Aggregate dividends paid during the period for each share of common stock outstanding.

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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Date the declared dividend will be paid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

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Date the holder must own the stock to be entitled to the dividend, in CCYY-MM-DD format.

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

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Subsequent Events (Narrative) (Details) - $ / shares					3 Months Ended
Subsequent Events (Narrative) (Details) - $ / shares	Apr. 15, 2018	Apr. 05, 2018	Mar. 22, 2018	Mar. 15, 2018	Mar. 31, 2018	Mar. 31, 2017
Subsequent Event [Line Items]
Dividends payable, date payable		Apr. 05, 2018			Jan. 05, 2018	Jan. 05, 2017
Dividend paid to common stockholders		$ 0.41			$ 0.39	$ 0.36
Dividends payable, date of record			Mar. 22, 2018		Dec. 05, 2017	Dec. 16, 2016
Dividend rate (as a percent)				7.125%
Common Stock \| Subsequent Event
Subsequent Event [Line Items]
Dividends payable, date payable		Apr. 05, 2018
Dividend paid to common stockholders		$ 0.41
Preferred Stock \| Subsequent Event
Subsequent Event [Line Items]
Dividends payable, date payable	Apr. 16, 2018
Dividend paid to common stockholders	$ 0.14844
Dividend rate (as a percent)	7.125%