CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	0 Months Ended
Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2015	Dec. 31, 2014
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	100,000,000us-gaap_PreferredStockSharesAuthorized	100,000,000us-gaap_PreferredStockSharesAuthorized	100,000,000us-gaap_PreferredStockSharesAuthorized	100,000,000us-gaap_PreferredStockSharesAuthorized
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000,000us-gaap_CommonStockSharesAuthorized	500,000,000us-gaap_CommonStockSharesAuthorized	500,000,000us-gaap_CommonStockSharesAuthorized	500,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued (in shares)	207,518,510us-gaap_CommonStockSharesIssued	204,766,718us-gaap_CommonStockSharesIssued	207,518,510us-gaap_CommonStockSharesIssued	204,766,718us-gaap_CommonStockSharesIssued
Common stock, shares outstanding (in shares)	207,518,510us-gaap_CommonStockSharesOutstanding	204,766,718us-gaap_CommonStockSharesOutstanding	207,518,510us-gaap_CommonStockSharesOutstanding	204,766,718us-gaap_CommonStockSharesOutstanding
Series D Cumulative Redeemable Preferred Stock
Preferred stock, 8.0% Cumulative Redeemable Preferred Stock, shares issued (in shares)	4,600,000	4,600,000	4,600,000	4,600,000
Preferred stock, 8.0% Cumulative Redeemable Preferred Stock, shares outstanding (in shares)	4,600,000	4,600,000	4,600,000	4,600,000
Preferred stock, 8.0% Cumulative Redeemable Preferred Stock, dividend rate (as a percent)	8.00%	8.00%
Preferred stock, 8.0% Cumulative Redeemable Preferred Stock, liquidation preference (in dollars per share)	$ 25.00	$ 25.00	$ 25.00	$ 25.00

Face amount or stated value per share of common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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The percentage rate used to calculate dividend payments on preferred stock.

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The per share liquidation preference (or restrictions) of nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) that has a preference in involuntary liquidation considerably in excess of the par or stated value of the shares. The liquidation preference is the difference between the preference in liquidation and the par or stated values of the share.

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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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