Segment Information (Schedule Of Financial Information Concerning Segments) (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Net interest income	$ 72,592	$ 54,168	$ 196,278	$ 164,439
Provision for loan losses	(82)	6,400	6,437	23,681
Noninterest income	47,326	41,979	133,736	127,945
Noninterest expense	95,158	76,102	254,841	231,033
Income (loss) before income taxes	24,842	13,645	68,736	37,670
Total assets	8,932,700	7,506,114	8,932,700	7,506,114	7,263,892
Community Banking [Member]
Net interest income	75,292	63,402	218,356	187,215
Provision for loan losses	(1,258)	6,400	5,261	23,706
Noninterest income	28,800	22,119	80,989	66,345
Noninterest expense	60,828	57,298	192,071	176,081
Income (loss) before income taxes	44,522	21,823	102,013	53,773
Total assets	5,156,030	3,828,941	5,156,030	3,828,941
Treasury Funds [Member]
Net interest income	(11,803)	(8,305)	(30,009)	(19,984)
Provision for loan losses	0	0	0	0
Noninterest income	4,756	4,506	8,816	13,139
Noninterest expense	8,840	3,358	10,617	7,603
Income (loss) before income taxes	(15,887)	(7,157)	(31,810)	(14,448)
Total assets	3,569,790	3,567,870	3,569,790	3,567,870
Other [Member]
Net interest income	9,103	(929)	7,931	(2,792)
Provision for loan losses	1,176	0	1,176	(25)
Noninterest income	13,770	15,354	43,931	48,461
Noninterest expense	25,490	15,446	52,153	47,349
Income (loss) before income taxes	(3,793)	(1,021)	(1,467)	(1,655)
Total assets	$ 206,880	$ 109,303	$ 206,880	$ 109,303