Indebtedness - Summary of Total Indebtedness (Detail) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Summary of Total Indebtedness [Abstract]
Principal Amount	$ 5,399.4	$ 5,721.6
Fair Value of Interest Rate Swap	32.8	2.2
Unamortized (Discount) Premium	(16.1)	(17.3)
Unamortized Debt Issuance Costs	(28.2)	(30.5)
Total Debt	5,387.9
Current portion	(129.9)
Carrying Amount	5,258.0	5,676.0
Current portion of long-term debt		(449.9)
Total long-term debt, non-current	5,258.0	5,226.1
Commercial Paper [Member]
Summary of Total Indebtedness [Abstract]
Principal Amount	130.0
Unamortized (Discount) Premium	(0.1)
Total Debt	129.9
5.50% 2010 Senior Notes, due 2020 [Member]
Summary of Total Indebtedness [Abstract]
Principal Amount	500.0	500.0
Fair Value of Interest Rate Swap	2.3	(3.7)
Unamortized (Discount) Premium	(0.5)	(0.6)
Unamortized Debt Issuance Costs	(0.5)	(0.7)
Carrying Amount	501.3	495.0
4.50% 2012 Senior Notes, due 2022 [Member]
Summary of Total Indebtedness [Abstract]
Principal Amount	500.0	500.0
Fair Value of Interest Rate Swap	10.1	1.9
Unamortized (Discount) Premium	(1.4)	(1.6)
Unamortized Debt Issuance Costs	(1.2)	(1.4)
Carrying Amount	507.5	498.9
4.875% 2013 Senior Notes, due 2024 [Member]
Summary of Total Indebtedness [Abstract]
Principal Amount	500.0	500.0
Unamortized (Discount) Premium	(1.4)	(1.5)
Unamortized Debt Issuance Costs	(1.8)	(2.0)
Carrying Amount	496.8	496.5
2.75% 2014 Senior Notes (5-Year), due 2019 [Member]
Summary of Total Indebtedness [Abstract]
Principal Amount		450.0
Unamortized (Discount) Premium		(0.1)
Carrying Amount		449.9
5.25% 2014 Senior Notes (30-Year), due 2044 [Member]
Summary of Total Indebtedness [Abstract]
Principal Amount	600.0	600.0
Unamortized (Discount) Premium	3.2	3.2
Unamortized Debt Issuance Costs	(5.4)	(5.5)
Carrying Amount	597.8	597.7
1.75% 2015 Senior Notes, due 2027 [Member]
Summary of Total Indebtedness [Abstract]
Principal Amount	569.4	571.6
Unamortized Debt Issuance Costs	(2.9)	(3.1)
Carrying Amount	566.5	568.5
2.75% 2017 Senior Notes, due 2021 [Member]
Summary of Total Indebtedness [Abstract]
Principal Amount	500.0	500.0
Fair Value of Interest Rate Swap	13.1	4.0
Unamortized (Discount) Premium	(0.8)	(1.0)
Unamortized Debt Issuance Costs	(2.0)	(2.4)
Carrying Amount	510.3	500.6
2.625% 2017 Notes, due 2023 [Member]
Summary of Total Indebtedness [Abstract]
Principal Amount	500.0	500.0
Fair Value of Interest Rate Swap	7.3
Unamortized (Discount) Premium	(0.8)	(0.9)
Unamortized Debt Issuance Costs	(2.6)	(2.8)
Carrying Amount	503.9	496.3
3.25% 2017 Notes, due 2028 [Member]
Summary of Total Indebtedness [Abstract]
Principal Amount	500.0	500.0
Unamortized (Discount) Premium	(4.5)	(4.7)
Unamortized Debt Issuance Costs	(3.5)	(3.7)
Carrying Amount	492.0	491.6
3.25% 2018 Notes, due 2021 [Member]
Summary of Total Indebtedness [Abstract]
Principal Amount	300.0	300.0
Unamortized (Discount) Premium	(0.3)	(0.4)
Unamortized Debt Issuance Costs	(1.2)	(1.5)
Carrying Amount	298.5	298.1
4.25% 2018 Notes, due 2029 [Member]
Summary of Total Indebtedness [Abstract]
Principal Amount	400.0	400.0
Unamortized (Discount) Premium	(2.9)	(3.0)
Unamortized Debt Issuance Costs	(3.1)	(3.3)
Carrying Amount	394.0	393.7
4.875% 2018 Notes, due 2048 [Member]
Summary of Total Indebtedness [Abstract]
Principal Amount	400.0	400.0
Unamortized (Discount) Premium	(6.6)	(6.7)
Unamortized Debt Issuance Costs	(4.0)	(4.1)
Carrying Amount	$ 389.4	$ 389.2

Amount of short-term debt and current maturity of long-term debt and capital lease obligations due within one year or the normal operating cycle, if longer.

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