Mortgage Loans on Real Estate (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Mortgage Loans on Real Estate
Prior Liens	$ 39,646
Face Amount of Mortgages	559,969
Carrying Amount of Mortgages	485,735
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 63,553
First mortgage loans | Triple Net [Member] | United Kingdom 1
Mortgage Loans on Real Estate
Interest Rate	7.25%
Final Maturity Date	Nov. 21, 2018
Periodic Payment Amount	$ 105,443
Prior Liens	0
Face Amount of Mortgages	17,149
Carrying Amount of Mortgages	17,149
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
First mortgage loans | Triple Net [Member] | United Kingdom 2
Mortgage Loans on Real Estate
Interest Rate	7.00%
Final Maturity Date	Dec. 31, 2019
Periodic Payment Amount	$ 133,193
Prior Liens	0
Face Amount of Mortgages	28,047
Carrying Amount of Mortgages	22,273
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
First mortgage loans | Triple Net [Member] | United Kingdom 3
Mortgage Loans on Real Estate
Interest Rate	8.55%
Final Maturity Date	Jul. 01, 2019
Periodic Payment Amount	$ 64,706
Prior Liens	0
Face Amount of Mortgages	14,122
Carrying Amount of Mortgages	9,022
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
First mortgage loans | Triple Net [Member] | United Kingdom 4
Mortgage Loans on Real Estate
Interest Rate	8.00%
Final Maturity Date	Jul. 06, 2019
Periodic Payment Amount	$ 48,485
Prior Liens	0
Face Amount of Mortgages	18,506
Carrying Amount of Mortgages	7,202
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
First mortgage loans | Triple Net [Member] | United Kingdom 5
Mortgage Loans on Real Estate
Interest Rate	8.04%
Final Maturity Date	Jan. 16, 2018
Periodic Payment Amount	$ 8,409
Prior Liens	0
Face Amount of Mortgages	2,591
Carrying Amount of Mortgages	1,233
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
First mortgage loans | Triple Net [Member] | United Kingdom 6
Mortgage Loans on Real Estate
Interest Rate	7.00%
Final Maturity Date	Feb. 28, 2021
Periodic Payment Amount	$ 107,010
Prior Liens	0
Face Amount of Mortgages	26,074
Carrying Amount of Mortgages	17,680
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
First mortgage loans | Triple Net [Member] | Oklahoma 1
Mortgage Loans on Real Estate
Interest Rate	8.72%
Final Maturity Date	Nov. 01, 2019
Periodic Payment Amount	$ 85,043
Prior Liens	0
Face Amount of Mortgages	11,610
Carrying Amount of Mortgages	11,486
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
First mortgage loans | Triple Net [Member] | Oregon 1
Mortgage Loans on Real Estate
Interest Rate	7.10%
Final Maturity Date	May 01, 2017
Periodic Payment Amount	$ 1,357
Prior Liens	0
Face Amount of Mortgages	225
Carrying Amount of Mortgages	225
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
First mortgage loans | Triple Net [Member] | Pennsylvania 1
Mortgage Loans on Real Estate
Interest Rate	7.10%
Final Maturity Date	Jun. 01, 2017
Periodic Payment Amount	$ 1,479
Prior Liens	0
Face Amount of Mortgages	250
Carrying Amount of Mortgages	250
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
First mortgage loans | Triple Net [Member] | Texas 1
Mortgage Loans on Real Estate
Interest Rate	8.00%
Final Maturity Date	Feb. 28, 2021
Periodic Payment Amount	$ 53,507
Prior Liens	0
Face Amount of Mortgages	7,875
Carrying Amount of Mortgages	7,875
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
First mortgage loans | Triple Net [Member] | Florida 1
Mortgage Loans on Real Estate
Interest Rate	8.11%
Final Maturity Date	Jun. 23, 2021
Periodic Payment Amount	$ 13,955
Prior Liens	0
Face Amount of Mortgages	17,100
Carrying Amount of Mortgages	2,029
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
First mortgage loans | Triple Net [Member] | 3 Properties in 2 states
Mortgage Loans on Real Estate
Interest Rate	10.00%
Final Maturity Date	Jan. 01, 2022
Periodic Payment Amount	$ 76,331
Prior Liens	0
Face Amount of Mortgages	9,000
Carrying Amount of Mortgages	9,000
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
First mortgage loans | Triple Net [Member] | 13 properties in Texas
Mortgage Loans on Real Estate
Interest Rate	10.00%
Final Maturity Date	Jan. 01, 2022
Periodic Payment Amount	$ 878,820
Prior Liens	0
Face Amount of Mortgages	103,620
Carrying Amount of Mortgages	103,620
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
First mortgage loans | Triple Net [Member] | 11 properties in 6 states
Mortgage Loans on Real Estate
Interest Rate	10.00%
Final Maturity Date	Jan. 01, 2022
Periodic Payment Amount	$ 558,025
Prior Liens	0
Face Amount of Mortgages	65,796
Carrying Amount of Mortgages	65,796
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
First mortgage loans | Triple Net [Member] | 18 properties in 6 states
Mortgage Loans on Real Estate
Interest Rate	10.00%
Final Maturity Date	Jan. 01, 2022
Periodic Payment Amount	$ 1,175,775
Prior Liens	0
Face Amount of Mortgages	138,634
Carrying Amount of Mortgages	138,634
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
First mortgage loans | Outpatient Medical [Member] | California 1
Mortgage Loans on Real Estate
Interest Rate	6.35%
Final Maturity Date	Dec. 22, 2017
Periodic Payment Amount	$ 348,542
Prior Liens	0
Face Amount of Mortgages	65,000
Carrying Amount of Mortgages	60,500
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 63,553
Second mortgage loans | Triple Net [Member] | Connecticut 1
Mortgage Loans on Real Estate
Interest Rate	8.11%
Final Maturity Date	Apr. 01, 2018
Periodic Payment Amount	$ 43,225
Prior Liens	16,709
Face Amount of Mortgages	6,270
Carrying Amount of Mortgages	6,270
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
Second mortgage loans | Triple Net [Member] | Texas 2
Mortgage Loans on Real Estate
Interest Rate	12.17%
Final Maturity Date	May 01, 2019
Periodic Payment Amount	$ 32,033
Prior Liens	11,751
Face Amount of Mortgages	3,100
Carrying Amount of Mortgages	3,100
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0
Second mortgage loans | Triple Net [Member] | Texas 3
Mortgage Loans on Real Estate
Interest Rate	10.00%
Final Maturity Date	Dec. 30, 2018
Periodic Payment Amount	$ 20,247
Prior Liens	11,186
Face Amount of Mortgages	25,000
Carrying Amount of Mortgages	2,391
Principal Amount of Loans Subject to Delinquent Principal or Interest	$ 0