Business Segment Information (Amounts Of Consolidated Revenue, Expense, Tax And Assets) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Net interest income	$ 163,562,000	$ 159,541,000	$ 487,068,000	$ 468,668,000
Provision/(provision credit) for loan losses	1,000,000	6,000,000	8,000,000	21,000,000
Noninterest income	125,103,000	157,815,000	385,093,000	430,446,000
Noninterest expense	215,436,000	244,016,000	810,051,000	625,222,000
Income/(loss) before income taxes	72,229,000	67,340,000	54,110,000	252,892,000
Provision/(benefit) for income taxes	8,897,000	16,842,000	8,226,000	70,486,000
Net income/(loss)	63,332,000	50,498,000	45,884,000	182,406,000
Average assets	25,314,761,000	23,802,334,000	25,456,596,000	23,786,429,000
Regional Banking [Member]
Segment Reporting Information [Line Items]
Net interest income	165,258,000	153,868,000	485,575,000	444,569,000
Provision/(provision credit) for loan losses	6,696,000	2,204,000	28,689,000	23,619,000
Noninterest income	62,773,000	64,155,000	188,966,000	190,374,000
Noninterest expense	135,776,000	135,903,000	415,759,000	401,442,000
Income/(loss) before income taxes	85,559,000	79,916,000	230,093,000	209,882,000
Provision/(benefit) for income taxes	30,809,000	28,561,000	82,186,000	74,714,000
Net income/(loss)	54,750,000	51,355,000	147,907,000	135,168,000
Average assets	14,991,229,000	13,575,811,000	14,750,532,000	13,084,962,000
Fixed Income [Member]
Segment Reporting Information [Line Items]
Net interest income	3,008,000	2,950,000	11,628,000	9,013,000
Noninterest income	51,756,000	49,896,000	169,322,000	154,219,000
Noninterest expense	59,783,000	47,915,000	165,680,000	100,629,000
Income/(loss) before income taxes	(5,019,000)	4,931,000	15,270,000	62,603,000
Provision/(benefit) for income taxes	(2,359,000)	1,696,000	4,979,000	23,682,000
Net income/(loss)	(2,660,000)	3,235,000	10,291,000	38,921,000
Average assets	2,189,076,000	2,003,401,000	2,349,551,000	2,038,659,000
Corporate [Member]
Segment Reporting Information [Line Items]
Net interest income	(19,037,000)	(14,246,000)	(52,497,000)	(36,137,000)
Noninterest income	8,559,000	4,139,000	17,845,000	22,569,000
Noninterest expense	11,521,000	16,511,000	39,460,000	47,370,000
Income/(loss) before income taxes	(21,999,000)	(26,618,000)	(74,112,000)	(60,938,000)
Provision/(benefit) for income taxes	(24,841,000)	(16,928,000)	(52,363,000)	(43,925,000)
Net income/(loss)	2,842,000	(9,690,000)	(21,749,000)	(17,013,000)
Average assets	5,888,475,000	5,228,339,000	5,954,239,000	5,471,945,000
Non Strategic [Member]
Segment Reporting Information [Line Items]
Net interest income	14,333,000	16,969,000	42,362,000	51,223,000
Provision/(provision credit) for loan losses	(5,696,000)	3,796,000	(20,689,000)	(2,619,000)
Noninterest income	2,015,000	39,625,000	8,960,000	63,284,000
Noninterest expense	8,356,000	43,687,000	189,152,000	75,781,000
Income/(loss) before income taxes	13,688,000	9,111,000	(117,141,000)	41,345,000
Provision/(benefit) for income taxes	5,288,000	3,513,000	(26,576,000)	16,015,000
Net income/(loss)	8,400,000	5,598,000	(90,565,000)	25,330,000
Average assets	$ 2,245,981,000	$ 2,994,783,000	$ 2,402,274,000	$ 3,190,863,000