Discontinued Operations (Details) (USD $) In Millions	3 Months Ended	12 Months Ended
Mar. 31, 2011	Dec. 31, 2010
Discontinued Operations
Proceeds from sale of wholly owned subsidiary	$ 20	$ 343

The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 15, 16

Name:	us-gaap_ProceedsFromDivestitureOfBusinesses
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration