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Risk Management and Derivatives (Risk Concentration) (Details) | 12 Months Ended
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Dec. 31, 2017 borrower
Land |
Concentration Risk [Line Items] |
Concentration risk, percentage | 22.10%
Office/Industrial |
Concentration Risk [Line Items] |
Concentration risk, percentage | 20.10%
Commercial Entertainment and Leisure Real Estate |
Concentration Risk [Line Items] |
Concentration risk, percentage | 11.50%
Condominium Units |
Concentration Risk [Line Items] |
Concentration risk, percentage | 11.10%
Mixed Use Collateral |
Concentration Risk [Line Items] |
Concentration risk, percentage | 11.90%
Customer Concentration Risk |
Concentration Risk [Line Items] |
Number of large borrowers or tenants | 5
Concentration risk percentage of revenue (no more than) | 15.00%
Concentration risk percentage of one single customer, revenue (no more than) | 5.70%
New York | Geographic Concentration Risk |
Concentration Risk [Line Items] |
Concentration risk, percentage | 21.70%
California | Geographic Concentration Risk |
Concentration Risk [Line Items] |
Concentration risk, percentage | 12.10%

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- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6351-108592 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13531-108611 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6404-108592 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13537-108611 + Details
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