Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
Dec. 31, 2015 USD ($) Segment Capital_Repayment CapitalClass	Dec. 31, 2014 USD ($) Segment	Dec. 31, 2013 USD ($) Segment
Basis Of Presentation [Line Items]
Number of operating segments \| Segment	2	2	2
Period for partner's capital redemption in the event of death	6 months
Number of annual capital repayments for withdrawal of limited partners \| Segment	3
Period to begin repaying capital upon withdrawal for limited partners	90 days
Number of annual capital repayments for withdrawal of subordinated limited partners \| Capital_Repayment	6
Period to begin repaying capital upon withdrawal for subordinated limited partners	90 days
Partnership's total revenue derived from one mutual fund company	20.00%	20.00%	19.00%
Fair value of level III, assets	$ 0	$ 0
Fair value of level III, liabilities	0	0
Transfers between levels I, II and III	0	0
Fair value of collateral related to resell agreements	$ 858,000,000	644,000,000
Retirement and transition employment agreement term	5 years
Retirement transition plan employment term	2 years
Retirement transition plan non-compete term	3 years
Retirement transition plan compensation paid term	4 years
Retirement transition plan compensation expense term	2 years
Retirement transition plan accrued future payments	$ 35,000,000
Net income	$ 0	$ 0	$ 0
Number of classes of capital \| CapitalClass	3
Limited Partnership's minimum annual return rate	7.50%	7.50%	7.50%
Building [Member]
Basis Of Presentation [Line Items]
Equipment, property and improvements estimated useful lives	30 years
Minimum [Member] \| Equipment [Member]
Basis Of Presentation [Line Items]
Equipment, property and improvements estimated useful lives	3 years
Minimum [Member] \| United States [Member]
Basis Of Presentation [Line Items]
Fair value of underlying collateral as percentage of carrying value of transaction	102.00%	102.00%
Minimum [Member] \| Canada [Member]
Basis Of Presentation [Line Items]
Fair value of underlying collateral as percentage of carrying value of transaction	100.00%	100.00%
Maximum [Member] \| Equipment [Member]
Basis Of Presentation [Line Items]
Equipment, property and improvements estimated useful lives	7 years
Securities Purchase Agreement [Member] \| Minimum [Member] \| United States [Member]
Basis Of Presentation [Line Items]
Fair value of underlying collateral as percentage of carrying value of transaction	102.00%
Securities Purchase Agreement [Member] \| Minimum [Member] \| Canada [Member]
Basis Of Presentation [Line Items]
Fair value of underlying collateral as percentage of carrying value of transaction	100.00%

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