Business Segment Information (Amounts Of Consolidated Revenue, Expense, Tax And Assets) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Net interest income	$ 209,817	$ 185,195	$ 600,226	$ 533,533
Provision/(provision credit) for loan losses	0	4,000	(3,000)	11,000
Noninterest income	112,417	148,545	357,029	428,364
Noninterest expense	236,869	233,558	676,991	687,307
Income/(loss) before income taxes	85,365	96,182	283,264	263,590
Provision/(benefit) for income taxes	13,596	28,547	57,903	82,802
Net income/(loss)	71,769	67,635	225,361	180,788
Average assets	28,874,827	27,609,702	28,852,679	27,021,137
Loss on repurchase of equity securities			(5)	181
Regional Banking
Segment Reporting Information [Line Items]
Net interest income	209,319	190,508	604,680	541,135
Provision/(provision credit) for loan losses	8,552	8,544	11,910	34,195
Noninterest income	64,369	65,128	188,082	185,679
Noninterest expense	150,464	145,050	451,175	454,970
Income/(loss) before income taxes	114,672	102,042	329,677	237,649
Provision/(benefit) for income taxes	41,267	37,027	118,986	84,736
Net income/(loss)	73,405	65,015	210,691	152,913
Average assets	19,158,458	17,582,899	18,519,584	16,704,462
Fixed Income
Segment Reporting Information [Line Items]
Net interest income	5,979	2,411	12,109	8,224
Noninterest income	55,802	72,073	161,829	217,278
Noninterest expense	53,105	59,423	155,791	180,850
Income/(loss) before income taxes	8,676	15,061	18,147	44,652
Provision/(benefit) for income taxes	2,979	5,518	5,949	16,195
Net income/(loss)	5,697	9,543	12,198	28,457
Average assets	2,586,997	2,305,986	2,388,984	2,348,640
Corporate Segment
Segment Reporting Information [Line Items]
Net interest income	(13,990)	(18,193)	(43,060)	(48,401)
Noninterest income	(9,477)	5,134	2,217	15,766
Noninterest expense	23,935	14,929	65,390	44,320
Income/(loss) before income taxes	(47,402)	(27,988)	(106,233)	(76,955)
Provision/(benefit) for income taxes	(34,255)	(16,736)	(83,019)	(40,695)
Net income/(loss)	(13,147)	(11,252)	(23,214)	(36,260)
Average assets	5,698,161	5,880,268	6,421,890	6,024,736
Loss on repurchase of equity securities	14,300		14,300
Non Strategic
Segment Reporting Information [Line Items]
Net interest income	8,509	10,469	26,497	32,575
Provision/(provision credit) for loan losses	(8,552)	(4,544)	(14,910)	(23,195)
Noninterest income	1,723	6,210	4,901	9,641
Noninterest expense	9,365	14,156	4,635	7,167
Income/(loss) before income taxes	9,419	7,067	41,673	58,244
Provision/(benefit) for income taxes	3,605	2,738	15,987	22,566
Net income/(loss)	5,814	4,329	25,686	35,678
Average assets	$ 1,431,211	$ 1,840,549	$ 1,522,221	$ 1,943,299