Consolidated Statements of Cash Flows (Unaudited) - USD ($)			3 Months Ended				6 Months Ended		12 Months Ended
	Jan. 01, 2019		Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Apr. 01, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income			$ 30,628,000	$ 35,225,000	$ 31,118,000	$ 27,555,000	$ 65,853,000	$ 58,673,000
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization							5,022,000	8,021,000
Provision for loan losses			1,000,000		2,000,000		2,000,000	2,500,000
Deferred income tax expense							399,000	283,000
Net unrealized (gain) loss on equity securities			(444,000)		(54,000)		(1,351,000)	431,000
Gain (Loss) on Investments							1,462,000
Net (gain) loss on bank premises and equipment							39,000	(4,000)
Net loss on other real estate owned and foreclosed assets								1,000
Realized gain on sale leaseback transaction							(289,000)	(441,000)
Stock based compensation							2,432,000	2,392,000
Increase in cash surrender value of life insurance policies							(2,268,000)	(1,945,000)
Operating Lease, Payments							(4,970,000)	0
Change in Fair Value on Loans Held for Sale			(919,000)		(70,000)		(920,000)	(44,000)
Net change in:
Trading assets							(435,000)	(274,000)
Loans held for sale							(30,220,000)	(4,802,000)
Other assets							(27,048,000)	(1,591,000)
Increase (Decrease) in Other Operating Liabilities							(24,566,000)	4,444,000
Total adjustments							(80,713,000)	8,971,000
Net cash provided by (used in) operating activities							(14,860,000)	67,644,000
Cash flows used in investing activities
Proceeds from Sale of Debt and Equity Securities, FV-NI, Held-for-investment							1,461,000	10,000
Increase (Decrease) in Equity Securities, FV-NI							(233,000)	(202,000)
Proceeds from Sale of Debt Securities, Available-for-sale							45,863,000
Proceeds from maturities and principal repayments of securities available for sale							24,594,000	27,625,000
Payments to Acquire Debt Securities, Available-for-sale							(9,058,000)	(53,559,000)
Proceeds from maturities and principal repayments of securities held to maturity							52,414,000	42,716,000
Purchases of securities held to maturity							(42,341,000)	(83,047,000)
Net redemption (purchases) of Federal Home Loan Bank stock							7,235,000	(1,510,000)
Investments in low income housing projects							(683,000)	(2,132,000)
Purchases of life insurance policies							(100,000)	(101,000)
Net increase in loans							(53,175,000)	(124,355,000)
Payments to Acquire Businesses, Net of Cash Acquired					0		(105,264,000)
Purchases of bank premises and equipment							(6,957,000)	(5,707,000)
Proceeds from the sale of bank premises and equipment							13,000	63,000
Proceeds from the sale of other real estate owned and foreclosed assets								253,000
Net cash used in investing activities							(86,231,000)	(199,946,000)
Cash flows provided by financing activities
Net increase in time deposits							1,632,000	15,522,000
Net increase (decrease) in other deposits							(49,833,000)	268,770,000
Increase (Decrease) in Federal Funds Purchased and Securities Sold under Agreements to Repurchase, Net							24,954,000
Increase Decrease in Federal Home Loan Bank Advances Long Term							(20,000,000)	(2,475,000)
Net decrease in customer repurchase agreements								(20,444,000)
Proceeds from Lines of Credit							49,980,000	0
Repayments of Lines of Credit							(49,980,000)	0
Proceeds from Debt, Net of Issuance Costs							74,867,000	0
Repayments of Subordinated Debt							(13,329,000)	0
Proceeds from Issuance of Subordinated Long-term Debt							49,526,000	0
Net proceeds from exercise of stock options							(281,000)	(184,000)
Restricted stock awards issued, net of awards surrendered							(1,431,000)	(1,338,000)
Proceeds from shares issued under direct stock purchase plan							1,034,000	1,312,000
Common dividends paid							(23,051,000)	(19,239,000)
Net cash provided by financing activities							44,650,000	242,292,000
Net increase (decrease) in cash and cash equivalents							(56,441,000)	109,990,000
Cash and cash equivalents at beginning of year	$ 250,455,000			250,455,000		$ 213,116,000	250,455,000	213,116,000	$ 213,116,000
Cash and cash equivalents at end of period			194,014,000		323,106,000		194,014,000	323,106,000	250,455,000
Supplemental schedule of noncash activities
Net increase in capital commitments relating to low income housing project investments					4,000		18,000
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	32,777,000	[1]			0		4,824,000
Operating Lease, Right-of-Use Asset	32,800,000		51,500,000				51,500,000
Operating Lease, Liability	$ 34,100,000		53,107,000				53,107,000
Deferred Rent Credit									1,300,000
Stock Issued During Period, Value, Acquisitions			$ 499,693,000	$ 0			$ 499,693,000		$ 0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets					0			0		$ 2,711,067,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities					$ 0			$ 0		$ 2,106,110,000

[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.