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Fair Value Measurements Long-term Debt (Details) - USD ($) $ in Thousands | Jun. 30, 2017 | Dec. 31, 2016
--- | --- | ---
6.50% Senior Notes Due 2021 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Face Amount | [1] | $ 344,611 |
6.125% Senior Notes Due 2022 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Face Amount |  | 561,796 |
6.50% Senior Notes Due 2023 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Face Amount |  | 394,985 |
5% Senior Notes Due 2024 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Face Amount |  | 500,000 |
5.625% Senior Notes Due 2025 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Face Amount |  | 500,000 |
6.75% Senior Notes Due 2026 [Domain] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Face Amount |  | $ 500,000 |
Senior Notes [Member] | 6.50% Senior Notes Due 2021 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 6.50% |
Debt Instrument, Face Amount |  | $ 344,611 | $ 346,955
Long-term Debt, Fair Value |  | $ 338,794 | 354,546
Senior Notes [Member] | 6.125% Senior Notes Due 2022 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 6.125% |
Debt Instrument, Face Amount |  | $ 561,796 | 561,796
Long-term Debt, Fair Value |  | $ 536,347 | 570,925
Senior Notes [Member] | 6.50% Senior Notes Due 2023 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 6.50% |
Debt Instrument, Face Amount |  | $ 394,985 | 394,985
Long-term Debt, Fair Value |  | $ 377,211 | 403,134
Senior Notes [Member] | 5% Senior Notes Due 2024 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 5.00% |
Debt Instrument, Face Amount |  | $ 500,000 | 500,000
Long-term Debt, Fair Value |  | $ 445,465 | 475,975
Senior Notes [Member] | 5.625% Senior Notes Due 2025 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 5.625% |
Debt Instrument, Face Amount |  | $ 500,000 | 500,000
Long-term Debt, Fair Value |  | $ 449,335 | 485,000
Senior Notes [Member] | 6.75% Senior Notes Due 2026 [Domain] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 6.75% |
Debt Instrument, Face Amount |  | $ 500,000 | 500,000
Long-term Debt, Fair Value |  | $ 479,840 | 516,565
Convertible Debt [Member] | 1.50% Senior Convertible Notes Due 2021 [Domain] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 1.50% |
Debt Instrument, Face Amount |  | $ 172,500 | 172,500
Long-term Debt, Fair Value |  | $ 154,612 | $ 202,189
[1] | During the first quarter of 2017, the Company repurchased a total of $2.3 million in aggregate principal amount of 6.50% Senior Notes due 2021 in open market transactions at a slight premium. The Company canceled all of these repurchased Senior Notes upon cash settlement.

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- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399 + Details
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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. + References No definition available. + Details
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