Indebtedness - Additional Information (Details)																				3 Months Ended		6 Months Ended		12 Months Ended
		Dec. 31, 2017 USD ($)	Dec. 12, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jul. 01, 2017 USD ($)	Jun. 15, 2017 USD ($)	May 23, 2017 USD ($)	May 08, 2017 USD ($)	Apr. 01, 2017 USD ($)	Sep. 26, 2016 USD ($)	Mar. 15, 2016 USD ($)	Mar. 07, 2016 USD ($)	Dec. 09, 2015 USD ($)	Apr. 08, 2015 EUR (€)	Apr. 08, 2015 USD ($)	Mar. 30, 2015 EUR (€)	Mar. 30, 2015 USD ($)	Dec. 05, 2014 USD ($)	Dec. 02, 2014 USD ($)	Dec. 31, 2017 USD ($)	Jul. 01, 2017 USD ($)	Dec. 31, 2015 USD ($)	Dec. 27, 2014 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 27, 2015 USD ($)	Mar. 30, 2015 USD ($)	Dec. 05, 2014 EUR (€)	Dec. 05, 2014 USD ($)	Nov. 08, 2013 USD ($)	Sep. 06, 2013 USD ($)
Debt Instrument [Line Items]
Debt instrument, issuance date												Mar. 07, 2016	Dec. 09, 2015					Dec. 05, 2014
Repayments of debt																								$ 2,611,000,000
Revolving credit agreements		$ 0																		$ 0				0	$ 0	$ 680,000,000
Extinguishment of debt										$ 500,000,000								$ 895,000,000
Loans payable																										300,000,000					$ 1,000,000,000
Loss on extinguishment of debt																					$ 135,200,000	$ 900,000	$ 9,600,000	135,200,000	1,100,000	10,500,000
Senior notes		2,906,000,000																		2,906,000,000				2,906,000,000	5,373,100,000	4,698,300,000				$ 2,300,000,000
Line of credit facility, fair value of amount outstanding		6,900,000																		6,900,000		$ 82,900,000		6,900,000	0
2015 Revolver
Debt Instrument [Line Items]
Debt instrument, face amount													$ 750,000,000
Repayments of debt											$ 750,000,000
Revolving credit agreements		0																		0				0	0	380,000,000
2014 Revolver
Debt Instrument [Line Items]
Debt instrument, face amount																													$ 600,000,000
Repayments of debt											$ 435,000,000
Revolving credit agreements		$ 0																		$ 0				0	0	300,000,000
Line of credit facility, maximum borrowing capacity																											$ 1,000,000,000
2014 Euro-Denominated Term Loan due December 5, 2019
Debt Instrument [Line Items]
Debt instrument, date of repayment		Dec. 31, 2017		Sep. 30, 2017	Jul. 01, 2017				Apr. 01, 2017											Dec. 31, 2017
Debt instrument, face amount																												€ 500,000,000	614,300,000
Repayments of debt		$ 15,000,000		$ 14,800,000	$ 14,300,000				$ 13,300,000
Loans payable	[1]	$ 420,000,000																		$ 420,000,000				$ 420,000,000	420,700,000	488,800,000
Debt instrument, description																								2014 term loan due December 5, 2019
Debt instrument, transaction type					Scheduled quarterly payment				Scheduled quarterly payment
5.125% Senior note due 2017
Debt Instrument [Line Items]
Debt instrument, date of repayment			Dec. 12, 2017
Repayments of debt			$ 352,300,000
Debt instrument, description			€300.0 5.125% senior notes due 2017
Debt instrument, transaction type			Scheduled maturity
2014 Euro-Denominated Term Loan due December 5, 2019 additional draw
Debt Instrument [Line Items]
Debt instrument, face amount																												€ 300,000,000	$ 368,600,000
3.500% Unsecured Senior notes due March 15, 2021
Debt Instrument [Line Items]
Debt instrument, date of repayment						Jun. 15, 2017
Debt instrument, face amount												$ 500,000,000.0
Repayments of debt						$ 219,600,000
Interest rate, stated percentage		3.50%										3.50%								3.50%				3.50%
Senior notes	[2]	$ 280,400,000																		$ 280,400,000				$ 280,400,000	500,000,000	0
Maturity date																								Mar. 15, 2021
Debt instrument, description						$500.0 3.500% senior notes due 2021
Debt instrument, transaction type						Tender offer
4.375% senior note due March 15, 2026
Debt Instrument [Line Items]
Debt instrument, face amount												$ 700,000,000.0
Interest rate, stated percentage		4.375%										4.375%								4.375%				4.375%
Senior notes	[2]	$ 700,000,000																		$ 700,000,000				$ 700,000,000	700,000,000	0
Maturity date																								Mar. 15, 2026
Debt securities
Debt Instrument [Line Items]
Senior notes												$ 1,200,000,000
4.5% Retail Bond
Debt Instrument [Line Items]
Debt instrument, date of repayment							May 23, 2017
Repayments of debt							$ 201,300,000
Debt instrument, description							€180.0 4.500% retail bonds due 2017
Debt instrument, transaction type							Scheduled maturity
3.5% Senior note due 2021
Debt Instrument [Line Items]
Debt instrument, date of repayment						Jun. 15, 2017
Debt instrument, issuance date																			Dec. 02, 2014
Debt instrument, face amount																			$ 500,000,000
Repayments of debt						$ 190,400,000
Interest rate, stated percentage		3.50%																	3.50%	3.50%				3.50%
Senior notes	[3]	$ 309,600,000																		$ 309,600,000				$ 309,600,000	500,000,000	500,000,000
Maturity date																			Jan. 01, 2021					Dec. 15, 2021
Debt instrument, description						$500.0 3.500% senior notes due 2021
Debt instrument, transaction type						Tender offer
3.9% senior note due 2024
Debt Instrument [Line Items]
Debt instrument, face amount																			$ 700,000,000
Interest rate, stated percentage		3.90%																	3.90%	3.90%				3.90%
Senior notes	[3]	$ 700,000,000																		$ 700,000,000				$ 700,000,000	700,000,000	700,000,000
Maturity date																			Jan. 01, 2024					Dec. 15, 2024
4.9% Senior Loan due 2044
Debt Instrument [Line Items]
Debt instrument, date of repayment						Jun. 15, 2017
Debt instrument, face amount																			$ 400,000,000
Repayments of debt						$ 96,100,000
Interest rate, stated percentage		4.90%																	4.90%	4.90%				4.90%
Senior notes	[3]	$ 303,900,000																		$ 303,900,000				$ 303,900,000	400,000,000	400,000,000
Maturity date																			Jan. 01, 2044					Dec. 15, 2044
Debt instrument, description						$400.0 4.900% senior notes due 2044
Debt instrument, transaction type						Tender offer
2014 bonds [Member]
Debt Instrument [Line Items]
Senior notes																			$ 1,600,000,000
1.30% Unsecured Senior Notes due November 8, 2016
Debt Instrument [Line Items]
Debt instrument, face amount																														$ 500,000,000.000
Interest rate, stated percentage		1.30%								1.30%										1.30%				1.30%						1.30%
Senior notes	[4]	$ 0																		$ 0				$ 0	0	500,000,000
Maturity date																								Nov. 08, 2016
2.30% Unsecured Senior notes November 8, 2018
Debt Instrument [Line Items]
Debt instrument, date of repayment								May 08, 2017
Debt instrument, face amount																														$ 600,000,000.000
Repayments of debt								$ 600,000,000
Interest rate, stated percentage		2.30%																		2.30%				2.30%						2.30%
Senior notes	[4]	$ 0																		$ 0				$ 0	600,000,000	600,000,000
Maturity date																								Nov. 08, 2018
Debt instrument, description								$600.0 2.300% senior notes due 2018
Debt instrument, transaction type								Early redemption
4.00% Unsecured Senior Notes due November 15, 2023
Debt Instrument [Line Items]
Debt instrument, date of repayment						Jun. 15, 2017
Debt instrument, face amount																														$ 800,000,000.000
Repayments of debt						$ 584,400,000															584,400,000
Interest rate, stated percentage		4.00%																		4.00%				4.00%						4.00%
Senior notes	[4]	$ 215,600,000																		$ 215,600,000				$ 215,600,000	800,000,000	800,000,000
Maturity date																								Nov. 15, 2023
Debt instrument, description						$800.0 4.000% senior notes due 2023
Debt instrument, transaction type						Tender offer
5.30% Unsecured Senior Notes due November 15, 2043
Debt Instrument [Line Items]
Debt instrument, date of repayment						Jun. 15, 2017
Debt instrument, face amount																														$ 400,000,000.000
Repayments of debt						$ 309,500,000															$ 309,500,000
Interest rate, stated percentage		5.30%																		5.30%				5.30%						5.30%
Senior notes	[4]	$ 90,500,000																		$ 90,500,000				$ 90,500,000	$ 400,000,000	$ 400,000,000
Maturity date																								Nov. 15, 2043
Debt instrument, description						$400.0 5.300% senior notes due 2043
Debt instrument, transaction type						Tender offer
2013 Term Loan due December 18, 2018
Debt Instrument [Line Items]
Loans payable																															700,000,000.000
2013 Term Loan due December 18, 2015
Debt Instrument [Line Items]
Loans payable																															$ 300,000,000.000
Omega
Debt Instrument [Line Items]
Extinguishment of debt														€ 500,000,000	$ 539,100,000
Long-term debt																											1,471,000,000
Omega | 6.19% Senior Note
Debt Instrument [Line Items]
Business combination, current liabilities, long-term debt																											$ 20,000,000.0
Interest rate, stated percentage																6.19%											6.19%
Maturity date																Jan. 01, 2016	Jan. 01, 2016
Omega | 5.1045% Senior Note
Debt Instrument [Line Items]
Interest rate, stated percentage																5.1045%											5.1045%
Maturity date																Jan. 01, 2023	Jan. 01, 2023
Long-term debt																€ 135,000,000.0											$ 147,000,000
Omega | 5.125% Retail Bond
Debt Instrument [Line Items]
Business combination, current liabilities, long-term debt																€ 300,000,000											$ 326,700,000
Interest rate, stated percentage																5.125%											5.125%
Maturity date																Jan. 01, 2017	Jan. 01, 2017
Omega | 4.5% Retail Bond
Debt Instrument [Line Items]
Business combination, current liabilities, long-term debt																€ 180,000,000											$ 196,000,000
Interest rate, stated percentage																4.50%											4.50%
Maturity date																Jan. 01, 2017	Jan. 01, 2017
Omega | 5.0% Retail Bond [Member]
Debt Instrument [Line Items]
Business combination, current liabilities, long-term debt																€ 120,000,000											$ 130,700,000
Interest rate, stated percentage																5.00%											5.00%
Maturity date																Jan. 01, 2019	Jan. 01, 2019
Omega | Credit facility indebtedness
Debt Instrument [Line Items]
Business combination, current liabilities, long-term debt																€ 500,000,000											$ 544,500,000
Omega | Over Draft
Debt Instrument [Line Items]
Business combination, current liabilities, long-term debt																51,400,000											$ 56,000,000
Omega
Debt Instrument [Line Items]
Amount debt exceeded par value																€ 93,600,000	$ 101,900,000

[1] Debt denominated in euros subject to fluctuations in the euro-to-U.S. dollar exchange rate.

[2] Discussed below collectively as the "2016 Notes."

[3] Discussed below collectively as the "2014 Notes."

[4] Discussed below collectively as the "2013 Notes."