Segment Information (Summary Of Certain Operating Information For Reportable Segments) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Net interest income	$ 167,206	$ 165,540	$ 156,892	$ 151,891	$ 153,719	$ 151,670	$ 149,180	$ 144,006	$ 641,529	$ 598,575	$ 550,627
Provision for credit losses	9,059	8,322	9,482	6,079	6,133	5,864	6,660	1,880	32,942	20,537	46,033
Non-interest income									271,597	215,240	222,397
Non-interest expense	166,829	159,974	154,297	147,318	143,441	138,500	133,591	131,315	628,419	546,847	502,551
Income tax expense	20,896	23,842	26,295	23,983	23,669	25,034	24,490	21,840	95,016	95,033	87,230
Net income	35,512	$ 38,355	$ 43,831	$ 39,052	38,133	$ 40,224	$ 38,541	$ 34,500	156,749	151,398	137,210
Total assets at end of year	22,917,166				20,010,727				22,917,166	20,010,727	18,097,783
Operating Segments
Segment Reporting Information [Line Items]
Net interest income									625,382	582,906	536,194
Provision for credit losses									32,942	20,537	46,033
Non-interest income									300,369	242,229	247,030
Non-interest expense									641,044	558,167	512,751
Income tax expense									95,016	95,033	87,230
Net income									156,749	151,398	137,210
Total assets at end of year	22,917,166				20,010,727				22,917,166	20,010,727	18,097,783
Operating Segments | Community Banking
Segment Reporting Information [Line Items]
Net interest income									523,112	484,523	448,173
Provision for credit losses									29,746	17,708	45,396
Non-interest income									191,248	136,307	150,543
Non-interest expense									522,199	444,416	409,780
Income tax expense									60,488	60,033	55,161
Net income									101,927	98,673	88,379
Total assets at end of year	19,251,616				16,724,834				19,251,616	16,724,834	15,132,912
Operating Segments | Specialty Finance
Segment Reporting Information [Line Items]
Net interest income									85,258	82,415	73,903
Provision for credit losses									3,196	2,829	637
Non-interest income									33,625	32,534	30,890
Non-interest expense									47,245	44,320	40,529
Income tax expense									26,352	27,167	25,508
Net income									42,090	40,633	38,119
Total assets at end of year	3,116,631				2,766,017				3,116,631	2,766,017	2,470,832
Operating Segments | Wealth Management
Segment Reporting Information [Line Items]
Net interest income									17,012	15,968	14,118
Provision for credit losses									0	0	0
Non-interest income									75,496	73,388	65,597
Non-interest expense									71,600	69,431	62,442
Income tax expense									8,176	7,833	6,561
Net income									12,732	12,092	10,712
Total assets at end of year	548,919				519,876				548,919	519,876	494,039
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net interest income									16,147	15,669	14,433
Provision for credit losses									0	0	0
Non-interest income									(28,772)	(26,989)	(24,633)
Non-interest expense									(12,625)	(11,320)	(10,200)
Income tax expense									0	0	0
Net income									0	0	0
Total assets at end of year	$ 0				$ 0				$ 0	$ 0	$ 0