CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
CONDENSED CONSOLIDATED BALANCE SHEETS [Abstract]
Natural gas and oil properties, using the full cost method, costs excluded from amortization	$ 878.7	$ 956.5
Common Stock, Par Value	$ 0.01	$ 0.01
Common Stock, Authorized, Shares	1,250,000,000	1,250,000,000
Common Stock, Issued, Shares	353,083,763	352,938,584
Common Stock in Treasury, Shares	10,608	9,924