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

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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.

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Amount of paid and unpaid preferred stock dividends declared with the form of settlement in cash.

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

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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Dividends Dividends (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		3 Months Ended	9 Months Ended
	Feb. 28, 2018	Feb. 28, 2017	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Payments of Ordinary Dividends, Common Stock	$ 654.9	$ 395.4		$ 654.9	$ 395.4
Dividends payable							$ 655.1	$ 395.4
Dividends, Preferred Stock, Cash			$ 13.5	$ 13.5	$ 0.0
Annual variable dividend [Member]
Common Stock, Dividends, Per Share, Cash Paid	$ 1.1247	$ 0.6808
Series B Preferred Stock [Member]
Preferred Stock, Dividends Per Share, Declared			$ 27.024	$ 27.024	$ 0.000
Preferred Stock, Shares Issued (shares)						500,000
Series B Preferred Stock [Member] \| Serial Preferred Stock [Member]
Preferred Stock, Shares Issued (shares)			500,000.0	500,000.0	0		0