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Long-Term Debt - Schedule of Long-Term Debt (Details) - USD ($)	Dec. 31, 2018	Oct. 01, 2018	Aug. 28, 2018	Dec. 31, 2017	Dec. 19, 2016	Dec. 07, 2015	Jun. 06, 2013	Nov. 21, 2012	Sep. 30, 2009
Debt Instrument [Line Items]
Total debt	$ 4,941,700,000			$ 5,155,500,000
Less current portion	1,500,000			800,900,000
Long-term debt	4,940,200,000			4,354,600,000
$800 2.050% senior notes due 2018
Debt Instrument [Line Items]
Face amount of debt				$ 800,000,000
Interest rate		2.05%		2.05%
$500 6.250% senior notes due 2019
Debt Instrument [Line Items]
Face amount of debt				$ 500,000,000
Interest rate				6.25%
$600 3.000% senior notes due 2020
Debt Instrument [Line Items]
Face amount of debt	$ 600,000,000
Interest rate	3.00%
$500 2.800% senior notes due 2021
Debt Instrument [Line Items]
Face amount of debt	$ 500,000,000
Interest rate	2.80%
$500 3.125% senior notes due 2022
Debt Instrument [Line Items]
Face amount of debt	$ 500,000,000
Interest rate	3.125%
$700 3.650% senior notes due 2023
Debt Instrument [Line Items]
Face amount of debt	$ 700,000,000
Interest rate	3.65%
$300 3.850% senior notes due 2025
Debt Instrument [Line Items]
Face amount of debt	$ 300,000,000
Interest rate	3.85%
$700 3.800% senior notes due 2026
Debt Instrument [Line Items]
Face amount of debt	$ 700,000,000
Interest rate	3.80%
$800 4.200% senior notes due 2028
Debt Instrument [Line Items]
Face amount of debt	$ 800,000,000
Interest rate	4.20%
Other
Debt Instrument [Line Items]
Face amount of debt	$ 3,000,000
Credit facility \| 2016 Facility
Debt Instrument [Line Items]
Long-term debt	865,000,000			$ 1,270,000,000
Senior notes
Debt Instrument [Line Items]
Less unamortized debt issuance costs	(26,300,000)			(17,600,000)
Face amount of debt	4,100,000,000
Senior notes \| $800 2.050% senior notes due 2018
Debt Instrument [Line Items]
Long-term debt	0			800,000,000
Face amount of debt							$ 800,000,000
Interest rate							2.05%
Senior notes \| $500 6.250% senior notes due 2019
Debt Instrument [Line Items]
Long-term debt	0			500,000,000
Face amount of debt									$ 500,000,000
Interest rate									6.25%
Senior notes \| $600 3.000% senior notes due 2020
Debt Instrument [Line Items]
Long-term debt	600,000,000			600,000,000
Face amount of debt						$ 600,000,000
Interest rate						3.00%
Senior notes \| $500 2.800% senior notes due 2021
Debt Instrument [Line Items]
Long-term debt	500,000,000			500,000,000
Face amount of debt					$ 500,000,000
Interest rate					2.80%
Senior notes \| $500 3.125% senior notes due 2022
Debt Instrument [Line Items]
Long-term debt	500,000,000			500,000,000
Face amount of debt								$ 500,000,000
Interest rate								3.125%
Senior notes \| $700 3.650% senior notes due 2023
Debt Instrument [Line Items]
Long-term debt	700,000,000			0
Face amount of debt			$ 700,000,000.0
Interest rate			3.65%
Senior notes \| $300 3.850% senior notes due 2025
Debt Instrument [Line Items]
Long-term debt	300,000,000			300,000,000
Face amount of debt						$ 300,000,000
Interest rate						3.85%
Senior notes \| $700 3.800% senior notes due 2026
Debt Instrument [Line Items]
Long-term debt	700,000,000			700,000,000
Face amount of debt					$ 700,000,000
Interest rate					3.80%
Senior notes \| $800 4.200% senior notes due 2028
Debt Instrument [Line Items]
Long-term debt	800,000,000			0
Face amount of debt			$ 800,000,000.0
Interest rate			4.20%
Senior notes \| Other
Debt Instrument [Line Items]
Long-term debt	$ 3,000,000			$ 3,100,000