Investments - Schedule of Minimum Future Contractual Rent to be Received Under Remaining Non-cancelable Term of Operating Leases (Details) $ in Thousands |
Dec. 31, 2017
USD ($)
|
|---|---|
| Investments in and Advances to Affiliates, Schedule of Investments [Abstract] | |
| 2018 | $ 599,194 |
| 2019 | 587,493 |
| 2020 | 570,820 |
| 2021 | 542,899 |
| 2022 | 507,936 |
| Thereafter | 3,637,342 |
| Total future minimum amortization | $ 6,445,684 |