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Consolidated Statements Of Changes In Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common stock dividends per share, declared	$ 0.85	$ 0.81	$ 0.80
Series A 3% Preferred Stock [Member]
Preferred stock dividends per share, declared	$ 3	$ 3	3
Preferred stock, dividend percentage	3.00%	3.00%
Series B-1 8.48% Preferred Stock [Member]
Preferred stock dividends per share, declared	$ 8.48	$ 8.48	$ 8.48
Preferred stock, dividend percentage	8.48%	8.48%

X

- Definition

Aggregate dividends declared 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

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- Definition

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+ References

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- Definition

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

+ References

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