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Stockholders' Equity of the Company - At-the-Market Equity Offering Program and Perpetual Preferred Stock (Details) - USD ($) | 1 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Aug. 31, 2012 | Dec. 31, 2019 | Dec. 31, 2018 | Mar. 31, 2015
2015 ATM Equity Offering Program |  |  |  |
Stockholders' Equity |  |  |  |
Aggregate value of the shares of common stock to be sold |  |  |  | $ 300,000,000.0
Series I Preferred Stock |  |  |  |
Stockholders' Equity |  |  |  |
Preferred stock, shares outstanding (in shares) | 9,200,000 | 9,200,000 | 9,200,000 |
Dividend rate preferred units (as a percent) | 6.50% | 6.50% |  |
Perpetual Preferred stock, liquidation preference (in dollars per share) |  | $ 25.00 | $ 25.00 |
Perpetual Preferred stock, annual dividends per share (in dollars per share) |  | $ 1.625 |  |
Contributions of net proceeds from sale of preferred stock | $ 221,900,000 |  |  |

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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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(d)(1)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(d)(1)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21484-112644 + Details
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