Bank Loans (Risk Category Of Loan Portfolio) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 3,180,584	$ 2,116,634
Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	3,153,743	2,105,155
Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	12,502	6,631
Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	14,339	4,848
Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,216,656	896,853
Commercial And Industrial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,191,030	896,853
Commercial And Industrial [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	11,320
Commercial And Industrial [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	14,306
Securities Based Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,388,953	732,799
Securities Based Loans [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,388,939	732,799
Securities Based Loans [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	14
Consumer [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	36,846	25,489
Consumer [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	36,846	25,447
Consumer [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio		28
Consumer [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio		14
Residential Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	429,132	432,646
Residential Real Estate [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	427,950	421,209
Residential Real Estate [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,182	6,603
Residential Real Estate [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio		4,834
Commercial Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	92,623	15,902
Commercial Real Estate [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	92,623	15,902
Home Equity Lines Of Credit [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	12,475	12,945
Home Equity Lines Of Credit [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	12,456	$ 12,945
Home Equity Lines Of Credit [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	19
Construction And Land [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	3,899
Construction And Land [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 3,899