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Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2016 | Sep. 30, 2016 | Jun. 30, 2016 | Mar. 31, 2016 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Income Tax [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Effective tax rate |  |  |  |  |  |  |  |  | 21.94% | 36.80% | 37.76% |
Income tax benefit resulting from the reduction of deferred tax liabilities | $ (70,000) |  |  |  |  |  |  |  | $ (70,000) |  |  |
Effective tax rate excluding impact of income tax benefit |  |  |  |  |  |  |  |  | 39.00% |  |  |
Effective income tax rate favorable impact of change in uncertain tax positions |  |  |  |  |  | $ 10,600 |  |  |  |  |  |
Effective tax rate excluding impact of tax settlement |  |  |  |  |  |  |  |  |  | 38.87% | 37.76% |
Increase (decrease) in net deferred tax liability |  |  |  |  |  |  |  |  | $ (74,600) |  |  |
Adjustment to additional paid-in capital for excess tax benefits related to stock-based awards |  |  |  |  |  |  |  |  |  | $ 4,200 | $ 11,600 |
Income tax expense for excess tax deficiencies |  |  |  |  |  |  |  |  | 200 |  |  |
Net operating loss carryforwards for federal and state tax | 116,000 |  |  |  | $ 130,000 |  |  |  | 116,000 | 130,000 | 136,600 |
Uncertain tax position liability | 10,972 |  |  |  | 9,469 |  |  |  | 10,972 | 9,469 | 18,447 | $ 17,165
Unrecognized tax benefits that would impact effective tax rate | 10,700 |  |  |  |  |  |  |  | 10,700 |  |  |
Increase (decrease) in uncertain tax position |  |  |  |  |  |  |  |  | 1,500 | (9,000) |  |
Expected decrease in uncertain tax position in the next twelve months | 1,100 |  |  |  |  |  |  |  | 1,100 |  |  |
Income tax expense (benefit) | (27,761) | $ 42,119 | $ 40,725 | $ 34,967 | 49,919 | $ 44,272 | $ 51,601 | $ 43,411 | 90,050 | 189,203 | 204,038 |
Company's accrued liability for interest and penalties related to income tax liabilities | $ 1,200 |  |  |  | $ 1,400 |  |  |  | 1,200 | 1,400 |  |
Interest and Penalties [Member] |  |  |  |  |  |  |  |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Income tax expense (benefit) |  |  |  |  |  |  |  |  | $ (200) | $ (7,900) | $ 600 |
Earliest Tax Year [Member] |  |  |  |  |  |  |  |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Federal and state income tax examinations |  |  |  |  |  |  |  |  | 2013 |  |  |
Latest Tax Year [Member] |  |  |  |  |  |  |  |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Federal and state income tax examinations |  |  |  |  |  |  |  |  |  | 2016 |  |
Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Expiration period of operating loss carryforwards |  |  |  |  |  |  |  |  | 2019 |  |  |
Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Expiration period of operating loss carryforwards |  |  |  |  |  |  |  |  | 2037 |  |  |

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