Investments - Schedule of Components of Real Estate Investments Held Under Direct Financing Leases (Details) - USD ($) $ in Thousands |
Mar. 31, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Investments in and Advances to Affiliates, Schedule of Investments [Abstract] | ||
| Minimum lease payments receivable | $ 6,842 | $ 7,325 |
| Estimated residual value of leased assets | 24,552 | 24,552 |
| Unearned income | (6,547) | (7,012) |
| Real estate assets under direct financing leases, net | $ 24,847 | $ 24,865 |