Derivatives (Schedule Of Subsequent Non-designated Hedges) (Details) - Natural gas - If Nymex $ in Millions	2 Months Ended	12 Months Ended
	Feb. 24, 2017 USD ($) $ / Unit MMBTU	Dec. 31, 2016 MMBTU $ / Unit
Jan'18 - Mar'18 | Three-way collar
Derivative Instruments, Gain (Loss) [Line Items]
Subfloor Price		2.50
Floor Price		3.25
Ceiling Price		4.43
Hedged Volume (MMBtu/day) | MMBTU		10,000
Subsequent to December 31, 2016 | Feb'17 - Oct'17 | Basis Swap
Derivative Instruments, Gain (Loss) [Line Items]
Liquidated derivatives | $	$ 0.6
Subsequent to December 31, 2016 | Apr'18 - Oct'18 | Basis Swap
Derivative Instruments, Gain (Loss) [Line Items]
Liquidated derivatives | $	$ 0.5
Subsequent to December 31, 2016 | Apr'17 - Oct'17 | Swap
Derivative Instruments, Gain (Loss) [Line Items]
Swap Price	3.505
Hedged Volume (MMBtu/day) | MMBTU	10,000
Subsequent to December 31, 2016 | Nov'17 - Dec'17 | Three-way collar
Derivative Instruments, Gain (Loss) [Line Items]
Subfloor Price	2.75
Floor Price	3.50
Ceiling Price	4
Hedged Volume (MMBtu/day) | MMBTU	10,000
Subsequent to December 31, 2016 | Jan'18 - Mar'18 | Three-way collar
Derivative Instruments, Gain (Loss) [Line Items]
Subfloor Price	2.69
Floor Price	3.38
Ceiling Price	4.17
Hedged Volume (MMBtu/day) | MMBTU	40,000
Subsequent to December 31, 2016 | Apr'18 - Dec'18 | Three-way collar
Derivative Instruments, Gain (Loss) [Line Items]
Subfloor Price	2.50
Floor Price	3
Ceiling Price	3.66
Hedged Volume (MMBtu/day) | MMBTU	10,000