Debt - Activity Related to Repurchase of Debt and Net Loss on Early Extinguishment of Debt (Detail) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Debt Instrument [Line Items] | |||
| Original principal amount | $ 2,033,600 | $ 1,881,200 | |
| Cash purchase/repayment price | 2,104,800 | 1,984,500 | |
| Losses (gains) on early extinguishment of debt, net | 68,379 | $ (2,484) | 86,303 |
| Senior Notes [Member] | |||
| Debt Instrument [Line Items] | |||
| Original principal amount | 1,495,300 | 709,700 | |
| Cash purchase/repayment price | 1,566,500 | 789,000 | |
| Term Loan [Member] | |||
| Debt Instrument [Line Items] | |||
| Original principal amount | 0 | 600,000 | |
| Cash purchase/repayment price | 0 | 600,000 | |
| Secured Mortgage Debt [Member] | |||
| Debt Instrument [Line Items] | |||
| Original principal amount | 538,300 | 571,500 | |
| Cash purchase/repayment price | $ 538,300 | $ 595,500 | |