Consolidated Statements of Cash Flows (Unaudited) - USD ($)			3 Months Ended		12 Months Ended
	Jan. 01, 2019		Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income			$ 35,225,000	$ 27,555,000
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization			3,648,000	4,181,000
Provision for loan losses			1,000,000	500,000
Deferred income tax expense			539,000	359,000
Net unrealized (gain) loss on equity securities			(907,000)	485,000
Net (gain) loss on bank premises and equipment			25,000	(7,000)
Net loss on other real estate owned and foreclosed assets				1,000
Realized gain on sale leaseback transaction			(145,000)	(258,000)
Stock based compensation			915,000	1,041,000
Increase in cash surrender value of life insurance policies			(972,000)	(947,000)
Operating Lease, Payments			(2,165,000)	0
Change in Fair Value on Loans Held for Sale			(1,000)	26,000
Net change in:
Trading assets			(333,000)	(277,000)
Loans held for sale			846,000	805,000
Other assets			1,721,000	2,594,000
Increase (Decrease) in Other Operating Liabilities			(5,228,000)	(2,175,000)
Total adjustments			(1,057,000)	6,328,000
Net cash provided by operating activities			34,168,000	33,883,000
Cash flows used in investing activities
Increase (Decrease) in Equity Securities, FV-NI			(105,000)	(78,000)
Proceeds from maturities and principal repayments of securities available for sale			11,318,000	11,040,000
Payments to Acquire Debt Securities, Available-for-sale				(37,201,000)
Proceeds from maturities and principal repayments of securities held to maturity			19,003,000	22,888,000
Purchases of securities held to maturity			(30,502,000)	(53,995,000)
Net redemption (purchases) of Federal Home Loan Bank stock			8,016,000	(1,430,000)
Investments in low income housing projects			(292,000)	(1,213,000)
Purchases of life insurance policies			(93,000)	(93,000)
Net increase in loans			(70,378,000)	(6,856,000)
Purchases of bank premises and equipment			(3,713,000)	(2,803,000)
Proceeds from the sale of bank premises and equipment			13,000	52,000
Proceeds from the sale of other real estate owned and foreclosed assets				253,000
Net cash used in investing activities			(66,733,000)	(69,436,000)
Cash flows provided by financing activities
Net increase in time deposits			12,464,000	10,486,000
Net increase in other deposits			24,034,000	11,804,000
Increase (Decrease) in Federal Funds Purchased and Securities Sold under Agreements to Repurchase, Net			(122,046,000)
Net increase (decrease) in customer repurchase agreements				(24,765,000)
Proceeds from Lines of Credit			49,993,000	0
Proceeds from Debt, Net of Issuance Costs			74,914,000	0
Repayments of Subordinated Debt			(3,093,000)		$ 0
Proceeds from Issuance of Subordinated Long-term Debt			49,556,000	0
Net proceeds from exercise of stock options			(165,000)	(143,000)
Restricted stock awards issued, net of awards surrendered			(1,419,000)	(1,318,000)
Proceeds from shares issued under direct stock purchase plan			487,000	419,000
Common dividends paid			(10,671,000)	(8,784,000)
Net cash provided by (used in) financing activities			74,384,000	(12,015,000)
Net increase (decrease) in cash and cash equivalents			41,819,000	(47,568,000)
Cash and cash equivalents at beginning of year	$ 250,455,000		250,455,000	213,116,000	213,116,000
Cash and cash equivalents at end of period			292,274,000	165,548,000	250,455,000
Supplemental schedule of noncash activities
Net increase in capital commitments relating to low income housing project investments			0	9,000
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	32,777,000	[1]	2,926,000	$ 0
Operating Lease, Right-of-Use Asset	32,800,000		33,700,000
Operating Lease, Liability	$ 34,100,000		$ 35,094,000
Deferred Rent Credit					$ 1,300,000

[1] (1) Represents adjustment needed to reflect the opening balance of the Company's ROU assets and lease liabilities pursuant to the adoption of Accounting Standards Update 2016-02 effective January 1, 2019. Upon adoption, the Company recognized on its balance sheet Right of Use ("ROU") assets of approximately $32.8 million, with a corresponding operating lease liability of approximately $34.1 million, with an adjustment to remove the Company's existing deferred rent liability of approximately $1.3 million.