Subsequent Events - Additional Information (Details) - Inventories - USD ($) $ in Millions		12 Months Ended
Feb. 28, 2018	Dec. 31, 2017
Subsequent Event [Line Items]
Purchase commitment		$ 372
Subsequent Event
Subsequent Event [Line Items]
Purchase commitment	$ 41

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

No definition available.

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