Unconsolidated Investments - Schedule of Projects Accounted under Equity Method of Accounting (Detail) - USD ($)
$ in Thousands |
Jun. 30, 2018 |
Dec. 31, 2017 |
| Schedule of Equity Method Investments [Line Items] |
|
|
| Unconsolidated investments |
$ 343,512
|
$ 311,223
|
| South Kent [Member] |
|
|
| Schedule of Equity Method Investments [Line Items] |
|
|
| Unconsolidated investments |
$ 9,538
|
$ 6,151
|
| Percentage of ownership |
50.00%
|
50.00%
|
| Grand [Member] |
|
|
| Schedule of Equity Method Investments [Line Items] |
|
|
| Unconsolidated investments |
$ 7,655
|
$ 6,611
|
| Percentage of ownership |
45.00%
|
45.00%
|
| K2 [Member] |
|
|
| Schedule of Equity Method Investments [Line Items] |
|
|
| Unconsolidated investments |
$ 94,894
|
$ 103,328
|
| Percentage of ownership |
33.30%
|
33.30%
|
| Armow [Member] |
|
|
| Schedule of Equity Method Investments [Line Items] |
|
|
| Unconsolidated investments |
$ 123,479
|
$ 132,890
|
| Percentage of ownership |
50.00%
|
50.00%
|
| PEGH2 [Member] |
|
|
| Schedule of Equity Method Investments [Line Items] |
|
|
| Unconsolidated investments |
$ 107,946
|
$ 62,243
|
| Percentage of ownership |
24.00%
|
20.90%
|