Risks And Uncertainties (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) business segment customer	Dec. 31, 2014 USD ($) customer	Dec. 31, 2013 USD ($) customer	Dec. 31, 2012 USD ($)
Unusual Risk or Uncertainty [Line Items]
Number of strategic business units | segment	6
Segment Reporting, Additional Information about Entity's Reportable Segments | business	2
Cash and cash equivalents	$ 1,262	$ 1,539	$ 1,642	$ 1,900
Percent of revenue generated outside US	76.00%
Number of customers that accounted for 10% of more of total revenue | customer	0	0	0
Maritza [Member]
Unusual Risk or Uncertainty [Line Items]
Allowance for Doubtful Accounts Receivable	$ 0
Total Maritza Receivables	351
Past due receivables [Member] | Maritza [Member]
Unusual Risk or Uncertainty [Line Items]
Total Maritza Receivables	$ 307