Consolidated Statements of Comprehensive Earnings - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
NET EARNINGS	$ 104,774	$ 100,381	$ 89,559
OTHER ITEMS OF COMPREHENSIVE EARNINGS (LOSS):
Change in unrealized gain (loss) on investment securities available-for-sale, before income tax	(44,679)	2,273	54,571
Reclassification adjustment for realized losses (gains) on investment securities included in net earnings, before income tax	(1,270)	(432)	4
Minimum liability pension adjustment, before income tax	1,410	(1,986)	2,540
Total other items of comprehensive earnings (losses)	(44,539)	(145)	57,115
Income tax benefit (expense) related to:
Investment securities	16,082	(644)	(19,101)
Minimum liability pension adjustment	(493)	695	(889)
Total income tax benefit (expense)	15,589	51	(19,990)
COMPREHENSIVE EARNINGS	$ 75,824	$ 100,287	$ 126,684