| Schedule I—Condensed Financial Information of Registrant - Footnotes - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands | 12 Months Ended | ||||
|---|---|---|---|---|---|
| Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | |||
| Parent Company [Member] | |||||
| Condensed Financial Statements, Captions [Line Items] | |||||
| Non-cash capital contributions | [1] | $ 138,577 | $ 301,781 | $ 395,259 | |
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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 value of the noncash (or part noncash) consideration given (for example, liability, equity) in a transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of a transaction not resulting in cash receipts or cash payments in the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Details 
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