Consolidated Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	$ 58,673,000	$ 41,288,000
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	8,021,000	7,454,000
Provision for loan losses	2,500,000	1,650,000
Deferred income tax expense	283,000	642,000
Unrealized Gain (Loss) on Investments	433,000
Net gain on sale of securities	(2,000)	(2,000)
Net gain on bank premises and equipment	(4,000)	(92,000)
Net loss on other real estate owned and foreclosed assets	1,000	70,000
Realized gain on sale leaseback transaction	(441,000)	(517,000)
Stock based compensation	2,392,000	1,560,000
Increase in cash surrender value of life insurance policies	(1,945,000)	(1,981,000)
Net change in:
Trading assets	(274,000)	(489,000)
Loans held for sale	(4,802,000)	(3,236,000)
Change in Fair Value on Loans Held for Sale	(44,000)	(6,000)
Other assets	(1,591,000)	8,973,000
Increase (Decrease) in Other Operating Liabilities	4,444,000	(6,104,000)
Total adjustments	8,971,000	7,922,000
Net cash provided by operating activities	67,644,000	49,210,000
Cash flows used in investing activities
Proceeds from Sale of Trading Securities Held-for-investment	10,000
Proceeds from Sale of Available-for-sale Securities, Equity		0
Payments to Acquire Trading Securities Held-for-investment	(202,000)
Payments to Acquire Available-for-sale Securities, Equity		0
Proceeds from sales of securities available for sale		35,000
Proceeds from maturities and principal repayments of securities available for sale	27,625,000	24,406,000
Purchases of securities available for sale	(53,559,000)	(74,956,000)
Proceeds from maturities and principal repayments of securities held to maturity	42,716,000	38,634,000
Purchases of securities held to maturity	(83,047,000)	(49,802,000)
Net purchases of Federal Home Loan Bank stock	(1,510,000)	(2,438,000)
Investments in low income housing projects	(2,132,000)	(3,871,000)
Purchases of life insurance policies	(101,000)	(101,000)
Net increase in loans	(124,355,000)	(118,579,000)
Cash Acquired in Excess of Payments to Acquire Business	0	6,289,000
Purchases of bank premises and equipment	(5,707,000)	(14,182,000)
Proceeds from the sale of bank premises and equipment	63,000	1,918,000
Proceeds from the sale of other real estate owned and foreclosed assets	253,000	1,531,000
Net cash used in investing activities	(199,946,000)	(191,116,000)
Cash flows provided by financing activities
Net increase (decrease) in time deposits	15,522,000	(55,787,000)
Net increase in other deposits	268,770,000	179,495,000
Increase Decrease in Federal Home Loan Bank Advances Long Term	(2,475,000)	0
Net decrease in customer repurchase agreements	(20,444,000)	(17,542,000)
Net proceeds from exercise of stock options	184,000	8,000
Restricted stock awards issued, net of awards surrendered	(1,338,000)	(1,361,000)
Proceeds from shares issued under direct stock purchase plan	1,312,000	807,000
Common dividends paid	(19,239,000)	(16,487,000)
Net cash provided by financing activities	242,292,000	89,133,000
Net increase (decrease) in cash and cash equivalents	109,990,000	(52,773,000)
Cash and cash equivalents at beginning of year	213,116,000	289,095,000
Cash and cash equivalents at end of period	323,106,000	236,322,000
Supplemental schedule of noncash investing and financing activities
Real Estate Owned, Transfer from Real Estate Owned		457,000
Net increase in capital commitments relating to low income housing project investments	4,000	46,000
Stock Issued During Period, Value, Acquisitions	0	23,468,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	0	179,252,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	$ 0	$ 162,073,000