Fair Value Measurement and Fair Value of Financial Instruments - Estimated Fair Values and Related Carrying Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Interest rate swap agreements
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carry value	$ 87	$ 1,163
Fair value	87	1,163
4.375% Senior Notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carry value	248,759	248,567
Fair value	$ 254,408	262,033
Stated interest rate (as a percent)	4.375%
3.45% Senior Notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carry value	$ 748,225	747,655
Fair value	$ 687,698	741,113
Stated interest rate (as a percent)	3.45%
Floating Rate Senior Notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carry value	$ 496,495	0
Fair value	501,065	0
Senior Notes due 2024
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carry value	742,616	0
Fair value	$ 745,350	0
Stated interest rate (as a percent)	4.15%
Senior Notes due 2028
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Carry value	$ 1,239,417	0
Fair value	$ 1,232,300	$ 0
Stated interest rate (as a percent)	4.70%

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

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))
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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

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-Publisher FASB
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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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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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No definition available.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Fair value portion of notes payable.

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