Employee Benefits - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) trust shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Total cost for retirement plans	$ 93.0	$ 91.0	$ 187.0
Settlement charge			113.0
Defined contribution plan cost	86.0	80.0	73.0
Pension trust assets	$ 2,231.0	2,243.0
U.S.
Defined Benefit Plan Disclosure [Line Items]
Number of pension trust accounts | trust	1
Pension trust assets	$ 1,600.0	$ 1,630.0
Stock purchased by US plan under defined contribution plan (shares) | shares	107,651	296,921
Stock sold by US plan under defined contribution plan (shares) | shares	160,415	331,088
Stock held by the US plan under defined contribution plan (shares) | shares	1,200,000	1,300,000
Market value of stock held by the US plan under defined contribution plan	$ 567.0	$ 414.0
S&P Global Inc. dividends received	$ 3.8	3.0
U.S. | Fixed income
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations	92.00%
U.S. | Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations	4.00%
U.S. | International equities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations	2.00%
U.S. | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations	2.00%
U.K.
Defined Benefit Plan Disclosure [Line Items]
Number of pension trust accounts | trust	1
Pension trust assets	$ 631.0	613.0
U.K. | Fixed income
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations	55.00%
U.K. | Diversified growth funds
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations	15.00%
U.K. | Infrastructure
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations	15.00%
U.K. | Equities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations	8.00%
U.K. | Real estate
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations	7.00%
Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Other components of net periodic benefit cost	$ (36.0)	(26.0)	84.0
Settlement charge	(2.0)	(2.0)	(85.0)
Expected required employer contribution	$ 11.0
Number of pension trust accounts | trust	2
Pension trust assets	$ 2,231.0	2,243.0	1,960.0
Retirement Plans | U.K.
Defined Benefit Plan Disclosure [Line Items]
Other components of net periodic benefit cost	(22.0)	(17.0)	(14.0)
Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Other components of net periodic benefit cost	(2.0)	(2.0)	(2.0)
Settlement charge	0.0	0.0	0.0
Expected required employer contribution	3.0
Pension trust assets	$ 6.0	$ 9.0	$ 13.0