Long-Term Debt (Details) (6 3/4% Senior Notes due 2021, USD $) In Billions, unless otherwise specified	Jun. 30, 2011	May 05, 2011
6 3/4% Senior Notes due 2021
Debt Instrument
Aggregate principal amount		$ 2.0
Term of debt instrument (in years)		10
Interest rate (as a percent)	6.75%	6.75%
Debt instrument issuance as a percentage of the face amount (as a percent)		99.093%
Percentage of principal amount at which the entity may redeem some or all of the notes at any time (as a percent)		100.00%
Maximum percentage of the aggregate principal amount of notes redeemable before June 15, 2014 with net cash proceeds of certain equity offerings or capital contributions (as a percent)		35.00%
Percentage of principal amount at which notes may be required to be repurchased in event of change of control (as a percent)		101.00%