Fair Value Measurements - Additional Information (Detail) - USD ($) |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
Dec. 31, 2015 |
|
| Fair Value Option Quantitative Disclosures [Line Items] | |||||
| Transfers between Level 1, 2 and 3 in fair value measurement hierarchy | $ 0 | $ 0 | $ 0 | $ 0 | |
| Unfunded commitments | 9,183,000 | 9,183,000 | $ 10,242,000 | ||
| EGCP III [Member] | |||||
| Fair Value Option Quantitative Disclosures [Line Items] | |||||
| Unfunded commitments | $ 8,613,000 | $ 8,613,000 | |||
| End of the investment period | Oct. 12, 2016 | ||||
| Remaining obligation date | Oct. 12, 2023 | ||||