Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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Amount of amortization expense attributable to debt issuance costs.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Face (par) amount of debt instrument at time of issuance.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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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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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Amount of the required periodic payments applied to principal.

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Weighted average interest rate of debt outstanding.

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Average fixed interest rate related to the group of interest rate derivatives.

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Variable interest rate in effect as of the balance sheet date related to the interest rate derivative.

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The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

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The carrying value as of the balance sheet date of the current portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Credit Arrangements and Debt Obligations - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Oct. 16, 2017
Debt Instrument [Line Items]
Borrowings under revolving credit facility	$ 129,400		$ 127,100
Amortization of deferred financing costs	400	$ 300
Amortization expense of original issuance discount costs	100
Derivative, Average Fixed Interest Rate				3.90%
Derivative, Variable Interest Rate				0.75%
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	1,200
Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, principal amount	1,100,000
Secured Debt [Member] \| Senior Credit Facilities [Member]
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 1,300,000
Maturity date	Jul. 31, 2022
Quarterly principal payments	$ 2,700
Secured Debt [Member] \| Amended Senior Credit Facility [Member]
Debt Instrument [Line Items]
Maturity date	Nov. 07, 2023
Term Loan [Member] \| Senior Credit Facilities [Member]
Debt Instrument [Line Items]
Effective interest rate for the term loans	3.88%		3.57%
Debt, Weighted Average Interest Rate	3.61%	3.50%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	3.70%	4.30%
Revolving Credit Facility [Member] \| Senior Credit Facilities [Member]
Debt Instrument [Line Items]
Debt instrument, principal amount	$ 225,000
Effective interest rate for the term loans	4.27%		3.70%
Base Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%
Base Rate [Member] \| Minimum [Member] \| Term Loan [Member] \| Senior Credit Facilities [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Base Rate [Member] \| Minimum [Member] \| Revolving Credit Facility [Member] \| Senior Credit Facilities [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%
Base Rate [Member] \| Maximum [Member] \| Revolving Credit Facility [Member] \| Senior Credit Facilities [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%
Eurodollar [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.00%
Eurodollar [Member] \| Minimum [Member] \| Term Loan [Member] \| Senior Credit Facilities [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.75%
Eurodollar [Member] \| Minimum [Member] \| Revolving Credit Facility [Member] \| Senior Credit Facilities [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Eurodollar [Member] \| Maximum [Member] \| Revolving Credit Facility [Member] \| Senior Credit Facilities [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.00%
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Derivative, Notional Amount				$ 500,000