Real Estate Securities - Summary of Significant Valuation Assumptions for Available for Sale Securities (Details) - Prime	12 Months Ended
Dec. 31, 2017
Minimum
Schedule of Available-for-sale Securities [Line Items]
Prepayment rates	8.00%
Projected losses	0.22%
Maximum
Schedule of Available-for-sale Securities [Line Items]
Prepayment rates	20.00%
Projected losses	5.00%

This item represents the default rate of the underlying assets in the security that were considered as one of the potential factors in reaching a conclusion that the available-for-sale investments are not other-than-temporarily impaired.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563

Name:	us-gaap_AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureOtherDefaultRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration