Partnership Capital - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 29, 2018	Jun. 30, 2017	Jun. 29, 2018	Jun. 30, 2017	Jan. 12, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 17, 2014
Partners Capital Account [Line Items]
Period of loans made by Partnership to general partners			1 year
Outstanding amount of partner loans financed through the Partnership	$ 353	$ 315	$ 353	$ 315		$ 297	$ 266
Interest income from outstanding amount of general partner loan	$ 4	$ 3	$ 8	$ 6
Limited partnership's minimum annual payment rate	7.50%	7.50%	7.50%	7.50%
Limited partnership's minimum return, value	$ 16	$ 17	$ 33	$ 34
2014 Limited Partnership Offering [Member]
Partners Capital Account [Line Items]
Limited partnership amount registered								$ 350
Limited partnership interests issued	$ 298		$ 298
2018 Limited Partnership Offering [Member]
Partners Capital Account [Line Items]
Limited partnership amount registered					$ 450