Long-Term Debt - Narrative (Details)	6 Months Ended
Jun. 30, 2018 USD ($) rating_agency
Debt Instrument [Line Items]
Number of rating agencies \| rating_agency	2
2018 Unsecured notes \| Unsecured Debt
Debt Instrument [Line Items]
Debt instrument face amount	$ 1,600,000,000
2018 Unsecured notes \| Unsecured Debt \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (percent)	1.17%
3.4% 2018 unsecured notes \| Unsecured Debt
Debt Instrument [Line Items]
Debt instrument face amount	$ 600,000,000
Interest rate per annum (percent)	3.40%
Maturity date	Dec. 31, 2021
3.8% 2018 unsecured notes \| Unsecured Debt
Debt Instrument [Line Items]
Debt instrument face amount	$ 500,000,000
Interest rate per annum (percent)	3.80%
Maturity date	Dec. 31, 2023
4.375% 2018 unsecured notes \| Unsecured Debt
Debt Instrument [Line Items]
Debt instrument face amount	$ 500,000,000
Interest rate per annum (percent)	4.375%
Maturity date	Dec. 31, 2028
2018 Unsecured revolving credit facility \| Unsecured Debt
Debt Instrument [Line Items]
Line of credit borrowing capacity	$ 2,650,000,000
2018 Unsecured revolving credit facility \| Unsecured Debt \| Letters of Credit
Debt Instrument [Line Items]
Component of line of credit available for letters of credit	500,000,000
Three-year revolving credit facility 2018 \| Unsecured Debt
Debt Instrument [Line Items]
Line of credit borrowing capacity	$ 1,325,000,000
Debt instrument term	3 years
Five-year revolving credit facility 2018 \| Unsecured Debt
Debt Instrument [Line Items]
Line of credit borrowing capacity	$ 1,325,000,000
Debt instrument term	5 years
NYTDC Special Facilities Revenue Bonds, Series 2018 \| Bonds
Debt Instrument [Line Items]
Debt instrument face amount	$ 1,400,000,000

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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

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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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

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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-Subparagraph (SX 210.5-02.22(a)(2))
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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

The maximum amount of borrowing capacity under a line of credit that is available as of the balance sheet date for a specific purpose other than for financing goods acquired for inventory or imminent delivery to a customer.

+ References

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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