Earnings and Dividends from Investment (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Investments in and Advances to Affiliates, Schedule of Investments [Abstract]
Earnings from equity method investments	$ 2.6	$ 3.8
Dividends received from equity method investments	$ 0.6	$ 0.5

Amount of income (loss) for proportionate share of equity method investee's income (loss).

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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