Unsecured Revolving Credit Facility (Narrative) (Details) (USD $) | 9 Months Ended | |
|---|---|---|
Sep. 30, 2011 | Dec. 31, 2010 | |
| Borrowing capacity under the credit facility | $ 600,000,000 | |
| Expandable borrowing capacity under the credit facility | 1,000,000,000 | |
| Credit facility extension fee, basis points | 20 | |
| Number of lending institutions | 20 | |
| Credit facility mature date | October 2015 | |
| Line of credit facility, bid feature, current borrowing capacity | 300,000,000 | |
| Terms of the unsecured facility | The terms of the unsecured facility include certain restrictions and covenants which limit, among other things the incurrence of additional indebtedness, the incurrence of liens and the disposition of real estate properties (to the extent that: (i) such property dispositions cause the Company to default on any of the financial ratios of the facility described below, or (ii) the property dispositions are completed while the Company is under an event of default under the facility, unless, under certain circumstances, such disposition is being carried out to cure such default), and which require compliance with financial ratios relating to the maximum leverage ratio, the maximum amount of secured indebtedness, the minimum amount of tangible net worth, the minimum amount of fixed charge coverage, the maximum amount of unsecured indebtedness, the minimum amount of unencumbered property interest coverage and certain investment limitations. | |
| Terms of dividend restriction | If an event of default has occurred and is continuing, the Company will not make any excess distributions except to enable the Company to continue to qualify as a REIT under the Code. | |
| Outstanding borrowings under the facility | 27,000,000 | 228,000,000 |
Previous Credit Facility [Member] | ||
| Borrowing capacity under the credit facility | 775,000,000 | |
| Interest rate on outstanding borrowings | LIBOR plus 55 | |
Money Market Loan [Member] | ||
| Borrowing capacity under the credit facility | 75,000,000 | |
| Spread over LIBOR | 55 | |
| Outstanding borrowings under the facility | $ 0 | $ 0 |
| Spread over LIBOR | 55 | |
| Maturity period of the unsecured borrowing | 30 days or less |