Segment Reporting - Operating Activity Within Reportable Segments (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2018 |
Sep. 30, 2017 |
Sep. 30, 2018 |
Sep. 30, 2017 |
|
| Segment Reporting Information [Line Items] | ||||
| Total revenues | $ 223,308 | $ 208,749 | $ 655,024 | $ 602,862 |
| Segment profit | 149,906 | 140,240 | 445,842 | 409,756 |
| Office Segment | ||||
| Segment Reporting Information [Line Items] | ||||
| Total revenues | 197,054 | 184,618 | 578,148 | 530,508 |
| Operating expenses | (66,288) | (62,468) | (188,462) | (175,240) |
| Segment profit | 130,766 | 122,150 | 389,686 | 355,268 |
| Multifamily Segment | ||||
| Segment Reporting Information [Line Items] | ||||
| Total revenues | 26,254 | 24,131 | 76,876 | 72,354 |
| Operating expenses | (7,114) | (6,041) | (20,720) | (17,866) |
| Segment profit | $ 19,140 | $ 18,090 | $ 56,156 | $ 54,488 |