Long-Term Debt	6 Months Ended
Jun. 30, 2012
Debt Disclosure [Abstract]
Long-Term Debt	Long-term Debt The Company's long-term debt consists of senior notes and revolving credit facilities, including the effects of net deferred fair value hedge losses and issuance discounts. As of June 30, 2012, the Company and Pioneer Southwest were in compliance with all of their debt covenants. Credit facility. During March 2011, the Company entered into a Second Amended and Restated 5-Year Revolving Credit Agreement (the "Credit Facility") with a syndicate of financial institutions that matures in March 2016, unless extended in accordance with the terms of the Credit Facility. As of June 30, 2012, the Company had $110.0 million of outstanding borrowings under the Credit Facility and $40.1 million of undrawn letters of credit, all of which were commitments under the Credit Facility, leaving the Company with $1.1 billion of unused borrowing capacity under the Credit Facility. During July 2012, $39.0 million of the undrawn letters of credit were canceled. Pioneer Southwest credit facility. During March 2012, Pioneer entered into an Amended and Restated 5-Year Revolving Credit Agreement (the "Pioneer Southwest Credit Facility") with a syndicate of financial institutions that matures in March 2017, unless extended in accordance with the terms of the Pioneer Southwest Credit Facility. The Pioneer Southwest Credit Facility provides for aggregate loan commitments of $300 million. As of June 30, 2012, Pioneer Southwest had $69.0 million of outstanding borrowings and $231.0 million of unused borrowing capacity under the Pioneer Southwest Credit Facility. The Pioneer Southwest Credit Facility is available for general partnership purposes, including working capital, capital expenditures and distributions. Borrowings under the Pioneer Southwest Credit Facility may be in the form of Eurodollar rate loans, base rate committed loans or swing line loans. The Pioneer Southwest Credit Facility contains certain financial covenants, including (i) the maintenance of a quarter end maximum leverage ratio of not more than 3.5 to 1.00 and (ii) the maintenance of a ratio of the net present value of Pioneer Southwest's projected future cash flows from its oil and gas properties to total debt of at least 1.75 to 1.0. Senior notes. During June 2012, the Company issued $600 million of 3.95% Senior Notes due 2022 and received proceeds, net of $8.5 million of offering discounts and costs, of $591.5 million. The Company used the net proceeds to reduce outstanding borrowings under the Credit Facility. Convertible senior notes. As of June 30, 2012 and December 31, 2011, the Company had $479.9 million of 2.875% Convertible Senior Notes outstanding. The 2.875% Convertible Senior Notes are convertible under certain circumstances, using a net share settlement process, into a combination of cash and the Company's common stock based on a formula set forth in the indenture supplement pursuant to which the 2.875% Convertible Senior Notes were issued. The Company's stock prices during March 2012 met the average price threshold that caused the Company's 2.875% Convertible Senior Notes to become convertible at the option of the holders during the following three months ended June 30, 2012. Associated therewith, certain holders of the 2.875% Convertible Senior Notes tendered $22 thousand principal amount of the notes for conversion. The Company paid certain of the tendering holders a total of $7 thousand cash and issued to the tendering holders 50 shares of the Company's common stock in May 2012 in accordance with the terms of the 2.875% Convertible Senior Notes indenture supplement. In August 2012, the Company anticipates paying the other tendering holders $15 thousand cash for the remaining notes tendered and issuing shares to be determined based upon the conversion calculation in accordance with the terms of the 2.875% Convertible Senior Notes indenture supplement. The Company's stock prices during March 2011 met the average price threshold that caused the Company's 2.875% Convertible Senior Notes to become convertible at the option of the holders during the following three month period. Associated therewith, certain holders of the 2.875% Convertible Senior Notes tendered $70 thousand principal amount of the notes for conversion during the three months ended June 30, 2011. During the third quarter of 2011, the Company paid the tendering holders a total of $71 thousand cash, including accrued interest, and issued to the tendering holders 340 shares of the Company's common stock in accordance with the terms of the 2.875% Convertible Senior Notes indenture supplement. During June 2012, the Company's stock price performance did not qualify the 2.875% Convertible Senior Notes for conversion at the option of the holders for the three months ended September 30, 2012. The Company's 2.875% Convertible Senior Notes may become convertible in future quarters depending on the Company's stock price or other conditions. If the 2.875% Convertible Senior Notes had qualified for and been converted as of June 30, 2012, the note holders would have received $479.9 million of cash and approximately 1.8 million shares of the Company's common stock, which was valued at $161.0 million at June 30, 2012. On January 15, 2013, the 2.875% Convertible Senior Notes become redeemable at the option of the Company and on January 15, 2013, January 15, 2018, January 15, 2023, January 15, 2028 and January 15, 2033 the holders may require the Company to repurchase the notes for cash. The Company has the intent and ability to fund cash payments that may be required upon the conversion, redemption or repurchase of the 2.875% Convertible Senior Notes with borrowing capacity under the Credit Facility. Accordingly, the 2.875% Convertible Senior Notes are classified as long-term debt in the accompanying balance sheets.

Long-term Debt

The Company's long-term debt consists of senior notes and revolving credit facilities, including the effects of net deferred fair value hedge losses and issuance discounts. As of June 30, 2012, the Company and Pioneer Southwest were in compliance with all of their debt covenants.

Credit facility. During March 2011, the Company entered into a Second Amended and Restated 5-Year Revolving Credit Agreement (the "Credit Facility") with a syndicate of financial institutions that matures in March 2016, unless extended in accordance with the terms of the Credit Facility. As of June 30, 2012, the Company had $110.0 million of outstanding borrowings under the Credit Facility and $40.1 million of undrawn letters of credit, all of which were commitments under the Credit Facility, leaving the Company with $1.1 billion of unused borrowing capacity under the Credit Facility. During July 2012, $39.0 million of the undrawn letters of credit were canceled.

Pioneer Southwest credit facility. During March 2012, Pioneer entered into an Amended and Restated 5-Year Revolving Credit Agreement (the "Pioneer Southwest Credit Facility") with a syndicate of financial institutions that matures in March 2017, unless extended in accordance with the terms of the Pioneer Southwest Credit Facility. The Pioneer Southwest Credit Facility provides for aggregate loan commitments of $300 million. As of June 30, 2012, Pioneer Southwest had $69.0 million of outstanding borrowings and $231.0 million of unused borrowing capacity under the Pioneer Southwest Credit Facility.

The Pioneer Southwest Credit Facility is available for general partnership purposes, including working capital, capital expenditures and distributions. Borrowings under the Pioneer Southwest Credit Facility may be in the form of Eurodollar rate loans, base rate committed loans or swing line loans. The Pioneer Southwest Credit Facility contains certain financial covenants, including (i) the maintenance of a quarter end maximum leverage ratio of not more than 3.5 to 1.00 and (ii) the maintenance of a ratio of the net present value of Pioneer Southwest's projected future cash flows from its oil and gas properties to total debt of at least 1.75 to 1.0.

Senior notes. During June 2012, the Company issued $600 million of 3.95% Senior Notes due 2022 and received proceeds, net of $8.5 million of offering discounts and costs, of $591.5 million. The Company used the net proceeds to reduce outstanding borrowings under the Credit Facility.

Convertible senior notes. As of June 30, 2012 and December 31, 2011, the Company had $479.9 million of 2.875% Convertible Senior Notes outstanding. The 2.875% Convertible Senior Notes are convertible under certain circumstances, using a net share settlement process, into a combination of cash and the Company's common stock based on a formula set forth in the indenture supplement pursuant to which the 2.875% Convertible Senior Notes were issued.

The Company's stock prices during March 2012 met the average price threshold that caused the Company's 2.875% Convertible Senior Notes to become convertible at the option of the holders during the following three months ended June 30, 2012. Associated therewith, certain holders of the 2.875% Convertible Senior Notes tendered $22 thousand principal amount of the notes for conversion. The Company paid certain of the tendering holders a total of $7 thousand cash and issued to the tendering holders 50 shares of the Company's common stock in May 2012 in accordance with the terms of the 2.875% Convertible Senior Notes indenture supplement. In August 2012, the Company anticipates paying the other tendering holders $15 thousand cash for the remaining notes tendered and issuing shares to be determined based upon the conversion calculation in accordance with the terms of the 2.875% Convertible Senior Notes indenture supplement.

The Company's stock prices during March 2011 met the average price threshold that caused the Company's 2.875% Convertible Senior Notes to become convertible at the option of the holders during the following three month period. Associated therewith, certain holders of the 2.875% Convertible Senior Notes tendered $70 thousand principal amount of the notes for conversion during the three months ended June 30, 2011. During the third quarter of 2011, the Company paid the tendering holders a total of $71 thousand cash, including accrued interest, and issued to the tendering holders 340 shares of the Company's common stock in accordance with the terms of the 2.875% Convertible Senior Notes indenture supplement.

During June 2012, the Company's stock price performance did not qualify the 2.875% Convertible Senior Notes for conversion at the option of the holders for the three months ended September 30, 2012. The Company's 2.875% Convertible Senior Notes may become convertible in future quarters depending on the Company's stock price or other conditions. If the 2.875% Convertible Senior Notes had qualified for and been converted as of June 30, 2012, the note holders would have received $479.9 million of cash and approximately 1.8 million shares of the Company's common stock, which was valued at $161.0 million at June 30, 2012.

On January 15, 2013, the 2.875% Convertible Senior Notes become redeemable at the option of the Company and on January 15, 2013, January 15, 2018, January 15, 2023, January 15, 2028 and January 15, 2033 the holders may require the Company to repurchase the notes for cash. The Company has the intent and ability to fund cash payments that may be required upon the conversion, redemption or repurchase of the 2.875% Convertible Senior Notes with borrowing capacity under the Credit Facility. Accordingly, the 2.875% Convertible Senior Notes are classified as long-term debt in the accompanying balance sheets.