Debt (Details 3) - USD ($) $ in Thousands |
Dec. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Carrying Amount [Member] | ||
| Debt Instrument [Line Items] | ||
| Long-term debt | $ 1,904,001 | $ 2,077,752 |
| Carrying Amount [Member] | Unsecured Senior Notes [Member] | ||
| Debt Instrument [Line Items] | ||
| Long-term debt | 1,187,515 | 1,185,842 |
| Carrying Amount [Member] | Other fixed-rate debt [Member] | ||
| Debt Instrument [Line Items] | ||
| Long-term debt | 155,544 | 282,716 |
| Carrying Amount [Member] | Variable-rate debt [Member] | ||
| Debt Instrument [Line Items] | ||
| Long-term debt | 560,942 | 609,194 |
| Estimated Fair Value [Member] | ||
| Debt Instrument [Line Items] | ||
| Long-term debt | 1,935,606 | 2,114,636 |
| Estimated Fair Value [Member] | Unsecured Senior Notes [Member] | ||
| Debt Instrument [Line Items] | ||
| Long-term debt | 1,220,282 | 1,211,658 |
| Estimated Fair Value [Member] | Other fixed-rate debt [Member] | ||
| Debt Instrument [Line Items] | ||
| Long-term debt | 156,887 | 291,991 |
| Estimated Fair Value [Member] | Variable-rate debt [Member] | ||
| Debt Instrument [Line Items] | ||
| Long-term debt | $ 558,437 | $ 610,987 |
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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. No definition available.
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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. No definition available.
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