Organization and Summary of Significant Accounting Policies (Accrued Expenses) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Organization and Summary of Significant Accounting Policies [Abstract]
Accrued Exploration Costs, Development Costs and Lease Operating Costs	$ 107.8	$ 84.9
Other Accrued Expenses	7.5	16.3
Accrued Interest on Indebtedness	$ 15.8	$ 16.2