Noncontrolling Interests In Subsidiaries (Narrative) (Details) (USD $) | 9 Months Ended | |
|---|---|---|
Sep. 30, 2011 | Dec. 31, 2010 | |
| Internal rate of return | 10.00% | |
| Preferred stock issued | $ 25,000,000 | |
| Rebalance of ownership percentage | 9,400,000 | |
| Percentage of noncontrolling interest | 12.80% | 14.00% |
| Excess net cash flow remaining after the distribution to the Company | 50.00% | |
| Square footage of office buildings | 860,246 | |
Series C Cumulative Redeemable Perpetual Preferred Stock [Member] | ||
| Preferred stock issued | 25,000,000 | |
Series C Preferred Stock [Member] | ||
| Preferred unit in operating partnership | $ 25,000,000 |