Long-Term Debt (Components Of Long-Term Debt) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013 Rate	Dec. 31, 2012	Jun. 30, 2012 Rate
Debt Instrument [Line Items]
Outstanding debt principal balances, gross	$ 2,689,985	$ 3,769,892
Issuance discounts and premiums, net	(35,885)	(47,309)
Net deferred fair value hedge losses	(1,041)	(1,390)
Long-term Debt	2,653,059	3,721,193
Pioneer Credit Facility [Member]
Debt Instrument [Line Items]
Outstanding borrowing	0	474,000
Pioneer Southwest Credit Facility [Member]
Debt Instrument [Line Items]
Outstanding borrowing	0	126,000
5.875% Senior Notes Due 2016 [Member]
Debt Instrument [Line Items]
Issuance of senior notes	455,385	455,385
Senior notes, interest rate	5.875%
6.65% Senior Notes Due 2017 [Member]
Debt Instrument [Line Items]
Issuance of senior notes	485,100	485,100
Senior notes, interest rate	6.65%
6.875% Senior Notes Due 2018 [Member]
Debt Instrument [Line Items]
Issuance of senior notes	449,500	449,500
Senior notes, interest rate	6.875%
7.500% Senior Notes Due 2020 [Member]
Debt Instrument [Line Items]
Issuance of senior notes	450,000	450,000
Senior notes, interest rate	7.50%
3.95% Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Issuance of senior notes	600,000	600,000	600,000
Senior notes, interest rate	3.95%		3.95%
7.20% Senior Notes Due 2028 [Member]
Debt Instrument [Line Items]
Issuance of senior notes	250,000	250,000
Senior notes, interest rate	7.20%
2.875% Convertible Senior Notes Due 2038 [Member]
Debt Instrument [Line Items]
Convertible debt	$ 0	$ 479,907
Senior notes, interest rate	2.875%