Segment Reporting (Narrative) (Details) ft² in Millions	9 Months Ended
	Sep. 30, 2015 ft² loan property security segment state	Dec. 31, 2014 security
Segment Reporting Information [Line Items]
Number of reportable segments | segment	2
Loans held for investment | loan	11
Commercial Mortgage Backed Securities [Member]
Segment Reporting Information [Line Items]
Number of securities acquired | security	10	10
REI Segment [Member] | Consolidated Properties [Member]
Segment Reporting Information [Line Items]
Number of properties owned | property	4,572
Square feet of property	100.9
Number of states in which entity operates | state	49
Percentage of rentable space leased	98.30%
Real estate property, weighted average remaining lease term	11 years 1 month 6 days