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	$ 208,393	$ 171,753	$ 161,625
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	46,907	23,305	13,182
Depreciation and amortization of premises and equipment	28,156	28,096	27,403
Accretion (Amortization) Of Discounts And Premiums, Tax Credit Investments	38,606	37,185	23,982
Net amortization of investment security premiums	9,297	10,107	10,430
Deferred income tax (benefit) expense	(15,749)	24,896	11,054
Re-measurement of net deferred tax asset	(809)	15,635	0
Investment securities gains, net	(37)	(9,071)	(2,550)
Gains on sales of mortgage loans held for sale	(13,021)	(13,036)	(15,685)
Proceeds from sales of mortgage loans held for sale	795,756	644,400	709,316
Originations of mortgage loans held for sale	(778,304)	(634,197)	(705,442)
Amortization of financing costs	813	845	617
Stock-based compensation	7,965	5,209	6,556
Excess tax benefits from stock-based compensation	0	0	(964)
Increase in accrued interest receivable	(5,969)	(6,616)	(3,527)
Increase in other assets	(26,090)	(7,958)	(53,922)
Increase (decrease) in accrued interest payable	1,212	(315)	(1,092)
(Decrease) increase in other liabilities	(306)	(2,480)	45,090
Total adjustments	88,427	116,005	64,448
Net cash provided by operating activities	296,820	287,758	226,073
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sales of securities available for sale	54,638	184,734	115,844
Proceeds from Maturities, Prepayments and Calls of Held-to-maturity Securities	35,900	0	0
Proceeds from principal repayments and maturities of available for sale securities	290,681	417,673	558,854
Purchase of securities available for sale	558,949	584,921	782,765
(Purchase) redemption of Federal Reserve Bank and Federal Home Loan Bank stock	(18,522)	(3,272)	4,727
Net increase in loans	(447,849)	(1,087,521)	(873,939)
Net purchases of premises and equipment	(39,883)	(33,092)	(19,674)
Increase (Decrease) In Tax Credit Investments	(56,733)	(28,932)	(40,663)
Net cash used in investing activities	(740,717)	(1,135,331)	(1,037,616)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in demand and savings deposits	435,872	782,525	992,253
Net increase (decrease) in time deposits	142,755	2,143	(111,706)
Increase in short-term borrowings	137,253	76,207	43,654
Additions to long-term debt	50,000	223,251	215,884
Repayments of long-term debt	(100,165)	(115,153)	(236,640)
Net proceeds from issuance of common stock	6,735	8,538	16,167
Excess tax benefits from stock-based compensation	0	0	964
Dividends paid	(89,654)	(80,368)	(69,382)
Acquisition of treasury stock	(95,308)	0	(18,545)
Net cash provided by financing activities	487,488	897,143	832,649
Net Increase in Cash and Cash Equivalents	43,591	49,570	21,106
Cash and Cash Equivalents at Beginning of Year	402,096	352,526	331,420
Cash and Cash Equivalents at End of Year	445,687	402,096	352,526
Cash paid during period for:
Interest	126,846	93,817	83,420
Income taxes	13,547	6,537	16,193
Supplemental schedule of certain noncash activities
Transfer of available for sale securities to held to maturity securities	$ 641,672	$ 0	$ 0