CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (UNAUDITED) (Parenthetical) shares in Millions	12 Months Ended
Dec. 31, 2017 shares
Common Stock
Increase in common stock outstanding (in shares, less than)	1

The increase (decrease) during the period in the number of shares issued.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644

Name:	us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration