Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Net income	$ 31,687	$ 33,521
Other comprehensive income, net of tax:
Net unrealized holding (losses) gains on securities available for sale arising during period (tax effects of $(3,959) and $2,013)	(7,352)	3,736
Reclassification adjustment for gains on securities available for sale included in net income (tax effects of $(410) and $(496))	(762)	(920)
Reclassification adjustment for impairment charges on available for sale securities included in net income (tax effects of $65 and $87)	121	162
Other comprehensive income, net of tax	(7,993)	2,978
Comprehensive income	$ 23,694	$ 36,499