Summarized Financial Information of Unconsolidated Affiliate Level 4 (Details) - HAI Balance Sheets (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
HAI Summarized Financial Information [Line Items]
Current Assets	$ 42	$ 29
Non-current assets	27	21
Current Liabilities	30	15
Non-current liabilities	$ 1	$ 0

Non-current Liabilities of Unconsolidated Affiliate

No definition available.

Name:	msc_NonCurrentLiabilitiesOfUnconsolidatedAffiliate
Namespace Prefix:	msc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant