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Long-Term Debt - Additional Information (Detail) - USD ($) | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Mar. 12, 2015 | Oct. 03, 2012
Debt Instrument [Line Items] |  |  |  |
Debt instrument covenant compliance leverage ratio, threshold | 3.5 |  |  |
Debt instrument covenant compliance leverage ratio, actual | 2.5 |  |  |
Amortization expense related to deferred debt issuance costs | $ 1,200,000 |  |  |
Other Assets [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Unamortized deferred debt issuance costs | $ 3,000,000 |  |  |
5.375% Notes [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Long-term debt, maturity date | Oct. 15, 2020 |  |  |
Aggregate principal amount |  |  |  | $ 250,000,000
Interest rate on debt | 5.375% |  |  | 5.375%
Frequency of interest payable | Semiannually |  |  |
Debt instrument redemption | The 5.375% Notes are redeemable, in whole or in part, at any time on or after October 15, 2016 at the redemption prices specified in the applicable Indenture. |  |  |
Revolving Credit Facility [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Line of credit facility, maximum borrowing capacity |  |  | $ 400,000,000 |
Long-term debt, maturity date | Mar. 12, 2020 |  |  |
Federal fund rate spread | 1.00% |  |  |
Revolving Credit Facility [Member] | Minimum [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Federal fund rate spread | 0.125% |  |  |
Revolving Credit Facility [Member] | Maximum [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Federal fund rate spread | 1.00% |  |  |
Revolving Credit Facility [Member] | Federal Funds Rate [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Federal fund rate spread | 0.50% |  |  |
Revolving Credit Facility [Member] | Daily Euro Rate [Member] | Minimum [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Federal fund rate spread | 1.125% |  |  |
Revolving Credit Facility [Member] | Daily Euro Rate [Member] | Maximum [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Federal fund rate spread | 2.00% |  |  |
Letters of Credit [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Letters of credit issued | $ 5,200,000 | $ 5,100,000 |  |
Letters of credit outstanding | $ 0 |  |  |

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