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Accounting Policies Deferred Financing Costs (Details) | Dec. 31, 2017 | May 23, 2017
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Senior Notes | 2025 Notes |  |
Debt Instrument [Line Items] |  |
Debt instrument, interest rate, stated percentage | 6.75% | 6.75%

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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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