Schedule I - Condensed Statements of Cash Flow (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 31, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
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	$ 244	$ 273	$ 240	$ 233	$ 239	$ 211	$ 225	$ 197	990	872	746
Changes in assets and liabilities:
Other assets									(14)
Accounts payable and accrued expenses									26	4	(20)
Net cash provided (used in) by operating activities									1,138	(244)	2,460
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of partnership interests									60	80	72
Redemption of partnership interests									(199)	(193)	(178)
Distributions from partnership capital									(694)	(598)	(616)
Net cash used in financing activities									(833)	(711)	(722)
Net increase (decrease) in cash, cash equivalents and restricted cash									200	(1,035)	1,665
CASH AND CASH EQUIVALENTS:
Beginning of year				8,537				9,572	8,537	9,572	7,907
End of year	8,737				8,537				8,737	8,537	9,572
NON-CASH ACTIVITIES:
Issuance of general partnership interests through partnership loans in current year									170	142	146
Repayment of partnership loans through distributions from partnership capital in current year									135	111	98
Declared distributions for retired partnership capital in current year but paid after year end									97
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									990	872	746
Changes in assets and liabilities:
Investment in subsidiaries									(134)	(312)	105
Investment securities									0	2	0
Other assets									(14)	0	(4)
Accounts payable and accrued expenses									1	1	0
Net cash provided (used in) by operating activities									843	563	847
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of partnership interests									60	80	72
Redemption of partnership interests									(199)	(193)	(178)
Distributions from partnership capital									(694)	(598)	(616)
Net cash used in financing activities									(833)	(711)	(722)
Net increase (decrease) in cash, cash equivalents and restricted cash									10	(148)	125
CASH AND CASH EQUIVALENTS:
Beginning of year				$ 308				$ 456	308	456	331
End of year	$ 318				$ 308				318	308	456
NON-CASH ACTIVITIES:
Issuance of general partnership interests through partnership loans in current year									170	142	146
Repayment of partnership loans through distributions from partnership capital in current year									135	111	98
Declaration of distributions from subsidiary in current year but received after year end									56	129	0
Declared distributions for retired partnership capital in current year but paid after year end									$ 97	$ 0	$ 0