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Stockholders' and Mezzanine Equity - Dividends Paid (Detail) - $ / shares | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Senior Common Stock |  |  |  |
Dividends Payable [Line Items] |  |  |  |
Common Stock, dividends paid per share | $ 0.2625 | $ 0.2625 | $ 0.525 | $ 0.525
Series A Preferred Stock |  |  |  |
Dividends Payable [Line Items] |  |  |  |
Preferred Stock, dividends paid per share | 0.4843749 | 0.4843749 | 0.9687498 | 0.9687498
Series B Preferred Stock |  |  |  |
Dividends Payable [Line Items] |  |  |  |
Preferred Stock, dividends paid per share | 0.46875 | 0.46875 | 0.9375 | 0.9375
Series D Preferred Stock |  |  |  |
Dividends Payable [Line Items] |  |  |  |
Preferred Stock, dividends paid per share | 0.4374999 | 0.4374999 | 0.8749998 | 0.8749998
Common Stock |  |  |  |
Dividends Payable [Line Items] |  |  |  |
Common Stock, dividends paid per share | $ 0.375 | $ 0.375 | $ 0.75 | $ 0.75

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- Definition Aggregate dividends paid during the period for each share of common stock outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
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