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Consolidated Statements Of Changes In Shareholders' Equity (Parenthetical) - $ / shares | 6 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Dec. 31, 2017
Common stock dividends per share, declared | $ 0.48 | $ 0.42 |
Series A 3% Preferred Stock [Member] |  |  |
Preferred stock, dividend percentage | 3.00% | 3.00% | 3.00%
Preferred stock dividends per share, declared | $ 1.50 | $ 1.50 |
Series B-1 8.48% Preferred Stock [Member] |  |  |
Preferred stock, dividend percentage | 8.48% | 8.48% | 8.48%
Preferred stock dividends per share, declared | $ 4.24 | $ 4.24 |

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- Definition Aggregate dividends declared during the period for each share of common stock outstanding. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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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