Fair Value Measurements (Fair Value Hierarchy Table) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Oil derivative contracts - current asset	$ 307	$ 142,846
Total Assets	307	142,846
Oil derivative contracts - current liability	74,229	0
Total Liabilities	74,229
Quoted Prices in Active Markets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Oil derivative contracts - current asset	0	0
Total Assets	0	0
Oil derivative contracts - current liability	0
Total Liabilities	0
Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Oil derivative contracts - current asset	302	90,012
Total Assets	302	90,012
Oil derivative contracts - current liability	73,699
Total Liabilities	73,699
Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Oil derivative contracts - current asset	5	52,834
Total Assets	5	$ 52,834
Oil derivative contracts - current liability	530
Total Liabilities	$ 530