Consolidated Statement of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net earnings	$ 168,905		$ 45,115		$ 56,801
Unrealized holding gains (losses) on securities available-for-sale	54,918		(57,136)		17,532
Income tax (expense) benefit related to unrealized holding (losses) gains arising during the year	(22,317)		26,190		(7,363)
Unrealized holding gains (losses) on securities available-for-sale, net of tax	32,601		(30,946)		10,169
Reclassification adjustment for gains included in net earnings (1)	(4,841)	[1]	(5,359)	[1]	(124)	[1]
Income tax expense related to reclassification adjustment	1,967		58		52
Reclassification adjustment for gains included in net earnings, net of tax	(2,874)		(5,301)		(72)
Other comprehensive income (loss), net of tax	29,727		(36,247)		10,097
Comprehensive income	$ 198,632		$ 8,868		$ 66,898

[1] For 2014 and 2013, entire amount recognized in "Gain on securities" on the Consolidated Statements of Earnings. For 2012, amount consists of: (1) $1.2 million recognized in "Gain on securities," offset by (2) $1.1 million recognized in "Other-than-temporary impairment loss on securities" on the Consolidated Statements of Earnings.