Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
NET EARNINGS	$ 54,854	$ 52,505
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	6,209	5,687
PROVISION FOR LOAN LOSSES	3,675	4,386
Securities premium amortization (discount accretion), net	15,592	13,912
Gain on sale of assets, net	(523)	(1,706)
Deferred federal income tax benefit	(614)	(1,288)
Change in loans held-for-sale	8,572	7,810
Change in other assets	4,210	5,861
Change in other liabilities	5,533	3,843
Total adjustments	42,654	38,505
Net cash provided by operating activities	97,508	91,010
CASH FLOWS FROM INVESTING ACTIVITIES:
Net decrease in interest-bearing time deposits in banks	249	1,068
Activity in available-for-sale securities:
Sales	36,971	13,382
Maturities	604,582	2,151,678
Purchases	(741,922)	(2,132,087)
Activity in held-to-maturity securities - maturities	17	141
Net increase in loans	(85,212)	30,500
Purchases of bank premises and equipment and other assets	(7,705)	(12,130)
Proceeds from sale of other assets	599	2,170
Net cash provided by (used in) investing activities	(192,421)	54,722
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase (decrease) in noninterest-bearing deposits	138,717	(101,140)
Net increase (decrease) in interest-bearing deposits	9,353	(32,740)
Net decrease in borrowings	(66,446)	(58,751)
Common stock transactions:
Proceeds from stock issuances	1,115	936
Dividends paid	(23,801)	(21,125)
Net cash provided by (used in) financing activities	58,938	(212,820)
NET DECREASE IN CASH AND CASH EQUIVALENTS	(35,975)	(67,088)
CASH AND CASH EQUIVALENTS, beginning of period	256,486	272,886
CASH AND CASH EQUIVALENTS, end of period	220,511	205,798
SUPPLEMENTAL INFORMATION AND NONCASH TRANSACTIONS:
Interest paid	3,921	2,599
Federal income tax paid	13,348	13,874
Transfer of loans and bank premises to other real estate owned	1,916	1,692
Investment securities purchased but not settled	4,325	62,124
Restricted stock grant to officers and directors	$ 600	$ 250