Segment Information (Summary Of Certain Operating Information For Reportable Segments) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Total net interest income	$ 149,180	$ 135,824	$ 293,186	$ 266,537
Total net interest income, Change in Contribution	13,356		26,649
Total net interest income, Change in Contribution Percentage	10.00%		10.00%
Total non-interest income	54,102	63,995	99,631	121,374
Total non-interest income, Change in Contribution	(9,893)		(21,743)
Total non-interest income, Change in Contribution Percentage	(15.00%)		(18.00%)
Total net revenue	203,282	199,819	392,817	387,911
Total net revenue, Change in Contribution	3,463		4,906
Total net revenue, Change in Contribution Percentage	2.00%		1.00%
Total segment profit	38,541	34,307	73,041	66,359
Total segment profit, Change in Contribution	4,234		6,682
Total segment profit, Change in Contribution Percentage	12.00%		10.00%
Total assets	18,895,681	17,613,546	18,895,681	17,613,546	18,097,783
Total segment assets, Change in Contribution	1,282,135
Total segment assets, Change in Contribution Percentage	7.00%
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total net interest income	145,026	132,031	285,092	259,190
Total net interest income, Change in Contribution	12,995		25,902
Total net interest income, Change in Contribution Percentage	10.00%		10.00%
Total non-interest income	61,027	70,239	113,168	133,587
Total non-interest income, Change in Contribution	(9,212)		(20,419)
Total non-interest income, Change in Contribution Percentage	(13.00%)		(15.00%)
Total net revenue	206,053	202,270	398,260	392,777
Total net revenue, Change in Contribution	3,783		5,483
Total net revenue, Change in Contribution Percentage	2.00%		1.00%
Operating Segments [Member] | Community banking
Segment Reporting Information [Line Items]
Total net interest income	121,228	111,366	237,983	217,596
Total net interest income, Change in Contribution	9,862		20,387
Total net interest income, Change in Contribution Percentage	9.00%		9.00%
Total non-interest income	33,337	45,365	60,656	85,966
Total non-interest income, Change in Contribution	(12,028)		(25,310)
Total non-interest income, Change in Contribution Percentage	(27.00%)		(29.00%)
Total net revenue	154,565	156,731	298,639	303,562
Total net revenue, Change in Contribution	(2,166)		(4,923)
Total net revenue, Change in Contribution Percentage	(1.00%)		(2.00%)
Total segment profit	24,628	21,995	47,209	42,974
Total segment profit, Change in Contribution	2,633		4,235
Total segment profit, Change in Contribution Percentage	12.00%		10.00%
Total assets	15,669,443	14,710,628	15,669,443	14,710,628
Total segment assets, Change in Contribution	958,815
Total segment assets, Change in Contribution Percentage	7.00%
Operating Segments [Member] | Specialty finance
Segment Reporting Information [Line Items]
Total net interest income	19,792	17,384	39,004	34,866
Total net interest income, Change in Contribution	2,408		4,138
Total net interest income, Change in Contribution Percentage	14.00%		12.00%
Total non-interest income	8,455	8,193	16,336	15,497
Total non-interest income, Change in Contribution	262		839
Total non-interest income, Change in Contribution Percentage	3.00%		5.00%
Total net revenue	28,247	25,577	55,340	50,363
Total net revenue, Change in Contribution	2,670		4,977
Total net revenue, Change in Contribution Percentage	10.00%		10.00%
Total segment profit	10,302	9,692	19,284	18,321
Total segment profit, Change in Contribution	610		963
Total segment profit, Change in Contribution Percentage	6.00%		5.00%
Total assets	2,703,761	2,418,208	2,703,761	2,418,208
Total segment assets, Change in Contribution	285,553
Total segment assets, Change in Contribution Percentage	12.00%
Operating Segments [Member] | Wealth management
Segment Reporting Information [Line Items]
Total net interest income	4,006	3,281	8,105	6,728
Total net interest income, Change in Contribution	725		1,377
Total net interest income, Change in Contribution Percentage	22.00%		20.00%
Total non-interest income	19,235	16,681	36,176	32,124
Total non-interest income, Change in Contribution	2,554		4,052
Total non-interest income, Change in Contribution Percentage	15.00%		13.00%
Total net revenue	23,241	19,962	44,281	38,852
Total net revenue, Change in Contribution	3,279		5,429
Total net revenue, Change in Contribution Percentage	16.00%		14.00%
Total segment profit	3,611	2,620	6,548	5,064
Total segment profit, Change in Contribution	991		1,484
Total segment profit, Change in Contribution Percentage	38.00%		29.00%
Total assets	522,477	484,710	522,477	484,710
Total segment assets, Change in Contribution	37,767
Total segment assets, Change in Contribution Percentage	8.00%
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total net interest income	4,154	3,793	8,094	7,347
Total net interest income, Change in Contribution	361		747
Total net interest income, Change in Contribution Percentage	10.00%		10.00%
Total non-interest income	(6,925)	(6,244)	(13,537)	(12,213)
Total non-interest income, Change in Contribution	(681)		(1,324)
Total non-interest income, Change in Contribution Percentage	(11.00%)		(11.00%)
Total net revenue	(2,771)	(2,451)	(5,443)	(4,866)
Total net revenue, Change in Contribution	$ (320)		$ (577)
Total net revenue, Change in Contribution Percentage	(13.00%)		(12.00%)