Investments - Schedule of Loans Receivable, Net of Premium and Allowance for Loan Losses (Details) - USD ($) $ in Thousands |
Jun. 30, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Loans and Leases Receivable Disclosure [Line Items] | ||
| Total loans receivable, net | $ 55,438 | $ 78,466 |
| Mortgage Loans | ||
| Loans and Leases Receivable Disclosure [Line Items] | ||
| Loans and leases receivable, gross | 46,830 | 69,963 |
| Mortgage loans - premium, net of amortization | 3,390 | 5,038 |
| Allowance for loan losses | 0 | (389) |
| Total loans receivable, net | 50,220 | 74,612 |
| Notes Receivable | ||
| Loans and Leases Receivable Disclosure [Line Items] | ||
| Loans and leases receivable, gross | 5,218 | 5,355 |
| Allowance for loan losses | 0 | 0 |
| Total loans receivable, net | 5,218 | 5,355 |
| Continuing and discontinuing operations | ||
| Loans and Leases Receivable Disclosure [Line Items] | ||
| Total loans receivable, net | $ 55,438 | $ 79,967 |