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Debt - Activity Related to Repurchase of Debt and Net Loss on Early Extinguishment of Debt (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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| Debt [Line Items] | |||
| Loss on early extinguishment of debt | $ 165,300,000 | $ 277,014,000 | $ 14,114,000 |
| Senior Notes [Member] | |||
| Debt [Line Items] | |||
| Repurchase of debt | 1,290,000,000 | 2,141,000,000 | |
| Secured Mortagage Debt [Member] | |||
| Debt [Line Items] | |||
| Repurchase of debt | $ 528,000,000 | $ 1,571,000,000 | |