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Income Taxes - Additional Information (Detail) (USD $)
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12 Months Ended |
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Dec. 31, 2014
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Dec. 31, 2013
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Dec. 31, 2012
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| Schedule Of Effective Tax Rate Reconciliation [Line Items] |
|
|
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| Operating loss carryforwards |
$ 227,800,000 |
$ 146,200,000 |
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| Realization of recorded tax benefits on tax loss carryforwards |
66,920,000 |
50,404,000 |
|
| Recognized interest and penalties |
100,000 |
700,000 |
800,000 |
| Accrued interest and penalties |
1,800,000 |
2,000,000 |
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| Impact of effective tax rate recognized |
16,100,000 |
|
|
| Income tax examination year |
2010 |
|
|
| 2015 Through 2019 [Member] |
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|
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| Schedule Of Effective Tax Rate Reconciliation [Line Items] |
|
|
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| Operating loss carryforwards |
13,100,000 |
|
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| Beyond 2019 [Member] |
|
|
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| Schedule Of Effective Tax Rate Reconciliation [Line Items] |
|
|
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| Operating loss carryforwards |
$ 214,700,000 |
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