Share-Based Compensation Share-Based Compensation - Share-Based Compensation Table (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 0	$ 11
Stock Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation General And Administrative Expense	12	20
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount	7	21
Share Based Compensation Natural Gas And Oil Production Expenses	4	6
Share Based Compensation Allocated To Marketing Gathering And Compression Expense	2	3
Share Based Compensation Service Operations Expense	2	3
Allocated Share-based Compensation Expense	$ 27	$ 53