Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash Flows From Operating Activities
Net income	$ 134,264	$ 116,716	$ 103,667
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	16,558	14,101	12,366
Amortization of other intangible assets	12,486	11,746	9,120
Net premium amortization on investment securities	18,633	18,609	15,430
Amortization of and net gains on termination of FDIC indemnification asset	(458)	9,034	43,162
Stock compensation expense	7,318	4,255	4,162
Provision for loan losses	960	2,923	3,097
Net securities gains	(5,848)	(5,718)	(9,830)
Impairment on available-for-sale securities			100
Recognition of deferred gain on sale leaseback transactions	(16,057)	(16,444)	(6,094)
Gain on sale of ONB Insurance Group, Inc.	(41,864)
Net gain on branch divestitures		(15,627)
Net gains on sales of loans and other assets	(4,741)	(5,232)	(3,546)
Increase in cash surrender value of company-owned life insurance	(8,479)	(8,604)	(6,924)
Residential real estate loans originated for sale	(637,639)	(350,846)	(148,946)
Proceeds from sale of residential real estate loans	578,653	362,157	147,566
Increase in interest receivable	(4,974)	(7,523)	(4,731)
Decrease in other real estate owned	11,301	4,538	7,049
Decrease in other assets	46,462	16,079	19,309
Increase (decrease) in accrued expenses and other liabilities	(24,524)	(26,408)	14,392
Total adjustments	(52,213)	7,040	95,682
Net cash flows provided by operating activities	82,051	123,756	199,349
Cash Flows From Investing Activities
Cash portion of bank purchase price, net of cash acquired	(62,532)	(37,098)	(3,050)
Proceeds from sale of ONB Insurance Group, Inc.	91,771
Payments related to branch divestitures		(333,095)
Purchases of investment securities available-for-sale	(1,625,746)	(832,419)	(568,993)
Purchases of investment securities held-to-maturity		(74,862)	(103,299)
Purchases of Federal Home Loan Bank/Federal Reserve Bank stock	(10,974)	(21,872)	(6,901)
Proceeds from maturities, prepayments, and calls of investment securities available-for-sale	1,177,130	764,649	468,764
Proceeds from sales of investment securities available-for-sale	243,312	343,486	214,912
Proceeds from maturities, prepayments, and calls of investment securities held-to-maturity	120,954	39,799	16,189
Proceeds from sales of investment securities held-to-maturity		855
Proceeds from sales of Federal Home Loan Bank/Federal Reserve Bank stock		8,711	7,507
Reimbursements under FDIC loss share agreements	10,000	3,548	26,342
Net principal collected from (loans made to) loan customers	(427,686)	(285,875)	(196,287)
Proceeds from settlements on company-owned life insurance	4,095	1,224	371
Proceeds from sale of premises and equipment and other assets	6,332	7,714	2,755
Purchases of premises and equipment and other assets	(224,659)	(85,661)	(20,473)
Net cash flows used in investing activities	(698,003)	(500,896)	(162,163)
Cash Flows From Financing Activities
Deposits	489,680	89,328	(304,510)
Federal funds purchased and interbank borrowings	(78,087)	95,903	69,665
Securities sold under agreements to repurchase	(23,489)	(31,205)	(10,006)
Payments for maturities on Federal Home Loan Bank advances	(594,541)	(229,109)	(211,101)
Payments for maturities on other borrowings	(67)	(63)	(58)
Proceeds from Federal Home Loan Bank advances	925,000	575,000	350,000
Proceeds from issuance of other borrowings			175,000
Cash dividends paid on common stock	(67,536)	(55,552)	(48,181)
Common stock repurchased	(2,044)	(88,695)	(25,830)
Proceeds from exercise of stock options, including tax benefit	2,349	997	749
Common stock issued	388	391	326
Net cash flows provided by (used in) financing activities	651,653	356,995	(3,946)
Net increase (decrease) in cash and cash equivalents	35,701	(20,145)	33,240
Cash and cash equivalents at beginning of period	219,818	239,963	206,723
Cash and cash equivalents at end of period	$ 255,519	$ 219,818	$ 239,963