Bank Loans (Risk Category Of Loan Portfolio) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 3,505,509	$ 3,180,584
Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	3,444,804	3,153,743
Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	12,014	12,502
Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	48,691	14,339
Commercial And Industrial [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,295,318	1,216,656
Commercial And Industrial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,246,548	1,191,030
Commercial And Industrial [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	11,704	11,320
Commercial And Industrial [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	37,066	14,306
Securities Based Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,345,719	1,388,953
Securities Based Loans [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	1,345,719	1,388,939
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	31,036	36,846
Consumer [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	30,169	36,846
Consumer [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	5
Consumer [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	862
Residential Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	730,683	429,132
Residential Real Estate [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	729,747	427,950
Residential Real Estate [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	305	1,182
Residential Real Estate [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	631
Commercial Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	83,273	92,623
Commercial Real Estate [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	73,464	92,623
Commercial Real Estate [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	9,809
Home Equity Lines Of Credit [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	12,511	12,475
Home Equity Lines Of Credit [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	12,188	12,456
Home Equity Lines Of Credit [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	323	19
Construction And Land [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	6,969	3,899
Construction And Land [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Total risk category of loan portfolio	$ 6,969	$ 3,899