Products and Services Revenues (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended							9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2011	Dec. 31, 2012 item	Dec. 31, 2011 Strategic services	Dec. 31, 2012 Strategic services	Dec. 31, 2011 Legacy services	Dec. 31, 2012 Legacy services	Dec. 31, 2011 Affiliates and other services	Dec. 31, 2012 Affiliates and other services	Mar. 31, 2011 Predecessor	Dec. 31, 2010 Predecessor	Mar. 31, 2011 Predecessor Strategic services	Dec. 31, 2010 Predecessor Strategic services	Mar. 31, 2011 Predecessor Legacy services	Dec. 31, 2010 Predecessor Legacy services	Mar. 31, 2011 Predecessor Affiliates and other services	Dec. 31, 2010 Predecessor Affiliates and other services
Products and Services Revenues
Number of categories of products and services									3
Products and Services Revenues
Operating revenues	$ 2,210	$ 2,183	$ 2,195	$ 2,260	$ 2,214	$ 2,190	$ 2,231	$ 6,635	$ 8,848	$ 2,406	$ 3,265	$ 2,796	$ 3,471	$ 1,433	$ 2,112	$ 2,268	$ 9,271	$ 792	$ 3,059	$ 1,003	$ 4,323	$ 473	$ 1,889
Taxes and surcharges included in operating revenues and expenses								$ 122	$ 171							$ 43	$ 186