Investments - Schedule of Lease Intangible Assets and Liabilities, Net of Accumulated Amortization (Details) - USD ($) $ in Thousands |
Sep. 30, 2015 |
Dec. 31, 2014 |
|---|---|---|
| Capital Leased Assets [Line Items] | ||
| Less: accumulated amortization | $ (211,403) | $ (187,160) |
| Intangible lease assets, net | 543,620 | 590,073 |
| Less: accumulated amortization | (41,735) | (31,625) |
| Intangible lease liabilities, net | 200,601 | 205,968 |
| In-Place Leases | ||
| Capital Leased Assets [Line Items] | ||
| Intangible lease assets, gross | 656,217 | 676,665 |
| Above-Market Leases | ||
| Capital Leased Assets [Line Items] | ||
| Intangible lease assets, gross | 98,806 | 100,568 |
| Below-Market Leases | ||
| Capital Leased Assets [Line Items] | ||
| Intangible lease liabilities, gross | $ 242,336 | $ 237,593 |