Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 54,784	$ 17,542	$ 101,913	$ 36,193
Available for sale securities:
Unrealized (losses) gains arising during the period	(24,303)	21,935	(11,563)	29,914
Reclassification adjustment for net gains realized in earnings (net of tax expense of $7 and $375 for the three months ended June 30, 2015 and 2014, respectively, and net of tax expense of $54 and $375 for the six months ended June 30, 2015 and 2014, respectively)	(10)	(585)	(81)	(585)
Income tax benefit (expense) related to unrealized gains	9,721	(8,774)	4,625	(11,966)
Net change in unrealized gains	(14,592)	12,576	(7,019)	17,363
Held to maturity securities:
Accretion of unrealized losses related to factors other than credit to investment securities held to maturity (net of tax benefit of $0 and $31 for the three months ended June 30, 2015 and 2014, respectively, and net of tax benefit of $0 and $37 for the six months ended June 30, 2015 and 2014, respectively)	0	47	0	57
Net change in unrealized losses related to factors other than credit	0	47	0	57
Other comprehensive (loss) income, net of tax	(14,592)	12,623	(7,019)	17,420
Comprehensive income	$ 40,192	$ 30,165	$ 94,894	$ 53,613