Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands |
9 Months Ended | |
|---|---|---|
|
Sep. 30, 2018
USD ($)
Property
|
Mar. 31, 2015
Property
|
|
| Accounting Policies [Line Items] | ||
| Remaining contractual payments under lease and sublease for office space | $ | $ 1,075,191 | |
| Corporate Office Leases [Member] | ||
| Accounting Policies [Line Items] | ||
| Remaining contractual payments under lease and sublease for office space | $ | $ 1,500 | |
| DISTRICT OF COLUMBIA | Sublease [Member] | ||
| Accounting Policies [Line Items] | ||
| Operating lease agreement expire date | Jun. 30, 2021 | |
| California [Member] | ||
| Accounting Policies [Line Items] | ||
| Number of properties | Property | 15 | |
| California [Member] | San Diego [Member] | ||
| Accounting Policies [Line Items] | ||
| Operating lease agreement expire date | Apr. 30, 2022 | |
| Error in Estimated Useful Life Utilized to Amortize Properties [Member] | ||
| Accounting Policies [Line Items] | ||
| Number of properties | Property | 3 |