Business Segment Information (Amounts Of Consolidated Revenue, Expense, Tax And Assets) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) segment	Jun. 30, 2017 USD ($)
Segment Reporting [Abstract]
Number of business segments | segment			4
Segment Reporting Information [Line Items]
Net interest income	$ 310,932	$ 200,701	$ 612,105	$ 390,409
Provision/(provision credit) for loan losses	0	(2,000)	(1,000)	(3,000)
Noninterest income	127,525	127,673	263,542	244,612
Noninterest expense	332,768	217,917	646,033	440,122
Income/(loss) before income taxes	105,689	112,457	230,614	197,899
Provision/(benefit) for income taxes	19,697	17,253	49,628	44,307
Net income/(loss)	85,992	95,204	180,986	153,592
Average assets	40,173,712	28,876,350	40,261,729	28,841,422
Regional Banking
Segment Reporting Information [Line Items]
Net interest income	308,870	201,658	607,569	394,740
Provision/(provision credit) for loan losses	6,139	260	11,451	3,358
Noninterest income	78,568	64,740	157,421	123,718
Noninterest expense	212,445	152,637	417,646	300,687
Income/(loss) before income taxes	168,854	113,501	335,893	214,413
Provision/(benefit) for income taxes	39,634	41,015	78,996	77,491
Net income/(loss)	129,220	72,486	256,897	136,922
Average assets	28,746,968	18,432,141	28,611,686	18,195,201
Fixed Income
Segment Reporting Information [Line Items]
Net interest income	9,174	4,985	17,637	6,141
Noninterest income	38,363	55,207	83,968	106,030
Noninterest expense	48,300	54,022	98,844	102,729
Income/(loss) before income taxes	(763)	6,170	2,761	9,442
Provision/(benefit) for income taxes	(414)	1,941	328	2,959
Net income/(loss)	(349)	4,229	2,433	6,483
Average assets	3,251,876	2,696,144	3,365,912	2,288,083
Corporate Segment
Segment Reporting Information [Line Items]
Net interest income	(14,002)	(14,637)	(27,192)	(28,408)
Noninterest income	8,848	6,219	18,327	11,695
Noninterest expense	66,020	24,566	117,136	41,440
Income/(loss) before income taxes	(71,174)	(32,984)	(126,001)	(58,153)
Provision/(benefit) for income taxes	(21,691)	(35,574)	(34,135)	(48,503)
Net income/(loss)	(49,483)	2,590	(91,866)	(9,650)
Average assets	6,956,898	6,226,499	7,033,090	6,789,515
Non-Strategic
Segment Reporting Information [Line Items]
Net interest income	6,890	8,695	14,091	17,936
Provision/(provision credit) for loan losses	(6,139)	(2,260)	(12,451)	(6,358)
Noninterest income	1,746	1,507	3,826	3,169
Noninterest expense	6,003	(13,308)	12,407	(4,734)
Income/(loss) before income taxes	8,772	25,770	17,961	32,197
Provision/(benefit) for income taxes	2,168	9,871	4,439	12,360
Net income/(loss)	6,604	15,899	13,522	19,837
Average assets	$ 1,217,970	$ 1,521,566	$ 1,251,041	$ 1,568,623