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Senior Notes (Narrative) (Details) |  |  |  | 1 Months Ended | 3 Months Ended | 4 Months Ended | 8 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Apr. 30, 2021 USD ($) | Feb. 05, 2021 | Aug. 18, 2020 USD ($) | Mar. 31, 2020 USD ($) | Dec. 31, 2014 USD ($) | Dec. 31, 2012 USD ($) | Apr. 30, 2021 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) $ / shares | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Sep. 25, 2020 USD ($) | Mar. 04, 2020 USD ($) | Mar. 31, 2019 USD ($) | Mar. 31, 2018
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt | $ 544,800,000 |  |  |  |  |  | $ 544,800,000 |  |  |  |  |  |  |  |  |  |  |
Debtor-in-Possession Financing, Amount Arranged |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 500,000,000 |  |  |
Debtor-in-Possession Financing, Borrowings Outstanding |  |  |  |  |  |  |  | $ 0 | $ 0 | $ 0 |  |  |  |  |  |  |  |
Liabilities Subject to Compromise | 0 |  |  |  |  |  | 0 | 0 | 0 | 7,313,700,000 |  |  |  |  |  |  |  |
Backstop Commitment Agreement, Backstop Premium |  |  |  |  |  |  | (30,000,000.0) | 0 |  | 0 |  |  |  |  |  |  |  |
BackstopCommitmentAgreementCashSettlement |  |  | $ 520,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
BackstopCommitmentAgreementNoteIssued |  |  | 550,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
BackstopCommitmentAgreementSharesToBeAllocated |  | 2.70% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liabilities Subject To Compromise, Accrued Interest On Notes |  |  |  |  |  |  |  | 203,500,000 | 203,500,000 | 201,900,000 |  |  |  |  |  |  |  |
Debt Instrument, Convertible, Carrying Amount of Equity Component |  |  |  |  |  |  |  |  |  | 220,000,000 |  |  |  |  |  |  |  |
Debt Instrument, Repurchased Face Amount |  |  |  | $ 12,800,000 |  |  |  | 951,800,000 | 951,800,000 | 951,800,000 |  |  |  |  |  |  |  |
Debt Instrument, Repurchase Amount |  |  |  | 9,700,000 |  |  |  | 724,100,000 | $ 724,100,000 | 724,100,000 |  |  |  |  |  |  |  |
Gain (Loss) on Extinguishment of Debt |  |  |  | $ 3,100,000 |  |  | 0 | 0 |  | 3,100,000 | $ 194,100,000 |  |  |  |  |  |  |
Debentures Due 2027 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Redemption Price, Percentage |  |  |  |  |  |  |  |  | 100.00% |  |  |  |  |  |  |  |  |
Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  | 545,300,000 | $ 545,300,000 | 7,096,300,000 |  |  |  |  |  |  |  |
Liabilities Subject to Compromise |  |  |  |  |  |  |  | $ 0 | $ 0 | $ 7,096,300,000 |  |  |  |  |  |  |  |
7.38%SeniorNotesDue2025 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 7.375% | 7.375% |  |  |  |  |  |  |  |  |
5.40%SeniorNotesDue2042 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 5.40% | 5.40% |  |  |  |  |  |  |  |  |
5.85%SeniorNotesDue2044 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 5.85% | 5.85% |  |  |  |  |  |  |  |  |
3.00% Exchangeable senior notes due 2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 3.00% | 3.00% |  |  |  |  |  |  |  |  |
4.875%SeniorNotesDue2022Member [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 4.875% | 4.875% |  |  |  |  |  |  |  |  |
4.75%SeniorNotesDue2024Member [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 4.75% | 4.75% |  |  |  |  |  |  |  |  |
7.75% Senior notes due 2026 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 7.75% | 7.75% |  |  |  |  |  |  |  |  |
5.20% Senior notes due 2025 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 5.20% | 5.20% |  |  |  |  |  |  |  |  |
5.75% Senior notes due 2044 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 5.75% | 5.75% |  |  |  |  |  |  |  |  |
4.50% Senior notes due 2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 4.50% | 4.50% |  |  |  |  |  |  |  |  |
4.70% Senior notes due 2021 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 4.70% | 4.70% |  |  |  |  |  |  |  |  |
6.875% Senior notes due 2020 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 6.875% | 6.875% |  |  |  |  |  |  |  |  |
7.875% Senior notes due 2040 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 7.875% | 7.875% |  |  |  |  |  |  |  |  |
7.20% Senior notes due 2027 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 7.20% | 7.20% |  |  |  |  |  |  |  |  |
8.00% Senior notes due 2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 8.00% | 8.00% |  |  |  |  |  |  |  |  |
Convertible Debt [Member] | 3.00% Exchangeable senior notes due 2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Conversion rate per $1,000 principal amount of shares |  |  |  |  |  |  |  |  |  | 17.8336 |  |  |  |  |  |  |  |
Debt Instrument, Convertible, Conversion Price | $ / shares |  |  |  |  |  |  |  |  |  | $ 56.08 |  |  |  |  |  |  |  |
Interest Expense, Debt, Excluding Amortization |  |  |  |  |  |  |  |  | $ 16,100,000 |  | 25,500,000 |  |  |  |  |  |  |
Amortization of Debt Issuance Costs and Discounts |  |  |  |  |  |  |  |  | 21,400,000 | $ 32,500,000 |  |  |  |  |  |  |  |
Convertible Debt [Member] | 3.00% Exchangeable senior notes due 2024 | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  | $ 0 | $ 0 | 849,500,000 |  |  |  |  |  |  |  |
Convertible Debt [Member] | Three percent exchangeable senior notes due twenty twenty four [Member] | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  |  |  | 849,500,000 |  |  |  |  |  |  |  |
Senior Notes [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Backstop Commitment Agreement, Backstop Premium |  |  | 50,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
BackstopCommitmentAgreementCommitmentFee |  |  | $ 20,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes [Member] | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liabilities Subject to Compromise |  |  |  |  |  |  |  |  |  | 6,500,000,000 |  |  |  |  |  |  |  |
Senior Notes [Member] | 7.38%SeniorNotesDue2025 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 7.375% | 7.375% |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  |  |  |  |  |  | $ 500,000,000 | $ 500,000,000 |  |  |  |  |  |  |  |  |
Debt Instrument, Repurchased Face Amount |  |  |  |  |  |  |  | 139,200,000 | 139,200,000 |  |  |  |  |  |  |  |  |
Debt Instrument, Repurchase Amount |  |  |  |  |  |  |  | 109,200,000 | 109,200,000 |  |  |  |  |  |  |  |  |
Senior Notes [Member] | 7.38%SeniorNotesDue2025 [Member] | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  | 0 | 0 | 360,800,000 |  |  |  |  |  |  |  |
Senior Notes [Member] | 5.40%SeniorNotesDue2042 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  |  |  |  |  |  | 400,000,000 | 400,000,000 |  |  |  |  |  |  |  |  |
Senior Notes [Member] | 5.40%SeniorNotesDue2042 [Member] | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  | $ 0 | $ 0 | 400,000,000.0 |  |  |  |  |  |  |  |
Senior Notes [Member] | 5.85%SeniorNotesDue2044 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 5.85% | 5.85% |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  |  |  |  |  |  | $ 400,000,000 | $ 400,000,000 |  |  |  |  |  |  |  |  |
Senior Notes [Member] | 5.85%SeniorNotesDue2044 [Member] | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  | $ 0 | $ 0 | 400,000,000.0 |  |  |  |  |  |  |  |
Senior Notes [Member] | 7.875% Senior Notes Due 2040 [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 7.875% | 7.875% |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  |  |  |  |  |  | $ 201,400,000 | $ 201,400,000 |  |  |  |  |  |  |  |  |
Senior Notes [Member] | 4.875%SeniorNotesDue2022Member [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 4.875% | 4.875% |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  |  |  |  |  |  | $ 620,800,000 | $ 620,800,000 |  |  |  |  |  |  |  |  |
Senior Notes [Member] | 4.875%SeniorNotesDue2022Member [Member] | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  | $ 0 | $ 0 | 620,800,000 |  |  |  |  |  |  |  |
Senior Notes [Member] | 4.75%SeniorNotesDue2024Member [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  | 4.75% | 4.75% |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  |  |  |  |  |  | $ 398,100,000 | $ 398,100,000 |  |  |  |  |  |  |  |  |
Debt Instrument, Repurchased Face Amount |  |  |  |  |  |  |  | 79,500,000 | 79,500,000 |  |  |  |  |  |  |  |  |
Debt Instrument, Repurchase Amount |  |  |  |  |  |  |  | 61,200,000 | 61,200,000 |  |  |  |  |  |  |  |  |
Senior Notes [Member] | 4.75%SeniorNotesDue2024Member [Member] | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  | 0 | 0 | 318,600,000 |  |  |  |  |  |  |  |
Senior Notes [Member] | 7.75% Senior notes due 2026 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7.75%
Debt Issuance Costs, Gross |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 16,500,000 |
Debt Instrument, Face Amount |  |  |  |  |  |  |  |  |  |  | $ 1,000,000,000 |  |  |  |  |  |  |
Senior Notes [Member] | 7.75% Senior notes due 2026 | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  | 0 | 0 | 1,000,000,000 |  |  |  |  |  |  |  |
Senior Notes [Member] | 5.20% Senior notes due 2025 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  |  |  |  |  |  | 5.20% |  |  |  |  |
Debt Instrument, Face Amount |  |  |  |  |  |  |  |  |  |  |  |  | $ 700,000,000 |  |  |  |  |
Senior Note Maturity Year |  |  |  |  |  |  |  |  |  |  |  |  | 2025 |  |  |  |  |
Debt Instrument, Unamortized Discount (Premium), Net |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,600,000 |  |  |  |  |
Debt Instrument, Repurchased Face Amount |  |  |  |  |  |  |  | 335,500,000 | 335,500,000 |  |  |  |  |  |  |  |  |
Debt Instrument, Repurchase Amount |  |  |  |  |  |  |  | 250,000,000.0 | 250,000,000.0 |  |  |  |  |  |  |  |  |
Senior Notes [Member] | 5.20% Senior notes due 2025 | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  | 0 | 0 | 333,700,000 |  |  |  |  |  |  |  |
Senior Notes [Member] | 5.75% Senior notes due 2044 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  |  |  |  |  |  | 5.75% | 5.75% |  |  |  |
Debt Instrument, Face Amount |  |  |  |  |  |  |  |  |  |  |  |  | $ 400,000,000 | $ 625,000,000 |  |  |  |
Senior Note Maturity Year |  |  |  |  |  |  |  |  |  |  |  |  | 2044 | 2044 |  |  |  |
Debt Instrument, Unamortized Discount (Premium), Net |  |  |  |  |  |  |  |  |  |  |  |  | $ 18,700,000 | $ 2,800,000 |  |  |  |
Senior Notes [Member] | 5.75% Senior notes due 2044 | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  | 0 | 0 | 1,000,500,000 |  |  |  |  |  |  |  |
Senior Notes [Member] | 4.50% Senior notes due 2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  |  |  |  |  |  |  | 4.50% |  |  |  |
Debt Instrument, Face Amount |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 625,000,000 |  |  |  |
Senior Note Maturity Year |  |  |  |  |  |  |  |  |  |  |  |  |  | 2024 |  |  |  |
Debt Instrument, Unamortized Discount (Premium), Net |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 900,000 |  |  |  |
Debt Instrument, Repurchased Face Amount |  |  |  |  |  |  |  | 320,000,000.0 | 320,000,000.0 |  |  |  |  |  |  |  |  |
Debt Instrument, Repurchase Amount |  |  |  |  |  |  |  | 240,000,000.0 | 240,000,000.0 |  |  |  |  |  |  |  |  |
Senior Notes [Member] | 4.50% Senior notes due 2024 | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  | 0 | 0 | 303,400,000 |  |  |  |  |  |  |  |
Senior Notes [Member] | 4.70% Senior notes due 2021 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  | 4.70% |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  |  |  |  | $ 1,500,000,000 |  |  |  |  |  |  |  |  |  |  |  |
Senior Note Maturity Year |  |  |  |  |  | 2021 |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Unamortized Discount (Premium), Net |  |  |  |  |  | $ 29,600,000 |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Repurchased Face Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 12,800,000 |  |
Debt Instrument, Repurchase Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 9,700,000 |  |
Senior Notes [Member] | 4.70% Senior notes due 2021 | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  | 0 | 0 | 100,700,000 |  |  |  |  |  |  |  |
Senior Notes [Member] | 6.875% Senior notes due 2020 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  | 6.875% |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  |  |  | $ 900,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Note Maturity Year |  |  |  |  | 2020 |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes [Member] | 6.875% Senior notes due 2020 | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  | 0 | 0 | 122,900,000 |  |  |  |  |  |  |  |
Senior Notes [Member] | 8.50% Senior notes due 2019(1) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  | 8.50% |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  |  |  | $ 500,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Note Maturity Year |  |  |  |  | 2019 |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes [Member] | 7.875% Senior notes due 2040 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  |  |  | $ 300,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes [Member] | 7.875% Senior notes due 2040 | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  | 0 | 0 | $ 300,000,000.0 |  |  |  |  |  |  |  |
Senior Notes [Member] | 7.20% Senior notes due 2027 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  |  |  | 7.20% |  |  |  |  |  |  |  |
Debt Instrument, Face Amount |  |  |  |  |  |  |  |  |  | $ 150,000,000 |  |  |  |  |  |  |  |
Debt Instrument, Repurchased Face Amount |  |  |  |  |  |  |  | 37,900,000 | 37,900,000 |  |  |  |  |  |  |  |  |
Debt Instrument, Repurchase Amount |  |  |  |  |  |  |  | 29,900,000 | 29,900,000 |  |  |  |  |  |  |  |  |
Senior Notes [Member] | 8.00% Senior notes due 2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, interest rate, stated percentage |  |  |  |  |  |  |  |  |  |  |  | 8.00% |  |  |  |  |  |
Debt Instrument, Face Amount |  |  |  |  |  |  |  |  |  |  |  | $ 332,000,000 |  |  |  |  |  |
Senior Note Maturity Year |  |  |  |  |  |  |  |  |  |  |  | 2024 |  |  |  |  |  |
Debt Instrument, Repurchased Face Amount |  |  |  |  |  |  |  | 39,700,000 | 39,700,000 |  |  |  |  |  |  |  |  |
Debt Instrument, Repurchase Amount |  |  |  |  |  |  |  | 33,800,000 | 33,800,000 |  |  |  |  |  |  |  |  |
Senior Notes [Member] | 8.00% Senior notes due 2024 | Reported Value Measurement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term Debt |  |  |  |  |  |  |  | $ 0 | $ 0 | $ 292,300,000 |  |  |  |  |  |  |  |
Senior Notes [Member] | First Lien Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument, Face Amount | 550,000,000 |  |  |  |  |  | 550,000,000 |  |  |  |  |  |  |  |  |  |  |
Debtor-in-Possession Financing, Amount Arranged | $ 520,000,000 |  |  |  |  |  | $ 520,000,000 |  |  |  |  |  |  |  |  |  |  |
DebtInstrumentPercentSecuredEquityInterest | 100.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
DebtInstrumentInterestRateAnnualPaymentPercent | 10.25% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
DebtInstrumentAllowableRedemptionPercentPriorToMaturity | 35.00% |  |  |  |  |  | 35.00% |  |  |  |  |  |  |  |  |  |  |
DebtInstrumentRedemptionPricePercentOfNetCashProceedsFromEquityOffering | 104.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
DebtInstrumentPercentOfNoteRemainingOutstanding | 65.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
DebtInstrumentRedemptionPeriodTiming | 12000.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes [Member] | First Lien Notes | Debt Instrument, Redemption, Period One |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
DebtInstrumentRedemptionPricePercentOfNetCashProceedsFromEquityOffering | 104.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes [Member] | First Lien Notes | Debt Instrument, Redemption, Period Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
DebtInstrumentRedemptionPricePercentOfNetCashProceedsFromEquityOffering | 100.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes [Member] | First Lien Notes | Debt Instrument, Redemption, Period Three |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
DebtInstrumentRedemptionPricePercentOfNetCashProceedsFromEquityOffering | 101.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes [Member] | First Lien Notes | Debt Instrument Interest Rate Payout Option One Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
DebtInstrumentInterestRateAnnualPaymentPercent | 8.25% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Senior Notes [Member] | First Lien Notes | Debt Instrument Interest Rate Payout Option Two Member |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
DebtInstrumentAnnualInterestPayoutPercentInCash | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
DebtInstrumentAnnualInterestPayoutPercentPaidInKind | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
DebtInstrumentInterestRateAnnualPaymentPercentPaidInKind | 12.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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- Definition The carrying amount of the equity component of convertible debt which may be settled in cash upon conversion. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870 + Details
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- Definition Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1B -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21521-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21506-112644 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(5)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21475-112644 + Details
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