Reporting Segments and Related Information - Distribution of Total Assets and Operating Performance (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
TOTAL ASSETS	$ 150,783.1	$ 155,036.7	$ 183,889.8
TOTAL REVENUE	6,773.5	6,761.2	6,464.5
INCOME BEFORE INCOME TAXES	1,464.8	1,766.3	2,010.1
NET INCOME	$ 1,107.3	$ 1,336.0	$ 1,545.3
TOTAL ASSETS \| Geographic Concentration Risk
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%
TOTAL REVENUE \| Geographic Concentration Risk
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%
INCOME BEFORE INCOME TAXES \| Geographic Concentration Risk
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%
NET INCOME \| Geographic Concentration Risk
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%
Non-U.S.
Segment Reporting Information [Line Items]
TOTAL ASSETS	$ 39,661.5	$ 35,991.3	$ 38,555.3
TOTAL REVENUE	2,156.1	2,273.3	2,017.5
INCOME BEFORE INCOME TAXES	473.7	560.9	569.4
NET INCOME	$ 354.0	$ 420.2	$ 426.7
Non-U.S. \| TOTAL ASSETS \| Geographic Concentration Risk
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	26.00%	23.00%	21.00%
Non-U.S. \| TOTAL REVENUE \| Geographic Concentration Risk
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	32.00%	34.00%	31.00%
Non-U.S. \| INCOME BEFORE INCOME TAXES \| Geographic Concentration Risk
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	32.00%	32.00%	28.00%
Non-U.S. \| NET INCOME \| Geographic Concentration Risk
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	32.00%	31.00%	28.00%
U.S.
Segment Reporting Information [Line Items]
TOTAL ASSETS	$ 111,121.6	$ 119,045.4	$ 145,334.5
TOTAL REVENUE	4,617.4	4,487.9	4,447.0
INCOME BEFORE INCOME TAXES	991.1	1,205.4	1,440.7
NET INCOME	$ 753.3	$ 915.8	$ 1,118.6
U.S. \| TOTAL ASSETS \| Geographic Concentration Risk
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	74.00%	77.00%	79.00%
U.S. \| TOTAL REVENUE \| Geographic Concentration Risk
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	68.00%	66.00%	69.00%
U.S. \| INCOME BEFORE INCOME TAXES \| Geographic Concentration Risk
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	68.00%	68.00%	72.00%
U.S. \| NET INCOME \| Geographic Concentration Risk
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	68.00%	69.00%	72.00%

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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