Derivative Instruments and Hedging Activities (Derivatives Fair Value By Balance Sheet Location) (Details) (USD $) In Thousands, unless otherwise specified
|
Sep. 30, 2012
|
Dec. 31, 2011
|
Derivative [Line Items] |
|
|
Derivative Asset, Fair Value, Net |
$ 2,982
|
$ 2,499
|
Derivative Liability, Fair Value, Net |
(536)
|
0
|
Derivative, Fair Value, Net |
2,446
|
2,499
|
Designated as Hedging Instrument [Member]
|
|
|
Derivative [Line Items] |
|
|
Derivative Asset, Fair Value, Net |
469
|
2,499
|
Derivative Liability, Fair Value, Net |
0
|
0
|
Derivative, Fair Value, Net |
469
|
2,499
|
Not Designated as Hedging Instrument [Member]
|
|
|
Derivative [Line Items] |
|
|
Derivative Asset, Fair Value, Net |
2,513
|
0
|
Derivative Liability, Fair Value, Net |
(536)
|
0
|
Derivative, Fair Value, Net |
1,977
|
0
|
Current assets - Fair market value of derivatives [Member] | Designated as Hedging Instrument [Member] | Natural gas [Member]
|
|
|
Derivative [Line Items] |
|
|
Derivative Asset, Fair Value, Gross Asset |
0
|
0
|
Derivative Liability, Fair Value, Gross Asset |
0
|
0
|
Derivative Assets (Liability), Fair Value, Gross Asset Net |
0
|
0
|
Current assets - Fair market value of derivatives [Member] | Not Designated as Hedging Instrument [Member] | Natural gas [Member]
|
|
|
Derivative [Line Items] |
|
|
Derivative Asset, Fair Value, Gross Asset |
0
|
0
|
Derivative Liability, Fair Value, Gross Asset |
(224)
|
0
|
Derivative Assets (Liability), Fair Value, Gross Asset Net |
(224)
|
0
|
Non-current assets - Other long-term assets [Member] | Designated as Hedging Instrument [Member] | Natural gas [Member]
|
|
|
Derivative [Line Items] |
|
|
Derivative Asset, Fair Value, Gross Asset |
0
|
0
|
Derivative Liability, Fair Value, Gross Asset |
0
|
0
|
Derivative Assets (Liability), Fair Value, Gross Asset Net |
0
|
0
|
Non-current assets - Other long-term assets [Member] | Not Designated as Hedging Instrument [Member] | Crude oil [Member]
|
|
|
Derivative [Line Items] |
|
|
Derivative Asset, Fair Value, Gross Asset |
969
|
0
|
Derivative Liability, Fair Value, Gross Asset |
0
|
0
|
Derivative Assets (Liability), Fair Value, Gross Asset Net |
969
|
0
|
Current liabilities - Fair market value of derivatives [Member] | Designated as Hedging Instrument [Member] | Crude oil [Member]
|
|
|
Derivative [Line Items] |
|
|
Derivative Asset, Fair Value, Gross Liability |
469
|
2,499
|
Derivative Liability, Fair Value, Gross Liability |
0
|
0
|
Derivative Assets (Liability), Fair Value, Gross Liability Net |
469
|
2,499
|
Current liabilities - Fair market value of derivatives [Member] | Not Designated as Hedging Instrument [Member] | Crude oil [Member]
|
|
|
Derivative [Line Items] |
|
|
Derivative Asset, Fair Value, Gross Liability |
1,544
|
0
|
Derivative Liability, Fair Value, Gross Liability |
0
|
0
|
Derivative Assets (Liability), Fair Value, Gross Liability Net |
1,544
|
0
|
Non-current liabilities - Other long-term liabilities [Member] | Designated as Hedging Instrument [Member] | Crude oil [Member]
|
|
|
Derivative [Line Items] |
|
|
Derivative Asset, Fair Value, Gross Liability |
0
|
0
|
Derivative Liability, Fair Value, Gross Liability |
0
|
0
|
Derivative Assets (Liability), Fair Value, Gross Liability Net |
0
|
0
|
Non-current liabilities - Other long-term liabilities [Member] | Not Designated as Hedging Instrument [Member] | Natural gas [Member]
|
|
|
Derivative [Line Items] |
|
|
Derivative Asset, Fair Value, Gross Liability |
0
|
0
|
Derivative Liability, Fair Value, Gross Liability |
(312)
|
0
|
Derivative Assets (Liability), Fair Value, Gross Liability Net |
$ (312)
|
$ 0
|