Long-Term Debt (Narrative) (Details) (USD $)	12 Months Ended			12 Months Ended		12 Months Ended					12 Months Ended			1 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2008	Dec. 31, 2011 PXD Credit Facility [Member]	Mar. 31, 2010 PXD Credit Facility [Member]	Dec. 31, 2011 Pioneer Southwest Credit Facility [Member]	Dec. 31, 2010 Pioneer Southwest Credit Facility [Member]	May 31, 2008 Pioneer Southwest Credit Facility [Member]	Dec. 31, 2011 Pioneer Credit Facility [Member]	Dec. 31, 2010 Pioneer Credit Facility [Member]	Dec. 31, 2011 Swing Line Loans [Member]	Dec. 31, 2011 7.500% Senior Notes Due 2020 [Member]	Dec. 31, 2010 7.500% Senior Notes Due 2020 [Member]	Jan. 31, 2008 2.875% Convertible Senior Notes Due 2038 [Member]	Dec. 31, 2011 2.875% Convertible Senior Notes Due 2038 [Member]	Dec. 31, 2010 2.875% Convertible Senior Notes Due 2038 [Member]	Dec. 31, 2009 2.875% Convertible Senior Notes Due 2038 [Member]	Dec. 31, 2011 Company's Oil And Gas Properties To Total Debt [Member] Pioneer Southwest Credit Facility [Member]	Dec. 31, 2011 Total Debt To Book Capitalization [Member]	Dec. 31, 2011 Maximum Leverage Ratio [Member] Pioneer Southwest Credit Facility [Member]	Dec. 31, 2011 Interest Coverage Ratio [Member] Pioneer Southwest Credit Facility [Member]	Dec. 31, 2011 If Converted [Member] 2.875% Convertible Senior Notes Due 2038 [Member]	Dec. 31, 2011 Noncash [Member] If Converted [Member] 2.875% Convertible Senior Notes Due 2038 [Member]
Line of credit facility, maximum borrowing capacity					$ 1,250,000,000			$ 300,000,000
Outstanding borrowings under the Credit Facility											150,000,000
Outstanding borrowings under the Credit Facility						32,000,000	81,200,000			49,000,000
Undrawn letters of credit				65,100,000
Unused borrowing capacity				1,200,000,000		268,000,000
Commitment fee percentage						0.175%
Debt instrument covenant description																		1.75 to 1.0	.60 to 1.0	3.5 to 1.00	2.5 to 1.0
Company debt rating				0.75%
Applicable margin	1.75%
Letters of credit outstanding under the Credit Facility, interest percentage	0.125%
Credit facility, description	(a) a rate per annum equal to the higher of the prime rate announced from time to time by Wells Fargo Bank, National Association or the weighted average of the rates on overnight Federal funds transactions with members of the Federal Reserve System during the last preceding business day plus 0.5 percent plus a defined alternate base rate spread margin, which is currently 0.75 percent based on the Company's debt rating or (b) a base Eurodollar rate, substantially equal to LIBOR, plus a margin (the "Applicable Margin"), which is currently 1.75 percent and is also determined by the Company's debt rating. Swing line loans under the Credit Facility bear interest at a rate per annum equal to the "ASK" rate for Federal funds periodically published by the Dow Jones Market Service plus the Applicable Margin. Letters of credit outstanding under the Credit Facility are subject to a per annum fee, representing the Applicable Margin plus 0.125 percent. The Company also pays commitment fees on undrawn amounts under the Credit Facility that are determined by the Company's debt rating (currently 0.325 percent).					Borrowings under the Pioneer Southwest Credit Facility may be in the form of Eurodollar rate loans, base rate committed loans or swing line loans. Eurodollar rate loans bear interest annually at LIBOR, plus a margin (the "Applicable Rate") (currently 0.875 percent) that is determined by a reference grid based on Pioneer Southwest's consolidated leverage ratio. Base rate committed loans bear interest annually at a base rate equal to the higher of (i) the Federal Funds Rate plus 0.5 percent or (ii) the Bank of America prime rate (the "Base Rate") plus a margin (currently zero percent). Swing line loans bear interest annually at the Base Rate plus the Applicable Rate.
Unused portion, fee percentage				0.325%
Debt instrument maturity period															January 15, 2038
Value of shares received for conversion of debt																							173,300,000
Shares received for conversion of debt															70,000							1,900,000
Cash received from note holders	71,000																					479,900,000
Applicable rate						0.875%
Federal fund rate				0.50%		0.50%
Issuance of senior notes												450,000,000	450,000,000
Senior Notes, interest rate, percentage			2.875%									7.50%			2.875%
Senior notes offering discounts and cost															18,500,000	35,000,000
Issuance of 2.875% senior convertible notes														500,000,000
Loss on extinguishment of debt to write off the unamortized issuance costs	2,400,000
Senior convertible notes, outstanding	2,601,915,000	2,700,185,000
Initial base conversion price	$ 72.60
Base conversion rate, shares per thousand dollars	13.7741
Common shares principal amount of convertible notes	1,000
Addition shares on the exceed of common stock conversion price	8.9532
Base conversion price percentage	130.00%														100.00%
Conversion rate of notes to common stock	97.00%
Threshold for average trading day price, which triggers interest change															1,200
Interest rate modified	2.375%
Unamortized discount															18,500,000	35,000,000
Debt instrument, effective interest rate, percentage															6.75%
Net carrying value															461,500,000	445,000,000
Interest expense relating to the contractual interest coupon and unamortized discount															32,300,000	31,100,000	29,900,000
Additional Paid-in Capital as the equity component	$ 49,500,000	$ 49,500,000