Condensed Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Condensed Consolidated Statements Of Comprehensive Income [Abstract]
Net income	$ 25,503	$ 13,467
Available for sale securities:
Unrealized gains arising during the period	2,022	815
Reclassification adjustment for net gains realized in earnings (net of tax expense $59 for the three months ended March 31,2012)	(89)
Income tax expense related to unrealized gains	(809)	(326)
Net change in unrealized gains	1,124	489
Held to maturity securities:
Unrealized gains related to factors other than credit (net of tax expense of $6 for the three months ended March 31, 2011)		8
Reclassification adjustment for impairments realized in net income (net of tax benefit of $10 for the three months ended March 31, 2011)		15
Accretion of unrealized losses related to factors other than credit to investment securities held to maturity (net of tax benefit of $28 and $18 for the three months ended March 31, 2012 and 2011, respectively)	41	26
Net change in unrealized losses related to factors other than credit	41	49
Other comprehensive income, net of tax	1,165	538
Comprehensive income	$ 26,668	$ 14,005