Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Debt - Borrowing Base Credit Facility (Detail) - USD ($)	Dec. 31, 2016	Dec. 22, 2016	Dec. 21, 2016	Dec. 01, 2016	Oct. 28, 2016	Apr. 14, 2016	Apr. 13, 2016
OLLC $2.0 billion revolving credit facility, variable-rate, due March 2018
Line of Credit Facility [Line Items]
Borrowing base	$ 530,653,000	$ 530,700,000	$ 619,000,000	$ 720,000,000	$ 740,000,000	$ 925,000,000	$ 1,175,000,000