Consolidated Statements of Comprehensive Earnings (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
NET EARNINGS	$ 25,603	$ 25,886	$ 78,108	$ 75,189
OTHER ITEMS OF COMPREHENSIVE EARNINGS (LOSS):
Change in unrealized gain (loss) on investment securities available-for-sale, before income taxes	(18,984)	23,025	27,235	5,318
Reclassification adjustment for realized gains on investment securities included in net earnings, before income tax	(239)	(136)	(1,153)	(380)
Minimum liability pension adjustment, before income taxes		(108)		(216)
Total other items of comprehensive earnings (losses)	(19,223)	22,781	26,082	4,722
Income tax benefit (expense) related to:
Investment securities	6,728	(8,011)	(9,129)	(1,728)
Minimum liability pension adjustment		38		76
Total income tax benefit (expense)	6,728	(7,973)	(9,129)	(1,652)
COMPREHENSIVE EARNINGS	$ 13,108	$ 40,694	$ 95,061	$ 78,259