Long-Term Debt - Long-Term Debt Instrument (Additional Information) (Detail)	6 Months Ended	12 Months Ended
Jun. 30, 2015	Dec. 31, 2014
5.370% senior notes, Series D, quarterly interest payments, balloon due 2015
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	5.37%	5.37%
Debt instrument maturity year	2015	2015
5.660% senior notes, Series C, semi-annual interest payments, balloon due 2016
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	5.66%	5.66%
Debt instrument maturity year	2016	2016
4.500% senior notes, Series E, quarterly interest payments, balloon due 2018
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	4.50%	4.50%
Debt instrument maturity year	2018	2018
4.200% senior notes, semi-annual interest payments, balloon due 2024
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	4.20%	4.20%
Debt instrument maturity year	2024	2024
5-year term-loan facility, periodic interest and principal payments, currently LIBOR plus 1.375%, expires May 20, 2019
Debt Instrument [Line Items]
Line of credit facility, expiration period	5 years	5 years
Line of credit facility, expiration date	May 20, 2019	May 20, 2019
5-year term-loan facility, periodic interest and principal payments, currently LIBOR plus 1.375%, expires May 20, 2019 \| LIBOR
Debt Instrument [Line Items]
Debt instrument, variable interest rate	1.375%	1.375%
5-year revolving-loan facility, periodic interest payments, currently LIBOR plus 1.175%, plus commitment fees of 0.20%, expires May 20, 2019
Debt Instrument [Line Items]
Line of credit facility, expiration period	5 years	5 years
Line of credit facility, commitment fee percentage	0.20%	0.20%
Line of credit facility, expiration date	May 20, 2019	May 20, 2019
5-year revolving-loan facility, periodic interest payments, currently LIBOR plus 1.175%, plus commitment fees of 0.20%, expires May 20, 2019 \| LIBOR
Debt Instrument [Line Items]
Debt instrument, variable interest rate	1.175%	1.175%
Revolving credit loan, quarterly interest payments, LIBOR plus up to 1.40% and availability fee up to 0.25%, expires December 31, 2016
Debt Instrument [Line Items]
Line of credit facility, expiration date	Dec. 31, 2016	Dec. 31, 2016
Maximum \| Revolving credit loan, quarterly interest payments, LIBOR plus up to 1.40% and availability fee up to 0.25%, expires December 31, 2016
Debt Instrument [Line Items]
Line of credit facility, commitment fee percentage	0.25%	0.25%
Maximum \| Revolving credit loan, quarterly interest payments, LIBOR plus up to 1.40% and availability fee up to 0.25%, expires December 31, 2016 \| LIBOR
Debt Instrument [Line Items]
Debt instrument, variable interest rate	1.40%	1.40%

Debt Instruments Maturity Year

No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

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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- Definition

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.

+ References

No definition available.

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- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ 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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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