Consolidated Statements of Cash Flows - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities:
Net income	$ 106,307,000	$ 72,573,000
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for Loan and Lease Losses	(1,068,000)	2,505,000
Specific reserve, other real estate owned	2,658,000	317,000
Depreciation of bank premises and equipment	12,637,000	12,529,000
Gain on sale of bank premises and equipment	(147,000)	(16,000)
(Gain) loss on sale of other real estate owned	(688,000)	3,000
Accretion of investment securities discounts	(133,000)	(219,000)
Amortization of investment securities premiums	10,857,000	12,577,000
Investment securities transactions, net		1,612,000
Unrealized loss on equity securities with readily determinable fair values	1,021,000
Amortization of identified intangible assets		25,000
Stock based compensation expense	470,000	484,000
Earnings from affiliates and other investments	(7,683,000)	(5,590,000)
Deferred tax expense	363,000	212,000
(Increase) decrease in accrued interest receivable	(1,306,000)	591,000
(Increase) decrease in other assets	(42,795,000)	720,000
Net increase in other liabilities	21,724,000	5,691,000
Net cash provided by operating activities	102,217,000	104,014,000
Investing activities:
Proceeds from maturities of securities	1,075,000
Proceeds from sales and calls of available for sale securities	18,145,000	272,184,000
Purchases of available for sale securities	(47,346,000)	(542,112,000)
Principal collected on mortgage backed securities	363,406,000	372,717,000
Net increase in loans	(126,153,000)	(244,855,000)
Purchases of other investments	(27,457,000)	(4,540,000)
Distributions from other investments	8,702,000	5,467,000
Purchases of bank premises and equipment	(10,274,000)	(7,615,000)
Proceeds from sales of bank premises and equipment	2,191,000	8,207,000
Proceeds from sales of other real estate owned	901,000	682,000
Net cash provided by (used in) investing activities	183,190,000	(139,865,000)
Financing activities:
Net increase in non-interest bearing demand deposits	193,768,000	124,390,000
Net (decrease) increase in savings and interest bearing demand deposits	(14,745,000)	31,011,000
Net decrease in time deposits	(54,287,000)	(59,556,000)
Net decrease in securities sold under repurchase agreements	(47,050,000)	(144,574,000)
Net (decrease) increase in other borrowed funds	(342,275,000)	153,125,000
Purchase of treasury stock	(57,000)	(121,000)
Proceeds from stock transactions	818,000	1,092,000
Payments of cash dividends - common	(21,814,000)	(21,793,000)
Net cash (used in) provided by financing activities	(285,642,000)	83,574,000
(Decrease) increase in cash and cash equivalents	(235,000)	47,723,000
Cash and cash equivalents at beginning of period	265,357,000	269,198,000
Cash and cash equivalents at end of period	265,122,000	316,921,000
Supplemental cash flow information:
Interest paid	11,593,000	10,242,000
Income taxes paid	27,948,000	34,941,000
Non-cash investing and financing activities:
Purchases of available-for-sale securities not yet settled		30,612,000
Net transfers from loans to other real estate owned	$ 31,139,000	$ 1,450,000