Bank Loans (Aging Of The Recorded Investment In Past Due Loans) (Details) - USD ($)		Dec. 31, 2015		Dec. 31, 2014
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		$ 4,116,000		$ 11,479,000
Current Balance		3,176,468,000		2,105,155,000
Recorded Investment in Loans, Total		3,180,584,000		2,116,634,000
Non-Accrual		737,000	[1]	4,885,000	[2]
Restructured	[1]	326,000
Total		1,063,000	[1]	4,885,000	[2]
Loans past due 90 days and still accruing interest		0		0
30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		3,640,000		6,631,000
90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		476,000		4,848,000
Commercial And Industrial [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Current Balance		1,216,656,000		896,853,000
Recorded Investment in Loans, Total		1,216,656,000		896,853,000
Securities Based Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Current Balance		1,388,953,000		732,799,000
Recorded Investment in Loans, Total		1,388,953,000		732,799,000
Consumer [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		14,000		42,000
Current Balance		36,832,000		25,447,000
Recorded Investment in Loans, Total		36,846,000		25,489,000
Non-Accrual		15,000	[1]	13,000	[2]
Total		15,000	[1]	13,000	[2]
Consumer [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		7,000		28,000
Consumer [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		7,000		14,000
Residential Real Estate [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		3,760,000		11,437,000
Current Balance		425,372,000		421,209,000
Recorded Investment in Loans, Total		429,132,000		432,646,000
Non-Accrual		380,000	[1]	4,321,000	[2]
Restructured	[1]	326,000
Total		706,000	[1]	4,321,000	[2]
Residential Real Estate [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		3,310,000		6,603,000
Residential Real Estate [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		450,000		4,834,000
Commercial Real Estate [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Current Balance		92,623,000		15,902,000
Recorded Investment in Loans, Total		92,623,000		15,902,000
Non-Accrual	[2]			228,000
Total	[2]			228,000
Home Equity Lines Of Credit [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		342,000
Current Balance		12,133,000		12,945,000
Recorded Investment in Loans, Total		12,475,000		12,945,000
Non-Accrual		342,000	[1]	323,000	[2]
Total		342,000	[1]	$ 323,000	[2]
Home Equity Lines Of Credit [Member] | 30 - 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		323,000
Home Equity Lines Of Credit [Member] | 90 or More Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		19,000
Construction And Land [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Current Balance		3,899,000
Recorded Investment in Loans, Total		$ 3,899,000

[1] There were no loans past due 90 days and still accruing interest at December 31, 2015

[2] There were no loans past due 90 days and still accruing interest at December 31, 2014.