Related Party Debt - Additional Information (Details) - USD ($)								12 Months Ended
	Sep. 27, 2016	Feb. 22, 2016	Nov. 11, 2015	Oct. 29, 2015	May 12, 2015	Nov. 03, 2014	Aug. 06, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jun. 29, 2015
Line Of Credit Facility [Line Items]
Interest paid								$ 7,000,000	$ 2,700,000	$ 100,000
Maximum time period		1 year
STCW | Pecten
Line Of Credit Facility [Line Items]
Amount borrowed and repaid				$ 6,000,000
Five Year Revolver
Line Of Credit Facility [Line Items]
Line of credit facility maximum borrowing capacity								$ 760,000,000
Interest rate								2.10%
Five Year Revolver | STCW
Line Of Credit Facility [Line Items]
Line of credit facility maximum borrowing capacity						$ 300,000,000
Line of credit facility, expiration period						6 months
Amended and Restated Revolver 1 | STCW
Line Of Credit Facility [Line Items]
Increase in maximum borrowing capacity					$ 400,000,000
Credit facility issuance fee					200,000
Amended and Restated Revolver 1 | STCW | Minimum
Line Of Credit Facility [Line Items]
Limit on indebtedness					$ 100,000,000.0
364 Day Revolver
Line Of Credit Facility [Line Items]
Line of credit facility maximum borrowing capacity								$ 180,000,000
364 Day Revolver | STCW
Line Of Credit Facility [Line Items]
Line of credit facility maximum borrowing capacity			$ 180,000,000								$ 100,000,000
Credit facility issuance fee			$ 100,000					$ 100,000
Interest rate								2.20%
Revolving Credit Facility
Line Of Credit Facility [Line Items]
Interest and fee expenses								$ 8,600,000	$ 4,000,000
Revolving Credit Facility | Zydeco
Line Of Credit Facility [Line Items]
Line of credit facility maximum borrowing capacity								$ 30,000,000
Interest rate								2.40%
Interest and fee expenses										100,000
Amount borrowed and repaid										$ 6,000,000
Revolving Credit Facility | Minimum | Zydeco
Line Of Credit Facility [Line Items]
Limit on indebtedness							$ 100,000,000
Revolving Credit Facility | STCW | Zydeco
Line Of Credit Facility [Line Items]
Line of credit facility maximum borrowing capacity							$ 30,000,000
Line of credit facility, expiration period							6 months
Five Year Revolver | Shell Treasury Center West Inc
Line Of Credit Facility [Line Items]
Debt instrument term								5 years
Line of credit facility maximum borrowing capacity	$ 760,000,000.0
Credit facility issuance fee	$ 600,000
364 Day Revolver | Shell Treasury Center West Inc
Line Of Credit Facility [Line Items]
Debt instrument term								364 days