Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Comprehensive Income [Abstract]
Net income	$ 98,361	$ 101,891	$ 74,496
Available for sale securities:
Unrealized (losses) gains arising during the period	(48,755)	(12,004)	22,101
Reclassification adjustment for net gains realized in earnings (net of tax expense $84, $1,609, and $3,094 in 2013, 2012, and 2011, respectively)	(125)	(2,414)	(4,641)
Income tax benefit (expense) related to unrealized (losses) gains	19,502	4,802	(8,840)
Net change in unrealized (losses) gains	(29,378)	(9,616)	8,620
Held to maturity securities:
Unrealized losses related to factors other than credit (net of tax benefit of $34 in 2011)	0	0	(52)
Reclassification adjustment for impairments realized in net income (net of tax benefit of $42 and $108 in 2012 and 2011, respectively)	0	62	161
Accretion of unrealized losses related to factors other than credit to investment securities held to maturity (net of tax benefit of $37, $84, and $66 in 2013, 2012, and 2011, respectively)	56	126	100
Net change in unrealized losses related to factors other than credit	56	188	209
Other comprehensive (loss) income, net of tax	(29,322)	(9,428)	8,829
Comprehensive income	$ 69,039	$ 92,463	$ 83,325