Schedule I - Condensed Statements of Cash Flow (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 24, 2016	Mar. 25, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income									$ 0	$ 0	$ 0
Adjustments to reconcile net income to net cash provided by operating activities:
Income before allocations to partners	$ 239	$ 211	$ 225	$ 197	$ 161	$ 186	$ 208	$ 191	872	746	838
Changes in assets and liabilities:
Accounts payable and accrued expenses									4	(20)	19
Net cash provided by operating activities									590	905	444
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of partnership interests									80	72	352
Redemption of partnership interests									(193)	(178)	(161)
Distributions from partnership capital									(598)	(616)	(637)
Net cash used in financing activities									(711)	(722)	(446)
Net (decrease) increase in cash and cash equivalents									(201)	110	(96)
CASH AND CASH EQUIVALENTS:
Beginning of year				1,047				937	1,047	937	1,033
End of year	846				1,047				846	1,047	937
NON-CASH ACTIVITIES:
Issuance of general partnership interests through partnership loans in current year									142	146	119
Repayment of partnership loans through distributions from partnership capital in current year									111	98	99
Parent Company [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income									0	0	0
Adjustments to reconcile net income to net cash provided by operating activities:
Income before allocations to partners									872	746	838
Changes in assets and liabilities:
Investment in subsidiaries									(312)	105	(179)
Investment securities									2	0	0
Other assets									0	(4)	0
Accounts payable and accrued expenses									1	0	(1)
Net cash provided by operating activities									563	847	658
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of partnership interests									80	72	352
Redemption of partnership interests									(193)	(178)	(161)
Distributions from partnership capital									(598)	(616)	(637)
Net cash used in financing activities									(711)	(722)	(446)
Net (decrease) increase in cash and cash equivalents									(148)	125	212
CASH AND CASH EQUIVALENTS:
Beginning of year				$ 456				$ 331	456	331	119
End of year	$ 308				$ 456				308	456	331
NON-CASH ACTIVITIES:
Issuance of general partnership interests through partnership loans in current year									142	146	119
Repayment of partnership loans through distributions from partnership capital in current year									111	98	99
Declaration of distributions from subsidiary in current year but received after year end									$ 129	$ 0	$ 0