Susequent Events	12 Months Ended
Dec. 31, 2012
Subsequent Events [Abstract]
Subsequent Events [Text Block]	25. Subsequent Events On February 19, 2013, we redeemed all of the outstanding 6.75% Series F Cumulative Redeemable Preferred Shares and 6.75% Series H Cumulative Redeemable Preferred Shares at par, for an aggregate of $262,500,000 in cash, plus accrued and unpaid dividends through the date of redemption. On January 25, 2013, we sold 12,000,000 5.40% Series L Cumulative Redeemable Preferred Shares at a price of $25.00 per share in an underwritten public offering pursuant to an effective registration statement. We retained aggregate net proceeds of $290,853,000, after underwriters' discounts and issuance costs and contributed the net proceeds to the Operating Partnership in exchange for 12,000,000 Series L Preferred Units (with economic terms that mirror those of the Series L Preferred Shares). Dividends on the Series L Preferred Shares are cumulative and payable quarterly in arrears. The Series L Preferred Shares are not convertible into, or exchangeable for, any of our properties or securities. On or after five years from the date of issuance (or sooner under limited circumstances), we may redeem the Series L Preferred Shares at a redemption price of $25.00 per share, plus accrued and unpaid dividends through the date of redemption. The Series L Preferred Shares have no maturity date and will remain outstanding indefinitely unless redeemed by us.

Susequent Events

12 Months Ended

Dec. 31, 2012

25. Subsequent Events

On February 19, 2013, we redeemed all of the outstanding 6.75% Series F Cumulative Redeemable Preferred Shares and 6.75% Series H Cumulative Redeemable Preferred Shares at par, for an aggregate of $262,500,000 in cash, plus accrued and unpaid dividends through the date of redemption.

On January 25, 2013, we sold 12,000,000 5.40% Series L Cumulative Redeemable Preferred Shares at a price of $25.00 per share in an underwritten public offering pursuant to an effective registration statement. We retained aggregate net proceeds of $290,853,000, after underwriters' discounts and issuance costs and contributed the net proceeds to the Operating Partnership in exchange for 12,000,000 Series L Preferred Units (with economic terms that mirror those of the Series L Preferred Shares). Dividends on the Series L Preferred Shares are cumulative and payable quarterly in arrears. The Series L Preferred Shares are not convertible into, or exchangeable for, any of our properties or securities. On or after five years from the date of issuance (or sooner under limited circumstances), we may redeem the Series L Preferred Shares at a redemption price of $25.00 per share, plus accrued and unpaid dividends through the date of redemption. The Series L Preferred Shares have no maturity date and will remain outstanding indefinitely unless redeemed by us.