Amount of expense (reversal of expense) which increases (decreases) the restructuring reserve from an adjustment to a previously accrued restructuring liability.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.P.4(b)(2))
-URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140904-122747

Name:	us-gaap_RestructuringReserveAccrualAdjustment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Restructuring and Asset Related Charges 2014 Restructuring Program (Details) - 2014 Restructuring Program [Member] - USD ($) $ in Millions	4 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Successor [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Other Adjustment	$ (2)
Predecessor [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Other Adjustment		$ (21)	$ (21)