Fair Value Disclosures (Fair Value Hierarchy, Carrying Values, and Estimated Fair Values of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2012	Nov. 30, 2011
Debt Instrument [Line Items]
Carrying Amount	$ 1,727,679	$ 1,583,571
Senior Notes due 2014 at 5 3/4%
Debt Instrument [Line Items]
Senior Notes, Rate (percent)	5.75%	5.75%
Carrying Amount	75,898	249,647
Senior Notes due 2014 at 5 3/4% | Level 2
Debt Instrument [Line Items]
Carrying Amount	75,898	249,647
Estimated Fair Value	78,439	232,500
Senior Notes due 2015 at 5 7/8%
Debt Instrument [Line Items]
Senior Notes, Rate (percent)	5.875%	5.875%
Carrying Amount	101,980	299,273
Senior Notes due 2015 at 5 7/8% | Level 2
Debt Instrument [Line Items]
Carrying Amount	101,980	299,273
Estimated Fair Value	104,599	270,000
Senior Notes due 2015 at 6 1/4%
Debt Instrument [Line Items]
Senior Notes, Rate (percent)	6.25%	6.25%
Carrying Amount	236,819	449,795
Senior Notes due 2015 at 6 1/4% | Level 2
Debt Instrument [Line Items]
Carrying Amount	236,819	449,795
Estimated Fair Value	239,867	401,625
Senior Notes due 2017 at 9.10%
Debt Instrument [Line Items]
Senior Notes, Rate (percent)	9.10%	9.10%
Carrying Amount	261,284	260,865
Senior Notes due 2017 at 9.10% | Level 2
Debt Instrument [Line Items]
Carrying Amount	261,284	260,865
Estimated Fair Value	290,175	235,519
Senior Notes due 2018 at 7 1/4%
Debt Instrument [Line Items]
Senior Notes, Rate (percent)	7.25%	7.25%
Carrying Amount	299,098	299,007
Senior Notes due 2018 at 7 1/4% | Level 2
Debt Instrument [Line Items]
Carrying Amount	299,098	299,007
Estimated Fair Value	306,000	251,625
Senior Notes due 2020 at 8.00%
Debt Instrument [Line Items]
Senior Notes, Rate (percent)	8.00%	8.00%
Carrying Amount	345,090	0
Senior Notes due 2020 at 8.00% | Level 2
Debt Instrument [Line Items]
Carrying Amount	345,090	0
Estimated Fair Value	374,500	0
Senior Notes due 2022 at 7.50%
Debt Instrument [Line Items]
Senior Notes, Rate (percent)	7.50%	7.50%
Carrying Amount	350,000	0
Senior Notes due 2022 at 7.50% | Level 2
Debt Instrument [Line Items]
Carrying Amount	350,000	0
Estimated Fair Value	$ 363,125	$ 0