Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Activities
Net income		$ 92,349	$ 82,064	$ 69,306
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses		30,983	21,152	19,168
Depreciation of premises, furniture, and equipment		12,804	13,367	12,224
Net amortization of premium on securities		13,653	4,849	8,218
Net securities gains		(1,420)	(2,373)	(8,097)
Gains on sales of 1-4 family mortgages and corporate loans held-for-sale		(8,931)	(6,847)	(4,069)
Net losses on early extinguishment of debt		0	0	2,059
Net losses on sales and valuation adjustments of OREO		1,196	2,631	3,325
Amortization of the FDIC indemnification asset		1,185	1,461	3,315
Net (gains) losses on sales and valuation adjustments of premises, furniture, and equipment		(4,762)	7,718	(3,277)
BOLI income		(3,647)	(4,185)	(2,873)
Net pension (income) cost		(513)	622	(959)
Share-based compensation expense	[1]	7,879	7,242	5,926
Tax expense related to share-based compensation		(685)	(1,200)	(106)
Provision for deferred income tax (benefit) expense		(1,367)	16,897	16,215
Amortization of other intangible assets		4,682	3,920	2,889
Originations of mortgage loans held-for-sale		(238,192)	(158,699)	(97,535)
Proceeds from sales of mortgage loans held-for-sale		246,642	158,791	96,006
Net (increase) decrease in trading securities		(1,026)	566	(143)
Net (increase) decrease in accrued interest receivable and other assets		(76,902)	10,023	(18,015)
Net increase (decrease) in accrued interest payable and other liabilities		47,118	(1,042)	22,367
Net cash provided by operating activities		121,046	156,957	125,944
Investing Activities
Proceeds from maturities, repayments, and calls of securities available-for-sale		360,303	322,764	172,001
Proceeds from sales of securities available-for-sale		53,186	93,909	27,805
Purchases of securities available-for-sale		(933,317)	(509,481)	(25,856)
Proceeds from maturities, repayments, and calls of securities held-to-maturity		8,077	4,645	4,675
Purchases of securities held-to-maturity		(5,352)	(1,242)	(2,638)
Purchases of FHLB stock		(18,276)	(1,190)	(427)
Net increase in loans		(714,213)	(399,807)	(279,654)
Proceeds from claims on BOLI, net of premiums paid		1,588	1,082	(85)
Proceeds from sales of OREO		7,539	18,572	22,368
Proceeds from sales of premises, furniture, and equipment		152,863	1,230	3,906
Purchases of premises, furniture, and equipment		(19,083)	(11,269)	(14,085)
Net cash received from (paid for) acquisitions		57,347	(16,047)	200,645
Net cash (used in) provided by investing activities		(1,049,338)	(496,834)	108,655
Financing Activities
Net increase (decrease) in deposit accounts		135,944	118,167	(73,244)
Net increase (decrease) in borrowed funds		711,496	25,902	(1,288)
Purchase of treasury stock		0	(120)	0
Net proceeds from the issuance of subordinated debt		146,484	0	0
Payments for the retirement of senior and subordinated debt		(153,500)	0	0
Payment for the termination of FHLB advances		0	0	(116,609)
Cash dividends paid		(29,198)	(27,036)	(22,568)
Restricted stock activity		(2,476)	(2,890)	(2,781)
Excess tax benefit related to share-based compensation		488	794	912
Net cash provided by (used in) financing activities		809,238	114,817	(215,578)
Net (decrease) increase in cash and cash equivalents		(119,054)	(225,060)	19,021
Cash and cash equivalents at beginning of year		381,202	606,262	587,241
Cash and cash equivalents at end of year		262,148	381,202	606,262
Supplemental Disclosures of Cash Flow Information:
Income taxes paid		57,553	25,022	16,375
Interest paid to depositors and creditors		27,400	24,535	23,088
Dividends declared, but unpaid		7,243	7,250	6,222
Common stock issued for acquisitions, net of issuance costs		54,896	0	38,300
Non-cash transfers of loans to OREO		4,173	13,504	18,079
Non-cash transfers of loans held-for-investment to loans held-for-sale		$ 93,981	$ 57,130	$ 76,446

[1] Comprised of restricted stock, restricted stock unit, and performance share awards expense.