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

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

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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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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Stockholders' Equity (Deficit) - Summary of Cash Dividends Paid (Detail) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended			36 Months Ended
	Feb. 14, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2016
Equity [Abstract]
Total Cash Dividends Paid		$ 102.9	$ 119.7	$ 121.6	$ 344.2
Total Cash Dividends Paid Per Common Share (in usd per share)		$ 0.64	$ 0.64	$ 0.61
Subsequent Event [Line Items]
Dividends per share on common stock (in usd per share)		$ 0.64	$ 0.64	$ 0.61
Common stock, shares outstanding		155,654,370	168,595,521	193,482,383	193,482,383
Subsequent Event
Subsequent Event [Line Items]
Dividends per share on common stock (in usd per share)	$ 0.16
Estimated dividend payment	$ 24.9
Common stock, shares outstanding	156,000,000