Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended				9 Months Ended		12 Months Ended
	Aug. 31, 2019	Sep. 30, 2019		Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2019		Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Impairment loss		$ 1,370.0	[1]		$ 0.0	$ 1,370.0	[1]	$ 2,200.0
Trade Names [Member]
Finite Lived Intangible Assets [Line Items]
Impairment of intangible assets	$ 140.0
Amortization expense of intangible assets, remainder of 2019		0.4				0.4
Amortization expense of intangible assets, 2020		1.6				1.6
Amortization expense of intangible assets, 2021		$ 10.0				10.0
Alloy Piping Products [Member]
Finite Lived Intangible Assets [Line Items]
Impairment loss				$ 90.0
NCSA [Member]
Finite Lived Intangible Assets [Line Items]
Impairment loss						$ 1,111.0
NCSA [Member] | Trade Names [Member]
Finite Lived Intangible Assets [Line Items]
Useful Life Range						1 year 9 months 18 days		8 years 8 months 12 days
Minimum [Member] | MENA [Member]
Finite Lived Intangible Assets [Line Items]
Fair value of reporting units exceeded		96.00%				96.00%
Minimum [Member] | Technology [Member]
Finite Lived Intangible Assets [Line Items]
Fair value of reporting units exceeded		28.00%				28.00%

[1] Represents impairment of goodwill associated with our NCSA and EARC reporting units, resulting from our interim impairment assessment during the third quarter of 2019. In addition, in the third quarter of 2019 we recorded $143 million of impairment associated with NCSA intangible assets. The goodwill impairment values are included within the applicable operating segment’s operating loss. See Note 9, Goodwill and Other Intangible Assets, for further discussion.