Recently Adopted and Recently Issued Accounting Guidance - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	6 Months Ended
Apr. 30, 2015	Jun. 30, 2015	Jun. 30, 2014
Accounting Changes and Error Corrections [Abstract]
Decrease in other noncurrent assets	$ (60)	$ 352	$ 25
Decrease in long term debt non current	$ (60)

The increase (decrease) during the reporting period in other noncurrent operating assets not separately disclosed in the statement of cash flows.

No definition available.

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