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Income Taxes - Summary of Changes In Tax Provisions (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Movement In Deferred Tax Asset [Roll Forward] |  |  |
Balance at December 31, 2014 | $ 0 | $ 902,300 |
Valuation allowance | $ 0 | 161,158 | $ 88,833
Balance at December 31, 2015 |  | 0 | $ 902,300
Deferred Tax Asset, Changes In Current Period |  |  |
Movement In Deferred Tax Asset [Roll Forward] |  |  |
Valuation allowance |  | (154,800) |
Deferred Tax Asset, Changes In Current Period | Other Comprehensive Income (Loss) |  |  |
Movement In Deferred Tax Asset [Roll Forward] |  |  |
Valuation allowance |  | 6,300 |
Deferred Tax Asset, Changes In Current Period | Income Tax Expense (Benefit) |  |  |
Movement In Deferred Tax Asset [Roll Forward] |  |  |
Valuation allowance |  | (161,100) |
Deferred Tax Asset, Changes In Future Periods |  |  |
Movement In Deferred Tax Asset [Roll Forward] |  |  |
Valuation allowance |  | (747,500) |
Deferred Tax Asset, Changes In Future Periods | Other Comprehensive Income (Loss) |  |  |
Movement In Deferred Tax Asset [Roll Forward] |  |  |
Valuation allowance |  | (60,800) |
Deferred Tax Asset, Changes In Future Periods | Income Tax Expense (Benefit) |  |  |
Movement In Deferred Tax Asset [Roll Forward] |  |  |
Valuation allowance |  | $ (686,700) |

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- Definition Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319 + Details
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