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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 505
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-Section S99
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Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
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-Section S99
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Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Topic 230
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Dividends Dividends (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended
	Feb. 28, 2018	Feb. 28, 2017	Feb. 29, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Dividends payable				$ 655.1	$ 395.4	$ 519.2
Payments of Ordinary Dividends, Common Stock		$ 395.4	$ 519.0
Annual variable dividend
Common Stock, Dividends, Per Share, Cash Paid		$ 0.6808	$ 0.8882
Subsequent Event \| Annual variable dividend
Common Stock, Dividends, Per Share, Cash Paid	$ 1.1247