Investments In Unconsolidated Joint Ventures (Gale Kimball, L.L.C.) (Details) (Gale Kimball [Member], USD $) | 0 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended |
|---|---|---|---|---|
Jun. 15, 2006
sqft | Sep. 30, 2010 | Sep. 30, 2010 | Dec. 31, 2010 | |
Gale Kimball [Member] | ||||
| Percentage of interest in venture | 8.33% | |||
| Date of acquisition | June 15,2006 | |||
| Area of office property | 175,000 | |||
| Venture sale of real estate | $ 60,000,000 | |||
| Management, leasing and other services fees | 71,000 | 213,300 | ||
| Share of gain on sale of real estate | 1,600,000 | |||
| Venture gain (loss) on sale of real estate | 19,800,000 | |||
| Distribution received | 5,400,000 | |||
| Payment of participation rights | $ 2,400,000 |