Consolidated Statements of Comprehensive Earnings (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Amounts Reclassified Out Of Accumulated Other Comprehensive Income Loss [Abstract]
Net earnings	$ 22,336	$ 18,577
OTHER ITEMS OF COMPREHENSIVE EARNINGS (LOSS):
Change in unrealized gain (loss) on investment securities available-for-sale, before income taxes	21,560	(6,115)
Reclassification adjustment for realized losses (gains) on investment securities included in net earnings, before income tax	4	(222)
Total other items of comprehensive earnings (losses)	21,564	(6,337)
Income tax benefit (expense) related to other items of comprehensive earnings	(7,547)	2,218
COMPREHENSIVE EARNINGS	$ 36,353	$ 14,458