of their related deferred federal income tax benefit. A reconciliation of the beginning and ending amount of unrecognized tax benefits was as follows: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Balance at beginning of period $ 874 $ 777 $ 124 Additions based on tax positions related to the current year — 162 118 Additions (reductions) based on tax positions related to prior years (78 ) — 537 Reductions due to statute of limitations expiring (301 ) (173 ) (2 ) Revaluation due to Tax Reform — 108 — Balance at end of period $ 495 $ 874 $ 777 If recognized, approximately $0.5 million of unrecognized tax benefits, net of interest, would favorably affect the effective income tax rate in future periods. Old National expects the total amount of unrecognized tax benefits to be reduced to zero in the next twelve months. It is our policy to recognize interest and penalties accrued relative to unrecognized tax benefits in their respective federal or state income tax accounts. We did not recognize any interest and penalties in 2018. We recorded interest and penalties in the income statement of $10 thousand in 2017 and $0.1 million in 2016. The amount accrued for interest and penalties in the balance sheet was $0.1 million at December 31, 2018 and 2017. Old National and its subsidiaries file a consolidated U.S. federal income tax return, as well as filing various state returns. The 2015 through 2018 tax years are open and subject to examination. Old National reversed $0.4 million in 2018 related to uncertain tax positions accounted for under FASB ASC 740-10 (FASB Interpretation No. 48, Accounting for Uncertainty in Income Taxes income tax reversal related to reductions for tax positions in prior years totaled $ 0.1 million. As a result, Old National reversed a total of $ million from its unrecognized tax benefit liability.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Employee Benefit Plans	NOTE 17 – EMPLOYEE BENEFIT PLANS Retirement Plan Old National had a funded noncontributory defined benefit plan (the “Retirement Plan”) that had been frozen since December 31, 2005. During the first quarter of 2016, we notified plan participants of our intent to terminate the Retirement Plan effective May 15, 2016. During October 2016, the Retirement Plan settled plan liabilities through either lump sum distributions to plan participants or annuity contracts purchased from a third party insurance company that provided for the payment of vested benefits to those participants that did not elect the lump sum option. At December 31, 2018, there were no remaining plan assets. Old National made contributions to the Retirement Plan totaling $7.6 million during 2016. As a result of the pension termination, unrecognized losses, which previously were recorded in accumulated other comprehensive loss on the consolidated balance sheets, were recognized as expense and the pension plan settlement loss of $9.8 million was recorded in the consolidated statements of income for the year ended December 31, 2016. Including this settlement charge, the total expense under the Retirement Plan was $11.6 million in 2016. Employee Stock Ownership Plan The Employee Stock Ownership and Savings Plan (the “401(k) Plan”) permits employees to participate the first month following one month of service. Effective as of April 1, 2010, we suspended safe harbor matching contributions to the 401(k) Plan. However, we may make discretionary matching contributions to the 401(k) Plan. During the second quarter of 2018, Old National increased its match to 75% of employee compensation deferral contributions of the first 4% of compensation, and 50% of the next 4% of compensation. The change was retroactive for all of 2018. For 2017 and 2016, we matched 50% of employee compensation deferral contributions, up to 6% of compensation. In addition to matching contributions, Old National may contribute to the 401(k) Plan an amount designated as a profit sharing contribution in the form of Old National stock or cash. Our Board of Directors designated no discretionary profit sharing contributions in 2018, 2017, or 2016. All contributions vest immediately and plan participants may elect to redirect funds among any of the investment options provided under the 401(k) Plan. The number of Old National shares in the 401(k) Plan were 0.7 million at December 31, 2018 and 2017. All shares owned through the 401(k) Plan are included in the calculation of weighted-average shares outstanding for purposes of calculating diluted and basic earnings per share. Contribution expense under the 401(k) Plan was $8.6 million in 2018, $4.7 million in 2017, and $5.0 million in 2016.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-Based Compensation	NOTE 18 – SHARE-BASED COMPENSATION Our Amended and Restated 2008 Incentive Compensation Plan (the “ICP”), which was shareholder-approved, permits the grant of share-based awards to its employees. At December 31, 2018, 4.4 million shares were available for issuance. The granting of awards to key employees is typically in the form of restricted stock awards or units. We believe that such awards better align the interests of our employees with those of our shareholders. Total compensation cost that has been charged against income for the ICP was $8.1 million in 2018, $6.3 million in 2017, and $7.3 million in 2016. The total income tax benefit was $2.0 million in 2018, $2.4 million in 2017, and $2.8 million in 2016. Restricted Stock Awards Restricted stock awards require certain service requirements and commonly have vesting periods of 3 years. Compensation expense is recognized on a straight-line basis over the vesting period. Shares are subject to certain restrictions and risk of forfeiture by the participants. A summary of changes in our nonvested shares for the year follows: Weighted Average Grant-Date (shares in thousands) Shares Fair Value Year Ended December 31, 2018 Nonvested balance at beginning of period 407 $ 15.41 Granted during the year 217 17.47 Vested during the year (195 ) 14.80 Forfeited during the year (10 ) 15.08 Nonvested balance at end of period 419 $ 16.77 As of December 31, 2018, there was $4.5 million of total unrecognized compensation cost related to nonvested shares granted under the ICP. The cost is expected to be recognized over a weighted-average period of 1.9 years. The total fair value of the shares vested was $3.4 million in 2018, $3.4 million in 2017, and $3.8 million in 2016. Restricted Stock Units Restricted stock units require certain performance requirements and have vesting periods of 3 years. Compensation expense is recognized on a straight-line basis over the vesting period. Shares are subject to certain restrictions and risk of forfeiture by the participants. A summary of changes in our nonvested shares for the year follows: Weighted Average Grant-Date (shares in thousands) Shares Fair Value Year Ended December 31, 2018 Nonvested balance at beginning of period 849 $ 13.30 Granted during the year 288 13.62 Vested during the year (92 ) 13.65 Forfeited during the year (185 ) 13.58 Dividend equivalents adjustment 33 13.32 Nonvested balance at end of period 893 $ 13.31 As of December 31, 2018, there was $4.3 million of total unrecognized compensation cost related to nonvested shares granted under the ICP. The cost is expected to be recognized over a weighted-average period of 1.6 years. Stock Options Option awards are generally granted with an exercise price equal to the market price of our Common Stock at the date of grant; these option awards have vesting periods ranging from 3 to 5 years and have 10-year contractual terms. Old National has not granted stock options since 2009. However, Old National did acquire stock options through prior year acquisitions. Old National recorded no incremental expense associated with the conversion of these options. A summary of the activity in the stock option plan in 2018 follows: Weighted Weighted Average Aggregate Average Remaining Intrinsic Exercise Contractual Value (shares in thousands) Shares Price Term in Years (in thousands) Year Ended December 31, 2018 Outstanding at beginning of period 225 $ 11.92 Exercised (76 ) 12.59 Forfeited/expired (57 ) 20.16 Outstanding at end of period 92 $ 6.30 2.08 $ 836.7 Options exercisable at end of year 92 $ 6.30 2.08 $ 836.7 Information related to the stock option plan during each year follows: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Intrinsic value of options exercised $ 385 $ 806 $ 660 Cash received from option exercises 948 2,655 2,349 Tax benefit realized from option exercises 154 318 264 As of December 31, 2018, all options were fully vested and all compensation costs had been expensed. Stock Appreciation Rights Old National has never granted stock appreciation rights. However, Old National did acquire stock appreciation rights through a prior year acquisition. Old National recorded no incremental expense associated with the conversion of these stock appreciation rights. At December 31, 2018, 61 thousand stock appreciation rights remained outstanding. Outside Director Stock Compensation Program Old National maintains a director stock compensation program covering all outside directors. Compensation shares are earned semi-annually. Beginning in 2017, any shares awarded to directors are anticipated to be issued from the ICP. In 2018, 16 thousand shares were issued to directors, compared to 20 thousand shares in 2017.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Shareholders' Equity	NOTE 19 – SHAREHOLDERS’ EQUITY Dividend Reinvestment and Stock Purchase Plan Old National has a dividend reinvestment and stock purchase plan under which common shares issued may be either repurchased shares or authorized and previously unissued shares. A new plan became effective on August 13, 2018, with total authorized and unissued common shares reserved for issuance of 3.3 million. At December 31, 2018, 3.3 million authorized and unissued common shares were available for issuance under the plan. Employee Stock Purchase Plan Old National has an employee stock purchase plan under which eligible employees can purchase common shares at a price not less than 95% of the fair market value of the common shares on the purchase date. The amount of common shares purchased cannot exceed 10% of the employee’s compensation. The maximum number of shares that may be purchased under this plan is 500,000 shares. In 2018, 29,000 shares were issued related to this plan with proceeds of approximately $497,000. In 2017, 24,000 shares were issued related to this plan with proceeds of approximately $404,000.

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value	NOTE 20 – FAIR VALUE Fair value is the exchange price that would be received for an asset or paid to transfer a liability (exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. There are three levels of inputs that may be used to measure fair values: • Level 1 – Quoted prices (unadjusted) for identical assets or liabilities in active markets that the entity has the ability to access as of the measurement date. • Level 2 – Significant other observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data. • Level 3 – Significant unobservable inputs that reflect a company’s own assumptions about the assumptions that market participants would use in pricing an asset or liability. Old National used the following methods and significant assumptions to estimate the fair value of each type of financial instrument: Investment securities Residential loans held for sale Derivative financial instruments Assets and liabilities measured at fair value on a recurring basis, including financial assets and liabilities for which we have elected the fair value option, are summarized below: Fair Value Measurements at December 31, 2018 Using Significant Quoted Prices in Other Significant Active Markets for Observable Unobservable Carrying Identical Assets Inputs Inputs (dollars in thousands) Value (Level 1) (Level 2) (Level 3) Financial Assets Equity securities $ 5,582 $ 5,582 $ — $ — Investment securities available-for-sale: U.S. Treasury 5,301 5,301 — — U.S. government-sponsored entities and agencies 628,151 — 628,151 — Mortgage-backed securities - Agency 2,209,295 — 2,209,295 — States and political subdivisions 940,429 — 936,321 4,108 Pooled trust preferred securities 8,495 — — 8,495 Other securities 331,745 30,259 301,486 — Residential loans held for sale 14,911 — 14,911 — Derivative assets 29,005 — 29,005 — Financial Liabilities Derivative liabilities 12,550 — 12,550 — Fair Value Measurements at December 31, 2017 Using Significant Quoted Prices in Other Significant Active Markets for Observable Unobservable Carrying Identical Assets Inputs Inputs (dollars in thousands) Value (Level 1) (Level 2) (Level 3) Financial Assets Equity securities $ 5,584 $ 5,584 $ — $ — Investment securities available-for-sale: U.S. Treasury 5,551 5,551 — — U.S. government-sponsored entities and agencies 664,286 — 664,286 — Mortgage-backed securities - Agency 1,667,682 — 1,667,682 — States and political subdivisions 530,193 — 530,193 — Pooled trust preferred securities 8,448 — — 8,448 Other securities 320,047 30,965 289,082 — Residential loans held for sale 17,930 — 17,930 — Derivative assets 14,118 — 14,118 — Financial Liabilities Derivative liabilities 16,292 — 16,292 — The table below presents a reconciliation of all assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3): Pooled Trust State and Preferred Political (dollars in thousands) Securities Subdivisions 2018 Balance at beginning of period $ 8,448 $ — Accretion (amortization) of discount 17 (56 ) Sales/payments received (338 ) — Increase in fair value of securities 368 28 Transfers into Level 3 — 4,136 Balance at end of period $ 8,495 $ 4,108 2017 Balance at beginning of period $ 8,119 $ — Accretion of discount 17 — Sales/payments received (424 ) — Increase in fair value of securities 736 — Balance at end of period $ 8,448 $ — The accretion or amortization of discounts on securities in the table above is included in interest income. An increase in fair value is reflected in the balance sheet as an increase in the fair value of investment securities available-for-sale, an increase in accumulated other comprehensive income, which is included in shareholders’ equity, and a decrease in other assets related to the tax impact. Old National transferred $4.1 million of state and political subdivisions securities to Level 3 during 2018 because Old National could no longer obtain evidence of observable inputs. The table below provides quantitative information about significant unobservable inputs used in fair value measurements within Level 3 of the fair value hierarchy: Valuation Unobservable Range (Weighted (dollars in thousands) Fair Value Techniques Input Average) December 31, 2018 Pooled trust preferred securities $ 8,495 Discounted cash flow Constant prepayment rate (a) 0.00% Additional asset defaults (b) 6.8% - 8.5% (7.3%) Expected asset recoveries (c) 0.0% - 0.0% (0.0%) State and political subdivisions 4,108 Discounted cash flow No observable inputs N/A Local municipality issuances Old National owns 100% Carried at par December 31, 2017 Pooled trust preferred securities $ 8,448 Discounted cash flow Constant prepayment rate (a) 0.00% Additional asset defaults (b) 4.2% - 9.6% (7.5%) Expected asset recoveries (c) 0.0% - 4.1% (0.6%) (a) Assuming no prepayments. (b) Each currently performing pool asset is assigned a default probability based on the banking environment, which is adjusted for specific issuer evaluation, of 0%, 50%, or 100%. (c) Each currently defaulted pool asset is assigned a recovery probability based on specific issuer evaluation of 0%, 25%, or 100%. Significant changes in any of the unobservable inputs used in the fair value measurement in isolation would result in a significant change to the fair value measurement. The pooled trust preferred securities Old National owns are subordinate note classes that rely on an ongoing cash flow stream to support their values. The senior note classes receive the benefit of prepayments to the detriment of subordinate note classes since the ongoing interest cash flow stream is reduced by the early redemption. Generally, a change in prepayment rates or additional pool asset defaults has an impact that is directionally opposite from a change in the expected recovery of a defaulted pool asset. Assets measured at fair value on a non-recurring basis at December 31, 2018 are summarized below: Fair Value Measurements at December 31, 2018 Using Significant Quoted Prices in Other Significant Active Markets for Observable Unobservable Carrying Identical Assets Inputs Inputs (dollars in thousands) Value (Level 1) (Level 2) (Level 3) Collateral Dependent Impaired Loans: Commercial loans $ 7,242 $ — $ — $ 7,242 Commercial real estate loans 29,125 — — 29,125 Foreclosed Assets: Residential 68 — — 68 Loan servicing rights 104 — 104 — Impaired commercial and commercial real estate loans that are deemed collateral dependent are valued based on the fair value of the underlying collateral. These estimates are based on the most recently available appraisals with certain adjustments made based on the type of property, age of appraisal, current status of the property, and other related factors to estimate the current value of the collateral. These impaired commercial and commercial real estate loans had a principal amount of $49.3 million, with a valuation allowance of $12.9 million at December 31, 2018. Old National recorded provision expense associated with these loans totaling $9.9 million in 2018. Other real estate owned and other repossessed property is measured at fair value less costs to sell and had a net carrying amount of $68 thousand at December 31, 2018. The estimates of fair value are based on the most recently available appraisals with certain adjustments made based on the type of property, age of appraisal, current status of the property, and other related factors to estimate the current value of the collateral. There were write-downs of other real estate owned of $0.6 million in 2018. Loan servicing rights are evaluated for impairment based upon the fair value of the rights as compared to the carrying amount. If the carrying amount of an individual tranche exceeds fair value, impairment is recorded on that tranche so that the servicing asset is carried at fair value. Fair value is determined at a tranche level, based on market prices for comparable mortgage servicing contracts when available, or alternatively based on a valuation model that calculates the present value of estimated future net servicing income. The valuation model utilizes a discount rate, weighted average prepayment speed, and other economic factors that market participants would use in estimating future net servicing income and that can be validated against available market data (Level 2). The valuation allowance for loan servicing rights with impairments at December 31, 2018 totaled $15 thousand. Old National recorded recoveries associated with these loan servicing rights totaling $14 thousand in 2018. Assets measured at fair value on a non-recurring basis at December 31, 2017 are summarized below: Fair Value Measurements at December 31, 2017 Using Significant Quoted Prices in Other Significant Active Markets for Observable Unobservable Carrying Identical Assets Inputs Inputs (dollars in thousands) Value (Level 1) (Level 2) (Level 3) Collateral Dependent Impaired Loans: Commercial loans $ 2,217 $ — $ — $ 2,217 Commercial real estate loans 26,319 — — 26,319 Foreclosed Assets: Commercial real estate 1,726 — — 1,726 Residential 55 — — 55 Loan servicing rights 2,964 — 2,964 — At December 31, 2017, impaired commercial and commercial real estate loans had a principal amount of $38.6 million, with a valuation allowance of $10.1 million. Old National recorded provision expense associated with these loans totaling $5.2 million in 2017. Other real estate owned and other repossessed property had a net carrying amount of $1.8 million at December 31, 2017. There were write-downs of other real estate owned of $2.5 million in 2017. The valuation allowance for loan servicing rights with impairments at December 31, 2017 totaled $29 thousand. There were recoveries associated with these loan servicing rights totaling $39 thousand in 2017. The table below provides quantitative information about significant unobservable inputs used in fair value measurements within Level 3 of the fair value hierarchy: Valuation Unobservable Range (Weighted (dollars in thousands) Fair Value Techniques Input Average) December 31, 2018 Collateral Dependent Impaired Loans Commercial loans $ 7,242 Fair value of collateral Discount for type of property, age of appraisal, and current status 0% - 90% (35%) Commercial real estate loans 29,125 Fair value of collateral Discount for type of property, age of appraisal and current status 0% - 50% (35%) Foreclosed Assets Residential 68 Fair value of collateral Discount for type of property, age of appraisal, and current status 15%-16% (15%) December 31, 2017 Collateral Dependent Impaired Loans Commercial loans $ 2,217 Fair value of collateral Discount for type of property, age of appraisal, and current status 0% - 98% (49%) Commercial real estate loans 26,319 Fair value of collateral Discount for type of property, age of appraisal, and current status 10% - 78% (32%) Foreclosed Assets Commercial real estate 1,726 Fair value of collateral Discount for type of property, age of appraisal, and current status 7% - 25% (18%) Residential (1) 55 Fair value of collateral Discount for type of property, age of appraisal, and current status 39% (1) There was only one foreclosed residential asset at December 31, 2017, so no range or weighted average rate is reported. Financial instruments recorded using fair value option Old National may elect to report most financial instruments and certain other items at fair value on an instrument-by instrument basis with changes in fair value reported in net income. After the initial adoption, the election is made at the acquisition of an eligible financial asset, financial liability or firm commitment or when certain specified reconsideration events occur. The fair value election may not be revoked once an election is made. Old National has elected the fair value option for residential loans held for sale. For these loans, interest income is recorded in the consolidated statements of income based on the contractual amount of interest income earned on the financial assets (except any that are on nonaccrual status). None of these loans are 90 days or more past due, nor are any on nonaccrual status. Included in the income statement is interest income for loans held for sale totaling $0.5 million in 2018 and $0.2 million in 2017. Residential loans held for sale Old National has elected the fair value option for newly originated conforming fixed-rate and adjustable-rate first mortgage loans held for sale. These loans are intended for sale and are hedged with derivative instruments. Old National has elected the fair value option to mitigate accounting mismatches in cases where hedge accounting is complex and to achieve operational simplification. The fair value option was not elected for loans held for investment. The difference between the aggregate fair value and the aggregate remaining principal balance for loans for which the fair value option has been elected as of December 31, 2018 and 2017 was as follows: Aggregate Contractual (dollars in thousands) Fair Value Difference Principal 2018 Residential loans held for sale $ 14,911 $ 475 $ 14,436 2017 Residential loans held for sale $ 17,930 $ 546 $ 17,384 Accrued interest at period end is included in the fair value of the instruments. The following table presents the amount of gains and losses from fair value changes included in income before income taxes for financial assets carried at fair value for the years ended December 31: Total Changes in Fair Values Other Included in Gains and Interest Interest Current Period (dollars in thousands) (Losses) Income (Expense) Earnings 2018 Residential loans held for sale $ (67 ) $ 6 $ (10 ) $ (71 ) 2017 Residential loans held for sale $ 409 $ 4 $ — $ 413 The carrying amounts and estimated fair values of financial instruments not carried at fair value at December 31, 2018 and 2017 were as follows: Fair Value Measurements at December 31, 2018 Using Significant Quoted Prices in Other Significant Active Markets for Observable Unobservable Carrying Identical Assets Inputs Inputs (dollars in thousands) Value (Level 1) (Level 2) (Level 3) Financial Assets Cash, due from banks, money market, and other interest-earning investments $ 317,165 $ 317,165 $ — $ — Investment securities held-to-maturity: U.S. government-sponsored entities and agencies 73,986 — 72,359 — Mortgage-backed securities - Agency 127,120 — 124,409 — State and political subdivisions 305,228 — 309,335 — Loans, net: Commercial 3,211,228 — — 3,161,132 Commercial real estate 4,935,381 — — 4,781,294 Residential real estate 2,246,127 — — 2,225,853 Consumer credit 1,795,695 — — 1,773,352 Accrued interest receivable 89,464 13 27,580 61,871 Financial Liabilities Deposits: Noninterest-bearing demand deposits $ 3,965,380 $ 3,965,380 $ — $ — Checking, NOW, savings, and money market interest-bearing deposits 8,360,313 8,360,313 — — Time deposits 2,024,256 — 2,002,187 — Federal funds purchased and interbank borrowings 270,135 270,135 — — Securities sold under agreements to repurchase 362,294 362,294 — — FHLB advances 1,613,481 — — 1,611,103 Other borrowings 247,883 — 248,065 — Accrued interest payable 9,871 — 9,871 — Standby letters of credit 525 — — 525 Off-Balance Sheet Financial Instruments Commitments to extend credit $ — $ — $ — $ 3,115 Fair Value Measurements at December 31, 2017 Using Significant Quoted Prices in Other Significant Active Markets for Observable Unobservable Carrying Identical Assets Inputs Inputs (dollars in thousands) Value (Level 1) (Level 2) (Level 3) Financial Assets Cash, due from banks, money market, and other interest-earning investments $ 290,432 $ 290,432 $ — $ — Investment securities held-to-maturity: Mortgage-backed securities - Agency 6,903 — 7,056 — State and political subdivisions 677,160 — 720,647 — Loans, net: Commercial 2,698,023 — — 2,707,385 Commercial real estate 4,333,116 — — 4,347,949 Residential real estate 2,165,290 — — 2,210,951 Consumer credit 1,871,311 — — 1,998,194 Accrued interest receivable 87,102 16 24,001 63,085 Financial Liabilities Deposits: Noninterest-bearing demand deposits $ 3,680,807 $ 3,680,807 $ — $ — Checking, NOW, savings, and money market interest-bearing deposits 7,290,521 7,290,521 — — Time deposits 1,634,436 — 1,620,685 — Federal funds purchased and interbank borrowings 335,033 335,033 — — Securities sold under agreements to repurchase 384,810 359,810 25,133 — FHLB advances 1,609,579 — — 1,607,189 Other borrowings 248,782 — 250,443 — Accrued interest payable 7,029 — 7,029 — Standby letters of credit 351 — — 351 Off-Balance Sheet Financial Instruments Commitments to extend credit $ — $ — $ — $ 2,449 The methods utilized to estimate the fair value of financial instruments at December 31, 2017 did not necessarily represent an exit price. In accordance with our adoption of ASU 2016-01 in 2018, the methods utilized to measure the fair value of financial instruments at December 31, 2018 represent an approximation of exit price, however, an actual exit price may differ.

Derivative Financial Instrument

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	NOTE 21 – DERIVATIVE FINANCIAL INSTRUMENTS As discussed in Note 1, Old National adopted ASU 2017-12 in the first quarter of 2018. This adoption primarily impacted our existing cash flow and fair value hedges related to certain FHLB advances. For cash flow hedges as of the date of adoption, the transition guidance in paragraph 815-20-65-3(d) eliminated the separate measurement of ineffectiveness by means of a cumulative-effect adjustment to accumulated other comprehensive income with a corresponding adjustment to the opening balance of retained earnings. For fair value hedges of interest rate risk, the provisions of paragraph 815-25-35-13 permit Old National to elect to modify the measurement methodology to be based on the benchmark rate component of the contractual coupon cash flows without dedesignation of the hedging relationship. The measurement methodology modification shall be applied as of the hedging relationship’s original inception date. The cumulative effect of applying this election shall be recognized as an adjustment to the basis adjustment of the hedged item recognized on the balance sheet with a corresponding adjustment to the opening balance of retained earnings as of the initial application date. As part of our overall interest rate risk management, Old National uses derivative instruments, including interest rate swaps, collars, caps, and floors. The notional amount of these derivative instruments was $1.482 billion at December 31, 2018 and $708.5 million at December 31, 2017. These derivative financial instruments at December 31, 2018 consisted of $757.0 million notional amount of receive-fixed, pay-variable interest rate swaps on certain of its FHLB advances, $525.0 million notional amount of pay-fixed, receive-variable interest rate swaps on certain of its FHLB advances, and $200.0 million notional amount interest rate collars related to a variable-rate commercial loan pool. Derivative financial instruments at December 31, 2017 consisted of $33.5 million notional amount of receive-fixed, pay-variable interest rate swaps on certain of its FHLB advances and $ 675.0 million notional amount of pay-fixed, receive-variable interest rate swaps on certain of its FHLB advances. These hedges were entered into to manage interest rate risk. Derivative instruments are recognized on the balance sheet at their fair value and are not reported on a net basis. In accordance with ASC 815-20-35-1, subsequent changes in fair value for a hedging instrument that has been designated and qualifies as part of a hedging relationship should be accounted for in the following manner: Cash flow hedges : changes in fair value will be recognized as a component in other comprehensive income. Fair value hedges : changes in fair value will be recognized concurrently in earnings. Consistent with this guidance, as long as a hedging instrument is designated and the results of the effectiveness testing support that the instrument qualifies for hedge accounting treatment, 100% of the periodic changes in fair value of the hedging instrument will be accounted for as outlined above. This is the case whether or not economic mismatches exist in the hedging relationship. As a result, there will be no periodic measurement or recognition of ineffectiveness. Rather, the full impact of hedge gains and losses will be recognized in the period in which the hedged transactions impact earnings. While separate measurement and presentation of ineffectiveness is being eliminated, paragraph 815-20-45-1A requires the change in fair value of the hedging instrument that is included in the assessment of hedge effectiveness be presented in the same income statement line item that is used to present the earnings effect of the hedged item. C ommitments to fund certain mortgage loans (interest rate lock commitments) and forward commitments for the future delivery of mortgage loans to third party investors are considered derivatives. These derivative contracts do not qualify for hedge accounting. At December 31, 2018, the notional amount of the interest rate lock commitments was $27.6 million and forward commitments were $34.5 million. At December 31, 2017, the notional amount of the interest rate lock commitments was $29.9 million and forward commitments were $41.2 million. It is our practice to enter into forward commitments for the future delivery of residential mortgage loans to third party investors when interest rate lock commitments are entered into in order to economically hedge the effect of changes in interest rates resulting from our commitment to fund the loans. Old National also enters into derivative instruments for the benefit of its customers. The notional amounts of these customer derivative instruments and the offsetting counterparty derivative instruments were $793.4 million at December 31 December 31 Old National enters into derivative financial instruments as part of its foreign currency risk management strategies. These derivative instruments consist of foreign currency forward contracts to accommodate the business needs of its customers. Old National does not designate these foreign currency forward contracts for hedge accounting treatment. The notional amounts of these foreign currency forward contracts and the offsetting counterparty derivative instruments were $3.6 million at December 31, 2018 and $0.8 million at December 31, 2017. Credit risk arises from the possible inability of counterparties to meet the terms of their contracts. Old National’s exposure is limited to the replacement value of the contracts rather than the notional, principal, or contract amounts. There are provisions in our agreements with the counterparties that allow for certain unsecured credit exposure up to an agreed threshold. Exposures in excess of the agreed thresholds are collateralized. In addition, we minimize credit risk through credit approvals, limits, and monitoring procedures. Amounts reported in AOCI related to cash flow hedges will be reclassified to interest income or interest expense as interest payments are received or paid on Old National’s derivative instruments. During the next 12 months, we estimate that $1.2 million will be reclassified to interest income and $0.4 million will be reclassified to interest expense. The following table summarizes the fair value of derivative financial instruments utilized by Old National: Balance Balance Sheet Fair Sheet Fair (dollars in thousands) Location Value Location Value December 31, 2018 Derivatives designated as hedging instruments Interest rate contracts Other Assets $ 12,741 Other Liabilities $ 1,603 Total derivatives designated as hedging instruments $ 12,741 $ 1,603 Derivatives not designated as hedging instruments Interest rate contracts Other Assets $ 15,278 Other Liabilities $ 10,562 Mortgage contracts Other Assets 874 Other Liabilities 316 Foreign currency contracts Other Assets 112 Other Liabilities 69 Total derivatives not designated as hedging instruments $ 16,264 $ 10,947 Total $ 29,005 $ 12,550 December 31, 2017 Derivatives designated as hedging instruments Interest rate contracts Other Assets $ 3,351 Other Liabilities $ 5,351 Total derivatives designated as hedging instruments $ 3,351 $ 5,351 Derivatives not designated as hedging instruments Interest rate contracts Other Assets $ 10,012 Other Liabilities $ 10,933 Mortgage contracts Other Assets 747 Other Liabilities — Foreign currency contracts Other Assets 8 Other Liabilities 8 Total derivatives not designated as hedging instruments $ 10,767 $ 10,941 Total $ 14,118 $ 16,292 The effect of derivative instruments in fair value hedging relationships on the consolidated statements of income for the years ended December 31 were as follows: (dollars in thousands) Gain (Loss) Recognized Location of Gain or Gain (Loss) Hedged Items Location of Gain or in Income on Derivatives in (Loss) Recognized in Recognized in Fair Value (Loss) Recognized in Related Fair Value Hedging in Income on in Income on Hedging in Income on Related Hedged Relationships Derivative Derivative Relationships Hedged Item Items 2018 Interest rate contracts Interest income / (expense) $ 7,662 Fixed-rate debt Interest income / (expense) $ (7,634 ) 2017 Interest rate contracts Interest income / (expense) $ (836 ) Fixed-rate debt Interest income / (expense) $ 1,006 2016 Interest rate contracts Interest income / (expense) $ (863 ) Fixed-rate debt Interest income / (expense) $ 991 The difference between the gain (loss) recognized in income on derivatives and the gain (loss) recognized in income on the related hedged items represents hedge ineffectiveness. In addition, the net swap settlements that accrue each period are also reported in interest expense. The effect of derivative instruments in cash flow hedging relationships on the consolidated statements of income for the years ended December 31 were as follows: Years Ended December 31, Years Ended December 31, (dollars in thousands) 2018 2017 2016 2018 2017 2016 Gain (Loss) Gain (Loss) Location of Gain or Recognized in Other Reclassified from Derivatives in (Loss) Reclassified Comprehensive AOCI into Cash Flow Hedging from AOCI into Income Income on Derivative Income (Effective Relationships (Effective Portion) (Effective Portion) Portion) Interest rate contracts Interest income/(expense) $ 5,145 $ 927 $ (2,323 ) $ (150 ) $ (6,135 ) $ (6,453 ) The ineffective portion and amount excluded from effectiveness testing related to derivatives in cash flow hedging relationships was immaterial for the years ended December 31, 2018, 2017, and 2016. The effect of derivatives not designated as hedging instruments on the consolidated statements of income for the years ended December 31 were as follows: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Location of Gain or (Loss) Gain (Loss) Derivatives Not Designated as Recognized in Income on Recognized in Income on Hedging Instruments Derivative Derivative Interest rate contracts (1) Other income/(expense) $ (7 ) $ 56 $ 28 Mortgage contracts Mortgage banking revenue (189 ) (1,995 ) 1,390 Foreign currency contracts Other income/(expense) 42 — — Total $ (154 ) $ (1,939 ) $ 1,418 (1) Includes the valuation difference between the customer and offsetting swaps.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	NOTE 22 – COMMITMENTS AND CONTINGENCIES Litigation In the normal course of business, Old National Bancorp and its subsidiaries have been named, from time to time, as defendants in various legal actions. Certain of the actual or threatened legal actions may include claims for substantial compensatory and/or punitive damages or claims for indeterminate amounts of damages. Old National contests liability and/or the amount of damages as appropriate in each pending matter. In view of the inherent difficulty of predicting the outcome of such matters, particularly in cases where claimants seek substantial or indeterminate damages or where investigations and proceedings are in the early stages, Old National cannot predict with certainty the loss or range of loss, if any, related to such matters, how or if such matters will be resolved, when they will ultimately be resolved, or what the eventual settlement, or other relief, if any, might be. Subject to the foregoing, Old National believes, based on current knowledge and after consultation with counsel, that the outcome of such pending matters will not have a material adverse effect on the consolidated financial condition of Old National, although the outcome of such matters could be material to Old National’s operating results and cash flows for a particular future period, depending on, among other things, the level of Old National’s revenues or income for such period. Old National will accrue for a loss contingency if (1) it is probable that a future event will occur and confirm the loss and (2) the amount of the loss can be reasonably estimated. Old National is not currently involved in any material litigation. Credit-Related Financial Instruments In the normal course of business, Old National’s banking affiliates have entered into various agreements to extend credit, including loan commitments of $3.566 billion and standby letters of credit of $319.0 million at December 31, 2018. At December 31, 2018, approximately $3.348 billion of the loan commitments had fixed rates and $218.1 million had floating rates, with the floating interest rates ranging from 1% to 16%. At December 31, 2017, loan commitments totaled $3.144 billion and standby letters of credit totaled $68.7 million. These commitments are not reflected in the consolidated financial statements. The allowance for unfunded loan commitments totaled $2.5 million at December 31, 2018 and $3.1 million at December 31, 2017. Old National had credit extensions with various unaffiliated banks related to letter of credit commitments issued on behalf of Old National’s clients totaling $15.5 million at December 31, 2018 and $12.4 million at December 31, 2017. Old National provided collateral to the unaffiliated banks to secure credit extensions totaling $7.8 million at December 31, 2018 and $11.5 million December 31, 2017. Old National did not provide collateral for the remaining credit extensions. Visa Class B Restricted Shares In 2008, Old National received Visa Class B restricted shares as part of Visa’s initial public offering. These shares are transferable only under limited circumstances until they can be converted into the publicly traded Class A common shares. This conversion will not occur until the final settlement of certain litigation for which Visa is indemnified by the holders of Visa’s Class B shares, including Old National. Visa funded an escrow account from its initial public offering to settle these litigation claims. Increases in litigation claims requiring Visa to fund the escrow account due to insufficient funds will result in a reduction of the conversion ratio of each Visa Class B share to unrestricted Class A shares. As of December 31, 2018, the conversion ratio was 1.6298 . Based on the existing transfer restriction and the uncertainty of the outcome of the Visa litigation, the 56,210 Class B shares that Old National owns at December 31, 2018 are carried at a zero cost basis .

Financial Guarantees

Financial Guarantees	12 Months Ended
	Dec. 31, 2018
Guarantees And Product Warranties [Abstract]
Financial Guarantees	NOTE 23 – FINANCIAL GUARANTEES Old National holds instruments, in the normal course of business with clients, that are considered financial guarantees in accordance with FASB ASC 460-10 (FIN 45, Guarantor’s Accounting and Disclosure Requirements for Guarantees, Including Indirect Guarantees of Indebtedness of Others , Old National is a party in risk participation transactions of interest rate swaps, which had total notional amount of $38.7 million at December 31, 2018.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	12 Months Ended
	Dec. 31, 2018
Revenue From Contract With Customer [Abstract]
Revenue from Contracts with Customers	NOTE 24 – REVENUE FROM CONTRACTS WITH CUSTOMERS Old National’s revenue from contracts with customers in the scope of Topic 606 is recognized within noninterest income. The consolidated statements of income include all categories of noninterest income. The following table reflects only the categories of noninterest income that are within the scope of Topic 606: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Wealth management fees $ 36,863 $ 37,316 $ 34,641 Service charges on deposit accounts 44,026 41,331 41,578 Debit card and ATM fees 20,216 17,676 16,769 Insurance premiums and commissions 399 617 20,527 Investment product fees 20,539 20,977 18,822 Other income: Merchant processing fees 2,927 2,634 2,574 Gain (loss) on other real estate owned 1,270 939 1,419 Safe deposit box fees 1,124 926 961 Total $ 127,364 $ 122,416 $ 137,291 The adoption of Topic 606 did not have a material impact on our consolidated financial position, results of operations, equity, or cash flows as of the adoption date or for the year ended December 31, 2018. A description of wealth management fees, service charges on deposit accounts, debit card and ATM fees, and investment product fees are provided below. Wealth management fees Service charges on deposit accounts maintenance, are earned over the course of a month, representing the period over which Old National satisfies its performance obligation. Debit card and ATM fees Investment product fees

Regulatory Restrictions

Regulatory Restrictions	12 Months Ended
	Dec. 31, 2018
Text Block [Abstract]
Regulatory Restrictions	NOTE 25 – REGULATORY RESTRICTIONS Restrictions on Cash and Due from Banks Old National’s affiliate bank is required to maintain reserve balances on hand and with the Federal Reserve Bank that are interest-bearing and unavailable for investment purposes. The reserve balances were $108.1 million at December 31, 2018 and $100.9 million at December 31, 2017. In addition, Old National had cash and due from banks which was held as collateral for collateralized swap positions of $5.7 million at December 31, 2017. Old National did not have any cash and due from banks held as collateral for collateralized swap positions at December 31, 2018. Restrictions on Transfers from Affiliate Bank Regulations limit the amount of dividends an affiliate bank can declare in any year without obtaining prior regulatory approval. Prior regulatory approval is required if dividends to be declared in any year would exceed net earnings of the current year plus retained net profits for the preceding two years. Prior regulatory approval to pay dividends was not required in 2016, 2017, or 2018 and is not currently required. Restrictions on the Payment of Dividends Old National has traditionally paid a quarterly dividend to common stockholders. The payment of dividends is subject to legal and regulatory restrictions. Any payment of dividends in the future will depend, in large part, on Old National’s earnings, capital requirements, financial condition, and other factors considered relevant by our Board of Directors. Capital Adequacy Old National and Old National Bank are subject to various regulatory capital requirements administered by the federal banking agencies. Failure to meet minimum capital requirements can elicit certain mandatory actions by regulators that, if undertaken, could have a direct material effect on Old National’s financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, Old National and Old National Bank must meet specific capital guidelines that involve quantitative measures of assets, liabilities, and certain off-balance sheet items as calculated under regulatory accounting practices. The capital amounts and classifications are also subject to qualitative judgments by the regulators about components, risk weightings, and other factors. Prompt corrective action provisions are not applicable to bank holding companies. Quantitative measures established by regulation to ensure capital adequacy require Old National and Old National Bank to maintain minimum amounts and ratios as set forth in the following tables. At December 31, 2018, Old National and Old National Bank exceeded the regulatory minimums and Old National Bank met the regulatory definition of well-capitalized based on the most recent regulatory notification. The following table summarizes capital ratios for Old National and Old National Bank as of December 31: Fully Phased-In Regulatory Well Capitalized Actual Guidelines Minimum (1) Guidelines (dollars in thousands) Amount Ratio Amount Ratio Amount Ratio 2018 Total capital to risk- weighted assets Old National Bancorp $ 1,748,231 12.27 % $ 1,496,099 10.50 % $ N/A N/A % Old National Bank 1,769,930 12.47 1,489,938 10.50 1,418,989 10.00 Common equity Tier 1 capital to risk-weighted assets Old National Bancorp 1,617,936 11.36 997,399 7.00 N/A N/A Old National Bank 1,699,945 11.98 993,292 7.00 922,343 6.50 Tier 1 capital to risk-weighted assets Old National Bancorp 1,617,936 11.36 1,211,128 8.50 N/A N/A Old National Bank 1,699,945 11.98 1,206,141 8.50 1,135,191 8.00 Tier 1 capital to average assets Old National Bancorp 1,617,936 9.17 705,681 4.00 N/A N/A Old National Bank 1,699,945 9.58 709,929 4.00 887,412 5.00 2017 Total capital to risk-weighted assets Old National Bancorp $ 1,424,123 11.40 % $ 1,311,600 10.50 % $ N/A N/A % Old National Bank 1,458,546 11.73 1,305,076 10.50 1,242,929 10.00 Common equity Tier 1 capital to risk-weighted assets Old National Bancorp 1,298,327 10.39 874,400 7.00 N/A N/A Old National Bank 1,393,059 11.21 870,051 7.00 807,904 6.50 Tier 1 capital to risk-weighted assets Old National Bancorp 1,298,327 10.39 1,061,772 8.50 N/A N/A Old National Bank 1,393,059 11.21 1,056,490 8.50 994,344 8.00 Tier 1 capital to average assets Old National Bancorp 1,298,327 8.28 627,258 4.00 N/A N/A Old National Bank 1,393,059 8.93 623,758 4.00 779,697 5.00 (1) As of January 1, 2019, Basel III Capital Rules required banking organizations to maintain: a minimum ratio of common equity Tier 1 to risk-weighted assets of at least 4.5%, plus a 2.5% “capital conservation buffer”; a minimum ratio of Tier 1 capital to risk-weighted assets of at least 6.0%, plus the 2.5% capital conservation buffer; a minimum ratio of total capital to risk-weighted assets of at least 8.0%, plus the 2.5% capital conservation buffer; and a minimum ratio of Tier 1 capital to adjusted average consolidated assets of at least 4.0%.

Parent Company Financial Statem

Parent Company Financial Statements	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Parent Company Financial Statements	NOTE 26 – PARENT COMPANY FINANCIAL STATEMENTS The following are the condensed parent company only financial statements of Old National: OLD NATIONAL BANCORP (PARENT COMPANY ONLY) CONDENSED BALANCE SHEETS December 31, (dollars in thousands) 2018 2017 Assets Deposits in affiliate bank $ 90,005 $ 43,538 Equity securities 5,582 5,584 Investment securities - available-for-sale 1,527 1,547 Investment in affiliates: Banking subsidiaries 2,769,166 2,248,700 Non-banks 5,151 5,142 Other assets 87,096 112,353 Total assets $ 2,958,527 $ 2,416,864 Liabilities and Shareholders' Equity Other liabilities $ 37,563 $ 31,768 Other borrowings 231,394 230,699 Shareholders' equity 2,689,570 2,154,397 Total liabilities and shareholders' equity $ 2,958,527 $ 2,416,864 OLD NATIONAL BANCORP (PARENT COMPANY ONLY) CONDENSED STATEMENTS OF INCOME Years Ended December 31, (dollars in thousands) 2018 2017 2016 Income Dividends from affiliates $ 105,000 $ 100,000 $ 160,007 Net securities gains 49 667 100 Other income 2,126 1,966 40,841 Other income from affiliates 5 5 6 Total income 107,180 102,638 200,954 Expense Interest on borrowings 10,425 9,298 9,077 Other expenses 21,936 16,335 18,460 Total expense 32,361 25,633 27,537 Income before income taxes and equity in undistributed earnings of affiliates 74,819 77,005 173,417 Income tax expense (benefit) (5,693 ) (6,240 ) 11,952 Income before equity in undistributed earnings of affiliates 80,512 83,245 161,465 Equity in undistributed earnings of affiliates 110,318 12,480 (27,201 ) Net income $ 190,830 $ 95,725 $ 134,264 OLD NATIONAL BANCORP (PARENT COMPANY ONLY) CONDENSED STATEMENT OF CASH FLOWS Years Ended December 31, (dollars in thousands) 2018 2017 2016 Cash Flows From Operating Activities Net income $ 190,830 $ 95,725 $ 134,264 Adjustments to reconcile net income to cash provided by operating activities: Depreciation 53 36 29 Net securities (gains) losses (49 ) (667 ) (100 ) Gain on sale of ONB Insurance Group, Inc. — — (41,864 ) Share-based compensation expense 8,118 6,275 7,318 (Increase) decrease in other assets 28,754 (24,005 ) (3,958 ) Increase (decrease) in other liabilities 3,147 3,968 (225 ) Equity in undistributed earnings of affiliates (110,318 ) (12,480 ) 27,201 Total adjustments (70,295 ) (26,873 ) (11,599 ) Net cash flows provided by (used in) operating activities 120,535 68,852 122,665 Cash Flows From Investing Activities Net cash and cash equivalents of acquisitions 8,281 (24,005 ) (100,220 ) Proceeds from sale of ONB Insurance Group, Inc. — — 91,771 Proceeds from sales of equity securities 128 127 — Purchases of investment securities (76 ) (62 ) (52 ) Net advances to affiliates — (250 ) (3,500 ) Proceeds from sale of premises and equipment 1,065 — — Purchases of premises and equipment (945 ) (612 ) (13 ) Net cash flows provided by (used in) investing activities 8,453 (24,802 ) (12,014 ) Cash Flows From Financing Activities Payments for maturities/redemptions of other borrowings — (19,856 ) — Cash dividends paid on common stock (82,161 ) (72,604 ) (67,536 ) Common stock repurchased (1,805 ) (2,761 ) (2,202 ) Proceeds from exercise of stock options 948 2,655 2,349 Common stock issued 497 404 388 Net cash flows provided by (used in) financing activities (82,521 ) (92,162 ) (67,001 ) Net increase (decrease) in cash and cash equivalents 46,467 (48,112 ) 43,650 Cash and cash equivalents at beginning of period 43,538 91,650 48,000 Cash and cash equivalents at end of period $ 90,005 $ 43,538 $ 91,650

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment Information	NOTE 27 – SEGMENT INFORMATION Operating segments are components of an enterprise about which separate financial information is available that is evaluated regularly by the chief operating decision maker in deciding how to allocate resources and in assessing performance. Old National Bank, Old National’s bank subsidiary, is the only significant subsidiary upon which management makes decisions regarding how to allocate resources and assess performance. Each of the branches of Old National Bank provide a group of similar community banking services, including such products and services as commercial, real estate and consumer loans, time deposits, checking and savings accounts, cash management, brokerage, trust, and investment advisory services. The individual bank branches located throughout our Midwest footprint have similar operating and economic characteristics. While the chief decision maker monitors the revenue streams of the various products, services, and regional locations, operations are managed and financial performance is evaluated on a Company-wide basis. Accordingly, all of the community banking services and branch locations are considered by management to be aggregated into one reportable operating segment, community banking.

Interim Financial Data (Unaudit

Interim Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Interim Financial Data (Unaudited)	NOTE 28 – INTERIM FINANCIAL DATA (UNAUDITED) The following table details the quarterly results of operations for the years ended December 31, 2018 and 2017. (unaudited, dollars and shares in thousands, Three Months Ended Three Months Ended except per share data) 12/31/2018 9/30/2018 6/30/2018 3/31/2018 12/31/2017 9/30/2017 6/30/2017 3/31/2017 Interest income $ 175,234 $ 155,369 $ 153,736 $ 147,706 $ 135,134 $ 123,525 $ 118,209 $ 118,468 Interest expense 29,009 24,527 21,773 19,134 16,578 15,047 13,876 12,667 Net interest income 146,225 130,842 131,963 128,572 118,556 108,478 104,333 105,801 Provision for loan losses 3,390 750 2,446 380 1,037 311 1,355 347 Noninterest income 58,154 45,957 49,289 41,905 44,825 46,366 49,271 42,920 Noninterest expense 150,268 119,376 130,460 117,157 140,432 103,702 102,811 101,891 Income before income taxes 50,721 56,673 48,346 52,940 21,912 50,831 49,438 46,483 Income tax expense 3,223 5,325 4,345 4,957 40,405 11,459 10,584 10,491 Net income (loss) $ 47,498 $ 51,348 $ 44,001 $ 47,983 $ (18,493 ) $ 39,372 $ 38,854 $ 35,992 Net income (loss) per share: Basic $ 0.28 $ 0.34 $ 0.29 $ 0.32 $ (0.13 ) $ 0.30 $ 0.28 $ 0.27 Diluted 0.28 0.34 0.29 0.31 (0.13 ) 0.29 0.28 0.27 Average shares: Basic 167,044 151,930 151,878 151,721 146,073 135,120 135,085 134,912 Diluted 167,992 152,784 152,568 152,370 146,875 135,796 135,697 135,431 Quarterly results, most notably interest income, noninterest income, and noninterest expense, were impacted by the acquisitions of Klein in November 2018 and Anchor (MN) in November 2017. Income tax expense in the three months ended December 31, 2017 included $39.3 million of additional tax expense to estimate the revaluation of Old National’s deferred tax assets due to the lowering of the federal corporate tax rate to 21%.

Basis of Presentation and Sig_2

Basis of Presentation and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of Old National Bancorp and its wholly-owned affiliates (hereinafter collectively referred to as “Old National”) and have been prepared in conformity with accounting principles generally accepted in the United States of America and prevailing practices within the banking industry. Such principles require management to make estimates and assumptions that affect the reported amounts of assets, liabilities and the disclosures of contingent assets and liabilities at the date of the financial statements and amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. All significant intercompany transactions and balances have been eliminated. Certain prior year amounts have been reclassified to conform to the 2018 presentation. Such reclassifications had no effect on net income or shareholders’ equity and were insignificant amounts.
Equity Securities	Equity Securities Equity securities consist of mutual funds held in trusts associated with deferred compensation plans for former directors and executives. These mutual funds are recorded as equity securities at fair value. Gains and losses are included in net securities gains.
Investment Securities	Investment Securities Old National classifies debt investment securities as available-for-sale or held-to-maturity on the date of purchase. Debt securities classified as available-for-sale are recorded at fair value with the unrealized gains and losses, net of tax effect, recorded in other comprehensive income. Realized gains and losses affect income and the prior fair value adjustments are reclassified within shareholders’ equity. Debt securities classified as held-to-maturity, which management has the intent and ability to hold to maturity, are reported at amortized cost. Premiums and discounts are amortized on the level-yield method. Anticipated prepayments are considered when amortizing premiums and discounts on mortgage backed securities. Gains and losses on the sale of available-for-sale debt securities are determined using the specific-identification method. Equity investments are measured at fair value with changes in fair value recognized in net income. Other-Than-Temporary Impairment – Management evaluates debt securities for OTTI at least on a quarterly basis, and more frequently when economic or market conditions warrant such evaluation. Consideration is given to (1) the length of time and the extent to which the fair value has been less than cost, (2) the financial condition and near-term prospects of the issuer including an evaluation of credit ratings, (3) whether the market decline was affected by macroeconomic conditions, (4) the intent of Old National to sell a debt security, and (5) whether it is more likely than not Old National will have to sell the debt security before recovery of its cost basis. If Old National intends to sell an impaired debt security, Old National records an other-than-temporary loss in an amount equal to the entire difference between fair value and amortized cost. If a debt security is determined to be other-than-temporarily impaired, but Old National does not intend to sell the debt security and it is not more likely than not that it will be required to sell the debt security, only the credit portion of the estimated loss is recognized in earnings, with the other portion of the loss recognized in other comprehensive income. See Note 3 to the consolidated financial statements for a detailed description of the quarterly evaluation process.
Federal Home Loan Bank (FHLB) Stock	Federal Home Loan Bank Stock Old National is a member of the FHLB system. Members are required to own a certain amount of stock based on the level of borrowings and other factors and may invest in additional amounts. FHLB stock is carried at cost, classified as a restricted security, and periodically evaluated for impairment based on ultimate recovery of par value. Both cash and stock dividends are reported as income.
Loans Held for Sale	Loans Held for Sale Loans that Old National has originated with an intent to sell are classified as loans held for sale and are recorded in accordance with FASB ASC 825-10 at fair value, determined individually, as of the balance sheet date. The loan’s fair value includes the servicing value of the loans as well as any accrued interest.
Loans	Loans Loans that Old National intends to hold for investment purposes are classified as portfolio loans. Portfolio loans are carried at the principal balance outstanding, net of earned interest, purchase premiums or discounts, deferred loan fees and costs, and an allowance for loan losses. Interest income is accrued on the principal balances of loans outstanding. For all loan classes, a loan is generally placed on nonaccrual status when principal or interest becomes 90 days past due unless it is well secured and in the process of collection, or earlier when concern exists as to the ultimate collectibility of principal or interest. Interest accrued during the current year on such loans is reversed against earnings. Interest accrued in the prior year, if any, is charged to the allowance for loan losses. Cash interest received on these loans is applied to the principal balance until the principal is recovered or until the loan returns to accrual status. Loans may be returned to accrual status when all the principal and interest amounts contractually due are brought current, remain current for a prescribed period, and future payments are reasonably assured. Purchased loans acquired in a business combination are recorded at estimated fair value on their purchase date with no carryover of the related allowance for loan and lease losses. In determining the estimated fair value of purchased loans, management considers a number of factors including, among others, the remaining life of the acquired loans, estimated prepayments, estimated loss ratios, estimated value of the underlying collateral, and net present value of cash flows expected to be received. Purchased loans are accounted for in accordance with guidance for certain loans acquired in a transfer (ASC 310-30), when the loans have evidence of credit deterioration since origination and it is probable at the date of acquisition that the acquirer will not collect all contractually required principal and interest payments. The difference between contractually required payments and the cash flows expected to be collected at acquisition is referred to as the non-accretable difference. Subsequent decreases to the expected cash flows will generally result in a provision for loan and lease losses. Subsequent increases in expected cash flows will result in a reversal of the provision for loan losses to the extent of prior charges and then an adjustment to accretable yield, which would have a positive impact on interest income.
Allowance for Loan Losses	Allowance for Loan Losses The allowance for loan losses is maintained at a level believed adequate by management to absorb probable losses incurred in the consolidated loan portfolio. Management’s evaluation of the adequacy of the allowance is an estimate based on reviews of individual loans, pools of homogeneous loans, assessments of the impact of current and anticipated economic conditions on the portfolio, and historical loss experience. The allowance is increased through a provision charged to operating expense. Loans deemed to be uncollectible are charged to the allowance. Recoveries of loans previously charged-off are added to the allowance. For all loan classes, a loan is considered impaired when it is probable that contractual interest and principal payments will not be collected either for the amounts or by the dates as scheduled in the loan agreement. If a loan is impaired, a portion of the allowance is allocated so that the loan is reported net, at the present value of estimated cash flows using the loan’s existing rate or at the fair value of collateral if repayment is expected solely from the collateral. Old National’s policy, for all but PCI loans, is to recognize interest income on impaired loans unless the loan is placed on nonaccrual status. Acquired loans accounted for under ASC Topic 310-30 accrue interest, even though they may be contractually past due, as any nonpayment of contractual principal or interest is considered in the periodic re-estimation of expected cash flows and is included in the resulting recognition of current period loan loss provision or prospective yield adjustments. Old National charges off small commercial loans scored through our small business credit center with contractual balances under $250,000 that are 90 days For all portfolio segments, the general component covers non-impaired loans and is based on historical loss experience adjusted for current factors. This actual loss experience is supplemented with other economic factors based on the risks present for each portfolio segment. These economic factors include consideration of the following: levels of and trends in delinquencies and impaired loans; levels of and trends in charge-offs and recoveries; trends in volume and terms of loans; effects of any changes in risk selection and underwriting standards; other changes in lending policies, procedures, and practices; experience, ability, and depth of lending management and other relevant staff; national and local economic trends and conditions; industry conditions; and effects of changes in credit concentrations. Further information regarding Old National’s policies and methodology used to estimate the allowance for loan losses is presented in Note 5.
Premises and Equipment	Premises and Equipment Premises and equipment are stated at cost less accumulated depreciation. Land is stated at cost. Depreciation is charged to operating expense over the useful lives of the assets, principally on the straight-line method. Useful lives for premises and equipment are as follows: buildings and building improvements – 15 to 39 years; and furniture and equipment – 3 to 7 years. Leasehold improvements are depreciated over the lesser of their useful lives or the term of the lease. Maintenance and repairs are expensed as incurred while major additions and improvements are capitalized. Interest costs on construction of qualifying assets are capitalized. Premises and equipment are reviewed for impairment when events indicate their carrying amount may not be recoverable from future undiscounted cash flows. If impaired, the assets are adjusted to fair value. Such impairments are included in other expense.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets The excess of the cost of acquired entities over the fair value of identifiable assets acquired less liabilities assumed is recorded as goodwill. In accordance with FASB ASC 350, Intangibles – Goodwill and Other
Company-Owned Life Insurance	Company-Owned Life Insurance Old National has purchased, as well as obtained through acquisitions, life insurance policies on certain key executives. Old National records company-owned life insurance at the amount that can be realized under the insurance contract at the balance sheet date, which is the cash surrender value adjusted for other charges or other amounts due that are probable at settlement.
Loan Servicing Rights	Loan Servicing Rights When loans are sold with servicing retained, servicing rights are initially recorded at fair value with the income statement effect recorded in gain on sales of loans. Fair value is based on market prices for comparable servicing contracts, when available or alternatively, is based on a valuation model that calculates the present value of estimated future net servicing income. All classes of servicing assets are subsequently measured using the amortization method which requires servicing rights to be amortized into noninterest income in proportion to, and over the period of, the estimated future net servicing income of the underlying loans. Loan servicing rights are evaluated for impairment based upon the fair value of the rights as compared to carrying amount. Impairment is determined by stratifying rights into groupings based on predominant risk characteristics, such as interest rate, loan type, term, and investor type. Impairment is recognized through a valuation allowance for an individual grouping, to the extent that fair value is less than the carrying amount. If Old National later determines that all or a portion of the impairment no longer exists for a particular grouping, a reduction of the allowance may be recorded as an increase to income. Changes in valuation allowances are reported with mortgage banking revenue on the income statement. The fair values of servicing rights are subject to significant fluctuations as a result of changes in estimated and actual prepayment speeds and default rates and losses. Servicing fee income, which is reported on the income statement as mortgage banking revenue, is recorded for fees earned for servicing loans. The fees are based on a contractual percentage of the outstanding principal , or a fixed amount per loan and are recorded as income when earned.
Derivative Financial Instruments	Derivative Financial Instruments As part of Old National’s overall interest rate risk management, Old National uses derivative instruments, including TBA The accrued net settlements on derivatives that qualify for hedge accounting are recorded in interest income or interest expense, consistent with the item being hedged. Old National formally documents all relationships between hedging instruments and hedged items, as well as its risk-management objective and strategy for undertaking various hedge transactions. This process includes linking all derivative instruments that are designated as fair-value or cash-flow hedges to specific assets and liabilities on the balance sheet or to specific firm commitments or forecasted transactions. Old National also formally assesses, both at the hedge’s inception and on an ongoing basis, whether the derivative instruments that are used in hedging transactions are highly effective in offsetting changes in fair values or cash flows of hedged items. Old National discontinues hedge accounting prospectively when it is determined that (1) the derivative is no longer effective in offsetting changes in the fair value or cash flows of the hedged item; (2) the derivative expires, is sold, or terminated; (3) the derivative instrument is de-designated as a hedge because the forecasted transaction is no longer probable of occurring; (4) a hedged firm commitment no longer meets the definition of a firm commitment; (5) or management otherwise determines that designation of the derivative as a hedging instrument is no longer appropriate. When hedge accounting is discontinued, the future changes in fair value of the derivative are recorded as noninterest income. When a fair value hedge is discontinued, the hedged asset or liability is no longer adjusted for changes in fair value and the existing basis adjustment is amortized or accreted over the remaining life of the asset or liability. When a cash flow hedge is discontinued but the hedged cash flows or forecasted transaction is still expected to occur, changes in value that were accumulated in other comprehensive income are amortized or accreted into earnings over the same periods which the hedged transactions will affect earnings. Old National enters into various stand-alone mortgage-banking derivatives in order to hedge the risk associated with the fluctuation of interest rates. Changes in fair value are recorded as mortgage banking revenue. Old National also enters into various stand-alone derivative contracts to provide derivative products to customers which are carried at fair value with changes in fair value recorded as other noninterest income. Old National is exposed to losses if a counterparty fails to make its payments under a contract in which Old National is in the net receiving position. Old National anticipates that the counterparties will be able to fully satisfy their obligations under the agreements. In addition, Old National obtains collateral above certain thresholds of the fair value of its hedges for each counterparty based upon their credit standing. All of the contracts to which Old National is a party settle monthly, quarterly, or semiannually. Further, Old National has netting agreements with the dealers with which it does business.
Credit-Related Financial Instruments	Credit-Related Financial Instruments In the ordinary course of business, Old National’s affiliate bank has entered into credit-related financial instruments consisting of commitments to extend credit, commercial letters of credit, and standby letters of credit. The notional amount of these commitments is not reflected in the consolidated financial statements until they are funded.
Repossessed Collateral	Repossessed Collateral Other real estate owned and repossessed personal property are initially recorded at the fair value of the property less estimated cost to sell. Physical possession of residential real estate property collateralizing a consumer mortgage loan occurs when legal title is obtained upon completion of foreclosure or when the borrower conveys all interest in the property to satisfy the loan through the completion of a deed in lieu of foreclosure or through a similar legal agreement Any excess recorded investment over the fair value of the property received is charged to the allowance for loan losses. Any subsequent write-downs are recorded in noninterest expense, as are the costs of operating the properties. Gains or losses resulting from the sale of collateral are recognized in noninterest expense at the date of sale.
Securities Purchased under Agreements to Resell and Securities Sold under Agreements to Repurchase	Securities Purchased Under Agreements to Resell and Securities Sold Under Agreements to Repurchase We purchase certain securities, generally U.S. government-sponsored entity and agency securities, under agreements to resell. The amounts advanced under these agreements represent short-term secured loans and are reflected as assets in the accompanying consolidated balance sheets. We also sell certain securities under agreements to repurchase. These agreements are treated as collateralized financing transactions. These secured borrowings are reflected as liabilities in the accompanying consolidated balance sheets and are recorded at the amount of cash received in connection with the transaction. Short-term securities sold under agreements to repurchase generally mature within one to four days from the transaction date. Securities, generally U.S. government and federal agency securities, pledged as collateral under these financing arrangements can be repledged by the secured party. Additional collateral may be required based on the fair value of the underlying securities.
Net Income per Share	Net Income per Share Basic and diluted net income per share are calculated using the two-class method. Net income is divided by the weighted-average number of common shares outstanding during the period. Adjustments to the weighted average number of common shares outstanding are made only when such adjustments will dilute net income per common share. Net income is then divided by the weighted-average number of common shares and common share equivalents during the period. The following table reconciles basic and diluted net income per share for the years ended December 31. (dollars and shares in thousands, Years Ended December 31, except per share data) 2018 2017 2016 Basic Net Income Per Share Net income $ 190,830 $ 95,725 $ 134,264 Weighted average common shares outstanding 155,675 137,821 127,705 Basic Net Income Per Share $ 1.23 $ 0.69 $ 1.05 Diluted Net Income Per Share Net income $ 190,830 $ 95,725 $ 134,264 Weighted average common shares outstanding 155,675 137,821 127,705 Effect of dilutive securities: Restricted stock 796 599 543 Stock options (1) 68 93 53 Weighted average shares outstanding 156,539 138,513 128,301 Diluted Earnings Per Share $ 1.22 $ 0.69 $ 1.05 (1) Options to purchase 14 thousand shares, 0.1 million shares, and 0.5 million shares outstanding at December 31, 2018, 2017, and 2016, respectively, were not included in the computation of net income per diluted share because the exercise price of these options was greater than the average market price of the common shares and, therefore, the effect would be antidilutive.
Stock-Based Compensation	Share-Based Compensation Compensation cost is recognized for stock options and restricted stock awards and units issued to employees based on the fair value of these awards at the date of grant. A Black-Scholes model is utilized to estimate the fair value of stock options, while the market price of our Common Stock at the date of grant is used for restricted stock awards. A third party provider is used to value certain restricted stock units where the performance measure is based on total shareholder return. Compensation expense is recognized over the requisite service period. Forfeitures are recognized as they occur.
Income Taxes	Income Taxes Income tax expense is the total of the current year income tax due or refundable and the change in deferred tax assets and liabilities. Deferred tax assets and liabilities are the expected future tax amounts for the temporary differences between carrying amounts and tax bases of assets and liabilities, computed using enacted tax rates. A valuation allowance, if needed, reduces deferred tax assets to the amount expected to be realized. We recognize a tax position as a benefit only if it is “more likely than not” that the tax position would be sustained in a tax examination, with a tax examination being presumed to occur. The amount recognized is the largest amount of tax benefit that is greater than 50% likely of being realized on examination. For tax positions not meeting the “more likely than not” test, no tax benefit is recorded. We recognize interest and/or penalties related to income tax matters in income tax expense. Old National is a limited partner in several tax-advantaged limited partnerships whose purpose is to invest in approved qualified affordable housing, renewable energy, or other renovation or community revitalization projects. These investments are included in other assets on the balance sheet, with any unfunded commitments included with other liabilities. Certain of these assets qualify for the proportional amortization method and are amortized over the period that Old National expects to receive the tax credits, with the expense included within income tax expense on the consolidated statements of income. The other investments are accounted for under the equity method, with the expense included within pre-tax income on the consolidated statements of income. All of our tax credit investments are evaluated for impairment at the end of each reporting period.
Loss Contingencies	Loss Contingencies Loss contingencies, including claims and legal actions arising in the normal course of business, are recorded as liabilities when the likelihood of loss is probable and an amount or range of loss can be reasonably estimated. See Note 22 to the consolidated financial statements for further disclosure.
Cash Equivalents and Cash Flows	Cash Equivalents and Cash Flows For the purpose of presentation in the accompanying consolidated statement of cash flows, cash and cash equivalents are defined as cash, due from banks, federal funds sold and resell agreements, and money market investments, which have maturities less than 90 days. Cash flows from loans, either originated or acquired, are classified at that time according to management’s intent to either sell or hold the loan for the foreseeable future. When management’s intent is to sell the loan, the cash flows of that loan are presented as operating cash flows. When management’s intent is to hold the loan for the foreseeable future, the cash flows of that loan are presented as investing cash flows. The following table summarizes the supplemental cash flow information for the years ended December 31: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Cash payments: Interest $ 91,813 $ 56,682 $ 43,698 Income taxes (net of refunds) (2,505 ) 4,326 23,636 Noncash Investing and Financing Activities: Securities transferred from held-to-maturity to available-for-sale 447,026 — — Securities transferred from available-for-sale to held-to-maturity 323,990 — — Transfer of premises and equipment to assets held for sale 9,634 16,617 4,620 The following table summarizes the common shares issued and resultant value of total shareholders’ equity associated with acquisitions for the years ended December 31: Total Shares of Shareholders' (dollars and shares in thousands) Common Stock Equity 2018 Acquisition of Klein 22,772 $ 406,474 2017 Acquisition of Anchor (MN) 16,527 $ 300,828 2016 Acquisition of Anchor (WI) 20,415 $ 273,565
Business Combinations	Business Combinations Old National accounts for business combinations using the acquisition method of accounting. The accounts of an acquired entity are included as of the date of acquisition, and any excess of purchase price over the fair value of the net assets acquired is capitalized as goodwill. Old National typically issues common stock and/or pays cash for an acquisition, depending on the terms of the acquisition agreement. The value of common shares issued is determined based on the market price of the stock as of the closing of the acquisition.
Impact of Accounting Changes	Impact of Accounting Changes Accounting Guidance Adopted in 2018 FASB ASC 606 – On January 1, 2018, Old National adopted ASU 2014-09, Revenue from Contracts with Customers and all subsequent amendments to the ASU (collectively, “Topic 606”), which creates a single framework for recognizing revenue from contracts with customers that fall within its scope. A significant majority of Old National’s revenues come from interest income and other sources, including loans, leases, securities and derivatives, that are not subject to Topic 606. Services within the scope of Topic 606 include wealth management fees, service charges on deposit accounts, debit card and ATM fees, and investment product fees, all of which are presented within noninterest income. Old National enters into various contracts with customers to provide these traditional banking services on a routine basis. Old National’s performance obligations are generally service-related and provided on a daily, monthly, or quarterly basis. The performance obligations are generally satisfied as services are rendered and the fees are collected at such time, or shortly thereafter. It is not typical for contracts to require significant judgment to determine the transaction price. See Note 24 for additional information. Old National adopted Topic 606 using the modified retrospective method applied to all contracts not completed as of January 1, 2018. Results for reporting periods beginning after adoption are presented under Topic 606. As allowed under the update, results for prior periods continue to be reported under the accounting standards in effect for those periods. The adoption of this update did not have a material impact on the measurement, timing, or recognition of revenue. Accordingly, no cumulative effect adjustment to opening retained earnings was deemed necessary. FASB ASC 825 – In January 2016, the FASB issued an update (ASU No. 2016-01, Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities) . The amendments in this update impact public business entities as follows: (1) require equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income; (2) simplify the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment; and when a qualitative assessment indicates that impairment exists, an entity is required to measure the investment at fair value; (3) eliminate the requirement to disclose the methods and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet; (4) require entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; (5) require an entity to present separately in other comprehensive income the portion of the total change in fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments; (6) require separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (that is, securities or loans and receivables) on the balance sheet or the accompanying notes to the financial statements; and (7) clarify that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity’s other deferred tax assets. The amendments in this update became effective for annual periods and interim periods within those annual periods beginning after December 15, 2017 and did not have a material impact on the consolidated financial statements. In February 2018, the FASB issued an update (ASU No. 2018-03, Technical Corrections and Improvements to Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities) FASB ASC 740 – In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory . Current guidance prohibits the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset has been sold to an outside party. This prohibition on recognition is an exception to the principle of comprehensive recognition of current and deferred income taxes in generally accepted accounting principles. The exception has led to diversity in practice and is a source of complexity in financial reporting. FASB decided that an entity should recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. Consequently, the amendments in this update eliminate the exception for an intra-entity transfer of an asset other than inventory. The amendments in this update do not include new disclosure requirements; however, existing disclosure requirements might be applicable when accounting for the current and deferred income taxes for an intra-entity transfer of an asset other than inventory. The amendments in this update became effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within those annual reporting periods. The amendments in this update were applied on a modified retrospective basis through a cumulative-effect reduction of $ 1.0 million directly to retained earnings as of the beginning of 2018. FASB ASC 805 – In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business . The amendments in this update provide a more robust framework to use in determining when a set of assets and activities is a business. Because the current definition of a business is interpreted broadly and can be difficult to apply, stakeholders indicated that analyzing transactions is inefficient and costly and that the definition does not permit the use of reasonable judgment. The amendments provide more consistency in applying the guidance, reduce the costs of application, and make the definition of a business more operable. The amendments in this update became effective for annual periods and interim periods within those annual periods beginning after December 15, 2017. Old National has completed its evaluation of adopting the new guidance on the consolidated financial statements and there is no impact. FASB ASC 610 – In February 2017, the FASB issued ASU No. 2017-05, Other Income – Gains and Losses from the Derecognition of Nonfinancial Assets (Topic 610): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets . Subtopic 610-20 was originally issued as part of ASU No. 2014-09 to provide guidance for recognizing gains and losses from the transfer of nonfinancial assets in contracts with noncustomers. This update was issued to help clarify uncertainties and complexities of ASU 2014-09. The amendments in this update define the term in substance nonfinancial asset, in part, as a financial asset promised to a counterparty in a contract if substantially all of its fair value of the assets (recognized and unrecognized) that are promised to the counterparty in the contract is concentrated in nonfinancial assets. If substantially all of the fair value of the assets that are promised to the counterparty in a contract is concentrated in nonfinancial assets, then all of the financial assets promised to the counterparty are in substance nonfinancial assets. The amendments in this update also clarify that nonfinancial assets within the scope of Subtopic 610-20 may include nonfinancial assets transferred within a legal entity to a counterparty. The amendments in this update require an entity to derecognize a distinct nonfinancial asset or distinct in substance nonfinancial asset in a partial sale transaction when it (1) does not have (or ceases to have) a controlling financial interest in the legal entity that holds the asset in accordance with Topic 810 and (2) transfers control of the asset in accordance with Topic 606. Once an entity transfers control of a distinct nonfinancial asset or distinct in substance nonfinancial asset, it is required to measure any noncontrolling interest it receives (or retains) at fair value. The amendments were effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period and did not have a material impact on the consolidated financial statements. FASB ASC 715 – In March 2017, the FASB issued ASU No. 2017-07, Compensation – Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost . The amendments in this update require that an employer disaggregate the service cost component from the other components of net benefit cost. The amendments also provide explicit guidance on how to present the service cost component and the other components of net benefit cost in the income statement and allow only the service cost component of net benefit cost to be eligible for capitalization. The amendments in this update improve the consistency, transparency, and usefulness of financial information to users that have communicated that the service cost component generally is analyzed differently from the other components of net benefit cost. The amendments in this update became effective for annual periods and interim periods within those annual periods beginning after December 15, 2017 and did not have a material impact on the consolidated financial statements. FASB ASC 718 – In May 2017, the FASB issued ASU No. 2017-09, Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting. The amendments in this update provide guidance about which changes to the terms and conditions of a share-based payment award require an entity to apply modification accounting. An entity should account for the effect of a modification unless all the following are met: (1) the fair value of the modified award is the same as the fair value of the original award immediately before the original award is modified – if the modification does not affect any of the inputs to the valuation technique that the entity uses to value the award, the entity is not required to estimate the value immediately before and after the modification; (2) the vesting conditions of the modified award are the same as the vesting conditions of the original award immediately before the original award is modified; (3) the classification of the modified award as an equity instrument or a liability instrument is the same as the classification of the original award immediately before the original award is modified. The amendments in this update became effective for annual periods and interim periods within those annual periods beginning after December 15, 2017 and did not have a material impact on the consolidated financial statements. FASB ASC 815 – In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities. The amendments in the update make certain targeted improvements to simplify the application of the hedge accounting guidance in GAAP. The amendments in this update better align an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. To meet that objective, the amendments expand and refine hedge accounting for both nonfinancial and financial risk components and align the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. This update addresses several limitations that GAAP placed on the risk components, how an entity can designate the hedged item in a fair value hedge of interest rate risk, and how an entity can measure changes in fair value of the hedged item attributable to interest rate risk. In addition to the amendments to the designation and measurement guidance for qualifying hedging relationships, the amendments in this update also align the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements to increase the understandability of the results of an entity’s intended hedging strategies. The amendments in this update require an entity to present the earnings effect of the hedging instrument in the same income statement line item in which the earnings effect of the hedged item is reported. Prior to the issuance of this update, GAAP provided special hedge accounting only for the portion of the hedge deemed to be “highly effective” and required an entity to separately reflect the amount by which the hedging instrument did not offset the hedged item, which is referred to as the “ineffective” amount. However, the concept and reporting of hedge ineffectiveness were difficult for financial statement users to understand and, at times, for preparers to explain. The FASB decided on an approach that no longer separately measures and reports hedge ineffectiveness. This update also includes certain targeted improvements to ease the application of current guidance related to the assessment of hedge effectiveness. Prior to the issuance of this update, GAAP contained specific requirements for initial and ongoing quantitative hedge effectiveness testing and strict requirements for specialized effectiveness testing methods that allowed an entity to forgo quantitative hedge effectiveness assessments for qualifying relationships. The amendments in this update become effective for annual periods and interim periods within those annual periods beginning after December 15, 2018. Early adoption is permitted in any interim period. Management elected to early adopt this update effective January 1, 2018 using the modified retrospective method. The impact of the adoption resulted in a reduction to Old National’s opening retained earnings of $3.2 million. In addition, as permitted by the amendments in the update, Old National reclassified $447.0 million in state and political subdivision securities with unrealized holding gains of $26.1 million from the held-to-maturity portfolio to the available-for-sale portfolio. FASB ASC 220 – In February 2018, the FASB issued ASU No. 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income . The amendments in this ASU help organizations address certain stranded income tax effects in AOCI resulting from the Tax Cuts and Jobs Act. The ASU provides financial statement preparers with an option to reclassify stranded tax effects within AOCI to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act (or portion thereof) is recorded. The amendments are effective for all organizations for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. Management has elected to early adopt this update effective January 1, 2018, which resulted in a reclassification that decreased beginning accumulated other comprehensive income and increased beginning retained earnings by $10.8 million. Accounting Guidance Issued But Not Yet Adopted in 2018 FASB ASC 842 – In February 2016, the FASB issued its new lease accounting guidance in ASU No. 2016-02, Leases (Topic 842) . Under the new guidance, lessees will be required to recognize the following for all leases, with the exception of short-term leases, at the commencement date: (1) a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and (2) a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. Under the new guidance, lessor accounting is largely unchanged. In July 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842, Leases and ASU No. 2018-11, Leases (Topic 842): Targeted Improvements . ASU No. 2018-10 provides improvements related to ASU No. 2016-02 to increase stakeholders’ awareness of the amendments and to expedite the improvements. The amendments affect narrow aspects of the guidance issued in ASU No. 2016-02. ASU No. 2018-11 allows entities adopting ASU No. 2016-02 to choose an additional (and optional) transition method, under which an entity initially applies the new leases standard at the adoption date and recognizes a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. ASU No. 2018-11 also allows lessors to not separate non-lease components from the associated lease component if certain conditions are met. The amendments in these updates become effective for annual periods and interim periods within those annual periods beginning after December 15, 2018 . Old National elected the optional transition method permitted by ASU No. 2018-11. Under this method, an entity shall recognize and measure leases that exist at the application date and prior comparative periods are not adjusted. In addition, Old National elected the package of practical expedients to leases that commenced before the effective date: 1. An entity need not reassess whether any expired or existing contracts contain leases. 2. An entity need not reassess the lease classification for any expired or existing leases. 3. An entity need not reassess initial direct costs for any existing leases. Old National also elected the practical expedient, which must be applied consistently to all leases, to use hindsight in determining the lease term and in assessing impairment of our right-of-use assets. We also elected a practical expedient to not assess whether existing or expired land easements that were not previously accounted for as leases under Topic 840 contain a lease under this Topic. Both of these practical expedients may be elected separately or in conjunction with each other or the package noted above. Based on leases outstanding at December 31, 2018, the impact of adoption on January 1, 2019 was recording a lease liability of approximately $123 million, a right-of-use asset of approximately $119 million, and a cumulative-effect adjustment to retained earnings of approximately $6 million. FASB ASC 326 – In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“CECL”). The main objective of this amendment is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The amendment requires the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Financial institutions and other organizations will now use forward-looking information to enhance their credit loss estimates. The amendment requires enhanced disclosures to help investors and other financial statement users better understand significant estimates and judgments used in estimating credit losses, as well as the credit quality and underwriting standards of an organization’s portfolio. In addition, the ASU amends the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. The amendments in this update become effective for annual periods and interim periods within those annual periods beginning after December 15, 2019. Early adoption will be permitted beginning after December 15, 2018. As previously disclosed, Old National formed a cross functional committee to oversee the adoption of the ASU at the effective date. A working group was also formed and has developed a project plan focused on understanding the ASU, researching issues, identifying data needs for modeling inputs, technology requirements, modeling considerations, and ensuring overarching governance has been achieved for each objective and milestone. The project plan is targeting data and model validation completion during the first half of 2019, with parallel processing of our existing allowance for loan losses model with the CECL for 2 – 3 quarters prior to implementation, depending on how model completion and validation occurs. Currently, the working group has identified seven distinct loan portfolios for which a model has been or is in the process of being developed. For five of the seven loan portfolios, the data sets have been identified, populated, and internally validated. During 2019, Old National is focused on the completion of its remaining models, refining assumptions, and continued review and challenge of its models. Concurrent with this, Old National is also focused on researching and resolving interpretive accounting issues in the ASU, contemplating various related accounting policies, developing processes and related controls, and considering various reporting disclosures. As of the beginning of the first reporting period in which the new standard is effective, Old National expects to recognize a one-time cumulative effect adjustment increasing the allowance for loan losses, since the ASU covers credit losses over the expected life of a loan as well as considering future changes in macroeconomic conditions. The magnitude of any such one-time adjustment or the overall impact of the new guidance on the consolidated financial statements cannot yet be reasonably estimated , however, we expect to identify a range in our Quarterly Report on Form 10-Q for the quarterly period ended September 30, 2019 . In December 2018, the OCC, the Board of Governors of the Federal Reserve System, and the FDIC approved a final rule to address changes to credit loss accounting under GAAP, including banking organizations’ implementation of CECL. The final rule provides banking organizations the option to phase in over a three-year period the day-one adverse effects on regulatory capital that may result from the adoption of the new accounting standard. FASB ASC 350 – In January 2017, the FASB issued ASU No. 2017-04, Intangibles: Goodwill and Other: Simplifying the Test for Goodwill Impairment . To simplify the subsequent measurement of goodwill, the amendments eliminate Step 2 from the goodwill impairment test. The annual, or interim, goodwill impairment test is performed by comparing the fair value of a reporting unit with its carrying amount. An impairment charge should be recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. In addition, the income tax effects of tax deductible goodwill on the carrying amount of the reporting unit should be considered when measuring the goodwill impairment loss, if applicable. The amendments also eliminate the requirements for any reporting unit with a zero or negative carrying amount to perform Step 2 of the goodwill impairment test. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the qualitative impairment test is necessary. The amendments should be applied on a prospective basis. The nature of and reason for the change in accounting principle should be disclosed upon transition. The amendments in this update should be adopted for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted on testing dates after January 1, 2017. Old National is currently evaluating the impact of adopting the new guidance on the consolidated financial statements, but it is not expected to have a material impact. FASB ASC 310 – In March 2017, the FASB issued ASU No. 2017-08, Receivables – Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities . This update amends the amortization period for certain purchased callable debt securities held at a premium. FASB is shortening the amortization period for the premium to the earliest call date. Under current GAAP, entities generally amortize the premium as an adjustment of yield over the contractual life of the instrument. Concerns were raised that current GAAP excludes certain callable debt securities from consideration of early repayment of principal even if the holder is certain that the call will be exercised. As a result, upon the exercise of a call on a callable debt security held at a premium, the unamortized premium is recorded as a loss in earnings. There is diversity in practice (1) in the amortization period for premiums of callable debt securities and (2) in how the potential for exercise of a call is factored into current impairment assessments. The amendments in this update become effective for annual periods and interim periods within those annual periods beginning after December 15, 2018. Old National completed the evaluation of adopting the new guidance on the consolidated financial statements and the impact was immaterial. FASB ASC 718 – In June 2018, the FASB issued ASU No. 2018-07, Compensation – Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. The amendments in this update expand the scope of Topic 718, Compensation—Stock Compensation (which currently only includes share-based payments to employees) to include share-based payments issued to nonemployees for goods or services. Consequently, the accounting for share-based payments to nonemployees and employees will be substantially aligned. The ASU supersedes Subtopic 505-50, Equity—Equity-Based Payments to Non-Employees. The amendments in this update become effective for annual periods beginning after December 15, 2018, including interim periods within that fiscal year and will not have a material impact on the consolidated financial statements. FASB ASC 958 – In June 2018, the FASB issued ASU No. 2018-08, Not-for-Profit Entities (Topic 958): Clarifying the Scope and the Accounting Guidance for Contributions Received and Contributions Made. The amendments in this update clarify and improve the scope and accounting guidance around contributions of cash and other assets received and made by not-for-profit organizations and business enterprises. The ASU clarifies and improves current guidance about whether a transfer of assets, or the reduction, settlement, or cancellation of liabilities, is a contribution or an exchange transaction. It provides criteria for determining whether the resource provider is receiving commensurate value in return for the resources transferred which, depending on the outcome, determines whether the organization follows contribution guidance or exchange transaction guidance in the revenue recognition and other applicable standards. It also provides a more robust framework for determining whether a contribution is conditional or unconditional, and for distinguishing a donor-imposed condition from a donor-imposed restriction. This is important because such classification affects the timing of contribution revenue and expense recognition. The new ASU does not apply to transfers of assets from governments to businesses. The amendments in this update become effective for a public business entity for transactions in which the entity serves as a resource recipient to annual periods beginning after June 15, 2018, including interim periods within those annual periods. The amendments in this update become effective for a public business entity for transactions in which the entity serves as a resource provider to annual periods beginning after December 15, 2018, including interim periods within those annual periods. Early adoption is permitted. Old National completed the evaluation of adopting the new guidance on the consolidated financial statements and there is no impact . In July 2018, the FASB issued an update (ASU No. 2018-09, Codification Improvements) FASB ASC 820 – In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement . The updated guidance improves the disclosure requirements on fair value measurements. The ASU removes certain disclosures required by Topic 820 related to transfers between Level 1 and Level 2 of the fair value hierarchy; the policy for timing of transfers between levels; the valuation processes for Level 3 fair value measurements; and for nonpublic entities, the changes in unrealized gains and losses for the period included in earnings for recurring Level 3 fair value measurements held at the end of the reporting period. The ASU modifies certain disclosures required by Topic 820 related to disclosure of transfers into and out of Level 3 of the fair value hierarchy and purchases and issues of Level 3 assets and liabilities for nonpublic entities; the requirement to disclose the timing of liquidation of an investee’s assets and the date when restrictions from redemption might lapse only if the investee has communicated the timing to the entity or announced the timing publicly for investments in certain entities that calculate net asset value; and clarification that the measurement uncertainty disclosure is to communicate information about the uncertainty in measurement as of the reporting date. The ASU adds certain disclosure requirements related to changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. For certain unobservable inputs, an entity may disclose other quantitative information in lieu of the weighted average if the entity determines that other quantitative information would be a more reasonable and rational method to reflect the distribution of unobservable inputs used to develop Level 3 fair value measurements. The amendments in this update become effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2019. Early adoption is permitted. Old National is currently evaluating the impact of adopting the new guidance on the consolidated financial statements, but it is not expected to have a material impact. FASB ASC 715 – In August 2018, the FASB issued ASU No. 2018-14, Compensation – Retirement Benefits – Defined Benefit Plans – General (Subtopic 715-20): Disclosure Framework – Changes to the Disclosure Requirements for Defined Benefit Plans . The amendments in this update modify the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The amendments in this update become effective for fiscal years ending after December 15, 2020 and will not have a material impact on the consolidated financial statements. FASB ASC 350 – In August 2018, the FASB issued ASU No. 2018-15, Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract . The amendments in this update align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The amendments in this update become effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted. Old National is currently evaluating the impact of adopting the new guidance on the consolidated financial statements. FASB ASC 815 – In October 2018, the FASB issued ASU No. 2018-16, Derivatives and Hedging (Topic 815): Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate for He

Basis of Presentation and Sig_3

Basis of Presentation and Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Table Reconciling Basic and Diluted Net Income Per Share	The following table reconciles basic and diluted net income per share for the years ended December 31. (dollars and shares in thousands, Years Ended December 31, except per share data) 2018 2017 2016 Basic Net Income Per Share Net income $ 190,830 $ 95,725 $ 134,264 Weighted average common shares outstanding 155,675 137,821 127,705 Basic Net Income Per Share $ 1.23 $ 0.69 $ 1.05 Diluted Net Income Per Share Net income $ 190,830 $ 95,725 $ 134,264 Weighted average common shares outstanding 155,675 137,821 127,705 Effect of dilutive securities: Restricted stock 796 599 543 Stock options (1) 68 93 53 Weighted average shares outstanding 156,539 138,513 128,301 Diluted Earnings Per Share $ 1.22 $ 0.69 $ 1.05 (1) Options to purchase 14 thousand shares, 0.1 million shares, and 0.5 million shares outstanding at December 31, 2018, 2017, and 2016, respectively, were not included in the computation of net income per diluted share because the exercise price of these options was greater than the average market price of the common shares and, therefore, the effect would be antidilutive.
Summary of Supplemental Cash Flow Information	The following table summarizes the supplemental cash flow information for the years ended December 31: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Cash payments: Interest $ 91,813 $ 56,682 $ 43,698 Income taxes (net of refunds) (2,505 ) 4,326 23,636 Noncash Investing and Financing Activities: Securities transferred from held-to-maturity to available-for-sale 447,026 — — Securities transferred from available-for-sale to held-to-maturity 323,990 — — Transfer of premises and equipment to assets held for sale 9,634 16,617 4,620
Summary of Common Shares Issued and Resultant Value of Total Shareholders' Equity	The following table summarizes the common shares issued and resultant value of total shareholders’ equity associated with acquisitions for the years ended December 31: Total Shares of Shareholders' (dollars and shares in thousands) Common Stock Equity 2018 Acquisition of Klein 22,772 $ 406,474 2017 Acquisition of Anchor (MN) 16,527 $ 300,828 2016 Acquisition of Anchor (WI) 20,415 $ 273,565

Acquisition and Divestiture A_2

Acquisition and Divestiture Activity (Tables)	12 Months Ended
	Dec. 31, 2018
Summary of Unaudited Pro-Forma Information	The unaudited pro-forma information below for 2018 and 2017 gives effect to the Klein acquisition as if it had occurred on January 1, 2017. The pro-forma financial information is not necessarily indicative of the results of operations if the acquisition had been effective as of this date. (dollars in thousands) 2018 2017 Revenue (1) $ 819,777 $ 708,422 Income before income taxes $ 273,125 $ 183,494 (1) Net interest income plus noninterest income.
Anchor Bank (MN) [Member] | Minnesota [Member]
Summary of Fair Values of Acquired Assets, Liabilities Assumed and Resulting Goodwill	A summary of the fair values of the acquired assets, liabilities assumed, and resulting goodwill follows (in thousands) : Cash and cash equivalents $ 34,501 Investment securities 302,195 FHLB/Federal Reserve Bank stock 6,585 Loans held for sale 1,407 Loans 1,593,991 Premises and equipment 33,433 Accrued interest receivable 5,872 Other real estate owned 1,058 Company-owned life insurance 44,490 Other assets 30,036 Deposits (1,777,588 ) Federal funds purchased and interbank borrowings (45,600 ) Securities sold under agreements to repurchase (22,965 ) Other borrowings (49,257 ) Accrued expenses and other liabilities (25,784 ) Net tangible assets acquired 132,374 Definite-lived intangible assets acquired 26,606 Goodwill 173,785 Total consideration $ 332,765
Summary of Acquired Loan Data	Acquired loan data for Anchor (MN) can be found in the table below: (in thousands) Fair Value of Acquired Loans at Acquisition Date Gross Contractual Amounts Receivable at Acquisition Date Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected Acquired receivables subject to ASC 310-30 $ 10,555 $ 16,898 $ 4,787 Acquired receivables not subject to ASC 310-30 $ 1,583,436 $ 1,879,449 $ 87,767
KleinBank [Member] | Minnesota [Member]
Summary of Fair Values of Acquired Assets, Liabilities Assumed and Resulting Goodwill	The following table reflects management’s preliminary valuation of the assets acquired and liabilities assumed (in thousands): Cash and cash equivalents $ 60,759 Investment securities 697,951 FHLB/Federal Reserve Bank stock 2,637 Loans held for sale 3,371 Loans 1,049,073 Premises and equipment 33,391 Accrued interest receivable 7,896 Company-owned life insurance 36,380 Net deferred tax assets 6,500 Other real estate owned 954 Other assets 10,299 Deposits (1,713,086 ) Securities sold under agreements to repurchase (19,481 ) Accrued expenses and other liabilities (17,506 ) Net tangible assets acquired 159,138 Definite-lived intangible assets acquired 39,017 Loan servicing rights 285 Goodwill 208,034 Total consideration $ 406,474
Summary of Acquired Loan Data	Acquired loan data for Klein can be found in the table below: (in thousands) Fair Value of Acquired Loans at Acquisition Date Gross Contractual Amounts Receivable at Acquisition Date Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected Acquired receivables subject to ASC 310-30 $ 11,663 $ 18,568 $ 4,521 Acquired receivables not subject to ASC 310-30 $ 1,037,410 $ 1,252,954 $ 76,534

Investment Securities (Tables)

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Amortized Cost and Fair Value of Available-for-Sale and Held-to-Maturity Investment Securities Portfolio	The following table summarizes the amortized cost and fair value of the available-for-sale and held-to-maturity investment securities portfolio at December 31 and the corresponding amounts of unrealized gains and losses therein: Amortized Unrealized Unrealized Fair (dollars in thousands) Cost Gains Losses Value December 31, 2018 Available-for-Sale U.S. Treasury $ 5,332 $ — $ (31 ) $ 5,301 U.S. government-sponsored entities and agencies 639,458 35 (11,342 ) 628,151 Mortgage-backed securities - Agency 2,243,774 9,738 (44,217 ) 2,209,295 States and political subdivisions 932,757 11,113 (3,441 ) 940,429 Pooled trust preferred securities 13,861 — (5,366 ) 8,495 Other securities 337,435 486 (6,176 ) 331,745 Total available-for-sale securities $ 4,172,617 $ 21,372 $ (70,573 ) $ 4,123,416 Held-to-Maturity U.S. government-sponsored entities and agencies $ 73,986 $ — $ (1,627 ) $ 72,359 Mortgage-backed securities - Agency 127,120 39 (2,750 ) 124,409 States and political subdivisions 305,228 6,208 (2,101 ) 309,335 Total held-to-maturity securities $ 506,334 $ 6,247 $ (6,478 ) $ 506,103 December 31, 2017 Available-for-Sale U.S. Treasury $ 5,473 $ 83 $ (5 ) $ 5,551 U.S. government-sponsored entities and agencies 675,643 3 (11,360 ) 664,286 Mortgage-backed securities - Agency 1,704,014 1,600 (37,932 ) 1,667,682 States and political subdivisions 529,835 5,085 (4,727 ) 530,193 Pooled trust preferred securities 16,605 — (8,157 ) 8,448 Other securities 321,016 1,172 (2,141 ) 320,047 Total available-for-sale securities $ 3,252,586 $ 7,943 $ (64,322 ) $ 3,196,207 Held-to-Maturity Mortgage-backed securities - Agency $ 6,903 $ 153 $ — $ 7,056 States and political subdivisions 677,160 43,495 (8 ) 720,647 Total held-to-maturity securities $ 684,063 $ 43,648 $ (8 ) $ 727,703
Schedule of Proceeds from Sales or Calls and Realized Gain and Losses of Available-for-Sale Investment Securities and Other Securities	Proceeds from sales or calls of available-for-sale investment securities, the resulting realized gains and realized losses, and other securities gains or losses were as follows for the years ended December 31: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Proceeds from sales of available-for-sale securities $ 139,364 $ 342,233 $ 243,312 Proceeds from calls of available-for-sale securities 32,437 88,233 635,624 Total $ 171,801 $ 430,466 $ 878,936 Realized gains on sales of available-for-sale securities $ 3,259 $ 8,710 $ 5,423 Realized gains on calls of available-for-sale securities 283 29 922 Realized losses on sales of available-for-sale securities (1,469 ) (263 ) (450 ) Realized losses on calls of available-for-sale securities (63 ) (8 ) (147 ) Other securities gains (losses) (1) 50 667 100 Net securities gains $ 2,060 $ 9,135 $ 5,848 (1) Other securities gains (losses) includes net realized and unrealized gains or losses associated with equity securities and mutual funds.
Expected Maturities of Investment Securities Portfolio	Weighted average yield is based on amortized cost. At December 31, 2018 (dollars in thousands) Weighted Amortized Fair Average Maturity Cost Value Yield Available-for-Sale Within one year $ 101,077 $ 101,138 2.58 % One to five years 532,706 527,283 2.39 Five to ten years 483,510 482,231 3.22 Beyond ten years 3,055,324 3,012,764 2.94 Total $ 4,172,617 $ 4,123,416 2.89 % Held-to-Maturity Within one year $ 30,188 $ 30,352 3.96 % One to five years 34,511 35,246 3.93 Five to ten years 72,442 74,199 4.44 Beyond ten years 369,193 366,306 3.58 Total $ 506,334 $ 506,103 3.75 %
Available-for-Sale and Held-to-Maturity Investment Securities with Unrealized Losses by Aggregated Major Security Type and Length of Time in Continuous Unrealized Loss Position	The following table summarizes the available-for-sale investment securities with unrealized losses at December 31 by aggregated major security type and length of time in a continuous unrealized loss position: Less than 12 months 12 months or longer Total Fair Unrealized Fair Unrealized Fair Unrealized (dollars in thousands) Value Losses Value Losses Value Losses December 31, 2018 Available-for-Sale U.S. Treasury $ 3,829 $ (12 ) $ 1,472 $ (19 ) $ 5,301 $ (31 ) U.S. government-sponsored entities and agencies 54,701 (594 ) 519,911 (10,748 ) 574,612 (11,342 ) Mortgage-backed securities - Agency 82,289 (742 ) 1,172,984 (43,475 ) 1,255,273 (44,217 ) States and political subdivisions 99,162 (1,340 ) 151,097 (2,101 ) 250,259 (3,441 ) Pooled trust preferred securities — — 8,495 (5,366 ) 8,495 (5,366 ) Other securities 94,607 (1,965 ) 143,842 (4,211 ) 238,449 (6,176 ) Total available-for-sale $ 334,588 $ (4,653 ) $ 1,997,801 $ (65,920 ) $ 2,332,389 $ (70,573 ) December 31, 2017 Available-for-Sale U.S. Treasury $ 1,480 $ (5 ) $ — $ — $ 1,480 $ (5 ) U.S. government-sponsored entities and agencies 201,773 (1,333 ) 408,493 (10,027 ) 610,266 (11,360 ) Mortgage-backed securities - Agency 789,804 (8,692 ) 774,825 (29,240 ) 1,564,629 (37,932 ) States and political subdivisions 196,024 (1,899 ) 90,637 (2,828 ) 286,661 (4,727 ) Pooled trust preferred securities — — 8,448 (8,157 ) 8,448 (8,157 ) Other securities 61,260 (429 ) 125,517 (1,712 ) 186,777 (2,141 ) Total available-for-sale $ 1,250,341 $ (12,358 ) $ 1,407,920 $ (51,964 ) $ 2,658,261 $ (64,322 ) The following table summarizes the held-to-maturity investment securities with unrecognized losses at December 31 by aggregated major security type and length of time in a continuous unrecognized loss position: Less than 12 months 12 months or longer Total Fair Unrecognized Fair Unrecognized Fair Unrecognized (dollars in thousands) Value Losses Value Losses Value Losses December 31, 2018 Held-to-Maturity U.S. government-sponsored entities and agencies $ — $ — $ 72,359 $ (4,642 ) $ 72,359 $ (4,642 ) Mortgage-backed securities - Agency 4,335 (24 ) 119,207 (8,006 ) 123,542 (8,030 ) States and political subdivisions 24,533 (983 ) 70,022 (3,556 ) 94,555 (4,539 ) Total held-to-maturity $ 28,868 $ (1,007 ) $ 261,588 $ (16,204 ) $ 290,456 $ (17,211 ) December 31, 2017 Held-to-Maturity States and political subdivisions $ 2,309 $ (8 ) $ — $ — $ 2,309 $ (8 ) Total held-to-maturity $ 2,309 $ (8 ) $ — $ — $ 2,309 $ (8 )
Trust Preferred Securities	The table below summarizes the relevant characteristics of our pooled trust preferred securities as well as our single issuer trust preferred securities that are included in the “other securities” category in this footnote. Each of the pooled trust preferred securities support a more senior tranche of security holders. Both pooled trust preferred securities have experienced credit defaults. However, these securities have excess subordination and are not other-than-temporarily impaired as a result of their class hierarchy, which provides more loss protection. Trust preferred securities Actual Expected Excess December 31, 2018 Deferrals Defaults as Subordination (dollars in thousands) # of Issuers and Defaults a % of as a % of Lowest Unrealized Realized Currently as a % of Remaining Current Credit Amortized Fair Gain/ Losses Performing/ Original Performing Performing Class Rating (1) Cost Value (Loss) 2018 Remaining Collateral Collateral Collateral Pooled trust preferred securities: Pretsl XXVII LTD B B 4,349 2,404 (1,945 ) $ — 33/43 17.3% 10.7% 38.8% Trapeza Ser 13A A2A BBB 9,512 6,091 (3,421 ) — 44/49 4.5% 7.2% 56.1% 13,861 8,495 (5,366 ) — Single Issuer trust preferred securities: JP Morgan Chase Cap XIII BBB- 4,788 4,500 (288 ) — 4,788 4,500 (288 ) — Total $ 18,649 $ 12,995 $ (5,654 ) $ —

Loans and Allowance for Loan _2

Loans and Allowance for Loan Losses (Tables)	12 Months Ended
	Dec. 31, 2018
Text Block [Abstract]
Schedule of Composition of Loans	The composition of loans at December 31 by lending classification was as follows: December 31, (dollars in thousands) 2018 2017 Commercial (1) $ 3,232,970 $ 2,717,269 Commercial real estate: Construction 504,625 374,306 Other 4,454,226 3,980,246 Residential real estate 2,248,404 2,167,053 Consumer credit: Home equity 589,322 507,507 Auto 1,059,633 1,148,672 Other 154,712 223,068 Total loans 12,243,892 11,118,121 Allowance for loan losses (55,461 ) (50,381 ) Net loans $ 12,188,431 $ 11,067,740 (1) Includes direct finance leases of $60.0 million at December 31, 2018 and $29.5 million at December 31, 2017.
Schedule of Activity in Related Party Loans	Activity in related party loans during 2018 is presented in the following table: Year Ended (dollars in thousands) December 31, 2018 Balance at beginning of period $ 9,481 New loans 9,152 Repayments (8,721 ) Officer and director changes (602 ) Balance at end of period $ 9,310
Schedule of Activity in Allowance for Loan Losses	Old National’s activity in the allowance for loan losses for the years ended December 31, 2018, 2017, and 2016 was as follows: Commercial (dollars in thousands) Commercial Real Estate Residential Consumer Total 2018 Allowance for loan losses: Balance at beginning of period $ 19,246 $ 21,436 $ 1,763 $ 7,936 $ 50,381 Charge-offs (3,087 ) (879 ) (1,100 ) (7,903 ) (12,969 ) Recoveries 1,519 2,740 2,118 4,706 11,083 Provision 4,064 173 (504 ) 3,233 6,966 Balance at end of period $ 21,742 $ 23,470 $ 2,277 $ 7,972 $ 55,461 2017 Allowance for loan losses: Balance at beginning of period $ 21,481 $ 18,173 $ 1,643 $ 8,511 $ 49,808 Charge-offs (1,108 ) (3,700 ) (985 ) (6,924 ) (12,717 ) Recoveries 2,281 3,777 255 3,927 10,240 Provision (3,408 ) 3,186 850 2,422 3,050 Balance at end of period $ 19,246 $ 21,436 $ 1,763 $ 7,936 $ 50,381 2016 Allowance for loan losses: Balance at beginning of period $ 26,347 $ 15,993 $ 2,051 $ 7,842 $ 52,233 Charge-offs (5,047 ) (2,632 ) (800 ) (6,131 ) (14,610 ) Recoveries 3,102 4,763 174 3,186 11,225 Provision (2,921 ) 49 218 3,614 960 Balance at end of period $ 21,481 $ 18,173 $ 1,643 $ 8,511 $ 49,808
Schedule of Recorded Investment in Loans	The following table provides Old National’s recorded investment in loans by portfolio segment at December 31, 2018 and 2017 and other information regarding the allowance: Commercial (dollars in thousands) Commercial Real Estate Residential Consumer Total December 31, 2018 Allowance for loan losses: Individually evaluated for impairment $ 6,035 $ 8,306 $ — $ — $ 14,341 Collectively evaluated for impairment 15,700 14,845 2,276 7,821 40,642 Loans acquired with deteriorated credit quality 7 319 1 151 478 Total allowance for loan losses $ 21,742 $ 23,470 $ 2,277 $ 7,972 $ 55,461 Loans and leases outstanding: Individually evaluated for impairment $ 35,410 $ 83,104 $ — $ — $ 118,514 Collectively evaluated for impairment 3,191,367 4,850,356 2,239,147 1,800,115 12,080,985 Loans acquired with deteriorated credit quality 6,193 25,391 9,257 3,552 44,393 Total loans and leases outstanding $ 3,232,970 $ 4,958,851 $ 2,248,404 $ 1,803,667 $ 12,243,892 December 31, 2017 Allowance for loan losses: Individually evaluated for impairment $ 3,424 $ 6,654 $ — $ — $ 10,078 Collectively evaluated for impairment 15,790 14,782 1,763 7,802 40,137 Loans acquired with deteriorated credit quality 32 — — 134 166 Total allowance for loan losses $ 19,246 $ 21,436 $ 1,763 $ 7,936 $ 50,381 Loans and leases outstanding: Individually evaluated for impairment $ 26,270 $ 66,061 $ — $ — $ 92,331 Collectively evaluated for impairment 2,685,847 4,266,665 2,155,750 1,874,002 10,982,264 Loans acquired with deteriorated credit quality 5,152 21,826 11,303 5,245 43,526 Total loans and leases outstanding $ 2,717,269 $ 4,354,552 $ 2,167,053 $ 1,879,247 $ 11,118,121
Schedule of Risk Category of Commercial and Commercial Real Estate Loans	The risk category of commercial and commercial real estate loans by class of loans at December 31, 2018 and 2017 was as follows: (dollars in thousands) Commercial Commercial Corporate Credit Exposure Real Estate - Real Estate - Credit Risk Profile by Commercial Construction Other Internally Assigned Grade 2018 2017 2018 2017 2018 2017 Grade: Pass $ 3,029,130 $ 2,577,824 $ 460,158 $ 357,438 $ 4,167,902 $ 3,762,896 Criticized 98,798 74,876 29,368 14,758 110,586 98,451 Classified - substandard 66,394 37,367 1,275 — 102,961 58,584 Classified - nonaccrual 29,003 24,798 13,824 2,110 37,441 30,108 Classified - doubtful 9,645 2,404 — — 35,336 30,207 Total $ 3,232,970 $ 2,717,269 $ 504,625 $ 374,306 $ 4,454,226 $ 3,980,246
Schedule of Recorded Investment in Residential and Consumer Loans Based on Payment Activity	. The following table presents the recorded investment in residential and consumer loans based on payment activity at December 31, 2018 and 2017 (dollars in thousands) Consumer Home Residential Equity Auto Other December 31, 2018 Performing $ 2,223,450 $ 586,235 $ 1,057,038 $ 153,113 Nonperforming 24,954 3,087 2,595 1,599 Total $ 2,248,404 $ 589,322 $ 1,059,633 $ 154,712 December 31, 2017 Performing $ 2,144,882 $ 502,322 $ 1,145,977 $ 217,819 Nonperforming 22,171 5,185 2,695 5,249 Total $ 2,167,053 $ 507,507 $ 1,148,672 $ 223,068
Schedule of Impaired Loans	The following table shows Old National’s impaired loans at December 31, 2018 and 2017, respectively. Only purchased loans that have experienced subsequent impairment since the date acquired (excluding loans acquired with deteriorated credit quality) are included in the table below. Unpaid Recorded Principal Related (dollars in thousands) Investment Balance Allowance December 31, 2018 With no related allowance recorded: Commercial $ 22,031 $ 22,292 $ — Commercial Real Estate - Other 41,126 41,914 — Residential 2,276 2,296 — Consumer 362 535 — With an allowance recorded: Commercial 13,379 13,432 6,035 Commercial Real Estate - Construction 13,824 13,824 1,830 Commercial Real Estate - Other 28,154 28,154 6,476 Residential 889 889 44 Consumer 2,013 2,013 101 Total $ 124,054 $ 125,349 $ 14,486 December 31, 2017 With no related allowance recorded: Commercial $ 20,557 $ 21,483 $ — Commercial Real Estate - Other 38,678 44,564 — Residential 2,443 2,464 — Consumer 1,685 2,105 — With an allowance recorded: Commercial 5,713 5,713 3,424 Commercial Real Estate - Construction 905 1,371 401 Commercial Real Estate - Other 26,478 26,902 6,253 Residential 870 870 44 Consumer 2,211 2,228 110 Total $ 99,540 $ 107,700 $ 10,232
Schedule of Average Balance of Impaired Loans	The average balance of impaired loans for the years ended December 31, 2018, 2017, and 2016 are included in the table below. Years Ended December 31, (dollars in thousands) 2018 2017 2016 Average Recorded Investment With no related allowance recorded: Commercial $ 21,295 $ 24,780 $ 34,708 Commercial Real Estate - Other 39,902 34,632 28,793 Residential 2,305 2,415 1,355 Consumer 832 1,761 855 With an allowance recorded: Commercial 9,546 7,002 16,669 Commercial Real Estate - Construction 7,365 453 352 Commercial Real Estate - Other 27,317 26,562 20,465 Residential 840 1,012 1,074 Consumer 1,957 2,155 2,367 Total $ 111,359 $ 100,772 $ 106,638
Schedule of Past Due Financing Receivables	Old National’s past due loans as of December 31 were as follows: Past Due 90 Days or 30-59 Days 60-89 Days More and Total (dollars in thousands) Past Due Past Due Accruing Nonaccrual (1) Past Due Current December 31, 2018 Commercial $ 3,627 $ 279 $ 52 $ 38,648 $ 42,606 $ 3,190,364 Commercial Real Estate: Construction — — — 13,824 13,824 490,801 Other 1,633 500 40 72,777 74,950 4,379,276 Residential 25,947 3,437 258 24,954 54,596 2,193,808 Consumer: Home equity 1,434 960 456 3,087 5,937 583,385 Auto 7,091 1,903 377 2,595 11,966 1,047,667 Other 711 210 170 1,599 2,690 152,022 Total $ 40,443 $ 7,289 $ 1,353 $ 157,484 $ 206,569 $ 12,037,323 December 31, 2017 Commercial $ 986 $ 360 $ 144 $ 27,202 $ 28,692 $ 2,688,577 Commercial Real Estate: Construction — — — 2,110 2,110 372,196 Other 2,247 89 — 60,315 62,651 3,917,595 Residential 18,948 3,416 — 22,171 44,535 2,122,518 Consumer: Home equity 1,467 230 68 5,185 6,950 500,557 Auto 6,487 1,402 532 2,695 11,116 1,137,556 Other 3,967 1,514 150 5,249 10,880 212,188 Total $ 34,102 $ 7,011 $ 894 $ 124,927 $ 166,934 $ 10,951,187 (1) Includes purchased credit impaired loans of $20.5 million at December 31, 2018 and $12.6 million at December 31, 2017 that are categorized as nonaccrual for credit analysis purposes because the collection of principal or interest is doubtful. However, these loans are accounted for under FASB ASC 310-30 and accordingly treated as performing assets.
Schedule of Activity in Trouble Debt Restructurings	The following table presents activity in TDRs for the years ended December 31, 2018, 2017, and 2016: Commercial (dollars in thousands) Commercial Real Estate Residential Consumer Total 2018 Balance at beginning of period $ 12,088 $ 34,705 $ 3,315 $ 3,895 $ 54,003 (Charge-offs)/recoveries (169 ) 561 23 16 431 (Payments)/disbursements (5,188 ) (8,808 ) (450 ) (1,969 ) (16,415 ) Additions 3,544 1,213 502 432 5,691 Balance at end of period $ 10,275 $ 27,671 $ 3,390 $ 2,374 $ 43,710 2017 Balance at beginning of period $ 16,802 $ 18,327 $ 2,985 $ 2,602 $ 40,716 (Charge-offs)/recoveries 417 381 — (294 ) 504 (Payments)/disbursements (18,519 ) (11,752 ) (608 ) (981 ) (31,860 ) Additions 13,388 27,749 938 2,568 44,643 Balance at end of period $ 12,088 $ 34,705 $ 3,315 $ 3,895 $ 54,003 2016 Balance at beginning of period $ 23,354 $ 14,602 $ 2,693 $ 3,602 $ 44,251 (Charge-offs)/recoveries (1,982 ) 953 42 (6 ) (993 ) (Payments)/disbursements (19,566 ) (8,358 ) (511 ) (1,379 ) (29,814 ) Additions 14,996 11,130 761 385 27,272 Balance at end of period $ 16,802 $ 18,327 $ 2,985 $ 2,602 $ 40,716
Schedule of Loans by Class Modified as Troubled Debt Restructuring	The following table presents loans by class modified as TDRs that occurred during the year s ended December 31, 201 8 , 201 7 , and 201 6 : Pre-modification Post-modification Number Outstanding Recorded Outstanding Recorded (dollars in thousands) of Loans Investment Investment 2018 Troubled Debt Restructuring: Commercial 6 $ 3,544 $ 3,544 Commercial Real Estate - Other 2 1,213 1,213 Residential 1 502 502 Consumer 1 432 432 Total 10 $ 5,691 $ 5,691 2017 Troubled Debt Restructuring: Commercial 11 $ 13,388 $ 13,388 Commercial Real Estate - Other 12 27,749 27,749 Residential 6 938 938 Consumer 7 2,568 2,568 Total 36 $ 44,643 $ 44,643 2016 Troubled Debt Restructuring: Commercial 20 $ 14,996 $ 14,996 Commercial Real Estate - Other 10 11,130 11,130 Residential 6 761 761 Consumer 8 385 385 Total 44 $ 27,272 $ 27,272
Schedule of Activity of Purchased Impaired Loans	For these loans that meet the criteria of ASC 310-30 treatment, the carrying amount was as follows: December 31, (dollars in thousands) 2018 2017 Commercial $ 6,193 $ 5,152 Commercial real estate 25,391 21,826 Residential 9,257 11,303 Consumer 3,552 5,245 Carrying amount 44,393 43,526 Allowance for loan losses (478 ) (166 ) Carrying amount, net of allowance $ 43,915 $ 43,360
Schedule of Accretable Yield of PCI Loans, or Income Expected to be Collected	Accretable yield of PCI loans, or income expected to be collected, was as follows: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Balance at beginning of period $ 27,835 $ 33,603 $ 45,310 New loans purchased 2,384 1,556 3,217 Accretion of income (12,252 ) (15,217 ) (23,447 ) Reclassifications from (to) nonaccretable difference 6,133 7,614 10,589 Disposals/other adjustments 951 279 (2,066 ) Balance at end of period $ 25,051 $ 27,835 $ 33,603
Schedule of Receivables for which Contractually Required Payments would not be Collected	PCI loans purchased during 2018 and 2017 for which it was probable at acquisition that all contractually required payments would not be collected were as follows: (dollars in thousands) Anchor (MN) (1) Klein (2) Contractually required payments $ 16,898 $ 18,568 Nonaccretable difference (4,787 ) (4,521 ) Cash flows expected to be collected at acquisition 12,111 14,047 Accretable yield (1,556 ) (2,384 ) Fair value of acquired loans at acquisition $ 10,555 $ 11,663 (1) Old National acquired Anchor (MN) effective November 1, 2017. (2) Old National acquired Klein effective November 1, 2018.

Other Real Estate Owned (Tables

Other Real Estate Owned (Tables)	12 Months Ended
	Dec. 31, 2018
Banking And Thrift [Abstract]
Activity in Other Real Estate Owned	The following table presents activity in other real estate owned for the years ended December 31, 2018 and 2017: Years Ended December 31, (dollars in thousands) 2018 2017 Balance at beginning of period $ 8,810 $ 18,546 Additions (1) 2,025 4,016 Sales (6,689 ) (11,160 ) Impairment (914 ) (2,592 ) Balance at end of period (2) $ 3,232 $ 8,810 (1) Additions in 2018 include other real estate owned of $1.0 million acquired from Klein in November 2018. Additions in 2017 include other real estate owned of $1.1 million acquired from Anchor (MN) in November 2017. (2) Includes repossessed personal property of $0.3 million at December 31, 2018 and 2017.

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Summary of Premises and Equipment	The composition of premises and equipment was as follows at December 31: December 31, (dollars in thousands) 2018 2017 Land $ 79,231 $ 73,046 Buildings 365,102 343,833 Furniture, fixtures, and equipment 107,862 94,254 Leasehold improvements 42,288 38,918 Total 594,483 550,051 Accumulated depreciation (108,571 ) (91,977 ) Premises and equipment, net $ 485,912 $ 458,074
Summary of Future Minimum Lease Commitments	The following is a summary of future minimum lease commitments as of December 31, 2018: (dollars in thousands) 2019 $ 19,480 2020 18,416 2021 17,400 2022 15,169 2023 9,697 Thereafter 65,612 Total $ 145,774

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Changes in Carrying Amount of Goodwill	The following table shows the changes in the carrying amount of goodwill for the years ended December 31, 2018 and 2017: Years Ended December 31, (dollars in thousands) 2018 2017 Balance at beginning of period $ 828,051 $ 655,018 Acquisitions 208,787 173,033 Divestitures (580 ) — Balance at end of period $ 1,036,258 $ 828,051
Schedule of Gross Carrying Amounts and Accumulated Amortization of Other Intangible Assets	The gross carrying amounts and accumulated amortization of other intangible assets at December 31, 2018 and 2017 were as follows: Gross Accumulated Net Carrying Amortization Carrying (dollars in thousands) Amount and Impairment Amount December 31, 2018 Core deposit $ 129,100 $ (57,524 ) $ 71,576 Customer trust relationships 16,547 (11,107 ) 5,440 Total intangible assets $ 145,647 $ (68,631 ) $ 77,016 December 31, 2017 Core deposit $ 108,923 $ (62,874 ) $ 46,049 Customer trust relationships 16,547 (9,533 ) 7,014 Customer loan relationships 4,413 (4,380 ) 33 Total intangible assets $ 129,883 $ (76,787 ) $ 53,096
Schedule of Estimated Amortization Expense for Future Years	Estimated amortization expense for future years is as follows: (dollars in thousands) 2019 $ 16,929 2020 14,091 2021 11,336 2022 9,014 2023 7,053 Thereafter 18,593 Total $ 77,016

Loan Servicing Rights (Tables)

Loan Servicing Rights (Tables)	12 Months Ended
	Dec. 31, 2018
Text Block [Abstract]
Components of Loan Servicing Rights and Valuation Allowance	The following table summarizes the activity related to loan servicing rights and the related valuation allowance in 2018 and 2017: Years Ended December 31, (dollars in thousands) 2018 2017 Balance at beginning of period $ 24,690 $ 25,629 Additions (1) 4,264 4,206 Amortization (4,442 ) (5,145 ) Balance before valuation allowance at end of period 24,512 24,690 Valuation allowance: Balance at beginning of period (29 ) (68 ) (Additions)/recoveries 14 39 Balance at end of period (15 ) (29 ) Loan servicing rights, net $ 24,497 $ 24,661 (1) Additions in 2018 include loan servicing rights of $0.3 million acquired from Klein in November 2018.

Qualified Affordable Housing _2

Qualified Affordable Housing Projects and Other Tax Credit Investments (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Schedule of Qualified Affordable Housing Projects and Other Tax Credit Investments	The following table summarizes Old National’s investments in qualified affordable housing projects and other tax credit investments at December 31, 2018 and 2017: (dollars in thousands) December 31, 2018 December 31, 2017 Unfunded Unfunded Investment Accounting Method Investment Commitment (1) Investment Commitment LIHTC Proportional amortization $ 28,396 $ 2,238 $ 31,183 $ 15,553 FHTC Equity 16,815 17,945 10,645 12,040 CReED Equity 17 538 704 1,502 Renewable Energy Equity 9,176 17,827 22,364 19,771 Total $ 54,404 $ 38,548 $ 64,896 $ 48,866 (1) All commitments will be paid by Old National by 2027. The following table summarizes the amortization expense and tax benefit recognized for Old National’s qualified affordable housing projects and other tax credit investments during 2018, 2017, and 2016: Tax Expense Amortization (Benefit) (dollars in thousands) Expense (1) Recognized (2) Year Ended December 31, 2018 LIHTC $ 2,585 $ (3,349 ) FHTC 9,206 (10,775 ) CReED (3) 687 (687 ) Renewable Energy 13,055 (14,566 ) Total $ 25,533 $ (29,377 ) Year Ended December 31, 2017 LIHTC $ 1,922 $ (2,666 ) FHTC 10,441 (11,348 ) CReED (3) 800 (1,074 ) Renewable Energy 492 (613 ) Total $ 13,655 $ (15,701 ) Year Ended December 31, 2016 LIHTC $ 804 $ (1,125 ) FHTC — — CReED (3) — — Total $ 804 $ (1,125 ) (1) The amortization expense for the LIHTC investments are included in our income tax expense. The amortization expense for the FHTC, CReED, and Renewable Energy tax credits are included in noninterest expense. (2) All of the tax benefits recognized are included in our income tax expense. The tax benefit recognized for the FHTC, CReED, and Renewable Energy investments primarily reflects the tax credits generated from the investments and excludes the net tax expense/benefit of the investments’ income (loss). (3) The CReED tax credit investment qualifies for an Indiana state tax credit.

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2018
Banking And Thrift [Abstract]
Schedule of Maturities of Total Time Deposits	At December 31, 2018, the scheduled maturities of total time deposits were as follows: (dollars in thousands) Due in 2019 $ 1,505,694 Due in 2020 277,142 Due in 2021 109,890 Due in 2022 52,697 Due in 2023 54,637 Thereafter 24,196 Total $ 2,024,256

Securities Sold Under Agreeme_2

Securities Sold Under Agreements to Repurchase (Tables)	12 Months Ended
	Dec. 31, 2018
Transfers And Servicing [Abstract]
Schedule Of Securities Sold Under Agreements To Repurchase And Weighted Average Interest Rates Table Text Block	The following table presents securities sold under agreements to repurchase and related weighted-average interest rates for each of the years ended December 31 (dollars in thousands) 2018 2017 Outstanding at year-end $ 362,294 $ 384,810 Average amount outstanding 344,964 336,539 Maximum amount outstanding at any month-end 364,001 402,543 Weighted-average interest rate: During year 0.57 % 0.38 % End of year 0.75 0.49
Schedule Of Remaining Contractual Maturity Of Secured Borrowings And Class Of Collateral Pledged Under Repurchase Agreements Table Text Block	The following table presents the contractual maturity of our secured borrowings and class of collateral pledged: At December 31, 2018 Remaining Contractual Maturity of the Agreements Overnight and Up to Greater Than (dollars in thousands) Continuous 30 Days 30-90 Days 90 days Total Repurchase Agreements: U.S. Treasury and agency securities $ 362,294 $ — $ — $ — $ 362,294 Total $ 362,294 $ — $ — $ — $ 362,294

Federal Home Loan Bank Advanc_2

Federal Home Loan Bank Advances (Tables)	12 Months Ended
	Dec. 31, 2018
Banking And Thrift [Abstract]
Summary of FHLB Advances	The following table summarizes Old National Bank’s FHLB advances at December 31: December 31, (dollars in thousands) 2018 2017 FHLB advances (fixed rates 1.50% to 6.08% and variable rates 2.51% to 2.75%) maturing January 2019 to October 2028 $ 1,603,643 $ 1,610,531 ASC 815 fair value hedge and other basis adjustments 9,838 (952 ) Total other borrowings $ 1,613,481 $ 1,609,579
Summary of Contractual Maturities of FHLB Advances	Contractual maturities of FHLB advances at December 31, 2018 were as follows: (dollars in thousands) Due in 2019 $ 326,474 Due in 2020 100,000 Due in 2021 20,000 Due in 2022 57,000 Due in 2023 169 Thereafter 1,100,000 ASC 815 fair value hedge and other basis adjustments 9,838 Total $ 1,613,481

Other Borrowings (Tables)

Other Borrowings (Tables)	12 Months Ended
	Dec. 31, 2018
Other Borrowings	The following table summarizes Old National’s other borrowings at December 31: December 31, (dollars in thousands) 2018 2017 Old National Bancorp: Senior unsecured notes (fixed rate 4.125%) maturing August 2024 $ 175,000 $ 175,000 Unamortized debt issuance costs related to senior unsecured bank notes (870 ) (1,026 ) Junior subordinated debentures (variable rates of 4.01% to 6.39%) maturing April 2032 to June 2037 60,310 60,310 Other basis adjustments (3,046 ) (3,585 ) Old National Bank: Capital lease obligations 5,262 5,389 Subordinated debentures (fixed rate 5.75%) 12,000 12,000 Other (773 ) 694 Total other borrowings $ 247,883 $ 248,782
Contractual Maturities of Other Borrowings	Contractual maturities of other borrowings at December 31, 2018 were as follows: (dollars in thousands) Due in 2019 $ 137 Due in 2020 147 Due in 2021 160 Due in 2022 172 Due in 2023 196 Thereafter 250,382 Unamortized debt issuance costs and other basis adjustments (3,311 ) Total $ 247,883
Future Minimum Lease Payments under Capital Lease Arrangements	At December 31, 2018, the future minimum lease payments under the capital lease arrangements were as follows: (dollars in thousands) 2019 $ 589 2020 589 2021 589 2022 589 2023 599 Thereafter 8,676 Total minimum lease payments 11,631 Less amounts representing interest (6,369 ) Present value of net minimum lease payments $ 5,262
Junior Subordinated Debt [Member]
Other Borrowings	The following table summarizes the terms of our outstanding junior subordinated debentures as of December 31, 2018: (dollars in thousands) Rate at Issuance December 31, Name of Trust Issuance Date Amount Rate 2018 Maturity Date VFSC Capital Trust I April 2002 $ 3,093 6-month LIBOR plus 3.70% 6.39% April 22, 2032 VFSC Capital Trust II October 2002 4,124 3-month LIBOR plus 3.45% 6.09% November 7, 2032 VFSC Capital Trust III April 2004 3,093 3-month LIBOR plus 2.80% 5.57% September 8, 2034 St. Joseph Capital Trust II March 2005 5,000 3-month LIBOR plus 1.75% 4.54% March 17, 2035 Anchor Capital Trust III August 2005 5,000 3-month LIBOR plus 1.55% 4.35% September 30, 2035 Tower Capital Trust 2 December 2005 8,000 3-month LIBOR plus 1.34% 4.14% December 30, 2035 Home Federal Statutory Trust I September 2006 15,000 3-month LIBOR plus 1.65% 4.44% September 15, 2036 Monroe Bancorp Capital Trust I July 2006 3,000 3-month LIBOR plus 1.60% 4.01% October 7, 2036 Tower Capital Trust 3 December 2006 9,000 3-month LIBOR plus 1.69% 4.43% March 1, 2037 Monroe Bancorp Statutory Trust II March 2007 5,000 3-month LIBOR plus 1.60% 4.39% June 15, 2037 Total $ 60,310

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Schedule of AOCI	The following table summarizes the changes within each classification of AOCI, net of tax, for the years ended December 31, 2018, 2017, and 2016: (dollars in thousands) Unrealized Gains and Losses on Available- for-Sale Debt Securities Unrealized Gains and Losses on Held-to- Maturity Securities Gains and Losses on Cash Flow Hedges Defined Benefit Pension Plans Total 2018 Balance at beginning of period $ (35,557 ) $ (12,107 ) $ (2,337 ) $ (271 ) $ (50,272 ) Other comprehensive income (loss) before reclassifications 7,454 4,514 3,884 — 15,852 Amounts reclassified from AOCI to income (1) (1,662 ) 1,678 113 144 273 Amount reclassified from AOCI to retained earnings for cumulative effect of change in accounting principle (2) — — (52 ) — (52 ) Amounts reclassified from AOCI to retained earnings related to the Tax Cuts and Jobs Act of 2017 (3) (7,583 ) (2,600 ) (509 ) (59 ) (10,751 ) Balance at end of period $ (37,348 ) $ (8,515 ) $ 1,099 $ (186 ) $ (44,950 ) 2017 Balance at beginning of period $ (39,012 ) $ (13,310 ) $ (6,715 ) $ (335 ) $ (59,372 ) Other comprehensive income (loss) before reclassifications 9,615 — 575 — 10,190 Amounts reclassified from AOCI (1) (6,160 ) 1,203 3,803 64 (1,090 ) Balance at end of period $ (35,557 ) $ (12,107 ) $ (2,337 ) $ (271 ) $ (50,272 ) 2016 Balance at beginning of period $ (3,806 ) $ (14,480 ) $ (9,276 ) $ (7,235 ) $ (34,797 ) Other comprehensive income (loss) before reclassifications (31,513 ) — (1,440 ) — (32,953 ) Amounts reclassified from AOCI (1) (3,693 ) 1,170 4,001 6,900 8,378 Balance at end of period $ (39,012 ) $ (13,310 ) $ (6,715 ) $ (335 ) $ (59,372 ) (1) See table below for details about reclassifications. (2) See Note 1 for details about reclassification from AOCI to beginning retained earnings resulting from the adoption of ASU 2017-12. (3) See Note 1 for details about reclassification from AOCI to beginning retained earnings resulting from the adoption of ASU 2018-02.
Reclassifications out of Accumulated Other Comprehensive Income (Loss)	The following tables summarize the significant amounts reclassified out of each component of AOCI for the years ended December 31, 2018, 2017, and 2016: Amount Reclassified Affected Line Item in the Details about AOCI Components from AOCI Statement of Income Years Ended December 31, (dollars in thousands) 2018 2017 2016 Unrealized gains and losses on available-for-sale debt securities $ 2,060 $ 9,135 $ 5,848 Net securities gains (398 ) (2,975 ) (2,155 ) Income tax (expense) benefit $ 1,662 $ 6,160 $ 3,693 Net income Unrealized gains and losses on held-to-maturity securities $ (2,181 ) $ (1,830 ) $ (1,776 ) Interest income (expense) 503 627 606 Income tax (expense) benefit $ (1,678 ) $ (1,203 ) $ (1,170 ) Net income Gains and losses on cash flow hedges Interest rate contracts $ (150 ) $ (6,135 ) $ (6,453 ) Interest income (expense) 37 2,332 2,452 Income tax (expense) benefit $ (113 ) $ (3,803 ) $ (4,001 ) Net income Amortization of defined benefit pension items Actuarial gains (losses) and settlement cost $ (191 ) $ (159 ) $ (11,203 ) Salaries and employee benefits 47 95 4,303 Income tax (expense) benefit $ (144 ) $ (64 ) $ (6,900 ) Net income Total reclassifications for the period $ (273 ) $ 1,090 $ (8,378 ) Net income

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Summary of Differences in Taxes from Continuing Operations Computed at Statutory Rate	Following is a summary of the major items comprising the differences in taxes from continuing operations computed at the federal statutory rate and as recorded in the consolidated statement of income: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Provision at statutory rate (1) $ 43,823 $ 59,032 $ 70,149 Tax-exempt income: Tax-exempt interest (9,021 ) (15,026 ) (14,356 ) Section 291/265 interest disallowance 321 289 191 Company-owned life insurance income (2,223 ) (3,029 ) (2,968 ) Tax-exempt income (10,923 ) (17,766 ) (17,133 ) State income taxes 5,621 998 3,461 Tax credit investments - federal (21,576 ) (8,500 ) (321 ) Revaluation of deferred tax assets — 39,300 — ONB Insurance Group, Inc. nondeductible goodwill — — 8,328 Other, net 905 (125 ) 1,678 Income tax expense $ 17,850 $ 72,939 $ 66,162 Effective tax rate 8.6 % 43.3 % 33.0 % (1) The statutory rate in effect was 21% for 2018, compared to 35% for 2017 and 2016.
Provision for Income Taxes	The provision for income taxes consisted of the following components for the years ended December 31: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Income taxes currently payable: Federal $ 12,256 $ — $ 23,735 State 4,601 — 2,242 Deferred income taxes related to: Federal (1,513 ) 31,915 35,955 Revaluation of deferred tax assets — 39,300 — State 2,506 1,724 4,230 Deferred income tax expense 993 72,939 40,185 Income tax expense $ 17,850 $ 72,939 $ 66,162
Schedule of Significant Components of Net Deferred Tax Assets (Liabilities)	Significant components of net deferred tax assets (liabilities) were as follows at December 31: (dollars in thousands) 2018 2017 Deferred Tax Assets Allowance for loan losses, net of recapture $ 14,514 $ 12,958 Benefit plan accruals 21,694 11,080 Alternative minimum tax credit 2,545 25,084 Unrealized losses on benefit plans 61 108 Net operating loss carryforwards 31,765 39,631 Federal tax credits 1,779 5,516 Deferred gain on securities 1,976 — Other-than-temporary impairment 37 1,424 Acquired loans 26,956 29,669 Lease exit obligation 1,025 1,337 Unrealized losses on available-for-sale investment securities 11,853 14,011 Unrealized losses on held-to-maturity investment securities 2,497 3,630 Unrealized losses on hedges — 923 Tax credit investments 662 — Other real estate owned 144 369 Other, net 5,471 829 Total deferred tax assets 122,979 146,569 Deferred Tax Liabilities Accretion on investment securities (595 ) (493 ) Purchase accounting (18,100 ) (16,718 ) Loan servicing rights (6,141 ) (6,058 ) Premises and equipment (8,507 ) (10,052 ) Prepaid expenses (681 ) (1,277 ) Tax credit investments — (168 ) Unrealized gains on hedges (358 ) — Other, net (1,549 ) (946 ) Total deferred tax liabilities (35,931 ) (35,712 ) Net deferred tax assets $ 87,048 $ 110,857
Summary of Reconciliation of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits was as follows: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Balance at beginning of period $ 874 $ 777 $ 124 Additions based on tax positions related to the current year — 162 118 Additions (reductions) based on tax positions related to prior years (78 ) — 537 Reductions due to statute of limitations expiring (301 ) (173 ) (2 ) Revaluation due to Tax Reform — 108 — Balance at end of period $ 495 $ 874 $ 777

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Changes in Nonvested Restricted Stock Awards	A summary of changes in our nonvested shares for the year follows: Weighted Average Grant-Date (shares in thousands) Shares Fair Value Year Ended December 31, 2018 Nonvested balance at beginning of period 407 $ 15.41 Granted during the year 217 17.47 Vested during the year (195 ) 14.80 Forfeited during the year (10 ) 15.08 Nonvested balance at end of period 419 $ 16.77
Summary of Changes in Nonvested Restricted Shares	A summary of changes in our nonvested shares for the year follows: Weighted Average Grant-Date (shares in thousands) Shares Fair Value Year Ended December 31, 2018 Nonvested balance at beginning of period 849 $ 13.30 Granted during the year 288 13.62 Vested during the year (92 ) 13.65 Forfeited during the year (185 ) 13.58 Dividend equivalents adjustment 33 13.32 Nonvested balance at end of period 893 $ 13.31
Summary of Activity in Stock Option Plan	A summary of the activity in the stock option plan in 2018 follows: Weighted Weighted Average Aggregate Average Remaining Intrinsic Exercise Contractual Value (shares in thousands) Shares Price Term in Years (in thousands) Year Ended December 31, 2018 Outstanding at beginning of period 225 $ 11.92 Exercised (76 ) 12.59 Forfeited/expired (57 ) 20.16 Outstanding at end of period 92 $ 6.30 2.08 $ 836.7 Options exercisable at end of year 92 $ 6.30 2.08 $ 836.7
Schedule of Information Related to Stock Option Plan	Information related to the stock option plan during each year follows: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Intrinsic value of options exercised $ 385 $ 806 $ 660 Cash received from option exercises 948 2,655 2,349 Tax benefit realized from option exercises 154 318 264

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis	Assets and liabilities measured at fair value on a recurring basis, including financial assets and liabilities for which we have elected the fair value option, are summarized below: Fair Value Measurements at December 31, 2018 Using Significant Quoted Prices in Other Significant Active Markets for Observable Unobservable Carrying Identical Assets Inputs Inputs (dollars in thousands) Value (Level 1) (Level 2) (Level 3) Financial Assets Equity securities $ 5,582 $ 5,582 $ — $ — Investment securities available-for-sale: U.S. Treasury 5,301 5,301 — — U.S. government-sponsored entities and agencies 628,151 — 628,151 — Mortgage-backed securities - Agency 2,209,295 — 2,209,295 — States and political subdivisions 940,429 — 936,321 4,108 Pooled trust preferred securities 8,495 — — 8,495 Other securities 331,745 30,259 301,486 — Residential loans held for sale 14,911 — 14,911 — Derivative assets 29,005 — 29,005 — Financial Liabilities Derivative liabilities 12,550 — 12,550 — Fair Value Measurements at December 31, 2017 Using Significant Quoted Prices in Other Significant Active Markets for Observable Unobservable Carrying Identical Assets Inputs Inputs (dollars in thousands) Value (Level 1) (Level 2) (Level 3) Financial Assets Equity securities $ 5,584 $ 5,584 $ — $ — Investment securities available-for-sale: U.S. Treasury 5,551 5,551 — — U.S. government-sponsored entities and agencies 664,286 — 664,286 — Mortgage-backed securities - Agency 1,667,682 — 1,667,682 — States and political subdivisions 530,193 — 530,193 — Pooled trust preferred securities 8,448 — — 8,448 Other securities 320,047 30,965 289,082 — Residential loans held for sale 17,930 — 17,930 — Derivative assets 14,118 — 14,118 — Financial Liabilities Derivative liabilities 16,292 — 16,292 —
Reconciliation of All Assets Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3)	The table below presents a reconciliation of all assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3): Pooled Trust State and Preferred Political (dollars in thousands) Securities Subdivisions 2018 Balance at beginning of period $ 8,448 $ — Accretion (amortization) of discount 17 (56 ) Sales/payments received (338 ) — Increase in fair value of securities 368 28 Transfers into Level 3 — 4,136 Balance at end of period $ 8,495 $ 4,108 2017 Balance at beginning of period $ 8,119 $ — Accretion of discount 17 — Sales/payments received (424 ) — Increase in fair value of securities 736 — Balance at end of period $ 8,448 $ —
Quantitative Information about Significant Unobservable Inputs Used in Fair Value Measurements	The table below provides quantitative information about significant unobservable inputs used in fair value measurements within Level 3 of the fair value hierarchy: Valuation Unobservable Range (Weighted (dollars in thousands) Fair Value Techniques Input Average) December 31, 2018 Pooled trust preferred securities $ 8,495 Discounted cash flow Constant prepayment rate (a) 0.00% Additional asset defaults (b) 6.8% - 8.5% (7.3%) Expected asset recoveries (c) 0.0% - 0.0% (0.0%) State and political subdivisions 4,108 Discounted cash flow No observable inputs N/A Local municipality issuances Old National owns 100% Carried at par December 31, 2017 Pooled trust preferred securities $ 8,448 Discounted cash flow Constant prepayment rate (a) 0.00% Additional asset defaults (b) 4.2% - 9.6% (7.5%) Expected asset recoveries (c) 0.0% - 4.1% (0.6%) (a) Assuming no prepayments. (b) Each currently performing pool asset is assigned a default probability based on the banking environment, which is adjusted for specific issuer evaluation, of 0%, 50%, or 100%. (c) Each currently defaulted pool asset is assigned a recovery probability based on specific issuer evaluation of 0%, 25%, or 100%. The table below provides quantitative information about significant unobservable inputs used in fair value measurements within Level 3 of the fair value hierarchy: Valuation Unobservable Range (Weighted (dollars in thousands) Fair Value Techniques Input Average) December 31, 2018 Collateral Dependent Impaired Loans Commercial loans $ 7,242 Fair value of collateral Discount for type of property, age of appraisal, and current status 0% - 90% (35%) Commercial real estate loans 29,125 Fair value of collateral Discount for type of property, age of appraisal and current status 0% - 50% (35%) Foreclosed Assets Residential 68 Fair value of collateral Discount for type of property, age of appraisal, and current status 15%-16% (15%) December 31, 2017 Collateral Dependent Impaired Loans Commercial loans $ 2,217 Fair value of collateral Discount for type of property, age of appraisal, and current status 0% - 98% (49%) Commercial real estate loans 26,319 Fair value of collateral Discount for type of property, age of appraisal, and current status 10% - 78% (32%) Foreclosed Assets Commercial real estate 1,726 Fair value of collateral Discount for type of property, age of appraisal, and current status 7% - 25% (18%) Residential (1) 55 Fair value of collateral Discount for type of property, age of appraisal, and current status 39% (1) There was only one foreclosed residential asset at December 31, 2017, so no range or weighted average rate is reported.
Assets Measured at Fair Value on a Non-Recurring Basis	Assets measured at fair value on a non-recurring basis at December 31, 2018 are summarized below: Fair Value Measurements at December 31, 2018 Using Significant Quoted Prices in Other Significant Active Markets for Observable Unobservable Carrying Identical Assets Inputs Inputs (dollars in thousands) Value (Level 1) (Level 2) (Level 3) Collateral Dependent Impaired Loans: Commercial loans $ 7,242 $ — $ — $ 7,242 Commercial real estate loans 29,125 — — 29,125 Foreclosed Assets: Residential 68 — — 68 Loan servicing rights 104 — 104 — Assets measured at fair value on a non-recurring basis at December 31, 2017 are summarized below: Fair Value Measurements at December 31, 2017 Using Significant Quoted Prices in Other Significant Active Markets for Observable Unobservable Carrying Identical Assets Inputs Inputs (dollars in thousands) Value (Level 1) (Level 2) (Level 3) Collateral Dependent Impaired Loans: Commercial loans $ 2,217 $ — $ — $ 2,217 Commercial real estate loans 26,319 — — 26,319 Foreclosed Assets: Commercial real estate 1,726 — — 1,726 Residential 55 — — 55 Loan servicing rights 2,964 — 2,964 —
Schedule of Difference Between the Aggregate Fair Value and the Aggregate Remaining Principal Balance	The difference between the aggregate fair value and the aggregate remaining principal balance for loans for which the fair value option has been elected as of December 31, 2018 and 2017 was as follows: Aggregate Contractual (dollars in thousands) Fair Value Difference Principal 2018 Residential loans held for sale $ 14,911 $ 475 $ 14,436 2017 Residential loans held for sale $ 17,930 $ 546 $ 17,384 The following table presents the amount of gains and losses from fair value changes included in income before income taxes for financial assets carried at fair value for the years ended December 31: Total Changes in Fair Values Other Included in Gains and Interest Interest Current Period (dollars in thousands) (Losses) Income (Expense) Earnings 2018 Residential loans held for sale $ (67 ) $ 6 $ (10 ) $ (71 ) 2017 Residential loans held for sale $ 409 $ 4 $ — $ 413
Carrying Amounts and Estimated Fair Values of Financial Instruments, Not Carried at Fair Value	The carrying amounts and estimated fair values of financial instruments not carried at fair value at December 31, 2018 and 2017 were as follows: Fair Value Measurements at December 31, 2018 Using Significant Quoted Prices in Other Significant Active Markets for Observable Unobservable Carrying Identical Assets Inputs Inputs (dollars in thousands) Value (Level 1) (Level 2) (Level 3) Financial Assets Cash, due from banks, money market, and other interest-earning investments $ 317,165 $ 317,165 $ — $ — Investment securities held-to-maturity: U.S. government-sponsored entities and agencies 73,986 — 72,359 — Mortgage-backed securities - Agency 127,120 — 124,409 — State and political subdivisions 305,228 — 309,335 — Loans, net: Commercial 3,211,228 — — 3,161,132 Commercial real estate 4,935,381 — — 4,781,294 Residential real estate 2,246,127 — — 2,225,853 Consumer credit 1,795,695 — — 1,773,352 Accrued interest receivable 89,464 13 27,580 61,871 Financial Liabilities Deposits: Noninterest-bearing demand deposits $ 3,965,380 $ 3,965,380 $ — $ — Checking, NOW, savings, and money market interest-bearing deposits 8,360,313 8,360,313 — — Time deposits 2,024,256 — 2,002,187 — Federal funds purchased and interbank borrowings 270,135 270,135 — — Securities sold under agreements to repurchase 362,294 362,294 — — FHLB advances 1,613,481 — — 1,611,103 Other borrowings 247,883 — 248,065 — Accrued interest payable 9,871 — 9,871 — Standby letters of credit 525 — — 525 Off-Balance Sheet Financial Instruments Commitments to extend credit $ — $ — $ — $ 3,115 Fair Value Measurements at December 31, 2017 Using Significant Quoted Prices in Other Significant Active Markets for Observable Unobservable Carrying Identical Assets Inputs Inputs (dollars in thousands) Value (Level 1) (Level 2) (Level 3) Financial Assets Cash, due from banks, money market, and other interest-earning investments $ 290,432 $ 290,432 $ — $ — Investment securities held-to-maturity: Mortgage-backed securities - Agency 6,903 — 7,056 — State and political subdivisions 677,160 — 720,647 — Loans, net: Commercial 2,698,023 — — 2,707,385 Commercial real estate 4,333,116 — — 4,347,949 Residential real estate 2,165,290 — — 2,210,951 Consumer credit 1,871,311 — — 1,998,194 Accrued interest receivable 87,102 16 24,001 63,085 Financial Liabilities Deposits: Noninterest-bearing demand deposits $ 3,680,807 $ 3,680,807 $ — $ — Checking, NOW, savings, and money market interest-bearing deposits 7,290,521 7,290,521 — — Time deposits 1,634,436 — 1,620,685 — Federal funds purchased and interbank borrowings 335,033 335,033 — — Securities sold under agreements to repurchase 384,810 359,810 25,133 — FHLB advances 1,609,579 — — 1,607,189 Other borrowings 248,782 — 250,443 — Accrued interest payable 7,029 — 7,029 — Standby letters of credit 351 — — 351 Off-Balance Sheet Financial Instruments Commitments to extend credit $ — $ — $ — $ 2,449

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Summary of Fair Value of Derivative Financial Instruments	The following table summarizes the fair value of derivative financial instruments utilized by Old National: Balance Balance Sheet Fair Sheet Fair (dollars in thousands) Location Value Location Value December 31, 2018 Derivatives designated as hedging instruments Interest rate contracts Other Assets $ 12,741 Other Liabilities $ 1,603 Total derivatives designated as hedging instruments $ 12,741 $ 1,603 Derivatives not designated as hedging instruments Interest rate contracts Other Assets $ 15,278 Other Liabilities $ 10,562 Mortgage contracts Other Assets 874 Other Liabilities 316 Foreign currency contracts Other Assets 112 Other Liabilities 69 Total derivatives not designated as hedging instruments $ 16,264 $ 10,947 Total $ 29,005 $ 12,550 December 31, 2017 Derivatives designated as hedging instruments Interest rate contracts Other Assets $ 3,351 Other Liabilities $ 5,351 Total derivatives designated as hedging instruments $ 3,351 $ 5,351 Derivatives not designated as hedging instruments Interest rate contracts Other Assets $ 10,012 Other Liabilities $ 10,933 Mortgage contracts Other Assets 747 Other Liabilities — Foreign currency contracts Other Assets 8 Other Liabilities 8 Total derivatives not designated as hedging instruments $ 10,767 $ 10,941 Total $ 14,118 $ 16,292
Schedule of Effect of Derivative Instruments on the Consolidated Statements of Income	The effect of derivative instruments in fair value hedging relationships on the consolidated statements of income for the years ended December 31 were as follows: (dollars in thousands) Gain (Loss) Recognized Location of Gain or Gain (Loss) Hedged Items Location of Gain or in Income on Derivatives in (Loss) Recognized in Recognized in Fair Value (Loss) Recognized in Related Fair Value Hedging in Income on in Income on Hedging in Income on Related Hedged Relationships Derivative Derivative Relationships Hedged Item Items 2018 Interest rate contracts Interest income / (expense) $ 7,662 Fixed-rate debt Interest income / (expense) $ (7,634 ) 2017 Interest rate contracts Interest income / (expense) $ (836 ) Fixed-rate debt Interest income / (expense) $ 1,006 2016 Interest rate contracts Interest income / (expense) $ (863 ) Fixed-rate debt Interest income / (expense) $ 991 The difference between the gain (loss) recognized in income on derivatives and the gain (loss) recognized in income on the related hedged items represents hedge ineffectiveness. In addition, the net swap settlements that accrue each period are also reported in interest expense. The effect of derivative instruments in cash flow hedging relationships on the consolidated statements of income for the years ended December 31 were as follows: Years Ended December 31, Years Ended December 31, (dollars in thousands) 2018 2017 2016 2018 2017 2016 Gain (Loss) Gain (Loss) Location of Gain or Recognized in Other Reclassified from Derivatives in (Loss) Reclassified Comprehensive AOCI into Cash Flow Hedging from AOCI into Income Income on Derivative Income (Effective Relationships (Effective Portion) (Effective Portion) Portion) Interest rate contracts Interest income/(expense) $ 5,145 $ 927 $ (2,323 ) $ (150 ) $ (6,135 ) $ (6,453 ) The ineffective portion and amount excluded from effectiveness testing related to derivatives in cash flow hedging relationships was immaterial for the years ended December 31, 2018, 2017, and 2016. The effect of derivatives not designated as hedging instruments on the consolidated statements of income for the years ended December 31 were as follows: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Location of Gain or (Loss) Gain (Loss) Derivatives Not Designated as Recognized in Income on Recognized in Income on Hedging Instruments Derivative Derivative Interest rate contracts (1) Other income/(expense) $ (7 ) $ 56 $ 28 Mortgage contracts Mortgage banking revenue (189 ) (1,995 ) 1,390 Foreign currency contracts Other income/(expense) 42 — — Total $ (154 ) $ (1,939 ) $ 1,418 (1) Includes the valuation difference between the customer and offsetting swaps.

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue From Contract With Customer [Abstract]
Revenue Information	The consolidated statements of income include all categories of noninterest income. The following table reflects only the categories of noninterest income that are within the scope of Topic 606: Years Ended December 31, (dollars in thousands) 2018 2017 2016 Wealth management fees $ 36,863 $ 37,316 $ 34,641 Service charges on deposit accounts 44,026 41,331 41,578 Debit card and ATM fees 20,216 17,676 16,769 Insurance premiums and commissions 399 617 20,527 Investment product fees 20,539 20,977 18,822 Other income: Merchant processing fees 2,927 2,634 2,574 Gain (loss) on other real estate owned 1,270 939 1,419 Safe deposit box fees 1,124 926 961 Total $ 127,364 $ 122,416 $ 137,291

Regulatory Restrictions (Tables

Regulatory Restrictions (Tables)	12 Months Ended
	Dec. 31, 2018
Text Block [Abstract]
Schedule of Capital Ratios	The following table summarizes capital ratios for Old National and Old National Bank as of December 31: Fully Phased-In Regulatory Well Capitalized Actual Guidelines Minimum (1) Guidelines (dollars in thousands) Amount Ratio Amount Ratio Amount Ratio 2018 Total capital to risk- weighted assets Old National Bancorp $ 1,748,231 12.27 % $ 1,496,099 10.50 % $ N/A N/A % Old National Bank 1,769,930 12.47 1,489,938 10.50 1,418,989 10.00 Common equity Tier 1 capital to risk-weighted assets Old National Bancorp 1,617,936 11.36 997,399 7.00 N/A N/A Old National Bank 1,699,945 11.98 993,292 7.00 922,343 6.50 Tier 1 capital to risk-weighted assets Old National Bancorp 1,617,936 11.36 1,211,128 8.50 N/A N/A Old National Bank 1,699,945 11.98 1,206,141 8.50 1,135,191 8.00 Tier 1 capital to average assets Old National Bancorp 1,617,936 9.17 705,681 4.00 N/A N/A Old National Bank 1,699,945 9.58 709,929 4.00 887,412 5.00 2017 Total capital to risk-weighted assets Old National Bancorp $ 1,424,123 11.40 % $ 1,311,600 10.50 % $ N/A N/A % Old National Bank 1,458,546 11.73 1,305,076 10.50 1,242,929 10.00 Common equity Tier 1 capital to risk-weighted assets Old National Bancorp 1,298,327 10.39 874,400 7.00 N/A N/A Old National Bank 1,393,059 11.21 870,051 7.00 807,904 6.50 Tier 1 capital to risk-weighted assets Old National Bancorp 1,298,327 10.39 1,061,772 8.50 N/A N/A Old National Bank 1,393,059 11.21 1,056,490 8.50 994,344 8.00 Tier 1 capital to average assets Old National Bancorp 1,298,327 8.28 627,258 4.00 N/A N/A Old National Bank 1,393,059 8.93 623,758 4.00 779,697 5.00 (1) As of January 1, 2019, Basel III Capital Rules required banking organizations to maintain: a minimum ratio of common equity Tier 1 to risk-weighted assets of at least 4.5%, plus a 2.5% “capital conservation buffer”; a minimum ratio of Tier 1 capital to risk-weighted assets of at least 6.0%, plus the 2.5% capital conservation buffer; a minimum ratio of total capital to risk-weighted assets of at least 8.0%, plus the 2.5% capital conservation buffer; and a minimum ratio of Tier 1 capital to adjusted average consolidated assets of at least 4.0%.

Parent Company Financial Stat_2

Parent Company Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Condensed Balance Sheets	OLD NATIONAL BANCORP (PARENT COMPANY ONLY) CONDENSED BALANCE SHEETS December 31, (dollars in thousands) 2018 2017 Assets Deposits in affiliate bank $ 90,005 $ 43,538 Equity securities 5,582 5,584 Investment securities - available-for-sale 1,527 1,547 Investment in affiliates: Banking subsidiaries 2,769,166 2,248,700 Non-banks 5,151 5,142 Other assets 87,096 112,353 Total assets $ 2,958,527 $ 2,416,864 Liabilities and Shareholders' Equity Other liabilities $ 37,563 $ 31,768 Other borrowings 231,394 230,699 Shareholders' equity 2,689,570 2,154,397 Total liabilities and shareholders' equity $ 2,958,527 $ 2,416,864
Condensed Statements of Income	OLD NATIONAL BANCORP (PARENT COMPANY ONLY) CONDENSED STATEMENTS OF INCOME Years Ended December 31, (dollars in thousands) 2018 2017 2016 Income Dividends from affiliates $ 105,000 $ 100,000 $ 160,007 Net securities gains 49 667 100 Other income 2,126 1,966 40,841 Other income from affiliates 5 5 6 Total income 107,180 102,638 200,954 Expense Interest on borrowings 10,425 9,298 9,077 Other expenses 21,936 16,335 18,460 Total expense 32,361 25,633 27,537 Income before income taxes and equity in undistributed earnings of affiliates 74,819 77,005 173,417 Income tax expense (benefit) (5,693 ) (6,240 ) 11,952 Income before equity in undistributed earnings of affiliates 80,512 83,245 161,465 Equity in undistributed earnings of affiliates 110,318 12,480 (27,201 ) Net income $ 190,830 $ 95,725 $ 134,264
Condensed Statement of Cash Flows	OLD NATIONAL BANCORP (PARENT COMPANY ONLY) CONDENSED STATEMENT OF CASH FLOWS Years Ended December 31, (dollars in thousands) 2018 2017 2016 Cash Flows From Operating Activities Net income $ 190,830 $ 95,725 $ 134,264 Adjustments to reconcile net income to cash provided by operating activities: Depreciation 53 36 29 Net securities (gains) losses (49 ) (667 ) (100 ) Gain on sale of ONB Insurance Group, Inc. — — (41,864 ) Share-based compensation expense 8,118 6,275 7,318 (Increase) decrease in other assets 28,754 (24,005 ) (3,958 ) Increase (decrease) in other liabilities 3,147 3,968 (225 ) Equity in undistributed earnings of affiliates (110,318 ) (12,480 ) 27,201 Total adjustments (70,295 ) (26,873 ) (11,599 ) Net cash flows provided by (used in) operating activities 120,535 68,852 122,665 Cash Flows From Investing Activities Net cash and cash equivalents of acquisitions 8,281 (24,005 ) (100,220 ) Proceeds from sale of ONB Insurance Group, Inc. — — 91,771 Proceeds from sales of equity securities 128 127 — Purchases of investment securities (76 ) (62 ) (52 ) Net advances to affiliates — (250 ) (3,500 ) Proceeds from sale of premises and equipment 1,065 — — Purchases of premises and equipment (945 ) (612 ) (13 ) Net cash flows provided by (used in) investing activities 8,453 (24,802 ) (12,014 ) Cash Flows From Financing Activities Payments for maturities/redemptions of other borrowings — (19,856 ) — Cash dividends paid on common stock (82,161 ) (72,604 ) (67,536 ) Common stock repurchased (1,805 ) (2,761 ) (2,202 ) Proceeds from exercise of stock options 948 2,655 2,349 Common stock issued 497 404 388 Net cash flows provided by (used in) financing activities (82,521 ) (92,162 ) (67,001 ) Net increase (decrease) in cash and cash equivalents 46,467 (48,112 ) 43,650 Cash and cash equivalents at beginning of period 43,538 91,650 48,000 Cash and cash equivalents at end of period $ 90,005 $ 43,538 $ 91,650

Interim Financial Data (Unaud_2

Interim Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Interim Financial Data	The following table details the quarterly results of operations for the years ended December 31, 2018 and 2017. (unaudited, dollars and shares in thousands, Three Months Ended Three Months Ended except per share data) 12/31/2018 9/30/2018 6/30/2018 3/31/2018 12/31/2017 9/30/2017 6/30/2017 3/31/2017 Interest income $ 175,234 $ 155,369 $ 153,736 $ 147,706 $ 135,134 $ 123,525 $ 118,209 $ 118,468 Interest expense 29,009 24,527 21,773 19,134 16,578 15,047 13,876 12,667 Net interest income 146,225 130,842 131,963 128,572 118,556 108,478 104,333 105,801 Provision for loan losses 3,390 750 2,446 380 1,037 311 1,355 347 Noninterest income 58,154 45,957 49,289 41,905 44,825 46,366 49,271 42,920 Noninterest expense 150,268 119,376 130,460 117,157 140,432 103,702 102,811 101,891 Income before income taxes 50,721 56,673 48,346 52,940 21,912 50,831 49,438 46,483 Income tax expense 3,223 5,325 4,345 4,957 40,405 11,459 10,584 10,491 Net income (loss) $ 47,498 $ 51,348 $ 44,001 $ 47,983 $ (18,493 ) $ 39,372 $ 38,854 $ 35,992 Net income (loss) per share: Basic $ 0.28 $ 0.34 $ 0.29 $ 0.32 $ (0.13 ) $ 0.30 $ 0.28 $ 0.27 Diluted 0.28 0.34 0.29 0.31 (0.13 ) 0.29 0.28 0.27 Average shares: Basic 167,044 151,930 151,878 151,721 146,073 135,120 135,085 134,912 Diluted 167,992 152,784 152,568 152,370 146,875 135,796 135,697 135,431

Basis of Presentation and Sig_4

Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) - USD ($)	Jan. 02, 2018	Dec. 31, 2018	Jan. 01, 2019	Dec. 31, 2017
Basis Of Presentation And Significant Accounting Policies [Line Items]
Loan placed on nonaccrual when past due, number of days		90 days
Nonaccrual period for loans		90 days
Percentage of income tax examination likelihood of tax benefits		50.00%
Retained earnings		$ 527,684,000		$ 413,130,000
Unrealized holding gains on available-for-sale portfolio		6,247,000		43,648,000
Reclassification of certain tax effects related to the Tax Cuts and Jobs Act of 2017 (Note 1)	$ 10,800,000
States and Political Subdivisions [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Unrealized holding gains on available-for-sale portfolio		6,208,000		$ 43,495,000
ASU No. 2016-16 [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Modified retrospective basis through a cumulative-effect adjustment to retained earnings	$ 1,000,000
Accounting Standards Update 2017-12 [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Retained earnings		3,200,000
Reclassification of securities		324,000,000
Unrealized holding gains on available-for-sale portfolio		26,100,000
Accounting Standards Update 2017-12 [Member] | States and Political Subdivisions [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Reclassification of securities		447,000,000
Accounting Standards Update 2016-02 [Member] | Subsequent Event [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Retained earnings			$ 6,000,000
Lease liability			123,000,000
Lease right-of-use asset			$ 119,000,000
Maximum [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Value of small commercial loans on nonaccrual status or 90 days or more delinquent		$ 250,000
Maturity of short-term securities sold under agreements to repurchase		4 days
Maximum [Member] | Core Deposits and Other Intangible Assets [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Estimated useful lives of core deposits and customer relationships		15 years
Maximum [Member] | Building and Building Improvements [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Useful lives for premises and equipment, years		39 years
Maximum [Member] | Furniture and Equipment [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Useful lives for premises and equipment, years		7 years
Minimum [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Maturity of short-term securities sold under agreements to repurchase		1 day
Minimum [Member] | Core Deposits and Other Intangible Assets [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Estimated useful lives of core deposits and customer relationships		5 years
Minimum [Member] | Building and Building Improvements [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Useful lives for premises and equipment, years		15 years
Minimum [Member] | Furniture and Equipment [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Useful lives for premises and equipment, years		3 years

Basis of Presentation and Sig_5

Basis of Presentation and Significant Accounting Policies - Summary of Table Reconciling Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income	$ 47,498	$ 51,348	$ 44,001	$ 47,983	$ (18,493)	$ 39,372	$ 38,854	$ 35,992	$ 190,830	$ 95,725	$ 134,264
Basic Net Income Share, Weighted average common shares outstanding	167,044	151,930	151,878	151,721	146,073	135,120	135,085	134,912	155,675	137,821	127,705
Basic Net Income Per Share	$ 0.28	$ 0.34	$ 0.29	$ 0.32	$ (0.13)	$ 0.30	$ 0.28	$ 0.27	$ 1.23	$ 0.69	$ 1.05
Effect of dilutive securities: Restricted stock									796	599	543
Effect of dilutive securities: Stock options									68	93	53
Diluted Net Income Per Share, Weighted average shares outstanding	167,992	152,784	152,568	152,370	146,875	135,796	135,697	135,431	156,539	138,513	128,301
Diluted Earnings Per Share	$ 0.28	$ 0.34	$ 0.29	$ 0.31	$ (0.13)	$ 0.29	$ 0.28	$ 0.27	$ 1.22	$ 0.69	$ 1.05

Basis of Presentation and Sig_6

Basis of Presentation and Significant Accounting Policies - Summary of Table Reconciling Basic and Diluted Net Income Per Share (Parenthetical) (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock Options [Member]
Summary Of Computation Of Basic And Diluted Earnings Per Share [Line Items]
Antidilutive securities not included in the computation of net income per diluted share	14	100	500

Basis of Presentation and Sig_7

Basis of Presentation and Significant Accounting Policies - Summary of Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash payments:
Interest	$ 91,813	$ 56,682	$ 43,698
Income taxes (net of refunds)	(2,505)	4,326	23,636
Noncash Investing and Financing Activities:
Securities transferred from held-to-maturity to available-for-sale	447,026
Securities transferred from available-for-sale to held-to-maturity	323,990
Transfer of premises and equipment to assets held for sale	$ 9,634	$ 16,617	$ 4,620

Basis of Presentation and Sig_8

Basis of Presentation and Significant Accounting Policies - Summary of Common Shares Issued and Resultant Value of Total Shareholders' Equity (Detail) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Common Shares Issued and Value of Shares Holders' Equity [Line Items]
Acquisition, Total Shareholders' Equity		$ 300,828	$ 273,565
Common Stock [Member]
Common Shares Issued and Value of Shares Holders' Equity [Line Items]
Acquisition, Total Shareholders' Equity		16,527	20,415
Minnesota-based Klein [Member]
Common Shares Issued and Value of Shares Holders' Equity [Line Items]
Acquisition, Total Shareholders' Equity	$ 406,474
Minnesota-based Klein [Member] | Common Stock [Member]
Common Shares Issued and Value of Shares Holders' Equity [Line Items]
Acquisition, Shares of Common Stock	22,772
Acquisition, Total Shareholders' Equity	$ 22,772
Anchor Bank (MN) [Member]
Common Shares Issued and Value of Shares Holders' Equity [Line Items]
Acquisition, Total Shareholders' Equity		$ 300,828
Anchor Bank (MN) [Member] | Common Stock [Member]
Common Shares Issued and Value of Shares Holders' Equity [Line Items]
Acquisition, Shares of Common Stock		16,527
AnchorBank WI [Member]
Common Shares Issued and Value of Shares Holders' Equity [Line Items]
Acquisition, Total Shareholders' Equity			$ 273,565
AnchorBank WI [Member] | Common Stock [Member]
Common Shares Issued and Value of Shares Holders' Equity [Line Items]
Acquisition, Shares of Common Stock			20,415

Acquisition and Divestiture A_3

Acquisition and Divestiture Activity - Additional Information (Detail) $ / shares in Units, $ in Thousands, shares in Millions	Nov. 01, 2018USD ($)Branchshares	Oct. 26, 2018USD ($)Branch	Nov. 01, 2017USD ($)Branch$ / sharesshares	Dec. 31, 2018USD ($)	Dec. 31, 2018USD ($)Branch	Dec. 31, 2017USD ($)Branch	Dec. 31, 2016USD ($)Branch	Jun. 30, 2018USD ($)
Business Acquisition [Line Items]
Net pre-tax gain					$ 13,989
Goodwill allocation				$ 1,036,258	$ 1,036,258	$ 828,051	$ 655,018
Number of banking centers consolidated | Branch					10	29	5
Marine Credit Union of La Crosse, Wisconsin [member]
Business Acquisition [Line Items]
Number of branches | Branch		10
Deposits		$ 230,600
Purchasers assumed loans		$ 0
Net pre-tax gain				14,000
Deposit premium				15,000
Goodwill allocation				600	$ 600
Other transaction expense related to divestitures				$ 400
Anchor Bank (MN) [Member] | Minnesota [Member]
Business Acquisition [Line Items]
Number of branches | Branch			17
Consideration received in cash by merged entity | $ / shares			$ 2.625
Portion of share received by merged entity			1.350
Total fair value of consideration paid			$ 332,800
Purchase price of acquisition, cash			$ 31,900
Issuance of common stock shares for acquisitions of business | shares			16.5
Value of issuance common stock shares			$ 300,800
Transaction and integration costs associated with the acquisition					19,200
Goodwill allocation								$ 173,785
Anchor Bank (MN) [Member] | Minnesota [Member] | Core Deposit [Member]
Business Acquisition [Line Items]
Estimated fair value of intangible assets acquired			$ 26,600
Estimated useful life of intangible assets			10 years
KleinBank [Member] | Minnesota [Member]
Business Acquisition [Line Items]
Number of branches | Branch	18
Portion of share received by merged entity	7.92
Total fair value of consideration paid	$ 406,500
Issuance of common stock shares for acquisitions of business | shares	22.8
Value of issuance common stock shares	$ 406,500
Transaction and integration costs associated with the acquisition					$ 14,300
Stock merger acquisition ratio	100.00%
Goodwill allocation	$ 208,034
KleinBank [Member] | Minnesota [Member] | Core Deposit [Member]
Business Acquisition [Line Items]
Estimated fair value of intangible assets acquired	$ 39,000
Estimated useful life of intangible assets	12 years

Acquisition and Divestiture A_4

Acquisition and Divestiture Activity - Summary of Fair Values of Acquired Assets, Liabilities Assumed and Resulting Goodwill (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Nov. 01, 2018	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 1,036,258			$ 828,051	$ 655,018
Anchor Bank (MN) [Member] | Minnesota [Member]
Business Acquisition [Line Items]
Cash and cash equivalents			$ 34,501
Investment securities			302,195
FHLB/Federal Reserve Bank stock			6,585
Loans held for sale			1,407
Loans			1,593,991
Premises and equipment			33,433
Accrued interest receivable			5,872
Other real estate owned			1,058
Company-owned life insurance			44,490
Other assets			30,036
Deposits			(1,777,588)
Federal funds purchased and interbank borrowings			(45,600)
Securities sold under agreements to repurchase			(22,965)
Other borrowings			(49,257)
Accrued expenses and other liabilities			(25,784)
Net tangible assets acquired			132,374
Definite-lived intangible assets acquired			26,606
Goodwill			173,785
Total consideration			$ 332,765
KleinBank [Member]
Business Acquisition [Line Items]
Premises and equipment	$ 33,400
KleinBank [Member] | Minnesota [Member]
Business Acquisition [Line Items]
Cash and cash equivalents		$ 60,759
Investment securities		697,951
Federal Home Loan Bank stock		2,637
Loans held for sale		3,371
Loans		1,049,073
Premises and equipment		33,391
Accrued interest receivable		7,896
Other real estate owned		954
Company-owned life insurance		36,380
Net deferred tax assets		6,500
Other assets		10,299
Deposits		(1,713,086)
Securities sold under agreements to repurchase		(19,481)
Accrued expenses and other liabilities		(17,506)
Net tangible assets acquired		159,138
Definite-lived intangible assets acquired		39,017
Loan servicing rights		285
Goodwill		208,034
Total consideration		$ 406,474

Acquisition and Divestiture A_5

Acquisition and Divestiture Activity - Schedule of Acquired Loan Data (Detail) - Minnesota [Member] - USD ($) $ in Thousands	Nov. 01, 2018	Jun. 30, 2018
Anchor Bank (MN) [Member]
Loans at Acquisition Date [Line Items]
Fair Value of Acquired Loans at Acquisition Date		$ 1,593,991
Anchor Bank (MN) [Member] | Acquired Receivables Subject to ASC 310-30 [Member]
Loans at Acquisition Date [Line Items]
Fair Value of Acquired Loans at Acquisition Date		10,555
Gross Contractual Cash Flows at Acquisition Date		16,898
Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected		4,787
Anchor Bank (MN) [Member] | Acquired Receivables Not Subject to ASC 310-30 [Member]
Loans at Acquisition Date [Line Items]
Fair Value of Acquired Loans at Acquisition Date		1,583,436
Gross Contractual Cash Flows at Acquisition Date		1,879,449
Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected		$ 87,767
KleinBank [Member]
Loans at Acquisition Date [Line Items]
Fair Value of Acquired Loans at Acquisition Date	$ 1,049,073
KleinBank [Member] | Acquired Receivables Subject to ASC 310-30 [Member]
Loans at Acquisition Date [Line Items]
Fair Value of Acquired Loans at Acquisition Date	11,663
Gross Contractual Cash Flows at Acquisition Date	18,568
Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected	4,521
KleinBank [Member] | Acquired Receivables Not Subject to ASC 310-30 [Member]
Loans at Acquisition Date [Line Items]
Fair Value of Acquired Loans at Acquisition Date	1,037,410
Gross Contractual Cash Flows at Acquisition Date	1,252,954
Best Estimate at Acquisition Date of Contractual Cash Flows Not Expected to be Collected	$ 76,534

Acquisition and Divestiture A_6

Acquisition and Divestiture Activity - Summary of Unaudited Pro-Forma Information (Detail) - KleinBank [Member] - Minnesota [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Revenue	$ 819,777	$ 708,422
Income before income taxes	$ 273,125	$ 183,494

Investment Securities - Amortiz

Investment Securities - Amortized Cost and Fair Value of Available-for-Sale and Held-to-Maturity Investment Securities Portfolio (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Amortized Cost	$ 4,172,617	$ 3,252,586
Available-for-Sale, Unrealized Gains	21,372	7,943
Available-for-Sale, Unrealized Losses	(70,573)	(64,322)
Available-for-Sale securities, Fair Value	4,123,416	3,196,207
Held-to-Maturity, Amortized Cost	506,334	684,063
Held-to-Maturity, Unrealized Gains	6,247	43,648
Held-to-Maturity, Unrealized Losses	(6,478)	(8)
Held-to-Maturity, Fair Value	506,103	727,703
U.S. Treasury [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Amortized Cost	5,332	5,473
Available-for-Sale, Unrealized Gains		83
Available-for-Sale, Unrealized Losses	(31)	(5)
Available-for-Sale securities, Fair Value	5,301	5,551
U.S. Government-Sponsored Entities and Agencies [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Amortized Cost	639,458	675,643
Available-for-Sale, Unrealized Gains	35	3
Available-for-Sale, Unrealized Losses	(11,342)	(11,360)
Available-for-Sale securities, Fair Value	628,151	664,286
Held-to-Maturity, Amortized Cost	73,986
Held-to-Maturity, Unrealized Losses	(1,627)
Held-to-Maturity, Fair Value	72,359
Mortgage-Backed Securities - Agency [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Amortized Cost	2,243,774	1,704,014
Available-for-Sale, Unrealized Gains	9,738	1,600
Available-for-Sale, Unrealized Losses	(44,217)	(37,932)
Available-for-Sale securities, Fair Value	2,209,295	1,667,682
Held-to-Maturity, Amortized Cost	127,120	6,903
Held-to-Maturity, Unrealized Gains	39	153
Held-to-Maturity, Unrealized Losses	(2,750)
Held-to-Maturity, Fair Value	124,409	7,056
States and Political Subdivisions [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Amortized Cost	932,757	529,835
Available-for-Sale, Unrealized Gains	11,113	5,085
Available-for-Sale, Unrealized Losses	(3,441)	(4,727)
Available-for-Sale securities, Fair Value	940,429	530,193
Held-to-Maturity, Amortized Cost	305,228	677,160
Held-to-Maturity, Unrealized Gains	6,208	43,495
Held-to-Maturity, Unrealized Losses	(2,101)	(8)
Held-to-Maturity, Fair Value	309,335	720,647
Pooled Trust Preferred Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Amortized Cost	13,861	16,605
Available-for-Sale, Unrealized Losses	(5,366)	(8,157)
Available-for-Sale securities, Fair Value	8,495	8,448
Other Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Amortized Cost	337,435	321,016
Available-for-Sale, Unrealized Gains	486	1,172
Available-for-Sale, Unrealized Losses	(6,176)	(2,141)
Available-for-Sale securities, Fair Value	$ 331,745	$ 320,047

Investment Securities - Additio

Investment Securities - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018USD ($)Security	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Investment [Line Items]
Securities pledged to secure public and other funds, carrying value	$ 2,400,000,000	$ 1,800,000,000
Securities portfolio at fair value	5,582,000	5,584,000
Held-to-Maturity, Unrecognized Losses	17,211,000	8,000
OTTI losses on securities	$ 0	0	$ 0
Number of securities in security portfolio | Security	2,100
Number of securities in unrealized loss position | Security	791
Investment securities - available-for-sale, at fair value	$ 4,123,416,000	3,196,207,000
Unrealized losses	70,573,000	64,322,000
Proceeds from sale of trust preferred securities	139,364,000	342,233,000	243,312,000
Loss from sale of trust preferred securities	1,469,000	263,000	$ 450,000
Held-to-maturity Securities [Member]
Investment [Line Items]
Unrealized holding loss net of tax		0
Held-to-Maturity, Unrecognized Losses	10,700,000
Eastern Indiana [Member]
Investment [Line Items]
Investment securities issued by states and political subdivisions, market value	$ 344,400,000
State and political subdivision investment, equity percentage	12.80%
Percentage of municipal bonds rated A or better	99.00%
Percentage of non rated local interest bonds	1.00%
Texas [Member]
Investment [Line Items]
Investment securities issued by states and political subdivisions, market value	$ 176,000,000
State and political subdivision investment, equity percentage	6.50%
Former Directors and Executives [Member]
Investment [Line Items]
Securities portfolio at fair value	$ 5,600,000	5,600,000
States and Political Subdivisions [Member]
Investment [Line Items]
Held-to-Maturity, Unrecognized Losses	4,539,000	8,000
Investment securities - available-for-sale, at fair value	940,429,000	530,193,000
Unrealized losses	$ 3,441,000	4,727,000
Pooled Trust Preferred Securities [Member]
Investment [Line Items]
Number of pooled trust preferred securities | Security	2
Investment securities - available-for-sale, at fair value	$ 8,495,000	8,448,000
Unrealized losses	5,366,000	8,157,000
OTTI losses on securities	0	$ 0
Pooled Trust Preferred Securities, Subject To FASB ASC 325-10 [Member]
Investment [Line Items]
Proceeds from sale of trust preferred securities	1,800,000
Loss from sale of trust preferred securities	900,000
Accounting Standards Update 2017-12 [Member]
Investment [Line Items]
Reclassification of securities	324,000,000
Unrealized holding loss net of tax	10,800,000
Accounting Standards Update 2017-12 [Member] | States and Political Subdivisions [Member]
Investment [Line Items]
Reclassification of securities	$ 447,000,000

Investment Securities - Schedul

Investment Securities - Schedule of Proceeds from Sales or Calls and Realized Gain and Losses of Available-for-sale Investment Securities and Other Securities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Securities, Available-for-sale [Line Items]
Proceeds from sales of available-for-sale securities	$ 139,364	$ 342,233	$ 243,312
Proceeds from calls of available-for-sale securities	419,270	438,818	1,177,130
Total	171,801	430,466	878,936
Realized gains on sales of available-for-sale securities	3,259	8,710	5,423
Realized losses on sales of available-for-sale securities	(1,469)	(263)	(450)
Other securities gains (losses)	50	667	100
Net securities gains	2,060	9,135	5,848
Calls [Member]
Debt Securities, Available-for-sale [Line Items]
Proceeds from calls of available-for-sale securities	32,437	88,233	635,624
Realized gains on calls of available-for-sale securities	283	29	922
Realized losses on calls of available-for-sale securities	$ (63)	$ (8)	$ (147)

Investment Securities - Expecte

Investment Securities - Expected Maturities of Investment Securities Portfolio (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Investments Debt And Equity Securities [Abstract]
Available-for-Sale, Maturity, Within one year, Amortized Cost	$ 101,077
Available-for-Sale, Maturity, One to five years, Amortized Cost	532,706
Available-for-Sale, Maturity, Five to ten years, Amortized Cost	483,510
Available-for-Sale, Maturity, Beyond ten years, Amortized Cost	3,055,324
Available-for-Sale, Amortized Cost	4,172,617	$ 3,252,586
Held-to-Maturity, Maturity, Within one year, Amortized Cost	30,188
Held-to-Maturity, Maturity, One to five years, Amortized Cost	34,511
Held-to-Maturity, Maturity, Five to ten years, Amortized Cost	72,442
Held-to-Maturity, Maturity, Beyond ten years, Amortized Cost	369,193
Held-to-Maturity, Amortized Cost	506,334	684,063
Available-for-Sale, Maturity, Within one year, Fair Value	101,138
Available-for-Sale, Maturity, One to five years, Fair Value	527,283
Available-for-Sale, Maturity, Five to ten years, Fair Value	482,231
Available-for-Sale, Maturity, Beyond ten years, Fair Value	3,012,764
Available-for-Sale securities, Fair Value	4,123,416	3,196,207
Held-to-Maturity, Maturity, Within one year, Fair Value	30,352
Held-to-Maturity, Maturity, One to five years, Fair Value	35,246
Held-to-Maturity, Maturity, Five to ten years, Fair Value	74,199
Held-to-Maturity, Maturity, Beyond ten years, Fair Value	366,306
Held-to-Maturity, Fair Value	$ 506,103	$ 727,703
Available-for-Sale, Maturity, Within one year, Weighted Average Yield	2.58%
Available-for-Sale, Maturity, One to five years, Weighted Average Yield	2.39%
Available-for-Sale, Maturity, Five to ten years, Weighted Average Yield	3.22%
Available-for-Sale, Maturity, Beyond ten years, Weighted Average Yield	2.94%
Available-for-Sale, Weighted Average Yield	2.89%
Held-to-Maturity, Maturity, Within one year, Weighted Average Yield	3.96%
Held-to-Maturity, Maturity, One to five years, Weighted Average Yield	3.93%
Held-to-Maturity, Maturity, Five to ten years, Weighted Average Yield	4.44%
Held-to-Maturity, Maturity, Beyond ten years, Weighted Average Yield	3.58%
Held-to-Maturity, Weighted Average Yield	3.75%

Investment Securities - Availab

Investment Securities - Available-for-Sale and Held-to-Maturity Investment Securities with Unrealized Losses by Aggregated Major Security Type and Length of Time in Continuous Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Less than 12 Months, Fair Value	$ 334,588	$ 1,250,341
Available-for-Sale, Less than 12 Months, Unrealized Losses	(4,653)	(12,358)
Available-for-Sale, 12 months or longer, Fair Value	1,997,801	1,407,920
Available-for-Sale, 12 months or longer, Unrealized Losses	(65,920)	(51,964)
Available-for-Sale, Fair Value	2,332,389	2,658,261
Available-for-Sale, Unrealized Losses	(70,573)	(64,322)
Held-to-Maturity, Less than 12 Months, Fair Value	28,868	2,309
Held-to-Maturity, Less than 12 Months, Unrecognized Losses	(1,007)	(8)
Held-to-Maturity, 12 months or longer, Fair Value	261,588
Held-to-Maturity, 12 months or longer, Unrecognized Losses	(16,204)
Held-to-Maturity, Fair Value	290,456	2,309
Held-to-Maturity, Unrecognized Losses	(17,211)	(8)
U.S. Treasury [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Less than 12 Months, Fair Value	3,829	1,480
Available-for-Sale, Less than 12 Months, Unrealized Losses	(12)	(5)
Available-for-Sale, 12 months or longer, Fair Value	1,472
Available-for-Sale, 12 months or longer, Unrealized Losses	(19)
Available-for-Sale, Fair Value	5,301	1,480
Available-for-Sale, Unrealized Losses	(31)	(5)
U.S. Government-Sponsored Entities and Agencies [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Less than 12 Months, Fair Value	54,701	201,773
Available-for-Sale, Less than 12 Months, Unrealized Losses	(594)	(1,333)
Available-for-Sale, 12 months or longer, Fair Value	519,911	408,493
Available-for-Sale, 12 months or longer, Unrealized Losses	(10,748)	(10,027)
Available-for-Sale, Fair Value	574,612	610,266
Available-for-Sale, Unrealized Losses	(11,342)	(11,360)
Held-to-Maturity, 12 months or longer, Fair Value	72,359
Held-to-Maturity, 12 months or longer, Unrecognized Losses	(4,642)
Held-to-Maturity, Fair Value	72,359
Held-to-Maturity, Unrecognized Losses	(4,642)
Mortgage-Backed Securities - Agency [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Less than 12 Months, Fair Value	82,289	789,804
Available-for-Sale, Less than 12 Months, Unrealized Losses	(742)	(8,692)
Available-for-Sale, 12 months or longer, Fair Value	1,172,984	774,825
Available-for-Sale, 12 months or longer, Unrealized Losses	(43,475)	(29,240)
Available-for-Sale, Fair Value	1,255,273	1,564,629
Available-for-Sale, Unrealized Losses	(44,217)	(37,932)
Held-to-Maturity, Less than 12 Months, Fair Value	4,335
Held-to-Maturity, Less than 12 Months, Unrecognized Losses	(24)
Held-to-Maturity, 12 months or longer, Fair Value	119,207
Held-to-Maturity, 12 months or longer, Unrecognized Losses	(8,006)
Held-to-Maturity, Fair Value	123,542
Held-to-Maturity, Unrecognized Losses	(8,030)
States and Political Subdivisions [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Less than 12 Months, Fair Value	99,162	196,024
Available-for-Sale, Less than 12 Months, Unrealized Losses	(1,340)	(1,899)
Available-for-Sale, 12 months or longer, Fair Value	151,097	90,637
Available-for-Sale, 12 months or longer, Unrealized Losses	(2,101)	(2,828)
Available-for-Sale, Fair Value	250,259	286,661
Available-for-Sale, Unrealized Losses	(3,441)	(4,727)
Held-to-Maturity, Less than 12 Months, Fair Value	24,533	2,309
Held-to-Maturity, Less than 12 Months, Unrecognized Losses	(983)	(8)
Held-to-Maturity, 12 months or longer, Fair Value	70,022
Held-to-Maturity, 12 months or longer, Unrecognized Losses	(3,556)
Held-to-Maturity, Fair Value	94,555	2,309
Held-to-Maturity, Unrecognized Losses	(4,539)	(8)
Pooled Trust Preferred Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, 12 months or longer, Fair Value	8,495	8,448
Available-for-Sale, 12 months or longer, Unrealized Losses	(5,366)	(8,157)
Available-for-Sale, Fair Value	8,495	8,448
Available-for-Sale, Unrealized Losses	(5,366)	(8,157)
Other Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Less than 12 Months, Fair Value	94,607	61,260
Available-for-Sale, Less than 12 Months, Unrealized Losses	(1,965)	(429)
Available-for-Sale, 12 months or longer, Fair Value	143,842	125,517
Available-for-Sale, 12 months or longer, Unrealized Losses	(4,211)	(1,712)
Available-for-Sale, Fair Value	238,449	186,777
Available-for-Sale, Unrealized Losses	$ (6,176)	$ (2,141)

Investment Securities - Trust P

Investment Securities - Trust Preferred Securities (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)Item	Dec. 31, 2017USD ($)
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Amortized Cost	$ 4,172,617	$ 3,252,586
Available-for-Sale securities, Fair Value	4,123,416	$ 3,196,207
Pooled Trust Preferred Securities One [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Amortized Cost	13,861
Available-for-Sale securities, Fair Value	8,495
Available-for-Sale, Unrealized Gain/ (Loss)	$ (5,366)
Pooled Trust Preferred Securities One [Member] | Pretsl XXVII LTD [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Pooled trust preferred securities, Class	B
Lowest Credit Rating	B
Available-for-Sale, Amortized Cost	$ 4,349
Available-for-Sale securities, Fair Value	2,404
Available-for-Sale, Unrealized Gain/ (Loss)	$ (1,945)
# of Issuers Currently Performing | Item	33
# of Issuers Currently Remaining | Item	43
Actual Deferrals and Defaults as a Percent of Original Collateral	17.30%
Expected Defaults as a % of Remaining Performing Collateral	10.70%
Excess Subordination as a % of Current Performing Collateral	38.80%
Pooled Trust Preferred Securities One [Member] | Trapeza Ser 13A [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Pooled trust preferred securities, Class	A2A
Lowest Credit Rating	BBB
Available-for-Sale, Amortized Cost	$ 9,512
Available-for-Sale securities, Fair Value	6,091
Available-for-Sale, Unrealized Gain/ (Loss)	$ (3,421)
# of Issuers Currently Performing | Item	44
# of Issuers Currently Remaining | Item	49
Actual Deferrals and Defaults as a Percent of Original Collateral	4.50%
Expected Defaults as a % of Remaining Performing Collateral	7.20%
Excess Subordination as a % of Current Performing Collateral	56.10%
Single Issuer Trust Preferred Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Amortized Cost	$ 4,788
Available-for-Sale securities, Fair Value	4,500
Available-for-Sale, Unrealized Gain/ (Loss)	$ (288)
Single Issuer Trust Preferred Securities [Member] | J P Morgan Chase Cap XIII [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Lowest Credit Rating	BBB
Available-for-Sale, Amortized Cost	$ 4,788
Available-for-Sale securities, Fair Value	4,500
Available-for-Sale, Unrealized Gain/ (Loss)	(288)
Trust Preferred Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-Sale, Amortized Cost	18,649
Available-for-Sale securities, Fair Value	12,995
Available-for-Sale, Unrealized Gain/ (Loss)	$ (5,654)

Loans Held for Sale - Additiona

Loans Held for Sale - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Servicing Assets at Fair Value [Line Items]
Mortgage loans held for sale	$ 14,911	$ 17,930
Residential Mortgage Loans [Member]
Servicing Assets at Fair Value [Line Items]
Mortgage loans held for sale	$ 14,900	$ 17,900

Loans and Allowance for Loan _3

Loans and Allowance for Loan Losses - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Nov. 01, 2018
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans		$ 12,243,892,000	$ 11,118,121,000
Loan placed on nonaccrual when past due, number of days		90 days
Loan participations		$ 924,800,000
Loan participations sold		461,700,000
Loan participations retained		$ 463,100,000
Troubled debt restructuring term		6 months
Minimum number of days for loan charge off to be recorded		120 days
Maximum number of days for loan charge off to be recorded		180 days
Nonaccrual period for loans		90 days
Financing receivable TDR's included with non-accrual loans		$ 26,300,000	34,000,000
Financing receivable troubled debt restructurings specific reserves		3,000,000	5,700,000
Unfunded commitments on TDRs		$ 4,400,000
Increase (decrease) in allowance for loan losses			2,700,000	$ (2,300,000)
Allowance for loan losses charge-offs			200,000	$ 800,000
Number of days for a loan to be considered to be in payment default		90 days
Outstanding loans including principal, interest, fees and penalties		$ 246,900,000	235,900,000
Accretion of income		12,300,000	15,200,000
Financing receivable allowance for loan losses related to purchased loans		478,000	166,000
Maximum [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Value of small commercial loans on nonaccrual status or 90 days or more delinquent		$ 250,000
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Percentage of risk-based capital		198.00%
Regulatory guideline limit		300.00%
Total loans		$ 4,958,851,000	4,354,552,000
Financing receivable allowance for loan losses related to purchased loans		319,000
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans		1,803,667,000	1,879,247,000
Financing receivable allowance for loan losses related to purchased loans		151,000	134,000
Consumer [Member] | Student Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans			$ 68,200,000
Loan sold	$ 64,900,000
Consumer [Member] | Student Loan [Member] | Other Income [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Gain on sale of student loan	$ 2,200,000
Consumer [Member] | Minimum [Member] | Student Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loan guarantee percentage			97.00%
Consumer [Member] | Maximum [Member] | Student Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loan guarantee percentage			100.00%
KleinBank [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial real estate					$ 559,500,000
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans		$ 2,248,404,000	$ 2,167,053,000
Credit Concentration Risk [Member] | Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Concentration Risk Percentage		10.00%
Credit Concentration Risk [Member] | Non Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Concentration Risk Percentage		10.00%

Loans and Allowance for Loan _4

Loans and Allowance for Loan Losses - Schedule of Composition of Loan (Detail) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	$ 12,243,892	$ 11,118,121
Allowance for loan losses	(55,461)	(50,381)	$ (49,808)	$ (52,233)
Net loans	12,188,431	11,067,740
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	3,232,970	2,717,269
Allowance for loan losses	(21,742)	(19,246)	$ (21,481)	$ (26,347)
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	2,248,404	2,167,053
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	4,958,851	4,354,552
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	1,803,667	1,879,247
Consumer [Member] | Consumer Credit - Home Equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	589,322	507,507
Construction [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	504,625	374,306
Other [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	4,454,226	3,980,246
Other [Member] | Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	154,712	223,068
Consumer Credit - Auto [Member] | Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans by lending classification	$ 1,059,633	$ 1,148,672

Loans and Allowance for Loan _5

Loans and Allowance for Loan Losses - Schedule of Composition of Loan (Detail) (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Direct finance leases	$ 60	$ 29.5

Loans and Allowance for Loan _6

Loans and Allowance for Loan Losses - Schedule of Activity in Related Party Loans (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Receivables [Abstract]
Balance at beginning of period	$ 9,481
New loans	9,152
Repayments	(8,721)
Officer and director changes	(602)
Balance at end of period	$ 9,310

Loans and Allowance for Loan _7

Loans and Allowance for Loan Losses - Schedule of Activity in Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				$ 50,381				$ 49,808	$ 50,381	$ 49,808	$ 52,233
Charge-offs									(12,969)	(12,717)	(14,610)
Recoveries									11,083	10,240	11,225
Provision	$ 3,390	$ 750	$ 2,446	380	$ 1,037	$ 311	$ 1,355	347	6,966	3,050	960
Ending balance	55,461				50,381				55,461	50,381	49,808
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				19,246				21,481	19,246	21,481	26,347
Charge-offs									(3,087)	(1,108)	(5,047)
Recoveries									1,519	2,281	3,102
Provision									4,064	(3,408)	(2,921)
Ending balance	21,742				19,246				21,742	19,246	21,481
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				21,436				18,173	21,436	18,173	15,993
Charge-offs									(879)	(3,700)	(2,632)
Recoveries									2,740	3,777	4,763
Provision									173	3,186	49
Ending balance	23,470				21,436				23,470	21,436	18,173
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				1,763				1,643	1,763	1,643	2,051
Charge-offs									(1,100)	(985)	(800)
Recoveries									2,118	255	174
Provision									(504)	850	218
Ending balance	2,277				1,763				2,277	1,763	1,643
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				$ 7,936				$ 8,511	7,936	8,511	7,842
Charge-offs									(7,903)	(6,924)	(6,131)
Recoveries									4,706	3,927	3,186
Provision									3,233	2,422	3,614
Ending balance	$ 7,972				$ 7,936				$ 7,972	$ 7,936	$ 8,511

Loans and Allowance for Loan _8

Loans and Allowance for Loan Losses - Schedule of Recorded Investment in Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses, Individually evaluated for impairment	$ 14,341	$ 10,078
Allowance for loan losses, Collectively evaluated for impairment	40,642	40,137
Allowance for loan losses, Loans acquired with deteriorated credit quality	478	166
Total allowance for loan losses	55,461	50,381
Loans and leases outstanding, Individually evaluated for impairment	118,514	92,331
Loans and leases outstanding, Collectively evaluated for impairment	12,080,985	10,982,264
Loans and leases outstanding, Loans acquired with deteriorated credit quality	44,393	43,526
Total loans and leases outstanding	12,243,892	11,118,121
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses, Individually evaluated for impairment	6,035	3,424
Allowance for loan losses, Collectively evaluated for impairment	15,700	15,790
Allowance for loan losses, Loans acquired with deteriorated credit quality	7	32
Total allowance for loan losses	21,742	19,246
Loans and leases outstanding, Individually evaluated for impairment	35,410	26,270
Loans and leases outstanding, Collectively evaluated for impairment	3,191,367	2,685,847
Loans and leases outstanding, Loans acquired with deteriorated credit quality	6,193	5,152
Total loans and leases outstanding	3,232,970	2,717,269
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses, Individually evaluated for impairment	8,306	6,654
Allowance for loan losses, Collectively evaluated for impairment	14,845	14,782
Allowance for loan losses, Loans acquired with deteriorated credit quality	319
Total allowance for loan losses	23,470	21,436
Loans and leases outstanding, Individually evaluated for impairment	83,104	66,061
Loans and leases outstanding, Collectively evaluated for impairment	4,850,356	4,266,665
Loans and leases outstanding, Loans acquired with deteriorated credit quality	25,391	21,826
Total loans and leases outstanding	4,958,851	4,354,552
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses, Collectively evaluated for impairment	2,276	1,763
Allowance for loan losses, Loans acquired with deteriorated credit quality	1
Total allowance for loan losses	2,277	1,763
Loans and leases outstanding, Collectively evaluated for impairment	2,239,147	2,155,750
Loans and leases outstanding, Loans acquired with deteriorated credit quality	9,257	11,303
Total loans and leases outstanding	2,248,404	2,167,053
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses, Collectively evaluated for impairment	7,821	7,802
Allowance for loan losses, Loans acquired with deteriorated credit quality	151	134
Total allowance for loan losses	7,972	7,936
Loans and leases outstanding, Collectively evaluated for impairment	1,800,115	1,874,002
Loans and leases outstanding, Loans acquired with deteriorated credit quality	3,552	5,245
Total loans and leases outstanding	$ 1,803,667	$ 1,879,247

Loans and Allowance for Loan _9

Loans and Allowance for Loan Losses - Schedule of Risk Category of Commercial and Commercial Real Estate Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Commercial [Member]
Risk Category Of Loans [Line Items]
Total	$ 3,232,970	$ 2,717,269
Commercial Real Estate [Member] | Construction [Member]
Risk Category Of Loans [Line Items]
Total	504,625	374,306
Commercial Real Estate [Member] | Other [Member]
Risk Category Of Loans [Line Items]
Total	4,454,226	3,980,246
Pass [Member] | Commercial [Member]
Risk Category Of Loans [Line Items]
Total	3,029,130	2,577,824
Pass [Member] | Commercial Real Estate [Member] | Construction [Member]
Risk Category Of Loans [Line Items]
Total	460,158	357,438
Pass [Member] | Commercial Real Estate [Member] | Other [Member]
Risk Category Of Loans [Line Items]
Total	4,167,902	3,762,896
Criticized [Member] | Commercial [Member]
Risk Category Of Loans [Line Items]
Total	98,798	74,876
Criticized [Member] | Commercial Real Estate [Member] | Construction [Member]
Risk Category Of Loans [Line Items]
Total	29,368	14,758
Criticized [Member] | Commercial Real Estate [Member] | Other [Member]
Risk Category Of Loans [Line Items]
Total	110,586	98,451
Classified - Substandard [Member] | Commercial [Member]
Risk Category Of Loans [Line Items]
Total	66,394	37,367
Classified - Substandard [Member] | Commercial Real Estate [Member] | Construction [Member]
Risk Category Of Loans [Line Items]
Total	1,275	0
Classified - Substandard [Member] | Commercial Real Estate [Member] | Other [Member]
Risk Category Of Loans [Line Items]
Total	102,961	58,584
Classified - Nonaccrual [Member] | Commercial [Member]
Risk Category Of Loans [Line Items]
Total	29,003	24,798
Classified - Nonaccrual [Member] | Commercial Real Estate [Member] | Construction [Member]
Risk Category Of Loans [Line Items]
Total	13,824	2,110
Classified - Nonaccrual [Member] | Commercial Real Estate [Member] | Other [Member]
Risk Category Of Loans [Line Items]
Total	37,441	30,108
Classified - Doubtful [Member] | Commercial [Member]
Risk Category Of Loans [Line Items]
Total	9,645	2,404
Classified - Doubtful [Member] | Commercial Real Estate [Member] | Construction [Member]
Risk Category Of Loans [Line Items]
Total	0	0
Classified - Doubtful [Member] | Commercial Real Estate [Member] | Other [Member]
Risk Category Of Loans [Line Items]
Total	$ 35,336	$ 30,207

Loans and Allowance for Loan_10

Loans and Allowance for Loan Losses - Schedule of Recorded Investment in Residential and Consumer Loans Based on Payment Activity (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance receivable recorded investment, Performing	$ 12,037,323	$ 10,951,187
Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Residential real estate	2,248,404	2,167,053
Residential [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance receivable recorded investment, Performing	2,223,450	2,144,882
Residential [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance receivable recorded investment, Nonperforming	24,954	22,171
Consumer Home Equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance receivable recorded investment	589,322	507,507
Consumer Home Equity [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance receivable recorded investment, Performing	586,235	502,322
Consumer Home Equity [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance receivable recorded investment, Nonperforming	3,087	5,185
Consumer Auto [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance receivable recorded investment	1,059,633	1,148,672
Consumer Auto [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance receivable recorded investment, Performing	1,057,038	1,145,977
Consumer Auto [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance receivable recorded investment, Nonperforming	2,595	2,695
Consumer - Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance receivable recorded investment	154,712	223,068
Consumer - Other [Member] | Performing Financing Receivable [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance receivable recorded investment, Performing	153,113	217,819
Consumer - Other [Member] | Nonperforming Financing Receivable [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Finance receivable recorded investment, Nonperforming	$ 1,599	$ 5,249

Loans and Allowance for Loan_11

Loans and Allowance for Loan Losses - Schedule of Impaired Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Recorded Investment, Total	$ 124,054	$ 99,540
Unpaid Principal Balance, Total	125,349	107,700
Related Allowance	14,486	10,232
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	6,035	3,424
Recorded Investment with no related allowance	22,031	20,557
Unpaid Principal Balance with no related allowance	22,292	21,483
Recorded Investment with related allowance	13,379	5,713
Unpaid Principal Balance with related allowance	13,432	5,713
Commercial Real Estate - Other [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	6,476	6,253
Recorded Investment with no related allowance	41,126	38,678
Unpaid Principal Balance with no related allowance	41,914	44,564
Recorded Investment with related allowance	28,154	26,478
Unpaid Principal Balance with related allowance	28,154	26,902
Residential [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	44	44
Recorded Investment with no related allowance	2,276	2,443
Unpaid Principal Balance with no related allowance	2,296	2,464
Recorded Investment with related allowance	889	870
Unpaid Principal Balance with related allowance	889	870
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	101	110
Recorded Investment with no related allowance	362	1,685
Unpaid Principal Balance with no related allowance	535	2,105
Recorded Investment with related allowance	2,013	2,211
Unpaid Principal Balance with related allowance	2,013	2,228
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Related Allowance	1,830	401
Recorded Investment with related allowance	13,824	905
Unpaid Principal Balance with related allowance	$ 13,824	$ 1,371

Loans and Allowance for Loan_12

Loans and Allowance for Loan Losses - Schedule of Average Balance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment, Total	$ 111,359	$ 100,772	$ 106,638
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment with no related allowance	21,295	24,780	34,708
Average Recorded Investment with an allowance recorded	9,546	7,002	16,669
Commercial Real Estate - Other [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment with no related allowance	39,902	34,632	28,793
Average Recorded Investment with an allowance recorded	27,317	26,562	20,465
Residential [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment with no related allowance	2,305	2,415	1,355
Average Recorded Investment with an allowance recorded	840	1,012	1,074
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment with no related allowance	832	1,761	855
Average Recorded Investment with an allowance recorded	1,957	2,155	2,367
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment with an allowance recorded	$ 7,365	$ 453	$ 352

Loans and Allowance for Credit

Loans and Allowance for Credit Losses - Schedule of Past Due Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	$ 206,569	$ 166,934
Past Due 90 Days or More and Accruing	1,353	894
Nonaccrual	157,484	124,927
Current	12,037,323	10,951,187
Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	54,596	44,535
Past Due 90 Days or More and Accruing	258
Nonaccrual	24,954	22,171
Current	2,193,808	2,122,518
Consumer Home Equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	5,937	6,950
Past Due 90 Days or More and Accruing	456	68
Nonaccrual	3,087	5,185
Current	583,385	500,557
Consumer Auto [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	11,966	11,116
Past Due 90 Days or More and Accruing	377	532
Nonaccrual	2,595	2,695
Current	1,047,667	1,137,556
Consumer - Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	2,690	10,880
Past Due 90 Days or More and Accruing	170	150
Nonaccrual	1,599	5,249
Current	152,022	212,188
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	42,606	28,692
Past Due 90 Days or More and Accruing	52	144
Nonaccrual	38,648	27,202
Current	3,190,364	2,688,577
Commercial Real Estate [Member] | Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	13,824	2,110
Nonaccrual	13,824	2,110
Current	490,801	372,196
Commercial Real Estate [Member] | Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	74,950	62,651
Past Due 90 Days or More and Accruing	40
Nonaccrual	72,777	60,315
Current	4,379,276	3,917,595
30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	40,443	34,102
30 to 59 Days Past Due [Member] | Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	25,947	18,948
30 to 59 Days Past Due [Member] | Consumer Home Equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	1,434	1,467
30 to 59 Days Past Due [Member] | Consumer Auto [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	7,091	6,487
30 to 59 Days Past Due [Member] | Consumer - Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	711	3,967
30 to 59 Days Past Due [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	3,627	986
30 to 59 Days Past Due [Member] | Commercial Real Estate [Member] | Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	1,633	2,247
60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	7,289	7,011
60 to 89 Days Past Due [Member] | Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	3,437	3,416
60 to 89 Days Past Due [Member] | Consumer Home Equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	960	230
60 to 89 Days Past Due [Member] | Consumer Auto [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	1,903	1,402
60 to 89 Days Past Due [Member] | Consumer - Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	210	1,514
60 to 89 Days Past Due [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	279	360
60 to 89 Days Past Due [Member] | Commercial Real Estate [Member] | Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivables, Past Due	$ 500	$ 89

Loans and Allowance for Credi_2

Loans and Allowance for Credit Losses - Schedule of Past Due Loans (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Purchased credit impaired loans	$ 20.5	$ 12.6

Loans and Allowance for Credi_3

Loans and Allowance for Credit Losses - Schedule of Activity in Troubled Debt Restructurings (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Balance at beginning of period	$ 54,003	$ 40,716	$ 44,251
(Charge-offs)/recoveries	431	504	(993)
(Payments)/disbursements	(16,415)	(31,860)	(29,814)
Additions	5,691	44,643	27,272
Balance at end of period	43,710	54,003	40,716
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Balance at beginning of period	12,088	16,802	23,354
(Charge-offs)/recoveries	(169)	417	(1,982)
(Payments)/disbursements	(5,188)	(18,519)	(19,566)
Additions	3,544	13,388	14,996
Balance at end of period	10,275	12,088	16,802
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Balance at beginning of period	34,705	18,327	14,602
(Charge-offs)/recoveries	561	381	953
(Payments)/disbursements	(8,808)	(11,752)	(8,358)
Additions	1,213	27,749	11,130
Balance at end of period	27,671	34,705	18,327
Residential [Member]
Financing Receivable, Impaired [Line Items]
Balance at beginning of period	3,315	2,985	2,693
(Charge-offs)/recoveries	23		42
(Payments)/disbursements	(450)	(608)	(511)
Additions	502	938	761
Balance at end of period	3,390	3,315	2,985
Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Balance at beginning of period	3,895	2,602	3,602
(Charge-offs)/recoveries	16	(294)	(6)
(Payments)/disbursements	(1,969)	(981)	(1,379)
Additions	432	2,568	385
Balance at end of period	$ 2,374	$ 3,895	$ 2,602

Loans and Allowance for Loan_13

Loans and Allowance for Loan Losses - Schedule of Loans by Class Modified as Troubled Debt Restructuring (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)SecurityLoan	Dec. 31, 2017USD ($)SecurityLoan	Dec. 31, 2016USD ($)SecurityLoan
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	10	36	44
Pre-modification Outstanding Recorded Investment	$ 5,691	$ 44,643	$ 27,272
Post-modification Outstanding Recorded Investment	$ 5,691	$ 44,643	$ 27,272
Commercial Loan [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	6	11	20
Pre-modification Outstanding Recorded Investment	$ 3,544	$ 13,388	$ 14,996
Post-modification Outstanding Recorded Investment	$ 3,544	$ 13,388	$ 14,996
Other [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	2	12	10
Pre-modification Outstanding Recorded Investment	$ 1,213	$ 27,749	$ 11,130
Post-modification Outstanding Recorded Investment	$ 1,213	$ 27,749	$ 11,130
Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	1	6	6
Pre-modification Outstanding Recorded Investment	$ 502	$ 938	$ 761
Post-modification Outstanding Recorded Investment	$ 502	$ 938	$ 761
Consumer - Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	1	7	8
Pre-modification Outstanding Recorded Investment	$ 432	$ 2,568	$ 385
Post-modification Outstanding Recorded Investment	$ 432	$ 2,568	$ 385

Loans and Allowance for Loan_14

Loans and Allowance for Loan Losses - Schedule of Activity of Purchased Impaired Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Purchased impaired loans	$ 44,393	$ 43,526
Allowance for loan losses	(478)	(166)
Carrying amount, net of allowance	43,915	43,360
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Purchased impaired loans	6,193	5,152
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Purchased impaired loans	25,391	21,826
Residential [Member]
Financing Receivable, Impaired [Line Items]
Purchased impaired loans	9,257	11,303
Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Purchased impaired loans	$ 3,552	$ 5,245

Loans and Allowance for Loan_15

Loans and Allowance for Loan Losses - Schedule of Accretable Yield of Noncovered PCI Loans, or Income Expected to be Collected (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Accretion of income	$ (12,300)	$ (15,200)
Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period	27,835	33,603	$ 45,310
New loans purchased	2,384	1,556	3,217
Accretion of income	(12,252)	(15,217)	(23,447)
Reclassifications from (to) nonaccretable difference	6,133	7,614	10,589
Disposals/other adjustments	951	279	(2,066)
Balance at end of period	$ 25,051	$ 27,835	$ 33,603

Loans and Allowance for Loan_16

Loans and Allowance for Loan Losses - Schedule of Receivables for which Contractually Required Payments would not be Collected (Detail) - Minnesota [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Anchor Bank (MN) [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contractually required payments		$ 16,898
Nonaccretable difference		(4,787)
Cash flows expected to be collected at acquisition		12,111
Accretable yield		(1,556)
Fair value of acquired loans at acquisition		$ 10,555
KleinBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contractually required payments	$ 18,568
Nonaccretable difference	(4,521)
Cash flows expected to be collected at acquisition	14,047
Accretable yield	(2,384)
Fair value of acquired loans at acquisition	$ 11,663

Loans and Allowance for Loan_17

Loans and Allowance for Loan Losses - Schedule of Receivables for which Contractually Required Payments would not be Collected (Parenthetical) (Detail) - Minnesota [Member]	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Anchor Bank (MN) [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Effective date of acquisition		Nov. 1, 2017
KleinBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Effective date of acquisition	Nov. 1, 2018

Other Real Estate Owned - Activ

Other Real Estate Owned - Activity in Other Real Estate Owned (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Regulatory Assets [Abstract]
Balance at beginning of period	$ 8,810	$ 18,546
Additions	2,025	4,016
Sales	(6,689)	(11,160)
Impairment	(914)	(2,592)
Balance at end of period	$ 3,232	$ 8,810

Other Real Estate Owned - Act_2

Other Real Estate Owned - Activity in Other Real Estate Owned (Parenthetical) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Real Estate Properties [Line Items]
Other real estate owned and repossessed personal property	$ 3,232	$ 8,810	$ 18,546
Repossessed personal property	300	300
Other Real Estate Owned [Member] | Klein Bank [Member]
Real Estate Properties [Line Items]
Other real estate owned and repossessed personal property	$ 1,000
Other Real Estate Owned [Member] | Anchor Bank (MN) [Member]
Real Estate Properties [Line Items]
Other real estate owned and repossessed personal property		$ 1,100

Other Real Estate Owned - Addit

Other Real Estate Owned - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Regulatory Assets [Abstract]
Value of foreclosed residential real estate property	$ 1.3	$ 1.6
Value of mortgage loans in process of foreclosure	$ 4.9	$ 5.2

Premises and Equipment - Summar

Premises and Equipment - Summary of Premises and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total	$ 594,483	$ 550,051
Accumulated depreciation	(108,571)	(91,977)
Premises and equipment, net	485,912	458,074
Land [Member]
Property, Plant and Equipment [Line Items]
Total	79,231	73,046
Buildings [Member]
Property, Plant and Equipment [Line Items]
Total	365,102	343,833
Furniture, Fixtures, and Equipment [Member]
Property, Plant and Equipment [Line Items]
Total	107,862	94,254
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total	$ 42,288	$ 38,918

Premises and Equipment - Additi

Premises and Equipment - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)BuildingTerm	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)Property
Property, Plant and Equipment [Line Items]
Depreciation	$ 23,773	$ 22,183	$ 16,558
Number of additional successive terms extendable at the option | Term	5
Period of extendable lease term, in years	5 years
Lease term, description	one year and five months.
Rent expense	$ 17,900	15,800	$ 25,400
Sale leaseback transaction, gain recognized over lease term	$ 6,500	$ 8,200
Number of branch buildings under capital leases | Building	2
Prior Sale Leaseback Transactions [Member]
Property, Plant and Equipment [Line Items]
Number of leased properties acquired with deferred gains | Property			20
Sale leaseback transaction, gain recognized over lease term			$ 12,000
Number of leased properties acquired | Property			23
Minimum [Member]
Property, Plant and Equipment [Line Items]
Lease Term	1 year 5 months
Maximum [Member]
Property, Plant and Equipment [Line Items]
Lease Term	25 years
KleinBank [Member]
Property, Plant and Equipment [Line Items]
Increase in assets due to acquisition	$ 33,400

Premises and Equipment - Summ_2

Premises and Equipment - Summary of Future Minimum Lease Commitments (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Property Plant And Equipment [Abstract]
2,019	$ 19,480
2,020	18,416
2,021	17,400
2,022	15,169
2,023	9,697
Thereafter	65,612
Total	$ 145,774

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Schedule of Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Balance at beginning of period	$ 828,051	$ 655,018
Acquisitions	208,787	173,033
Divestitures	(580)	0
Balance at end of period	$ 1,036,258	$ 828,051

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Goodwill associated with the sale of branches	$ 580,000	$ 0
Amortization of other intangible assets	14,442,000	11,841,000	$ 12,486,000
Impairment charges	$ 0	$ 0	$ 0
Core Deposits and Other Intangible Assets [Member] | Minimum [Member]
Goodwill [Line Items]
Estimated useful lives of core deposits and customer relationships	5 years
Core Deposits and Other Intangible Assets [Member] | Maximum [Member]
Goodwill [Line Items]
Estimated useful lives of core deposits and customer relationships	15 years
Minnesota-based Klein [Member]
Goodwill [Line Items]
Increase (decrease) to goodwill	$ 208,000,000
Minnesota-based Klein [Member] | Core Deposit [Member]
Goodwill [Line Items]
Increase (decrease) in core deposit intangibles	39,000,000
Anchor (MN) [Member]
Goodwill [Line Items]
Increase (decrease) to goodwill	800,000
Marine Credit Union [Member]
Goodwill [Line Items]
Goodwill associated with the sale of branches	$ 600,000

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Schedule of Gross Carrying Amounts and Accumulated Amortization of Other Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 145,647	$ 129,883
Accumulated Amortization and Impairment	(68,631)	(76,787)
Net Carrying Amount	77,016	53,096
Core Deposit [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	129,100	108,923
Accumulated Amortization and Impairment	(57,524)	(62,874)
Net Carrying Amount	71,576	46,049
Customer Trust Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	16,547	16,547
Accumulated Amortization and Impairment	(11,107)	(9,533)
Net Carrying Amount	$ 5,440	7,014
Customer Loan Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		4,413
Accumulated Amortization and Impairment		(4,380)
Net Carrying Amount		$ 33

Goodwill and Other Intangible_6

Goodwill and Other Intangible Assets - Schedule of Estimated Amortization Expense for Future Years (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
2,019	$ 16,929
2,020	14,091
2,021	11,336
2,022	9,014
2,023	7,053
Thereafter	18,593
Net Carrying Amount	$ 77,016	$ 53,096

Loan Servicing Rights - Additio

Loan Servicing Rights - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Transfers And Servicing [Abstract]
Loan servicing rights	$ 24,497	$ 24,661
Principal balance of loans serviced for others	3,306,000	3,321,000
Funds held in escrow	$ 10,700	8,900
Percentage of mortgage loan	99.70%
Fair value of servicing rights	$ 27,400	$ 25,800
Fair value at discount rate	12.00%	13.00%
Fair value inputs weighted average prepayment speed	119.00%	140.00%

Loan Servicing Rights - Compone

Loan Servicing Rights - Components of Loan Servicing Rights and Valuation Allowance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Transfers And Servicing [Abstract]
Balance at beginning of period	$ 24,690	$ 25,629
Additions	4,264	4,206
Amortization	(4,442)	(5,145)
Balance before valuation allowance at end of period	24,512	24,690
Valuation allowance:
Balance at beginning of period	(29)	(68)
(Additions)/recoveries	14	39
Balance at end of period	(15)	(29)
Loan servicing rights, net	$ 24,497	$ 24,661

Loan Servicing Rights - Compo_2

Loan Servicing Rights - Components of Loan Servicing Rights and Valuation Allowance (Parenthetical) (Detail) $ in Millions	Nov. 30, 2018USD ($)
KleinBank [Member]
Servicing Assets and Liabilities at Fair Value [Line Items]
Loan servicing rights	$ 0.3

Qualified Affordable Housing _3

Qualified Affordable Housing Projects and Other Tax Credit Investments - Schedule of Qualified Affordable Housing Projects and Other Tax Credit Investments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investment Holdings [Line Items]
Total	$ 54,404	$ 64,896
Total	38,548	48,866
Amortization Expense	25,533	13,655	$ 804
Tax Expense (Benefit) Recognized	(29,377)	(15,701)	(1,125)
LIHTC [Member]
Investment Holdings [Line Items]
Proportional amortization method of investment	28,396	31,183
Unfunded commitment, Proportional amortization	2,238	15,553
Amortization Expense	2,585	1,922	804
Tax Expense (Benefit) Recognized	(3,349)	(2,666)	$ (1,125)
FHTC [Member]
Investment Holdings [Line Items]
Equity method investment	16,815	10,645
Unfunded commitment, Equity	17,945	12,040
Amortization Expense	9,206	10,441
Tax Expense (Benefit) Recognized	(10,775)	(11,348)
CReED [Member]
Investment Holdings [Line Items]
Equity method investment	17	704
Unfunded commitment, Equity	538	1,502
Amortization Expense	687	800
Tax Expense (Benefit) Recognized	(687)	(1,074)
Renewable Energy [Member]
Investment Holdings [Line Items]
Equity method investment	9,176	22,364
Unfunded commitment, Equity	17,827	19,771
Amortization Expense	13,055	492
Tax Expense (Benefit) Recognized	$ (14,566)	$ (613)

Deposits - Additional Informati

Deposits - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Maturities Of Time Deposits [Abstract]
Time deposits, $250,000 or more, total	$ 612.7	$ 422.3

Deposits - Schedule of Maturiti

Deposits - Schedule of Maturities of Total Time Deposits (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Maturities Of Time Deposits [Abstract]
Due in 2019	$ 1,505,694
Due in 2020	277,142
Due in 2021	109,890
Due in 2022	52,697
Due in 2023	54,637
Thereafter	24,196
Total	$ 2,024,256	$ 1,634,436

Securities Sold Under Agreeme_3

Securities Sold Under Agreements to Repurchase - Schedule of Securities Sold under Agreements to Repurchase and Related Weighted-Average Interest Rates (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Securities Sold Under Agreements To Repurchase [Abstract]
Outstanding at year-end	$ 362,294,000	$ 384,810,000
Average amount outstanding	344,964,000	336,539,000
Maximum amount outstanding at any month-end	$ 364,001,000	$ 402,543,000
Weighted average interest rate during period	0.57%	0.38%
Weighted average interest rate at end of period	0.75%	0.49%

Securities Sold Under Agreeme_4

Securities Sold Under Agreements to Repurchase - Schedule of Remaining Contractual Maturity of Secured Borrowings and Class of Collateral Pledged Under Repurchase Agreements (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets Sold Under Agreements To Repurchase [Line Items]
Secured borrowings and class of collateral pledged under repurchase agreements	$ 362,294	$ 384,810
U.S. Treasury [Member]
Assets Sold Under Agreements To Repurchase [Line Items]
Secured borrowings and class of collateral pledged under repurchase agreements	362,294
Overnight and Continuous [Member]
Assets Sold Under Agreements To Repurchase [Line Items]
Secured borrowings and class of collateral pledged under repurchase agreements	362,294
Overnight and Continuous [Member] | U.S. Treasury [Member]
Assets Sold Under Agreements To Repurchase [Line Items]
Secured borrowings and class of collateral pledged under repurchase agreements	362,294
Up to 30 Days [Member]
Assets Sold Under Agreements To Repurchase [Line Items]
Secured borrowings and class of collateral pledged under repurchase agreements	0
Up to 30 Days [Member] | U.S. Treasury [Member]
Assets Sold Under Agreements To Repurchase [Line Items]
Secured borrowings and class of collateral pledged under repurchase agreements	0
30-90 Days [Member]
Assets Sold Under Agreements To Repurchase [Line Items]
Secured borrowings and class of collateral pledged under repurchase agreements	0
30-90 Days [Member] | U.S. Treasury [Member]
Assets Sold Under Agreements To Repurchase [Line Items]
Secured borrowings and class of collateral pledged under repurchase agreements	0
Greater Than 90 days [Member]
Assets Sold Under Agreements To Repurchase [Line Items]
Secured borrowings and class of collateral pledged under repurchase agreements	0
Greater Than 90 days [Member] | U.S. Treasury [Member]
Assets Sold Under Agreements To Repurchase [Line Items]
Secured borrowings and class of collateral pledged under repurchase agreements	$ 0

Securities Sold Under Agreeme_5

Securities Sold Under Agreements to Repurchase - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018
Securities Sold Under Agreements To Repurchase [Abstract]
Gross outstanding balance of repurchase agreements collateralized by securities percentage	122.00%

Federal Home Loan Bank Advanc_3

Federal Home Loan Bank Advances - Summary of FHLB Advances (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Federal Home Loan Bank, Advances [Line Items]
ASC 815 fair value hedge and other basis adjustments	$ 9,838
Total other borrowings	1,613,481	$ 1,609,579
Old National Bank [Member]
Federal Home Loan Bank, Advances [Line Items]
FHLB advances (fixed rates 1.50% to 6.08% and variable rates 2.51% to 2.75%) maturing January 2019 to October 2028	1,603,643	1,610,531
ASC 815 fair value hedge and other basis adjustments	$ 9,838	$ (952)

Federal Home Loan Bank Advanc_4

Federal Home Loan Bank Advances - Summary of FHLB Advances (Parenthetical) (Detail) - Old National Bank [Member] - Federal Home Loan Bank Advances [Member]	12 Months Ended
	Dec. 31, 2018
Federal Home Loan Bank, Advances [Line Items]
Maturity, Start date	Jan. 31, 2019
Maturity, End date	Oct. 31, 2028
Minimum [Member]
Federal Home Loan Bank, Advances [Line Items]
Fixed rates	1.50%
Variable rates	2.51%
Maximum [Member]
Federal Home Loan Bank, Advances [Line Items]
Fixed rates	6.08%
Variable rates	2.75%

Federal Home Loan Bank Advanc_5

Federal Home Loan Bank Advances - Additional Information (Detail)	Dec. 31, 2018	Dec. 31, 2017
Federal Home Loan Bank, Advances [Line Items]
Weighted-average rates of FHLB advances	2.56%	1.55%
Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank, Advances [Line Items]
Percentage of borrowings collateralized by investment securities and residential real estate loans	140.00%

Federal Home Loan Bank Advanc_6

Federal Home Loan Bank Advances - Summary of Contractual Maturities of FHLB Advances (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Federal Home Loan Banks [Abstract]
Due in 2019	$ 326,474
Due in 2020	100,000
Due in 2021	20,000
Due in 2022	57,000
Due in 2023	169
Thereafter	1,100,000
ASC 815 fair value hedge and other basis adjustments	9,838
Total	$ 1,613,481	$ 1,609,579

Other Borrowings - Other Borrow

Other Borrowings - Other Borrowings (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Aug. 31, 2014
Debt Instrument [Line Items]
Other borrowings	$ 247,883	$ 248,782
Old National Bank [Member]
Debt Instrument [Line Items]
Other basis adjustments	(773)	694
Capital lease obligations	5,262	5,389
Old National Bancorp [Member]
Debt Instrument [Line Items]
Other basis adjustments	(3,046)	(3,585)
Other borrowings	231,394	230,699
5.75% Fixed Rate Subordinated Debentures [Member] | Old National Bank [Member]
Debt Instrument [Line Items]
Subordinated debentures (fixed rate 5.75%)	12,000	12,000
Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Senior unsecured notes (fixed rate 4.125%) maturing August 2024			$ 175,000
Senior Unsecured Notes [Member] | Old National Bancorp [Member]
Debt Instrument [Line Items]
Senior unsecured notes (fixed rate 4.125%) maturing August 2024	175,000	175,000
Unamortized debt issuance costs related to senior unsecured bank notes	(870)	(1,026)
Junior Subordinated Debt [Member] | Old National Bancorp [Member]
Debt Instrument [Line Items]
Junior subordinated debentures (variable rates of 4.01% to 6.39%) maturing April 2032 to June 2037	$ 60,310	$ 60,310

Other Borrowings - Other Borr_2

Other Borrowings - Other Borrowings (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2018	Aug. 31, 2014
Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Fixed rates		4.125%
Maturity Date	Aug. 15, 2024
Old National Bank [Member] | 5.75% Fixed Rate Subordinated Debentures [Member]
Debt Instrument [Line Items]
Fixed rates	5.75%
Old National Bancorp [Member] | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Fixed rates	4.125%
Maturity Date	Aug. 15, 2024
Old National Bancorp [Member] | Trust Preferred Securities [Member] | Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Maturity, Start date	Apr. 22, 2032
Maturity, End date	Jun. 15, 2037
Old National Bancorp [Member] | Trust Preferred Securities [Member] | Junior Subordinated Debt [Member] | Minimum [Member]
Debt Instrument [Line Items]
Variable rates	4.01%
Old National Bancorp [Member] | Trust Preferred Securities [Member] | Junior Subordinated Debt [Member] | Maximum [Member]
Debt Instrument [Line Items]
Variable rates	6.39%

Other Borrowings - Contractual

Other Borrowings - Contractual Maturities of Other Borrowings (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Due in 2019	$ 137
Due in 2020	147
Due in 2021	160
Due in 2022	172
Due in 2023	196
Thereafter	250,382
Unamortized debt issuance costs and other basis adjustments	(3,311)
Total	$ 247,883	$ 248,782

Other Borrowings - Additional I

Other Borrowings - Additional Information (Detail) $ in Millions	Nov. 01, 2017USD ($)	Jan. 01, 2004Item	Dec. 31, 2018	Aug. 31, 2014USD ($)
Debt Instrument [Line Items]
Long-term capital lease obligation period, in years		25 years
Long-term capital lease obligation renewal period, in years		10 years
Number of renewal option for 10 years period | Item		1
Anchor Bank (MN) [Member]
Debt Instrument [Line Items]
Remaining base term of lease	5 years
Renewal option available for lease in years	10 years
Capital lease obligation	$ 1.5
Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Senior unsecured notes				$ 175
Fixed rates				4.125%
Maturity Date			Aug. 15, 2024
Subordinated Debentures [Member] | Anchor Bank (MN) [Member] | Subordinated Fixed-To-Floating Notes [Member]
Debt Instrument [Line Items]
Fixed rates	5.75%
Maturity Date	Oct. 30, 2025
Value of subordinated fixed-to-floating notes assumed	$ 12
Subordinated debentures, maturity date	Oct. 29, 2020
Description of LIBOR Rate	three-month LIBOR rate plus 4.356%
LIBOR rate	0.04356%
Debt instrument start date	Oct. 30, 2020

Other Borrowings - Summary of T

Other Borrowings - Summary of Terms of Outstanding Junior Subordinated Debentures (Detail) - Trust Preferred Securities [Member] - Junior Subordinated Debt [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Debt Instrument [Line Items]
Issuance Amount	$ 60,310
VFSC Capital Trust I [Member]
Debt Instrument [Line Items]
Issuance Date	Apr. 30, 2002
Issuance Amount	$ 3,093
Description of LIBOR Rate	6-month LIBOR plus 3.70%
Rate	6.39%
Maturity Date	Apr. 22, 2032
VFSC Capital Trust II [Member]
Debt Instrument [Line Items]
Issuance Date	Oct. 31, 2002
Issuance Amount	$ 4,124
Description of LIBOR Rate	3-month LIBOR plus 3.45%
Rate	6.09%
Maturity Date	Nov. 7, 2032
VFSC Capital Trust III [Member]
Debt Instrument [Line Items]
Issuance Date	Apr. 30, 2004
Issuance Amount	$ 3,093
Description of LIBOR Rate	3-month LIBOR plus 2.80%
Rate	5.57%
Maturity Date	Sep. 8, 2034
St Joseph Capital Trust II [Member]
Debt Instrument [Line Items]
Issuance Date	Mar. 31, 2005
Issuance Amount	$ 5,000
Description of LIBOR Rate	3-month LIBOR plus 1.75%
Rate	4.54%
Maturity Date	Mar. 17, 2035
Anchor Capital Trust III [Member]
Debt Instrument [Line Items]
Issuance Date	Aug. 31, 2005
Issuance Amount	$ 5,000
Description of LIBOR Rate	3-month LIBOR plus 1.55%
Rate	4.35%
Maturity Date	Sep. 30, 2035
Tower Capital Trust 2 [Member]
Debt Instrument [Line Items]
Issuance Date	Dec. 31, 2005
Issuance Amount	$ 8,000
Description of LIBOR Rate	3-month LIBOR plus 1.34%
Rate	4.14%
Maturity Date	Dec. 30, 2035
Home Federal Statutory Trust I [Member]
Debt Instrument [Line Items]
Issuance Date	Sep. 30, 2006
Issuance Amount	$ 15,000
Description of LIBOR Rate	3-month LIBOR plus 1.65%
Rate	4.44%
Maturity Date	Sep. 15, 2036
Monroe Bancorp Capital Trust I [Member]
Debt Instrument [Line Items]
Issuance Date	Jul. 31, 2006
Issuance Amount	$ 3,000
Description of LIBOR Rate	3-month LIBOR plus 1.60%
Rate	4.01%
Maturity Date	Oct. 7, 2036
Monroe Bancorp Statutory Trust II [Member]
Debt Instrument [Line Items]
Issuance Date	Mar. 31, 2007
Issuance Amount	$ 5,000
Description of LIBOR Rate	3-month LIBOR plus 1.60%
Rate	4.39%
Maturity Date	Jun. 15, 2037
Tower Capital Trust 3 [Member]
Debt Instrument [Line Items]
Issuance Date	Dec. 31, 2006
Issuance Amount	$ 9,000
Description of LIBOR Rate	3-month LIBOR plus 1.69%
Rate	4.43%
Maturity Date	Mar. 1, 2037

Other Borrowings - Summary of_2

Other Borrowings - Summary of Terms of Outstanding Junior Subordinated Debentures (Parenthetical) (Detail) - Trust Preferred Securities [Member] - Junior Subordinated Debt [Member] - London Interbank Offered Rate (LIBOR) [Member]	12 Months Ended
	Dec. 31, 2018
VFSC Capital Trust I [Member]
Debt Instrument [Line Items]
LIBOR rate	3.70%
VFSC Capital Trust II [Member]
Debt Instrument [Line Items]
LIBOR rate	3.45%
VFSC Capital Trust III [Member]
Debt Instrument [Line Items]
LIBOR rate	2.80%
St Joseph Capital Trust II [Member]
Debt Instrument [Line Items]
LIBOR rate	1.75%
Anchor Capital Trust III [Member]
Debt Instrument [Line Items]
LIBOR rate	1.55%
Tower Capital Trust 2 [Member]
Debt Instrument [Line Items]
LIBOR rate	1.34%
Home Federal Statutory Trust I [Member]
Debt Instrument [Line Items]
LIBOR rate	1.65%
Monroe Bancorp Capital Trust I [Member]
Debt Instrument [Line Items]
LIBOR rate	1.60%
Tower Capital Trust 3 [Member]
Debt Instrument [Line Items]
LIBOR rate	1.69%
Monroe Bancorp Statutory Trust II [Member]
Debt Instrument [Line Items]
LIBOR rate	1.60%

Other Borrowings - Future Minim

Other Borrowings - Future Minimum Lease Payments under Capital Lease Arrangements (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Debt Disclosure [Abstract]
2,019	$ 589
2,020	589
2,021	589
2,022	589
2,023	599
Thereafter	8,676
Total minimum lease payments	11,631
Less amounts representing interest	(6,369)
Present value of net minimum lease payments	$ 5,262

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Schedule of AOCI (Detail) - USD ($) $ in Thousands	Jan. 02, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 2,154,397	$ 2,154,397	$ 1,814,417	$ 1,491,170
Other comprehensive income (loss) before reclassifications		15,852	10,190	(32,953)
Amounts reclassified from AOCI to income		273	(1,090)	8,378
Amount reclassified from AOCI to retained earnings for cumulative effect of change in accounting principle			(4,179)
Amounts reclassified from AOCI to retained earnings related to the Tax Cuts and Jobs Act of 2017	10,800
Ending Balance		2,689,570	2,154,397	1,814,417
Gains and Losses on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(2,337)	(2,337)	(6,715)	(9,276)
Other comprehensive income (loss) before reclassifications		3,884	575	(1,440)
Amounts reclassified from AOCI to income		113	3,803	4,001
Amount reclassified from AOCI to retained earnings for cumulative effect of change in accounting principle		(52)
Amounts reclassified from AOCI to retained earnings related to the Tax Cuts and Jobs Act of 2017		(509)
Ending Balance		1,099	(2,337)	(6,715)
Unrealized Gains and Losses on Available- for-Sale Debt Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(35,557)	(35,557)	(39,012)	(3,806)
Other comprehensive income (loss) before reclassifications		7,454	9,615	(31,513)
Amounts reclassified from AOCI to income		(1,662)	(6,160)	(3,693)
Amounts reclassified from AOCI to retained earnings related to the Tax Cuts and Jobs Act of 2017		(7,583)
Ending Balance		(37,348)	(35,557)	(39,012)
Accumulated Unrealized Gains and Losses on Held-to-Maturity Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(12,107)	(12,107)	(13,310)	(14,480)
Other comprehensive income (loss) before reclassifications		4,514
Amounts reclassified from AOCI to income		1,678	1,203	1,170
Amounts reclassified from AOCI to retained earnings related to the Tax Cuts and Jobs Act of 2017		(2,600)
Ending Balance		(8,515)	(12,107)	(13,310)
Defined Benefit Pension Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(271)	(271)	(335)	(7,235)
Amounts reclassified from AOCI to income		144	64	6,900
Amounts reclassified from AOCI to retained earnings related to the Tax Cuts and Jobs Act of 2017		(59)
Ending Balance		(186)	(271)	(335)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (50,272)	(50,272)	(59,372)	(34,797)
Amount reclassified from AOCI to retained earnings for cumulative effect of change in accounting principle		(52)	(52)
Amounts reclassified from AOCI to retained earnings related to the Tax Cuts and Jobs Act of 2017		(10,751)
Ending Balance		$ (44,950)	$ (50,272)	$ (59,372)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) - Reclassifications out of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net securities gains									$ (2,060)	$ (9,135)	$ (5,848)
Interest income (expense)	$ (146,225)	$ (130,842)	$ (131,963)	$ (128,572)	$ (118,556)	$ (108,478)	$ (104,333)	$ (105,801)	(537,602)	(437,168)	(402,703)
Salaries and employee benefits									(191)	(159)	(11,203)
Income tax (expense) benefit	3,223	5,325	4,345	4,957	40,405	11,459	10,584	10,491	17,850	72,939	66,162
Net income	$ (47,498)	$ (51,348)	$ (44,001)	$ (47,983)	$ 18,493	$ (39,372)	$ (38,854)	$ (35,992)	(190,830)	(95,725)	(134,264)
Total reclassifications for the period									(273)	1,090	(8,378)
Gains and Losses on Cash Flow Hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period									(113)	(3,803)	(4,001)
Unrealized Gains and Losses on Available- for-Sale Debt Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period									1,662	6,160	3,693
Accumulated Unrealized Gains and Losses on Held-to-Maturity Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period									(1,678)	(1,203)	(1,170)
Defined Benefit Pension Plans [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period									(144)	(64)	(6,900)
Reclassifications out of Accumulated Other Comprehensive Income (Loss) [Member] | Gains and Losses on Cash Flow Hedges [Member] | Interest Rate Contracts [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest income (expense)									(150)	(6,135)	(6,453)
Income tax (expense) benefit									37	2,332	2,452
Net income									(113)	(3,803)	(4,001)
Reclassifications out of Accumulated Other Comprehensive Income (Loss) [Member] | Unrealized Gains and Losses on Available- for-Sale Debt Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net securities gains									2,060	9,135	5,848
Income tax (expense) benefit									(398)	(2,975)	(2,155)
Net income									1,662	6,160	3,693
Reclassifications out of Accumulated Other Comprehensive Income (Loss) [Member] | Accumulated Unrealized Gains and Losses on Held-to-Maturity Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest income (expense)									(2,181)	(1,830)	(1,776)
Income tax (expense) benefit									503	627	606
Net income									(1,678)	(1,203)	(1,170)
Reclassifications out of Accumulated Other Comprehensive Income (Loss) [Member] | Defined Benefit Pension Plans [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits									(191)	(159)	(11,203)
Income tax (expense) benefit									47	95	4,303
Net income									$ (144)	$ (64)	$ (6,900)

Income Taxes - Summary of Diffe

Income Taxes - Summary of Differences in Taxes from Continuing Operations Computed at Statutory Rate (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Provision at statutory rate									$ 43,823	$ 59,032	$ 70,149
Tax-exempt interest									(9,021)	(15,026)	(14,356)
Section 291/265 interest disallowance									321	289	191
Company-owned life insurance income									(2,223)	(3,029)	(2,968)
Tax-exempt income									(10,923)	(17,766)	(17,133)
State income taxes									5,621	998	3,461
Tax credit investments - federal									(21,576)	(8,500)	(321)
Revaluation of deferred tax assets					$ 39,300					39,300
ONB Insurance Group, Inc. nondeductible goodwill											8,328
Other, net									905	(125)	1,678
Income tax expense	$ 3,223	$ 5,325	$ 4,345	$ 4,957	$ 40,405	$ 11,459	$ 10,584	$ 10,491	$ 17,850	$ 72,939	$ 66,162
Effective tax rate									8.60%	43.30%	33.00%

Income Taxes - Summary of Dif_2

Income Taxes - Summary of Differences in Taxes from Continuing Operations Computed at Statutory Rate (Parenthetical) (Detail)	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Statutory rate	21.00%	21.00%	35.00%	35.00%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Statutory rate		21.00%	21.00%	35.00%	35.00%
Estimated revaluation of deferred tax assets		$ 39,300,000		$ 39,300,000
Bad debt reserves, created for tax purposes			$ 52,800,000
Unrecognized deferred income tax liability			13,000,000
Valuation allowance recorded		0	0	0
Operating loss carryforwards, federal		130,700,000	104,500,000	130,700,000
AMT carryforwards		25,084,000	2,545,000	25,084,000
Federal tax credits		5,516,000	1,779,000	5,516,000
Operating loss carryforwards, state		203,600,000	165,600,000	203,600,000
Unrecognized tax benefits, if recognized, would favorably affect the effective tax rate			500,000
Reduction in unrecognized tax benefits			0
Interest and penalties			0	10,000	$ 100,000
Interest and penalties, accrued		100,000	100,000	100,000
Income tax reversal related to reductions for tax positions in prior years	$ 100,000		78,000
Uncertain tax position reversal	$ 300,000		301,000	173,000	$ 2,000
Amount reversed in unrecognized tax benefit			400,000
Internal Revenue Code Section Three Eight Two [Member]
Income Taxes [Line Items]
AMT carryforwards			2,500,000
Tax credit carryforwards reclassified to current tax asset			21,500,000
Minimum [Member]
Income Taxes [Line Items]
AMT carryforwards		$ 25,100,000	$ 10,100,000	$ 25,100,000
Minimum [Member] | State Net Operating Loss [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration date			2,024
Minimum [Member] | Federal Net Operating Loss [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration date			2,028
Minimum [Member] | Federal Tax Credits [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration date			2,025
Maximum [Member] | State Net Operating Loss [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration date			2,033
Maximum [Member] | Federal Net Operating Loss [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration date			2,033
Maximum [Member] | Federal Tax Credits [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration date			2,038
AnchorBank WI [Member]
Income Taxes [Line Items]
Bad debt reserves, created for tax purposes			$ 50,900,000
Lafayette Savings Bank [Member]
Income Taxes [Line Items]
Bad debt reserves, created for tax purposes			$ 1,900,000

Income Taxes - Provision for In

Income Taxes - Provision for Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Federal income taxes currently payable									$ 12,256		$ 23,735
State income taxes currently payable									4,601		2,242
Federal income taxes deferred									(1,513)	$ 31,915	35,955
Revaluation of deferred tax assets					$ 39,300					39,300
State income taxes deferred									2,506	1,724	4,230
Deferred income tax expense									993	72,939	40,185
Income tax expense	$ 3,223	$ 5,325	$ 4,345	$ 4,957	$ 40,405	$ 11,459	$ 10,584	$ 10,491	$ 17,850	$ 72,939	$ 66,162

Income Taxes - Schedule of Sign

Income Taxes - Schedule of Significant Components of Net Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Assets
Allowance for loan losses, net of recapture	$ 14,514	$ 12,958
Benefit plan accruals	21,694	11,080
Alternative minimum tax credit	2,545	25,084
Unrealized losses on benefit plans	61	108
Net operating loss carryforwards	31,765	39,631
Federal tax credits	1,779	5,516
Deferred gain on securities	1,976
Other-than-temporary impairment	37	1,424
Acquired loans	26,956	29,669
Lease exit obligation	1,025	1,337
Unrealized losses on available-for-sale investment securities	11,853	14,011
Unrealized losses on held-to-maturity investment securities	2,497	3,630
Unrealized losses on hedges		923
Tax credit investments	662
Other real estate owned	144	369
Other, net	5,471	829
Total deferred tax assets	122,979	146,569
Deferred Tax Liabilities
Accretion on investment securities	(595)	(493)
Purchase accounting	(18,100)	(16,718)
Loan servicing rights	(6,141)	(6,058)
Premises and equipment	(8,507)	(10,052)
Prepaid expenses	(681)	(1,277)
Tax credit investments		(168)
Unrealized gains on hedges	(358)
Other, net	(1,549)	(946)
Total deferred tax liabilities	(35,931)	(35,712)
Net deferred tax assets	$ 87,048	$ 110,857

Income Taxes - Summary of Recon

Income Taxes - Summary of Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Balance at beginning of period		$ 874	$ 777	$ 124
Additions based on tax positions related to the current year			162	118
Additions (reductions) based on tax positions related to prior years				537
Additions (reductions) based on tax positions related to prior years	$ (100)	(78)
Reductions due to statute of limitations expiring	$ (300)	(301)	(173)	(2)
Revaluation due to Tax Reform			108
Balance at end of period		$ 495	$ 874	$ 777

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Detail) - USD ($) shares in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Discretionary profit sharing	$ 0	$ 0	$ 0
Contribution plan, employer matching contribution percentage		50.00%	50.00%
Defined contribution plans employee contribution percentage of eligible compensation matched by employer		6.00%	6.00%
Shares allocated to the employee stock ownership plan	0.7	0.7
Contribution expense under employee stock ownership plan	$ 8,600,000	$ 4,700,000	$ 5,000,000
Employer Matching Contribution Tranche One [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution plan, employer matching contribution percentage	75.00%
Defined contribution plans employee contribution percentage of eligible compensation matched by employer	4.00%
Employer Matching Contribution Tranche Two [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution plan, employer matching contribution percentage	50.00%
Defined contribution plans employee contribution percentage of eligible compensation matched by employer	4.00%
Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 0
Discretionary profit sharing			7,600,000
Settlement loss			9,800,000
Benefit cost, net periodic benefit cost			$ 11,600,000

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining shares available for issuance	4,400,000
Stock based compensation expense	$ 8,100,000	$ 6,300,000	$ 7,300,000
Total income tax benefit, stock-based compensation cost	$ 2,000,000	2,400,000	2,800,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation awards, vesting period	3 years
Unrecognized compensation expense	$ 4,500,000
Expected weighted-average period for cost recognition (in years)	1 year 10 months 24 days
Total fair value of shares vested	$ 3,400,000	$ 3,400,000	$ 3,800,000
Stock appreciation rights, Outstanding	419,000	407,000
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation awards, vesting period	3 years
Unrecognized compensation expense	$ 4,300,000
Expected weighted-average period for cost recognition (in years)	1 year 7 months 6 days
Stock appreciation rights, Outstanding	893,000	849,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term, in years	10 years
Stock Options [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation awards, vesting period	3 years
Stock Options [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation awards, vesting period	5 years
Stock Appreciation Rights (SARs) [Member] | Old National Bancorp [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock appreciation rights, Outstanding	61,000
Incremental expense associated with conversion of stock appreciation rights	$ 0	$ 0
Outside Director Stock Compensation Program [Member] | Amended and Restated 2008 Incentive Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, issued	16,000	20,000

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Changes in the Nonvested Restricted Shares (Detail) - Restricted Stock [Member] shares in Thousands	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested shares, Beginning balance | shares	407
Nonvested shares, Granted, Number Outstanding | shares	217
Nonvested shares, Vested, Number Outstanding | shares	(195)
Nonvested shares, Forfeited, Number Outstanding | shares	(10)
Nonvested shares, Ending balance | shares	419
Nonvested shares, Weighted Average Grant-Date Fair Value, Beginning of Period | $ / shares	$ 15.41
Nonvested shares, Granted, Weighted Average Grant-Date Fair Value | $ / shares	17.47
Nonvested shares, Vested, Weighted Average Grant-Date Fair Value | $ / shares	14.80
Nonvested shares, Forfeited, Weighted Average Grant-Date Fair Value | $ / shares	15.08
Nonvested shares, Weighted Average Grant-Date Fair Value, Ending of Period | $ / shares	$ 16.77

Share-Based Compensation - Su_2

Share-Based Compensation - Summary of Changes in the Nonvested Restricted Stock Units (Detail) - Restricted Stock Units [Member] shares in Thousands	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested shares, Beginning balance | shares	849
Nonvested shares, Granted, Number Outstanding | shares	288
Nonvested shares, Vested, Number Outstanding | shares	(92)
Nonvested shares, Forfeited, Number Outstanding | shares	(185)
Nonvested Shares,dividend equivalents adjustment, Number Outstanding | shares	33
Nonvested shares, Ending balance | shares	893
Nonvested shares, Weighted Average Grant-Date Fair Value, Beginning of Period | $ / shares	$ 13.30
Nonvested shares, Granted, Weighted Average Grant-Date Fair Value | $ / shares	13.62
Nonvested shares, Vested, Weighted Average Grant-Date Fair Value | $ / shares	13.65
Nonvested shares, Forfeited, Weighted Average Grant-Date Fair Value | $ / shares	13.58
Nonvested shares, dividend equivalents adjustment, Weighted Average Grant-Date Fair Value | $ / shares	13.32
Nonvested shares, Weighted Average Grant-Date Fair Value, Ending of Period | $ / shares	$ 13.31

Share-Based Compensation - Su_3

Share-Based Compensation - Summary of the Activity in the Stock Option Plan (Detail) $ / shares in Units, shares in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)$ / sharesshares
Stock Based Compensation [Abstract]
Outstanding, Shares, Beginning Balance | shares	225
Exercised, Shares | shares	(76)
Forfeited/expired, Shares | shares	(57)
Outstanding, Shares, Ending Balance | shares	92
Options exercisable at end of year, Shares | shares	92
Weighted Average Exercise Price, Beginning of Period | $ / shares	$ 11.92
Exercised, Weighted Average Exercise Price | $ / shares	12.59
Forfeited/expired, Weighted Average Exercise Price | $ / shares	20.16
Weighted Average Exercise Price, End of Period | $ / shares	6.30
Options exercisable at end of year, Weighted Average Exercise Price | $ / shares	$ 6.30
Weighted Average Remaining Contractual Term in Years, End of Period	2 years 29 days
Options exercisable at end of year, Weighted Average Remaining Contractual Terms in Years	2 years 29 days
Aggregate Intrinsic Value, End of Period | $	$ 836,700
Options exercisable at end of year, Aggregate Intrinsic Value | $	$ 836,700

Share-Based Compensation - Sche

Share-Based Compensation - Schedule of Information Related to the Stock Option Plan (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock Based Compensation [Abstract]
Intrinsic value of options exercised	$ 385	$ 806	$ 660
Cash received from option exercises	948	2,655	2,349
Tax benefit realized from option exercises	$ 154	$ 318	$ 264

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Aug. 13, 2018
Shareholders' Equity [Line Items]
Authorized and unissued common shares available for issuance	300,000,000	300,000,000
Common shares purchase price as percentage of fair market value	95.00%
Maximum value of shares purchased as percentage of employee compensation	10.00%
Common stock issued	$ 497,000	$ 404,000	$ 388,000
Dividend Reinvestment and Stock Purchase Plan [Member]
Shareholders' Equity [Line Items]
Authorized and unissued common shares available for issuance	3,300,000			3,300,000
Employee Stock Purchase Plan [Member]
Shareholders' Equity [Line Items]
Number of shares available for purchase, maximum	500,000
Shares issued related to dividend reinvestment and stock purchase plan	29,000	24,000
Common stock issued	$ 497,000	$ 404,000

Fair Value - Schedule of Fair V

Fair Value - Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity securities	$ 5,582	$ 5,584
Investment securities available-for-sale	4,123,416	3,196,207
Derivative assets	29,005	14,118
Derivative liabilities	12,550	16,292
U.S. Treasury [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	5,301	5,551
U.S. Government-Sponsored Entities and Agencies [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	628,151	664,286
Mortgage-Backed Securities - Agency [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	2,209,295	1,667,682
States and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	940,429	530,193
Pooled Trust Preferred Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	8,495	8,448
Other Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	331,745	320,047
Fair Value on Recurring Basis [Member] | Carrying Value [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity securities	5,582	5,584
Residential loans held for sale	14,911	17,930
Derivative assets	29,005	14,118
Derivative liabilities	12,550	16,292
Fair Value on Recurring Basis [Member] | Carrying Value [Member] | U.S. Treasury [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	5,301	5,551
Fair Value on Recurring Basis [Member] | Carrying Value [Member] | U.S. Government-Sponsored Entities and Agencies [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	628,151	664,286
Fair Value on Recurring Basis [Member] | Carrying Value [Member] | Mortgage-Backed Securities - Agency [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	2,209,295	1,667,682
Fair Value on Recurring Basis [Member] | Carrying Value [Member] | States and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	940,429	530,193
Fair Value on Recurring Basis [Member] | Carrying Value [Member] | Pooled Trust Preferred Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	8,495	8,448
Fair Value on Recurring Basis [Member] | Carrying Value [Member] | Other Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	331,745	320,047
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity securities	5,582	5,584
Residential loans held for sale	0	0
Derivative assets	0	0
Derivative liabilities	0	0
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	5,301	5,551
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Government-Sponsored Entities and Agencies [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	0	0
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage-Backed Securities - Agency [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	0	0
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | States and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	0	0
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Pooled Trust Preferred Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	0	0
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	30,259	30,965
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity securities	0	0
Residential loans held for sale	14,911	17,930
Derivative assets	29,005	14,118
Derivative liabilities	12,550	16,292
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	0	0
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Government-Sponsored Entities and Agencies [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	628,151	664,286
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage-Backed Securities - Agency [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	2,209,295	1,667,682
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Significant Other Observable Inputs (Level 2) [Member] | States and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	936,321	530,193
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Significant Other Observable Inputs (Level 2) [Member] | Pooled Trust Preferred Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	0	0
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	301,486	289,082
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Equity securities	0	0
Residential loans held for sale	0	0
Derivative assets	0	0
Derivative liabilities	0	0
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	0	0
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Government-Sponsored Entities and Agencies [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	0	0
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage-Backed Securities - Agency [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	0	0
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Inputs (Level 3) [Member] | States and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	4,108	0
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Inputs (Level 3) [Member] | Pooled Trust Preferred Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	8,495	8,448
Fair Value on Recurring Basis [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investment securities available-for-sale	$ 0	$ 0

Fair Value - Reconciliation of

Fair Value - Reconciliation of All Assets Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) (Detail) - Significant Unobservable Inputs (Level 3) [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Pooled Trust Preferred Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	$ 8,448	$ 8,119
Accretion (amortization) of discount	17	17
Sales/payments received	(338)	(424)
Increase in fair value of securities	368	736
Transfers into Level 3	0
Balance at end of period	8,495	8,448
State and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	0	0
Accretion (amortization) of discount	(56)	0
Sales/payments received	0	0
Increase in fair value of securities	28	0
Transfers into Level 3	4,136
Balance at end of period	$ 4,108	$ 0

Fair Value - Additional Informa

Fair Value - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net carrying amount other real estate owned and other repossessed property	$ 68	$ 1,800
Other real estate owned property write-downs	600	2,500
Valuation allowance for loan servicing rights with impairments	15	29	$ 68
Recoveries on loan servicing rights	$ (14)	(39)
Past due period of mortgage loans held for sale, days	90 days
Interest income for residential loans held for sale	$ 500	200
States and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Pooled trust preferred securities	4,108
States and Political Subdivisions [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Pooled trust preferred securities	4,100
Impaired Commercial and Commercial Real Estate Loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Principal amount of impaired commercial and commercial real estate loans	49,300	38,600
Valuation allowance	12,900	10,100
Provision for loan losses expensed	$ 9,900
Recapture of provision loan		$ 5,200

Fair Value - Quantitative Infor

Fair Value - Quantitative Information about Significant Unobservable Inputs Used in Fair Value Measurements (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Commercial Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 29,125	$ 26,319
Valuation Techniques	Fair value of collateral	Fair value of collateral
Commercial Real Estate Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		$ 1,726
Valuation Techniques		Fair value of collateral
Commercial Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 7,242	$ 2,217
Valuation Techniques	Fair value of collateral	Fair value of collateral
Minimum [Member] | Measurement Input, Discount Rate [Member] | Commercial Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	0	0.10
Minimum [Member] | Measurement Input, Discount Rate [Member] | Commercial Real Estate Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status		0.07
Minimum [Member] | Measurement Input, Discount Rate [Member] | Commercial Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	0	0
Maximum [Member] | Measurement Input, Discount Rate [Member] | Commercial Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	0.50	0.78
Maximum [Member] | Measurement Input, Discount Rate [Member] | Commercial Real Estate Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status		0.25
Maximum [Member] | Measurement Input, Discount Rate [Member] | Commercial Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	0.90	0.98
Weighted Average [Member] | Measurement Input, Discount Rate [Member] | Commercial Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	0.35	0.32
Weighted Average [Member] | Measurement Input, Discount Rate [Member] | Commercial Real Estate Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status		0.18
Weighted Average [Member] | Measurement Input, Discount Rate [Member] | Commercial Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	0.35	0.49
Pooled Trust Preferred Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 8,495	$ 8,448
Valuation Techniques	Discounted cash flow	Discounted cash flow
Pooled Trust Preferred Securities [Member] | Constant Prepayment Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Constant prepayment rate	0.00%	0.00%
Pooled Trust Preferred Securities [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additional asset defaults	4.20%	4.20%
Expected asset recoveries	0.00%	0.00%
Pooled Trust Preferred Securities [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additional asset defaults	9.60%	9.60%
Expected asset recoveries	0.00%	4.10%
Pooled Trust Preferred Securities [Member] | Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Additional asset defaults	7.30%	7.50%
Expected asset recoveries	0.00%	0.60%
States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 4,108
Valuation Techniques	Discounted cash flow
Residential Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 68	$ 55
Valuation Techniques	Fair value of collateral	Fair value of collateral
Residential Foreclosed Assets [Member] | Measurement Input, Discount Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status		0.39
Residential Foreclosed Assets [Member] | Minimum [Member] | Measurement Input, Discount Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	0.15
Residential Foreclosed Assets [Member] | Maximum [Member] | Measurement Input, Discount Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	0.16
Residential Foreclosed Assets [Member] | Weighted Average [Member] | Measurement Input, Discount Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount for type of property, age of appraisal and current status	0.15

Fair Value - Quantitative Inf_2

Fair Value - Quantitative Information about Significant Unobservable Inputs Used in Fair Value Measurements (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percentage of adjusted specific issuer evaluation defaults	100.00%
Percentage of adjusted specific issuer evaluation recoveries	100.00%
Pooled Trust Preferred Securities [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percentage of adjusted specific issuer evaluation defaults	0.00%
Percentage of adjusted specific issuer evaluation recoveries	0.00%
Pooled Trust Preferred Securities [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percentage of adjusted specific issuer evaluation defaults	50.00%
Percentage of adjusted specific issuer evaluation recoveries	25.00%

Fair Value - Assets Measured at

Fair Value - Assets Measured at Fair Value on a Non-Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Residential Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 68	$ 55
Commercial Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	7,242	2,217
Commercial Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	29,125	26,319
Fair Value on Non-recurring Basis [Member] | Residential Foreclosed Assets [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	68	55
Fair Value on Non-recurring Basis [Member] | Residential Foreclosed Assets [Member] | Estimate of Fair Value Measurement [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value on Non-recurring Basis [Member] | Residential Foreclosed Assets [Member] | Estimate of Fair Value Measurement [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value on Non-recurring Basis [Member] | Residential Foreclosed Assets [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	68	55
Fair Value on Non-recurring Basis [Member] | Loan Servicing Rights [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	104	2,964
Fair Value on Non-recurring Basis [Member] | Loan Servicing Rights [Member] | Estimate of Fair Value Measurement [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value on Non-recurring Basis [Member] | Loan Servicing Rights [Member] | Estimate of Fair Value Measurement [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	104	2,964
Fair Value on Non-recurring Basis [Member] | Loan Servicing Rights [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value on Non-recurring Basis [Member] | Commercial Real Estate Foreclosed Assets [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		1,726
Fair Value on Non-recurring Basis [Member] | Commercial Real Estate Foreclosed Assets [Member] | Estimate of Fair Value Measurement [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		0
Fair Value on Non-recurring Basis [Member] | Commercial Real Estate Foreclosed Assets [Member] | Estimate of Fair Value Measurement [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		0
Fair Value on Non-recurring Basis [Member] | Commercial Real Estate Foreclosed Assets [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		1,726
Fair Value on Non-recurring Basis [Member] | Commercial Loan [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	7,242	2,217
Fair Value on Non-recurring Basis [Member] | Commercial Loan [Member] | Estimate of Fair Value Measurement [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value on Non-recurring Basis [Member] | Commercial Loan [Member] | Estimate of Fair Value Measurement [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value on Non-recurring Basis [Member] | Commercial Loan [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	7,242	2,217
Fair Value on Non-recurring Basis [Member] | Commercial Real Estate [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	29,125	26,319
Fair Value on Non-recurring Basis [Member] | Commercial Real Estate [Member] | Estimate of Fair Value Measurement [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value on Non-recurring Basis [Member] | Commercial Real Estate [Member] | Estimate of Fair Value Measurement [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value on Non-recurring Basis [Member] | Commercial Real Estate [Member] | Estimate of Fair Value Measurement [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 29,125	$ 26,319

Fair Value - Schedule of Differ

Fair Value - Schedule of Difference between the Aggregate Fair Value and the Aggregate Remaining Principal Balance (Detail) - Residential Loans Held for Sale [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Option, Quantitative Disclosures [Line Items]
Aggregate Fair Value	$ 14,911	$ 17,930
Difference	475	546
Contractual Principal	$ 14,436	$ 17,384

Fair Value - Changes in Fair Va

Fair Value - Changes in Fair Value for Items Measured at Fair Value Pursuant to Election of the Fair Value (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Trading Securities and Other Trading Assets [Line Items]
Interest Income	$ 146,225	$ 130,842	$ 131,963	$ 128,572	$ 118,556	$ 108,478	$ 104,333	$ 105,801	$ 537,602	$ 437,168	$ 402,703
Interest (Expense)	$ (29,009)	$ (24,527)	$ (21,773)	$ (19,134)	$ (16,578)	$ (15,047)	$ (13,876)	$ (12,667)	(94,443)	(58,168)	$ (44,431)
Residential Loans Held for Sale [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other Gains and (Losses)									(67)	409
Interest Income									6	4
Interest (Expense)									(10)	0
Total Changes in Fair Values Included in Current Period Earnings									$ (71)	$ 413

Fair Value - Carrying Amounts a

Fair Value - Carrying Amounts and Estimated Fair Values of Financial Instruments, Not Carried at Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, due from banks, money market, and other interest-earning investments	$ 317,165	$ 290,432	$ 255,519	$ 219,818
Investment securities held to maturity	506,334	684,063
Accrued interest receivable	89,464	87,102
Noninterest-bearing demand deposits	3,965,380	3,680,807
Time deposits	2,024,256	1,634,436
Federal funds purchased and interbank borrowings	270,135	335,033
Securities sold under agreements to repurchase	362,294	384,810
Other borrowings	1,613,481	1,609,579
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, due from banks, money market, and other interest-earning investments	317,165	290,432
Commercial	0	0
Commercial real estate	0	0
Residential real estate	0	0
Consumer credit	0	0
Accrued interest receivable	13	16
Noninterest-bearing demand deposits	3,965,380	3,680,807
Checking, NOW, savings, and money market interest-bearing deposits	8,360,313	7,290,521
Time deposits	0	0
Federal funds purchased and interbank borrowings	270,135	335,033
Securities sold under agreements to repurchase	362,294	359,810
FHLB advances	0	0
Other borrowings	0	0
Accrued interest payable	0	0
Standby letters of credit	0	0
Commitments to extend credit	0	0
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, due from banks, money market, and other interest-earning investments	0	0
Commercial	0	0
Commercial real estate	0	0
Residential real estate	0	0
Consumer credit	0	0
Accrued interest receivable	27,580	24,001
Noninterest-bearing demand deposits	0	0
Checking, NOW, savings, and money market interest-bearing deposits	0	0
Time deposits	2,002,187	1,620,685
Federal funds purchased and interbank borrowings	0	0
Securities sold under agreements to repurchase	0	25,133
FHLB advances	0	0
Other borrowings	248,065	250,443
Accrued interest payable	9,871	7,029
Standby letters of credit	0	0
Commitments to extend credit	0	0
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, due from banks, money market, and other interest-earning investments	0	0
Commercial	3,161,132	2,707,385
Commercial real estate	4,781,294	4,347,949
Residential real estate	2,225,853	2,210,951
Consumer credit	1,773,352	1,998,194
Accrued interest receivable	61,871	63,085
Noninterest-bearing demand deposits	0	0
Checking, NOW, savings, and money market interest-bearing deposits	0	0
Time deposits	0	0
Federal funds purchased and interbank borrowings	0	0
Securities sold under agreements to repurchase	0	0
FHLB advances	1,611,103	1,607,189
Other borrowings	0	0
Accrued interest payable	0	0
Standby letters of credit	525	351
Commitments to extend credit	3,115	2,449
US Government Agencies Debt Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	0
US Government Agencies Debt Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	72,359
US Government Agencies Debt Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	0
Mortgage-Backed Securities - Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	127,120	6,903
Mortgage-Backed Securities - Agency [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	0	0
Mortgage-Backed Securities - Agency [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	124,409	7,056
Mortgage-Backed Securities - Agency [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	0	0
States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	305,228	677,160
States and Political Subdivisions [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	0	0
States and Political Subdivisions [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	309,335	720,647
States and Political Subdivisions [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	0	0
Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, due from banks, money market, and other interest-earning investments	317,165	290,432
Commercial	3,211,228	2,698,023
Commercial real estate	4,935,381	4,333,116
Residential real estate	2,246,127	2,165,290
Consumer credit	1,795,695	1,871,311
Accrued interest receivable	89,464	87,102
Noninterest-bearing demand deposits	3,965,380	3,680,807
Checking, NOW, savings, and money market interest-bearing deposits	8,360,313	7,290,521
Time deposits	2,024,256	1,634,436
Federal funds purchased and interbank borrowings	270,135	335,033
Securities sold under agreements to repurchase	362,294	384,810
FHLB advances	1,613,481	1,609,579
Other borrowings	247,883	248,782
Accrued interest payable	9,871	7,029
Standby letters of credit	525	351
Commitments to extend credit	0	0
Carrying Value [Member] | US Government Agencies Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	73,986
Carrying Value [Member] | Mortgage-Backed Securities - Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	127,120	6,903
Carrying Value [Member] | States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities held to maturity	$ 305,228	$ 677,160

Derivative Financial Instrume_3

Derivative Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Notional amount	$ 1,482,000,000				$ 708,500,000				$ 1,482,000,000	$ 708,500,000
Percentage of periodic changes in fair value qualifies for hedge accounting treatment	100.00%								100.00%
Reclassified interest income (expense)	$ 146,225,000	$ 130,842,000	$ 131,963,000	$ 128,572,000	118,556,000	$ 108,478,000	$ 104,333,000	$ 105,801,000	$ 537,602,000	437,168,000	$ 402,703,000
Reclassifications out of Accumulated Other Comprehensive Income (Loss) [Member] | Interest Income [Member]
Derivative [Line Items]
Reclassified interest income (expense)									1,200,000
Reclassifications out of Accumulated Other Comprehensive Income (Loss) [Member] | Interest Expense [Member]
Derivative [Line Items]
Reclassified interest income (expense)									(400,000)
Fixed Interest Swap [Member]
Derivative [Line Items]
Notional amount	757,000,000				33,500,000				757,000,000	33,500,000
Variable Interest Rate Swap [Member]
Derivative [Line Items]
Notional amount	525,000,000				675,000,000				525,000,000	675,000,000
Variable Interest Rate Collars [Member]
Derivative [Line Items]
Notional amount	200,000,000								200,000,000
Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Notional amount	27,600,000				29,900,000				27,600,000	29,900,000
Forward Commitments [Member]
Derivative [Line Items]
Notional amount	34,500,000				41,200,000				34,500,000	41,200,000
Customer Derivative Instrument [Member]
Derivative [Line Items]
Notional amount	793,400,000				826,600,000				793,400,000	826,600,000
Offsetting Counter Party Derivative Instrument [Member]
Derivative [Line Items]
Notional amount	793,400,000				826,600,000				793,400,000	826,600,000
Offsetting Counter Party Derivative Instrument [Member] | Foreign Currency Contracts [Member]
Derivative [Line Items]
Notional amount	3,600,000				800,000				3,600,000	800,000
Foreign Currency Forward Contract [Member] | Foreign Currency Contracts [Member]
Derivative [Line Items]
Notional amount	$ 3,600,000				$ 800,000				$ 3,600,000	$ 800,000

Derivative Financial Instrume_4

Derivative Financial Instruments - Summary of Fair Value of Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Total derivative assets	$ 29,005	$ 14,118
Total derivative liabilities	12,550	16,292
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Total derivative assets	12,741	3,351
Total derivative liabilities	1,603	5,351
Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Total derivative assets	12,741	3,351
Total derivative liabilities	1,603	5,351
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Total derivative assets	16,264	10,767
Total derivative liabilities	10,947	10,941
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Total derivative assets	15,278	10,012
Total derivative liabilities	10,562	10,933
Not Designated as Hedging Instrument [Member] | Mortgage Contracts [Member]
Derivative [Line Items]
Total derivative assets	874	747
Total derivative liabilities	316	0
Not Designated as Hedging Instrument [Member] | Foreign Currency Contracts [Member]
Derivative [Line Items]
Total derivative assets	112	8
Total derivative liabilities	$ 69	$ 8

Derivative Financial Instrume_5

Derivative Financial Instruments - Schedule of Effect of Derivative Instruments on the Consolidated Statements of Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Net unrealized derivative gains (losses) on cash flow hedges	$ 5,145	$ 927	$ (2,323)
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	(154)	(1,939)	1,418
Interest Rate Contracts [Member] | Interest Income / (Expense) [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	7,662	(836)	(863)
Interest Rate Contracts [Member] | Interest Income / (Expense) [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net unrealized derivative gains (losses) on cash flow hedges	5,145	927	(2,323)
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	(150)	(6,135)	(6,453)
Interest Rate Contracts [Member] | Other Income / (Expense) [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	(7)	56	28
Fixed Rate Debt [Member] | Interest Income / (Expense) [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income on Related Hedged Items	(7,634)	1,006	991
Mortgage Contracts [Member] | Mortgage banking revenue [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	(189)	(1,995)	1,390
Foreign Currency Contracts [Member] | Other Income / (Expense) [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	$ 42	$ 0	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018USD ($)shares	Dec. 31, 2017USD ($)
Loss Contingencies [Line Items]
Loan commitments	$ 3,566,000,000	$ 3,144,000,000
Fixed rate loan commitment	3,348,000,000
Floating rate loan commitment	218,100,000
Standby letters of credit	$ 319,000,000	68,700,000
Loan commitments floating rate, minimum	1.00%
Loan commitments floating rate, maximum	16.00%
Allowance for unfunded loan commitments	$ 2,500,000	3,100,000
Extended credit	15,500,000	12,400,000
Credit extensions with collateral	$ 7,800,000	$ 11,500,000
Class B Restricted Shares [Member] | Visa [Member]
Loss Contingencies [Line Items]
Restricted stock conversion ratio	1.6298
Investment owned, balance, shares | shares	56,210
Investment owned, at cost	$ 0

Financial Guarantees - Addition

Financial Guarantees - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Financial Guarantees [Line Items]
Term of standby letters of credit, years	1 year
Notional amount of standby letters of credit	$ 319,000,000	$ 68,700,000
Carrying value of letters of credit	500,000	400,000
Notional amount	1,482,000,000	$ 708,500,000
Interest Rate Swap [Member]
Financial Guarantees [Line Items]
Notional amount	$ 38,700,000

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Summary of Topic 606 Revenue Items (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation Of Revenue [Line Items]
Noninterest income within scope of Topic 606	$ 127,364	$ 122,416	$ 137,291
Wealth Management Fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest income within scope of Topic 606	36,863	37,316	34,641
Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Noninterest income within scope of Topic 606	44,026	41,331	41,578
Debit Card and ATM Fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest income within scope of Topic 606	20,216	17,676	16,769
Insurance Premiums and Commissions [Member]
Disaggregation Of Revenue [Line Items]
Noninterest income within scope of Topic 606	399	617	20,527
Investment Product Fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest income within scope of Topic 606	20,539	20,977	18,822
Merchant Processing Fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest income within scope of Topic 606	2,927	2,634	2,574
Gain (Loss) on Other Real Estate Owned [Member]
Disaggregation Of Revenue [Line Items]
Noninterest income within scope of Topic 606	1,270	939	1,419
Safe Deposit Box Fees [Member]
Disaggregation Of Revenue [Line Items]
Noninterest income within scope of Topic 606	$ 1,124	$ 926	$ 961

Regulatory Restrictions - Addit

Regulatory Restrictions - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Maturities Of Time Deposits [Abstract]
Reserve balances	$ 108,100,000	$ 100,900,000
Cash and due from banks held as collateral	$ 0	$ 5,700,000
Dividend approval threshold, years	2 years

Regulatory Restrictions - Sched

Regulatory Restrictions - Schedule of Capital Ratios (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Old National Bancorp [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital to risk-weighted assets Actual, Amount	$ 1,748,231	$ 1,424,123
Common equity Tier 1 capital to risk-weighted assets Actual, Amount	1,617,936	1,298,327
Tier 1 capital to risk-weighted assets Actual, Amount	1,617,936	1,298,327
Tier 1 capital to average assets Actual, Amount	$ 1,617,936	$ 1,298,327
Total capital to risk-weighted assets Actual, Ratio	12.27%	11.40%
Common equity Tier 1 capital to risk-weighted assets Actual, Ratio	11.36%	10.39%
Tier 1 capital to risk-weighted assets Actual, Ratio	11.36%	10.39%
Tier 1 capital to average assets Actual, Ratio	9.17%	8.28%
Total capital to risk-weighted assets Fully Phased-In Regulatory Guidelines Minimum, Amount	$ 1,496,099	$ 1,311,600
Common equity Tier 1 capital to risk-weighted assets Fully Phased-In Regulatory Guidelines Minimum, Amount	997,399	874,400
Tier 1 capital to risk-weighted assets Fully Phased-In Regulatory Guidelines Minimum, Amount	1,211,128	1,061,772
Tier 1 capital to average assets Fully Phased-In Regulatory Guidelines Minimum, Amount	$ 705,681	$ 627,258
Total capital to risk-weighted assets Fully Phased-In Regulatory Guidelines Minimum, Ratio	10.50%	10.50%
Common equity Tier 1 capital to risk-weighted assets Fully Phased-In Regulatory Guidelines Minimum, Ratio	7.00%	7.00%
Tier 1 capital to risk-weighted assets Fully Phased-In Regulatory Guidelines Minimum, Ratio	8.50%	8.50%
Tier 1 capital to average assets Fully Phased-In Regulatory Guidelines Minimum, Ratio	4.00%	4.00%
Old National Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital to risk-weighted assets Actual, Amount	$ 1,769,930	$ 1,458,546
Common equity Tier 1 capital to risk-weighted assets Actual, Amount	1,699,945	1,393,059
Tier 1 capital to risk-weighted assets Actual, Amount	1,699,945	1,393,059
Tier 1 capital to average assets Actual, Amount	$ 1,699,945	$ 1,393,059
Total capital to risk-weighted assets Actual, Ratio	12.47%	11.73%
Common equity Tier 1 capital to risk-weighted assets Actual, Ratio	11.98%	11.21%
Tier 1 capital to risk-weighted assets Actual, Ratio	11.98%	11.21%
Tier 1 capital to average assets Actual, Ratio	9.58%	8.93%
Total capital to risk-weighted assets Fully Phased-In Regulatory Guidelines Minimum, Amount	$ 1,489,938	$ 1,305,076
Common equity Tier 1 capital to risk-weighted assets Fully Phased-In Regulatory Guidelines Minimum, Amount	993,292	870,051
Tier 1 capital to risk-weighted assets Fully Phased-In Regulatory Guidelines Minimum, Amount	1,206,141	1,056,490
Tier 1 capital to average assets Fully Phased-In Regulatory Guidelines Minimum, Amount	$ 709,929	$ 623,758
Total capital to risk-weighted assets Fully Phased-In Regulatory Guidelines Minimum, Ratio	10.50%	10.50%
Common equity Tier 1 capital to risk-weighted assets Fully Phased-In Regulatory Guidelines Minimum, Ratio	7.00%	7.00%
Tier 1 capital to risk-weighted assets Fully Phased-In Regulatory Guidelines Minimum, Ratio	8.50%	8.50%
Tier 1 capital to average assets Fully Phased-In Regulatory Guidelines Minimum, Ratio	4.00%	4.00%
Total capital to risk-weighted assets Well Capitalized Guidelines, Amount	$ 1,418,989	$ 1,242,929
Common equity Tier 1 capital to risk-weighted assets Well Capitalized Guidelines, Amount	922,343	807,904
Tier 1 capital to risk-weighted assets Well Capitalized Guidelines, Amount	1,135,191	994,344
Tier 1 capital to average assets Well Capitalized Guidelines, Amount	$ 887,412	$ 779,697
Total capital to risk-weighted assets Well Capitalized Guidelines, Ratio	10.00%	10.00%
Common equity Tier 1 capital to risk-weighted assets Well Capitalized Guidelines, Ratio	6.50%	6.50%
Tier 1 capital to risk-weighted assets Well Capitalized Guidelines, Ratio	8.00%	8.00%
Tier 1 capital to average assets Well Capitalized Guidelines, Ratio	5.00%	5.00%

Regulatory Restrictions - Sch_2

Regulatory Restrictions - Schedule of Capital Ratios (Parenthetical) (Detail) - Basel III Capital Rules [Member]	12 Months Ended
	Dec. 31, 2018
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital conservation buffer	2.50%
Minimum [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital to risk-weighted assets Actual, Ratio	8.00%
Common equity Tier 1 capital to risk-weighted assets Actual, Ratio	4.50%
Tier 1 capital to risk-weighted assets Actual, Ratio	6.00%
Tier 1 capital to average assets Fully Phased-In Regulatory Guidelines Minimum, Ratio	4.00%

Parent Company Financial Stat_3

Parent Company Financial Statements - Condensed Balance Sheets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Equity securities	$ 5,582	$ 5,584
Available-for-Sale securities, Fair Value	4,123,416	3,196,207
Other assets	178,712	155,066
Total assets	19,728,435	17,518,292
Liabilities and Shareholders' Equity
Other borrowings	247,883	248,782
Shareholders' equity	2,689,570	2,154,397	$ 1,814,417	$ 1,491,170
Total liabilities and shareholders' equity	19,728,435	17,518,292
Old National Bancorp [Member]
Assets
Deposits in affiliate bank	90,005	43,538
Equity securities	5,582	5,584
Available-for-Sale securities, Fair Value	1,527	1,547
Investment in affiliates, Banking subsidiaries	2,769,166	2,248,700
Investment in affiliates, Non-banks	5,151	5,142
Other assets	87,096	112,353
Total assets	2,958,527	2,416,864
Liabilities and Shareholders' Equity
Other liabilities	37,563	31,768
Other borrowings	231,394	230,699
Shareholders' equity	2,689,570	2,154,397
Total liabilities and shareholders' equity	$ 2,958,527	$ 2,416,864

Parent Company Financial Stat_4

Parent Company Financial Statements - Condensed Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income
Net securities gains (losses)									$ 2,060	$ 9,135	$ 5,848
Expense
Interest on borrowings	$ 29,009	$ 24,527	$ 21,773	$ 19,134	$ 16,578	$ 15,047	$ 13,876	$ 12,667	94,443	58,168	44,431
Other expenses									32,846	24,993	28,715
Income before income taxes	50,721	56,673	48,346	52,940	21,912	50,831	49,438	46,483	208,680	168,664	200,426
Income tax (expense) benefit	3,223	5,325	4,345	4,957	40,405	11,459	10,584	10,491	17,850	72,939	66,162
Net income	$ 47,498	$ 51,348	$ 44,001	$ 47,983	$ (18,493)	$ 39,372	$ 38,854	$ 35,992	190,830	95,725	134,264
Old National Bancorp [Member]
Income
Dividends from affiliates									105,000	100,000	160,007
Net securities gains (losses)									49	667	100
Other income									2,126	1,966	40,841
Other income from affiliates									5	5	6
Total income									107,180	102,638	200,954
Expense
Interest on borrowings									10,425	9,298	9,077
Other expenses									21,936	16,335	18,460
Total expense									32,361	25,633	27,537
Income before income taxes									74,819	77,005	173,417
Income tax (expense) benefit									(5,693)	(6,240)	11,952
Income before equity in undistributed earnings of affiliates									80,512	83,245	161,465
Equity in undistributed earnings of affiliates									110,318	12,480	(27,201)
Net income									$ 190,830	$ 95,725	$ 134,264

Parent Company Financial Stat_5

Parent Company Financial Statements - Condensed Statement of Cash Flows (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows From Operating Activities
Net income	$ 190,830	$ 95,725	$ 134,264
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	23,773	22,183	16,558
Net securities (gains) losses	(2,060)	(9,135)	(5,848)
Gain on sale of ONB Insurance Group, Inc.			(41,864)
Share-based compensation expense	8,118	6,275	7,318
(Increase) decrease in other assets	2,046	45,008	46,004
Increase (decrease) in other liabilities	134	12,141	(24,524)
Total adjustments	43,577	154,358	(109,457)
Net cash flows provided by (used in) operating activities	234,407	250,083	24,807
Cash Flows From Investing Activities
Proceeds from sale of ONB Insurance Group, Inc.			91,771
Purchases of investment securities	(663,338)	(874,555)	(1,625,746)
Proceeds from sale of premises and equipment and other assets	7,341	18,592	6,332
Purchases of premises and equipment	(33,391)	(37,303)	(224,659)
Net cash flows provided by (used in) investing activities	(271,416)	(536,399)	(640,759)
Cash Flows From Financing Activities
Cash dividends paid on common stock	(82,161)	(72,604)	(67,536)
Common stock repurchased	(1,805)	(2,761)	(2,044)
Proceeds from exercise of stock options	948	2,655	2,349
Common stock issued	497	404	388
Net cash flows provided by (used in) financing activities	63,742	321,229	651,653
Net increase (decrease) in cash and cash equivalents	26,733	34,913	35,701
Cash and cash equivalents at beginning of period	290,432	255,519	219,818
Cash and cash equivalents at end of period	317,165	290,432	255,519
Old National Bancorp [Member]
Cash Flows From Operating Activities
Net income	190,830	95,725	134,264
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	53	36	29
Net securities (gains) losses	(49)	(667)	(100)
Gain on sale of ONB Insurance Group, Inc.			(41,864)
Share-based compensation expense	8,118	6,275	7,318
(Increase) decrease in other assets	28,754	(24,005)	(3,958)
Increase (decrease) in other liabilities	3,147	3,968	(225)
Equity in undistributed earnings of affiliates	(110,318)	(12,480)	27,201
Total adjustments	(70,295)	(26,873)	(11,599)
Net cash flows provided by (used in) operating activities	120,535	68,852	122,665
Cash Flows From Investing Activities
Net cash and cash equivalents of acquisitions	8,281	(24,005)	(100,220)
Proceeds from sale of ONB Insurance Group, Inc.			91,771
Proceeds from sales of equity securities	128	127
Purchases of investment securities	(76)	(62)	(52)
Net advances to affiliates		(250)	(3,500)
Proceeds from sale of premises and equipment and other assets	1,065
Purchases of premises and equipment	(945)	(612)	(13)
Net cash flows provided by (used in) investing activities	8,453	(24,802)	(12,014)
Cash Flows From Financing Activities
Payments for maturities/redemptions of other borrowings		(19,856)
Cash dividends paid on common stock	(82,161)	(72,604)	(67,536)
Common stock repurchased	(1,805)	(2,761)	(2,202)
Proceeds from exercise of stock options	948	2,655	2,349
Common stock issued	497	404	388
Net cash flows provided by (used in) financing activities	(82,521)	(92,162)	(67,001)
Net increase (decrease) in cash and cash equivalents	46,467	(48,112)	43,650
Cash and cash equivalents at beginning of period	43,538	91,650	48,000
Cash and cash equivalents at end of period	$ 90,005	$ 43,538	$ 91,650

Segment Information - Additiona

Segment Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018Segment
Community Banking Segment [Member]
Segment Reporting Information [Line Items]
Number of reportable operating segment	1

Interim Financial Data (Unaud_3

Interim Financial Data (Unaudited) - Interim Financial Data (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Interest income	$ 175,234	$ 155,369	$ 153,736	$ 147,706	$ 135,134	$ 123,525	$ 118,209	$ 118,468	$ 632,045	$ 495,336	$ 447,134
Interest expense	29,009	24,527	21,773	19,134	16,578	15,047	13,876	12,667	94,443	58,168	44,431
Net interest income	146,225	130,842	131,963	128,572	118,556	108,478	104,333	105,801	537,602	437,168	402,703
Provision for loan losses	3,390	750	2,446	380	1,037	311	1,355	347	6,966	3,050	960
Noninterest income	58,154	45,957	49,289	41,905	44,825	46,366	49,271	42,920	195,305	183,382	252,830
Noninterest expense	150,268	119,376	130,460	117,157	140,432	103,702	102,811	101,891	517,261	448,836	454,147
Income before income taxes	50,721	56,673	48,346	52,940	21,912	50,831	49,438	46,483	208,680	168,664	200,426
Income tax expense	3,223	5,325	4,345	4,957	40,405	11,459	10,584	10,491	17,850	72,939	66,162
Net income	$ 47,498	$ 51,348	$ 44,001	$ 47,983	$ (18,493)	$ 39,372	$ 38,854	$ 35,992	$ 190,830	$ 95,725	$ 134,264
Net income (loss) per share, Basic	$ 0.28	$ 0.34	$ 0.29	$ 0.32	$ (0.13)	$ 0.30	$ 0.28	$ 0.27	$ 1.23	$ 0.69	$ 1.05
Net income (loss) per share, Dulited	$ 0.28	$ 0.34	$ 0.29	$ 0.31	$ (0.13)	$ 0.29	$ 0.28	$ 0.27	$ 1.22	$ 0.69	$ 1.05
Average shares, Basic	167,044	151,930	151,878	151,721	146,073	135,120	135,085	134,912	155,675	137,821	127,705
Average shares, Diluted	167,992	152,784	152,568	152,370	146,875	135,796	135,697	135,431	156,539	138,513	128,301

Interim Financial Data (Unaud_4

Interim Financial Data (Unaudited) - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Estimated revaluation of deferred tax assets	$ 39,300		$ 39,300
Statutory rate	21.00%	21.00%	35.00%	35.00%