Stockholders' Equity - Schedule of Preferred Stock Issued and Outstanding (Details) - USD ($)	9 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	200,000,000	200,000,000
Preferred stock, shares issued (in shares)	20,872,888	20,872,888
Preferred stock, carrying value	$ 504,765,000	$ 504,765,000
Preferred stock, liquidation preference per share (in dollars per share)	$ 25
Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	6,000,000
Preferred stock, shares issued (in shares)	3,156,087
Preferred stock, carrying value	$ 76,180,000
Preferred stock, liquidation preference	$ 78,902,000
Preferred stock, contractual rate, percentage	7.75%
Series C Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	6,600,000
Preferred stock, shares issued (in shares)	4,181,807
Preferred stock, carrying value	$ 101,102,000
Preferred stock, liquidation preference	$ 104,545,000
Preferred stock, contractual rate, percentage	7.875%
Series D Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	8,400,000
Preferred stock, shares issued (in shares)	6,123,495
Preferred stock, carrying value	$ 148,134,000
Preferred stock, liquidation preference	$ 153,087,000
Preferred stock, contractual rate, percentage	8.00%
Series D Preferred Stock \| LIBOR
Class of Stock [Line Items]
Preferred stock, floating annual rate, percentage	0.00057%
Series E Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	9,900,000
Preferred stock, shares issued (in shares)	7,411,499
Preferred stock, carrying value	$ 179,349,000
Preferred stock, liquidation preference	$ 185,288,000
Preferred stock, contractual rate, percentage	7.875%
Series E Preferred Stock \| LIBOR
Class of Stock [Line Items]
Preferred stock, floating annual rate, percentage	0.06429%
Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	30,900,000	30,900,000
Preferred stock, shares issued (in shares)	20,872,888	20,872,888
Preferred stock, carrying value	$ 504,765,000
Preferred stock, liquidation preference	$ 521,822,000	$ 521,822,000

Preferred Stock, Dividend Payment Rate, Basis Spread On Variable Rate

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

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(d))
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-Name Accounting Standards Codification
-Topic 505
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Value of the difference between preference in liquidation and the par or stated values of the preferred shares.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(d))
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- Definition

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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-SubTopic 10
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-Paragraph 1
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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 par or stated value of issued nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable preferred shares, par value and other disclosure concepts are in another section within stockholders' equity.

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