Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Compensation And Retirement Disclosure [Abstract]
Partnership's contribution to compensation plans	$ 213	$ 197	$ 178
Amount withheld for contribution to compensation plans	$ 32

Defined contribution plan amount withheld in future mandatory profit sharing contributions from service partners.

No definition available.

Name:	ck0000815917_DefinedContributionPlanAmountWithheldInFutureMandatoryProfitSharingContributionsFromServicePartners
Namespace Prefix:	ck0000815917_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant