Segment Reporting - Information about Operations in Different Segments (Parenthetical) (Detail) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended
		Jan. 31, 2017	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Capital expenditures	[1]		$ 62,849	$ 31,900
Amazon Pipelay and Construction Vessel [Member]
Segment Reporting Information [Line Items]
Bareboat charter agreement, term		11 years	11 years
Accrued Capital Expenditures of 2017 [Member]
Segment Reporting Information [Line Items]
Capital expenditures			$ 2,000
Accrued Capital Expenditures of 2016 [Member]
Segment Reporting Information [Line Items]
Capital expenditures				2,000
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Gain on sale of assets			3,000
Asset Impairment Charges				32,000
Capital expenditures	[1],[2]		$ 48,234	$ 73

[1] Total capital expenditures represent expenditures for which cash payments were made during the period. Capital expenditures for the first quarter of 2017 and 2016 exclude $2 million in accrued liabilities related to capital expenditures outstanding as of beginning of each respective period.

[2] Corporate and Other capital expenditures in the first quarter of 2017 include the purchase of the Amazon, a pipelay and construction vessel. Following the purchase we sold this vessel to an unrelated third party and simultaneously entered into an 11-year bareboat charter agreement, see Note 8, Sale Leaseback.