Summary of Significant Accounting Policies - Principal Service Lives (Detail)	12 Months Ended
	Dec. 31, 2018
Minimum [Member] | Pipeline Equipment [Member]
Property, Plant and Equipment [Line Items]
Principal service life	30 years
Minimum [Member] | Offshore Drilling Equipment [Member]
Property, Plant and Equipment [Line Items]
Principal service life	15 years
Minimum [Member] | Other [Member]
Property, Plant and Equipment [Line Items]
Principal service life	3 years
Maximum [Member] | Pipeline Equipment [Member]
Property, Plant and Equipment [Line Items]
Principal service life	50 years
Maximum [Member] | Offshore Drilling Equipment [Member]
Property, Plant and Equipment [Line Items]
Principal service life	30 years
Maximum [Member] | Other [Member]
Property, Plant and Equipment [Line Items]
Principal service life	40 years