Unconsolidated Entities - Summary of Investments in and Advances to our Unconsolidated Entities (Detail) - USD ($) $ in Thousands |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Schedule Of Equity Method Investments [Line Items] | ||
| Investments in and advances to unconsolidated entities | $ 5,496,450 | $ 4,230,429 |
| Unconsolidated Co-Investment Ventures [Member] | ||
| Schedule Of Equity Method Investments [Line Items] | ||
| Investments in and advances to unconsolidated entities | 5,274,702 | 4,057,524 |
| Other Ventures [Member] | ||
| Schedule Of Equity Method Investments [Line Items] | ||
| Investments in and advances to unconsolidated entities | $ 221,748 | $ 172,905 |