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	$ 149,296	$ 131,461	$ 175,722
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	28,363	28,763	30,310
Provision for loan losses	110,659	73,038	33,840
(Gain) loss on other real estate owned	(4,444)	635	(105)
Deferred tax (benefit) expense	(7,839)	16,685	23,537
Increase in cash surrender value of life insurance contracts	(11,112)	(9,789)	(11,774)
Writedowns on closed branch transfers to other real estate owned			2,132
(Gain) loss on disposal of other assets	(9,594)	1,815	(1,282)
Net (increase) decrease in loans held for sale	(14,267)	(289)	18,234
Net amortization of securities premium/discount	29,048	21,105	16,977
Amortization of intangible assets	19,781	24,184	26,797
Amortization of FDIC loss share receivable	5,918	5,747	12,102
Stock-based compensation expense	14,266	12,944	13,958
Increase (decrease) in interest payable and other liabilities	7,137	(8,107)	(15,235)
Net payments (to) from FDIC for loss share claims	(3,134)	14,051	14,395
Decrease in FDIC loss share receivable	5,667	6,407	5,723
Decrease (increase) in other assets	15,197	(94,816)	10,393
Other, net	5,795	8,511	(3,296)
Net cash provided by operating activities	340,737	232,345	352,428
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sales of securities available for sale	173,215	9,289	1,455
Proceeds from maturities of securities available for sale	408,311	842,114	283,982
Purchases of securities available for sale	(1,071,869)	(1,323,853)	(512,088)
Proceeds from maturities of securities held to maturity	425,453	538,777	442,559
Purchases of securities held to maturity	(563,661)	(749,102)	(1,031)
Net decrease (increase) in short-term investments	487,378	237,393	(534,108)
Net increase in loans	(1,153,480)	(1,865,015)	(1,622,867)
Purchase of life insurance contracts	(40,000)		(30,000)
Purchases of property and equipment	(19,272)	(23,804)	(20,449)
Proceeds from sales of property and equipment	7,445	14,259	12,235
Proceeds from sales of other real estate	24,624	47,115	59,752
Other, net	825	(3,604)	10,101
Net cash used in investing activities	(1,321,031)	(2,276,431)	(1,910,459)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in deposits	1,075,370	1,776,081	1,212,315
Net (decrease) increase in short-term borrowings	(198,238)	272,071	493,613
Repayments of long-term debt	(21,271)	(157,933)	(35,360)
Issuance of long-term debt	6,838	273,565	21,000
Dividends paid	(76,551)	(77,013)	(80,392)
Repurchase of common stock		(95,613)	(47,618)
Proceeds from exercise of stock options	2,147	347	2,488
Proceeds from issuance of common stock in public offering	259,299
Proceeds from dividend reinvestment and stock purchase plan	1,515
Net cash provided by financing activities	1,049,109	1,991,505	1,566,046
NET INCREASE (DECREASE) IN CASH AND DUE FROM BANKS	68,815	(52,581)	8,015
CASH AND DUE FROM BANKS, BEGINNING	303,874	356,455	348,440
CASH AND DUE FROM BANKS, ENDING	372,689	303,874	356,455
SUPPLEMENTAL INFORMATION
Income taxes paid	30,184	31,896	24,114
Interest paid	69,624	51,201	38,268
SUPPLEMENTAL INFORMATION FOR NON-CASH INVESTING AND FINANCING ACTIVITIES
Assets acquired in settlement of loans	$ 16,314	$ 15,462	$ 31,371