Consolidated Statements of Comprehensive Earnings - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
NET EARNINGS	$ 42,093	$ 37,633	$ 80,345	$ 72,152
OTHER ITEMS OF COMPREHENSIVE EARNINGS (LOSS):
Change in unrealized gain on investment securities available-for-sale, before income taxes	37,057	(11,600)	72,071	(54,306)
Reclassification adjustment for realized gains on investment securities included in net earnings, before income tax	(676)	(67)	(676)	(1,288)
Total other items of comprehensive earnings	36,381	(11,667)	71,395	(55,594)
Income tax benefit (expense) related to other items of comprehensive earnings	(7,640)	2,450	(14,993)	11,675
Reclassification of certain income tax effects related to the change in the U.S. statutory federal income tax rate under the Tax Cuts and Jobs Act to retained earnings.				5,759
COMPREHENSIVE EARNINGS	$ 70,834	$ 28,416	$ 136,747	$ 33,992