Fair Value of Financial Instruments Fair Value, Assets and Liabilities Measured on a Recuring Basis (Details) (USD $) | Dec. 31, 2014 | Dec. 31, 2013 |
In Thousands, unless otherwise specified |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | $91,295 | | $14,623 | |
Short-term Investments | 153,448 | | 0 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | 0 | | -14,871 | |
Fair Value, Measurements, Recurring [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 244,743 | | 9,430 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | 0 | | -11,186 | |
Fair Value, Measurements, Recurring [Member] | Crude Oil Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 78,516 | | 4,435 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | | | -76 | |
Fair Value, Measurements, Recurring [Member] | Natural Gas Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 18,585 | | 4,995 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | | | -936 | |
Fair Value, Measurements, Recurring [Member] | Natural Gas Liquids Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | | | 0 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | | | -1,079 | |
Fair Value, Measurements, Recurring [Member] | Interest Rate Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | -5,806 | | | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | 0 | | -9,095 | |
Fair Value, Measurements, Recurring [Member] | Short-term Investments [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 153,448 | | | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 153,448 | | 0 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | 0 | | 0 | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Crude Oil Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 0 | | 0 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | | | 0 | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Natural Gas Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 0 | | 0 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | | | 0 | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Natural Gas Liquids Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | | | 0 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | | | 0 | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Interest Rate Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 0 | | | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | 0 | | 0 | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 97,101 | | 12,755 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | -5,806 | | -14,511 | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Crude Oil Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 78,516 | | 6,151 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | | | -1,792 | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Natural Gas Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 18,585 | | 6,562 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | | | -2,503 | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Natural Gas Liquids Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | | | 42 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | | | -1,121 | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 0 | | | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | -5,806 | | -9,095 | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Short-term Investments [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 0 | | | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 0 | | 0 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | 0 | | 0 | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Crude Oil Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 0 | | 0 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | | | 0 | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Natural Gas Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 0 | | 0 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | | | 0 | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Natural Gas Liquids Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | | | 0 | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | | | 0 | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Interest Rate Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 0 | | | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | 0 | | 0 | |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Short-term Investments [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 0 | | | |
Fair Value, Measurements, Recurring [Member] | Netting [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | -5,806 | [1] | -3,325 | [1] |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | -5,806 | [1] | 3,325 | [1] |
Fair Value, Measurements, Recurring [Member] | Netting [Member] | Crude Oil Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 0 | [1] | -1,716 | [1] |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | | | 1,716 | [1] |
Fair Value, Measurements, Recurring [Member] | Netting [Member] | Natural Gas Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | 0 | [1] | -1,567 | [1] |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | | | 1,567 | [1] |
Fair Value, Measurements, Recurring [Member] | Netting [Member] | Natural Gas Liquids Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | | | -42 | [1] |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | | | 42 | [1] |
Fair Value, Measurements, Recurring [Member] | Netting [Member] | Interest Rate Contract [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | -5,806 | [1] | | |
Liabilities: | | | | |
Derivative Financial Instruments, Liabilities, Fair Value Disclosure | -5,806 | [1] | 0 | [1] |
Fair Value, Measurements, Recurring [Member] | Netting [Member] | Short-term Investments [Member] | | | | |
Assets: | | | | |
Derivative Financial Instruments, Assets, Fair Value Disclosure | $0 | [1] | | |
|
[1] | Represents counterparty netting under agreement governing such derivative contracts. |