Supplemental Cash Flow Information - Changes in Non-Cash Working Capital Items Related to Operating Activities (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Accounts receivable	$ 22,320	$ (54,830)	$ 34,669
Prepaid expenses and other assets	(2,104)	(6,618)	5,983
Accounts payable and accrued liabilities	(32,800)	43,113	38,627
Advances (to) from affiliate	(70,643)	51,841	(5,061)
Change in non-cash working capital items related to operating activities	$ (83,227)	$ 33,506	$ 74,218

The increase (decrease) during the reporting period in the amounts payable to vendors for goods and services received and the amount of obligations and expenses incurred but not paid.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

+ Details

Name:	us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The increase (decrease) during the reporting period in amount due within one year (or one business cycle) from customers for the credit sale of goods and services.

+ References

+ Details

Name:	us-gaap_IncreaseDecreaseInAccountsReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The increase (decrease) in obligations owed to an entity that is controlling, under the control of, or within the same control group as the reporting entity by means of direct or indirect ownership.

+ References

+ Details

Name:	us-gaap_IncreaseDecreaseInDueToAffiliates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The increase (decrease) during the reporting period of all assets and liabilities used in operating activities.

+ References

+ Details

Name:	us-gaap_IncreaseDecreaseInOperatingCapital
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase (decrease) in prepaid expenses, and assets classified as other.

+ References

+ Details

Name:	us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_SupplementalCashFlowElementsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration