Summary of Long-Term Debt (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Obligations under capitalized leases	$ 21,785
Term Loan A
Debt Instrument [Line Items]
Unamortized discount	$ 708	$ 1,151
3.75% Senior Secured Notes due 2019
Debt Instrument [Line Items]
Debt instruments, maturity date	2019
Unamortized discount	$ 69	112
Senior notes, interest rate	3.75%
4.75% Senior Secured Notes due 2022
Debt Instrument [Line Items]
Debt instruments, maturity date	2022
Unamortized discount	$ 124	150
Senior notes, interest rate	4.75%
Unamortized net premium	$ 4,430	5,400
5.00% Senior Secured Notes due 2026
Debt Instrument [Line Items]
Debt instruments, maturity date	2026
Senior notes, interest rate	5.00%
Notes Payable And Mortgages Payable
Debt Instrument [Line Items]
Obligations under capitalized leases	$ 21,780	$ 23,446
Weighted average interest	9.10%	8.90%
Term Loans With Varying Maturities
Debt Instrument [Line Items]
Debt instruments, maturity date	2027

Debt instruments maturity date.

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Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Section S99
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Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Amount, after accumulated amortization, of debt discount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

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-Name Accounting Standards Codification
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Amount, after accumulated amortization, of debt premium.

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Weighted average interest rate of long-term debt outstanding calculated at point in time.

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