Income Taxes (Summary Of Differences In Taxes From Continuing Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended										9 Months Ended	12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Sep. 30, 2009	Mar. 31, 2008	Sep. 30, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Tax Contingency [Line Items]
Provision at statutory rate of 35%												$ 34,917	$ 15,218	$ (2,582)
Tax-exempt interest												(13,571)	(16,294)	(22,532)
Bank owned life insurance income												(5,322)	(4,052)	(2,355)
Tax-exempt income												(9,685)	(10,149)	(14,854)
Reserve for unrecognized tax benefits						620			650	700		(623)	(652)	(706)
State income taxes												3,188	518	(3,829)
Other, net												(495)	331	857
Provision for (benefit from) income taxes	8,812	8,045	5,927	4,518	84	1,749	1,734	1,699				27,302	5,266	(21,114)
Effective tax rate												27.40%	12.10%	286.20%
Statutory percentage rate of provision											35.00%
Tax-Exempt Income [Member]
Income Tax Contingency [Line Items]
Tax-exempt interest												(8,035)	(9,060)	(14,545)
Section 291/265 interest disallowance												213	329	515
Bank owned life insurance income												$ (1,863)	$ (1,418)	$ (824)