Aggregate value of common shares reserved for future issuance.

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Minimum Number of Quarters with No Dividends that Results in Voting Rights

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Preferred Stock, Shares Reserved For Future Issuance, Value

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Preferred Stock, Voting Rights, Number of Additional Directors Elected

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Aggregate dividends declared during the period for each share of common stock outstanding.

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Face amount or stated value per share of common stock.

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Monetary value of common stock allocated to investors to buy shares of a new issue of common stock before they are offered to the public. When stock is sold on a subscription basis, the issuer does not initially receive the total proceeds. In general, the issuer does not issue the shares to the investor until it receives the entire proceeds.

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

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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 price per share at which the preferred stock of an entity that has priority over common stock in the distribution of dividends and in the event of liquidation of the entity is redeemed or may be called at. The redemption features of this preferred stock are solely within the control 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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Amount of subscription received from investors who have been allocated nonredeemable preferred stock or preferred stock redeemable solely at the option of the issuer.

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The cash inflow from the additional capital contribution to the entity.

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Stockholders' Equity - Narrative (Details) $ / shares in Units, $ in Thousands	3 Months Ended							9 Months Ended
	Sep. 30, 2020 USD ($) quarter $ / shares shares	Jun. 30, 2020 $ / shares	Mar. 31, 2020 $ / shares	Dec. 31, 2019 $ / shares shares	Sep. 30, 2019 USD ($) $ / shares shares	Jun. 30, 2019 $ / shares	Mar. 31, 2019 $ / shares	Sep. 30, 2020 USD ($) quarter $ / shares shares	Sep. 30, 2019 USD ($) $ / shares shares	Nov. 27, 2019 USD ($)	Mar. 29, 2019 USD ($)	Sep. 10, 2018 USD ($)	Aug. 10, 2017 USD ($) $ / shares
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	200,000,000			200,000,000				200,000,000
Preferred stock, par value (in dollars per share) \| $ / shares	$ 0.01			$ 0.01				$ 0.01
Preferred stock, shares issued (in shares)	20,872,888			20,872,888				20,872,888
Preferred stock, shares outstanding (in shares)	20,872,888			20,872,888				20,872,888
Redemption price (in dollars per share) \| $ / shares	$ 25.00							$ 25.00
Preferred stock redemption period								120 days
Number of quarters with no dividends that results in voting rights \| quarter	6							6
Number of elected directors pending preferred stock voting rights \| quarter	2							2
Cash dividend per share (in dollars per share) \| $ / shares	$ 0.075	$ 0.050	$ 0	$ 0.200	$ 0.200	$ 0.200	$ 0.200
Common stock, par value (in dollars per share) \| $ / shares	$ 0.01			$ 0.01				$ 0.01
Net proceeds \| $								$ 511,924	$ 632,248
Preferred stock issuance, net \| $								$ 0	$ 30,490
Equity Distribution Agreements
Class of Stock [Line Items]
Common stock, par value (in dollars per share) \| $ / shares													$ 0.01
Common stock that may be sold (up to) \| $												$ 177,100	$ 100,000
Shares Issued (in shares)	0							0	2,260,200
Price per share (in usd per share) \| $ / shares					$ 6.12				$ 6.12
Net proceeds \| $									$ 13,600
Common stock reserved for issuance \| $	$ 72,500							$ 72,500
Equity agreement for preferred stock maximum aggregate sales price (up to) \| $										$ 131,500
Preferred Equity Distribution Agreement
Class of Stock [Line Items]
Shares Issued (in shares)	0				589,420			0	1,250,707,000
Price per share (in usd per share) \| $ / shares					$ 24.78				$ 24.78
Net proceeds \| $					$ 14,400
Equity agreement for preferred stock maximum aggregate sales price (up to) \| $											$ 50,000
Preferred stock available for future issuance, value \| $	$ 82,400							$ 82,400
Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	6,000,000							6,000,000
Preferred stock, shares issued (in shares)	3,156,087							3,156,087
Preferred stock, cumulative redeemable dividend rate								7.75%
Series C Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	6,600,000							6,600,000
Preferred stock, shares issued (in shares)	4,181,807							4,181,807
Preferred stock, cumulative redeemable dividend rate								7.875%
Series D Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	8,400,000							8,400,000
Preferred stock, shares issued (in shares)	6,123,495							6,123,495
Preferred stock, cumulative redeemable dividend rate								8.00%
Series E Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	9,900,000							9,900,000
Preferred stock, shares issued (in shares)	7,411,499							7,411,499
Preferred stock, cumulative redeemable dividend rate								7.875%
Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	30,900,000			30,900,000				30,900,000
Preferred stock, shares issued (in shares)	20,872,888			20,872,888				20,872,888
Preferred stock, shares outstanding (in shares)	20,872,888			20,872,888				20,872,888
Preferred Stock \| Preferred Equity Distribution Agreement
Class of Stock [Line Items]
Price per share (in usd per share) \| $ / shares					$ 24.75				$ 24.75
Preferred stock issuance, net \| $									$ 30,500