Related Parties - Additional Information (Detail) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Rent and other lease-related expenses		$ 305,000,000	$ 284,000,000
Lease right-of-use assets	$ 876,000,000	0
Lease liabilities	898,000,000	0
Passport Research, Ltd [Member]
Related Party Transaction [Line Items]
Total fees waived	$ 0	0	0
Financial Advisor [Member]
Related Party Transaction [Line Items]
Percentage of branch office space leased from its financial advisors	10.00%
Lease cost	$ 34,000,000
Rent and other lease-related expenses		32,000,000	30,000,000
Financial Advisor [Member] \| Edward D. Jones & Co., L. P [Member]
Related Party Transaction [Line Items]
Lease right-of-use assets	83,000,000
Lease liabilities	83,000,000
BB Trust [Member] \| Olive Street [Member]
Related Party Transaction [Line Items]
Expense paid to sub-advisers	147,000,000	123,000,000	91,000,000
Investment advisory fee revenue	147,000,000	123,000,000	91,000,000
Edward Jones Money Market Fund [Member] \| Edward D. Jones & Co., L. P [Member]
Related Party Transaction [Line Items]
Total fees waived	30,000,000	30,000,000	22,000,000
Total fees earned	138,000,000	113,000,000	98,000,000
Edward Jones Money Market Fund [Member] \| Passport Research, Ltd [Member]
Related Party Transaction [Line Items]
Investment advisory fee revenue	$ 58,000,000	$ 48,000,000	$ 39,000,000

Percentage of branch office space leased from its financial advisors.

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Amount of fee contractually waived by investment company.

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Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

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Present value of lessee's discounted obligation for lease payments from operating lease.

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Amount of lessee's right to use underlying asset under operating lease.

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Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

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Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

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