Risk Management and Derivatives (Risk Concentration) (Details)	12 Months Ended
Dec. 31, 2018 borrower
Office/Industrial
Concentration Risk [Line Items]
Concentration risk, percentage	32.70%
Land
Concentration Risk [Line Items]
Concentration risk, percentage	18.40%
Entertainment/Leisure
Concentration Risk [Line Items]
Concentration risk, percentage	17.40%
Hotel
Concentration Risk [Line Items]
Concentration risk, percentage	7.10%
Mixed Use/Mixed Collateral
Concentration Risk [Line Items]
Concentration risk, percentage	7.00%
Customer Concentration Risk
Concentration Risk [Line Items]
Number of large borrowers or tenants	5
Concentration risk percentage of revenue (no more than)	14.40%
Concentration risk percentage of one single customer, revenue (no more than)	6.70%
California \| Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	16.50%
New York \| Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	11.00%

Represents the number of large borrowers considered for evaluating concentration risk.

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- Definition

Concentration Risk Percentage of Revenue Accounted by Large Borrowers or Tenants

+ References

No definition available.

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Concentration Risk, Percentage of Revenue Accounted by One Single Borrower or Tenant

+ References

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13531-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
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-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13537-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 275
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

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