Business Segment Information (Amounts Of Consolidated Revenue, Expense, Tax And Assets) (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)
Segment Reporting Information [Line Items]
Net interest income	$ 185,195	$ 163,562	$ 533,533	$ 487,068
Provision/(provision credit) for loan losses	4,000	1,000	11,000	8,000
Noninterest income	148,545	125,103	428,364	385,093
Noninterest expense	233,558	215,436	687,307	810,051
Income/(loss) before income taxes	96,182	72,229	263,590	54,110
Provision/(benefit) for income taxes	28,547	8,897	82,802	8,226
Net income/(loss)	67,635	63,332	180,788	45,884
Average assets	27,609,702	25,312,903	$ 27,021,137	25,454,266
Number of Operating Segments			4
Regional Banking [Member]
Segment Reporting Information [Line Items]
Net interest income	190,510	165,253	$ 541,144	485,564
Provision/(provision credit) for loan losses	8,544	6,696	34,194	28,689
Noninterest income	65,128	62,763	185,679	188,942
Noninterest expense	144,972	135,589	454,638	415,026
Income/(loss) before income taxes	102,122	85,731	237,991	230,791
Provision/(benefit) for income taxes	37,095	30,876	84,976	82,458
Net income/(loss)	65,027	54,855	153,015	148,333
Average assets	17,582,996	14,989,007	16,704,503	14,748,349
Fixed Income [Member]
Segment Reporting Information [Line Items]
Net interest income	2,412	3,003	8,225	11,616
Noninterest income	72,073	51,757	217,278	169,323
Noninterest expense	59,575	59,844	181,124	165,836
Income/(loss) before income taxes	14,910	(5,084)	44,379	15,103
Provision/(benefit) for income taxes	5,459	(2,384)	16,089	4,914
Net income/(loss)	9,451	(2,700)	28,290	10,189
Average assets	2,305,968	2,190,624	2,348,619	2,350,786
Corporate [Member]
Segment Reporting Information [Line Items]
Net interest income	(18,195)	(19,027)	(48,409)	(52,467)
Noninterest income	5,134	8,559	15,766	17,845
Noninterest expense	14,841	11,804	44,392	40,207
Income/(loss) before income taxes	(27,902)	(22,272)	(77,035)	(74,829)
Provision/(benefit) for income taxes	(16,739)	(24,946)	(40,833)	(52,640)
Net income/(loss)	(11,163)	2,674	(36,202)	(22,189)
Average assets	5,880,090	5,886,929	6,024,553	5,951,999
Non Strategic [Member]
Segment Reporting Information [Line Items]
Net interest income	10,468	14,333	32,573	42,355
Provision/(provision credit) for loan losses	(4,544)	(5,696)	(23,194)	(20,689)
Noninterest income	6,210	2,024	9,641	8,983
Noninterest expense	14,170	8,199	7,153	188,982
Income/(loss) before income taxes	7,052	13,854	58,255	(116,955)
Provision/(benefit) for income taxes	2,732	5,351	22,570	(26,506)
Net income/(loss)	4,320	8,503	35,685	(90,449)
Average assets	$ 1,840,648	$ 2,246,343	$ 1,943,462	$ 2,403,132