Debt - Summary of Debt (Detail) - USD ($)		Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	May 31, 2023	Mar. 31, 2022	Mar. 31, 2020	Oct. 31, 2018	Mar. 31, 2018	Apr. 30, 2017	Aug. 31, 2016	Jan. 31, 2015	Apr. 30, 2014	Nov. 30, 2002	Mar. 31, 1999
Debt Instrument [Line Items]
Debt	[1]	$ 6,890,700,000	$ 6,888,600,000	$ 6,886,500,000
Fair value		6,165,500,000	6,431,300,000	6,224,000,000
2.45% Senior Notes due 2027 (issued: $500.0, August 2016)
Debt Instrument [Line Items]
Long-term debt		498,800,000	498,600,000	498,400,000
Fair value		468,800,000	468,900,000	459,400,000
Debt, stated interest rate											2.45%
Debt, face amount											$ 500,000,000.0
2.50% Senior Notes due 2027 (issued: $500.0, March 2022)
Debt Instrument [Line Items]
Long-term debt		498,400,000	498,100,000	497,800,000
Fair value		468,000,000.0	469,100,000	458,400,000
Debt, stated interest rate						2.50%
Debt, face amount						$ 500,000,000.0
6 5/8% Senior Notes due 2029 (issued: $300.0, March 1999)
Debt Instrument [Line Items]
Long-term debt		298,000,000.0	297,800,000	297,600,000
Fair value		320,900,000	328,700,000	324,200,000
Debt, stated interest rate															6.625%
Debt, face amount															$ 300,000,000.0
4.00% Senior Notes due 2029 (issued: $550.0, October 2018)
Debt Instrument [Line Items]
Long-term debt		547,200,000	546,900,000	546,700,000
Fair value		526,700,000	542,600,000	526,400,000
Debt, stated interest rate								4.00%
Debt, face amount								$ 550,000,000.0
3.20% Senior Notes due 2030 (issued: $500.0, March 2020)
Debt Instrument [Line Items]
Long-term debt		497,500,000	497,300,000	497,100,000
Fair value		455,400,000	462,200,000	449,200,000
Debt, stated interest rate							3.20%
Debt, face amount							$ 500,000,000.0
3.00% Senior Notes due 2032 (issued: $500.0, March 2022)
Debt Instrument [Line Items]
Long-term debt		496,500,000	496,300,000	496,100,000
Fair value		433,700,000	446,000,000.0	434,500,000
Debt, stated interest rate						3.00%
Debt, face amount						$ 500,000,000.0
6.25% Senior Notes due 2032 (issued: $400.0, November 2002)
Debt Instrument [Line Items]
Long-term debt		396,800,000	396,700,000	396,600,000
Fair value		428,100,000	445,600,000	432,000,000.0
Debt, stated interest rate														6.25%
Debt, face amount														$ 400,000,000.0
4.95% Senior Notes due 2033 (issued: $500.0, May 2023)
Debt Instrument [Line Items]
Long-term debt		496,600,000	496,400,000	496,300,000
Fair value		494,600,000	513,000,000.0	489,900,000
Debt, stated interest rate					4.95%
Debt, face amount					$ 500,000,000.0
4.35% Senior Notes due 2044 (issued: $350.0, April 2014)
Debt Instrument [Line Items]
Long-term debt		347,000,000.0	347,000,000.0	346,900,000
Fair value		301,100,000	314,200,000	304,000,000.0
Debt, stated interest rate													4.35%
Debt, face amount													$ 350,000,000.0
3.70% Senior Notes due 2045 (issued: $400.0, January 2015)
Debt Instrument [Line Items]
Long-term debt		395,900,000	395,900,000	395,800,000
Fair value		309,800,000	325,100,000	313,600,000
Debt, stated interest rate												3.70%
Debt, face amount												$ 400,000,000.0
4.125% Senior Notes due 2047 (issued: $850.0, April 2017)
Debt Instrument [Line Items]
Long-term debt		842,400,000	842,300,000	842,200,000
Fair value		698,700,000	756,200,000	727,000,000.0
Debt, stated interest rate										4.125%
Debt, face amount										$ 850,000,000.0
4.20% Senior Notes due 2048 (issued: $600.0, March 2018)
Debt Instrument [Line Items]
Long-term debt		590,700,000	590,600,000	590,500,000
Fair value		493,900,000	534,100,000	510,300,000
Debt, stated interest rate									4.20%
Debt, face amount									$ 600,000,000.0
3.95% Senior Notes due 2050 (issued: $500.0, March 2020)
Debt Instrument [Line Items]
Long-term debt		491,200,000	491,100,000	491,000,000.0
Fair value		392,400,000	422,300,000	408,400,000
Debt, stated interest rate							3.95%
Debt, face amount							$ 500,000,000.0
3.70% Senior Notes due 2052 (issued: $500.0, March 2022)
Debt Instrument [Line Items]
Long-term debt		493,700,000	493,600,000	493,500,000
Fair value		$ 373,400,000	$ 403,300,000	$ 386,700,000
Debt, stated interest rate						3.70%
Debt, face amount						$ 500,000,000.0

[1] Consists of long-term debt. See Note 4 – Debt for further discussion.