Segment Information (Schedule Of Financial Information Concerning Segments) (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Net interest income	$ 62,319	$ 55,154	$ 123,686	$ 110,271
Provision for loan losses	3,207	8,000	6,519	17,281
Noninterest income	43,589	42,974	86,410	85,966
Noninterest expense	79,758	77,871	159,683	154,931
Income (loss) before income taxes	22,943	12,257	43,894	24,025
Total assets	8,018,848	7,701,064	8,018,848	7,701,064	7,263,892
Community Banking [Member]
Net interest income	73,975	62,088	143,064	123,813
Provision for loan losses	3,207	8,000	6,519	17,306
Noninterest income	30,173	22,689	52,189	44,226
Noninterest expense	69,066	58,755	131,243	118,783
Income (loss) before income taxes	31,875	18,022	57,491	31,950
Total assets	4,405,806	3,916,001	4,405,806	3,916,001
Treasury Funds [Member]
Net interest income	(11,035)	(5,991)	(18,206)	(11,679)
Provision for loan losses	0	0	0	0
Noninterest income	1,633	4,397	4,060	8,633
Noninterest expense	363	2,964	1,777	4,245
Income (loss) before income taxes	(9,765)	(4,558)	(15,923)	(7,291)
Total assets	3,518,480	3,676,436	3,518,480	3,676,436
Other [Member]
Net interest income	(621)	(943)	(1,172)	(1,863)
Provision for loan losses	0	0	0	(25)
Noninterest income	11,783	15,888	30,161	33,107
Noninterest expense	10,329	16,152	26,663	31,903
Income (loss) before income taxes	833	(1,207)	2,326	(634)
Total assets	$ 94,562	$ 108,627	$ 94,562	$ 108,627