CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($)		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018
OPERATING ACTIVITIES:
Net income		$ 57,219,000	$ 56,757,000
Adjustments to reconcile net income to net cash provided by operations:
Depreciation and net amortization		9,110,000	10,571,000
Securities premium amortization (discount accretion), net		9,370,000	10,875,000
Loan (discount accretion) premium amortization, net		(1,056,000)	(2,021,000)
Provision for loan losses	[1]	2,593,000	5,991,000
Stock compensation expense		1,754,000	1,626,000
Deferred tax (income) expense		(4,000)	4,535,000
Net (gain) loss on sale of securities available for sale		(714,000)	1,900,000
Net loss on premises and equipment		258,000	379,000
Gross proceeds from sales of loans held for sale		16,862,000	19,612,000
Gross originations of loans held for sale		(17,261,000)	(18,565,000)
Net (gain) loss on other real estate owned		(93,000)	411,000
Loans and Leases Receivable, Gain (Loss) on Sales, Net		0	124,000
Net change in:
Interest receivable		4,804,000	6,035,000
Other assets		(15,280,000)	(1,672,000)
Interest payable		16,000	(839,000)
Other liabilities		(7,624,000)	7,639,000
Net cash provided by operating activities		59,954,000	103,110,000
Securities available for sale:
Purchases		(999,403,000)	(228,281,000)
Sales		728,107,000	394,232,000
Maturities, calls and principal repayments		114,739,000	122,135,000
Securities held to maturity:
Maturities, calls and principal repayments		21,809,000	2,656,000
Proceeds from redemption of Federal Home Loan Bank stock and equity investments		8,788,000	24,360,000
Purchases of Federal Home Loan Bank stock and equity investments		(21,504,000)	(1,174,000)
Net loan (originations) paydowns		(191,116,000)	15,892,000
Proceeds from Sale of Loans Receivable		0	4,300,000
Purchases of premises and equipment		(11,449,000)	(8,863,000)
Proceeds from sales of premises and equipment		94,000	1,905,000
Proceeds from sales of other real estate owned		674,000	771,000
Proceeds from sales of repossessed assets		275,000	378,000
Net cash (used in) provided by investing activities		(348,986,000)	328,311,000
FINANCING ACTIVITIES:
Net change in deposits		80,711,000	27,809,000
Net decrease in other borrowings		(27,184,000)	(523,000)
Proceeds from Federal Home Loan Bank borrowings		4,368,700,000	2,569,000,000
Repayment of Federal Home Loan Bank borrowings		(4,108,812,000)	(3,025,088,000)
Proceeds from stock option exercises		1,284,000	2,655,000
Cash paid to tax authority related to tax withholding on share-based awards		(263,000)	(125,000)
Purchase of common stock		(1,325,000)	0
Proceeds from the issuance of common stock for dividend reinvestment plan		1,057,000	1,089,000
Cash dividends paid		(31,031,000)	(30,858,000)
Net cash provided by (used in) financing activities		283,137,000	(456,041,000)
Net decrease in cash and cash equivalents		(5,895,000)	(24,620,000)
Cash and cash equivalents at beginning of period		120,719,000	198,692,000
Cash and cash equivalents at end of period		114,824,000	174,072,000
SUPPLEMENTAL DISCLOSURES FOR CASH FLOW INFORMATION:
Interest paid		53,610,000	42,209,000
Income taxes paid		7,500,000	2,000,000
SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Loans transferred to other repossessed assets and real estate through foreclosure		606,000	1,220,000
Loans transferred from portfolio to held for sale		0	3,984,000
Transfer of held to maturity securities to available for sale securities		0	743,421,000
Adjustment to pension liability		(1,784,000)	(1,637,000)
Unsettled trades to purchase securities		(30,270,000)	(28,662,000)
Unsettled trades to sell securities		0	14,602,000
Unsettled issuances of brokered certificates of deposit		$ 0	$ 10,000,000

[1] Of the $1.0 million provision for loan losses for the three months ended September 30, 2019, $2,000 related to provision expense on PCI loans. Of the $2.6 million provision for loan losses for the nine months ended September 30, 2019, $161,000 related to provision expense reversed on PCI loans. Of the $975,000 and $6.0 million recorded in provision for loan losses for the three and nine months ended September 30, 2018, $466,000 and $824,000 related to provision expense on PCI loans, respectively.