Leases - Summary of Future Minimum Lease Payments For Noncancelable Operating And Financing Leases (Detail) - USD ($) $ in Thousands	Sep. 29, 2019	Dec. 31, 2018	Dec. 30, 2018
Lessee Disclosure [Line Items]
Operating Leases, Remainder of 2019	$ 4,556
Operating Leases, 2020	19,387
Operating Leases, 2021	17,386
Operating Leases, 2022	13,965
Operating Leases, 2023	11,702
Operating Leases, Thereafter	78,543
Total operating leases including interest	145,539
Less: Amounts representing interest	28,726
Present value of minimum lease principal payments	116,813	$ 88,200
Less: Current portion of lease liabilities - operating leases	14,929
Noncurrent portion of lease liabilities - operating leases	101,884
Financing Leases, Remainder of 2019	2,612
Financing Leases, 2020	10,611
Financing Leases, 2021	6,215
Financing Leases, 2022	2,694
Financing Leases, 2023	2,750
Financing Leases, Thereafter	8,213
Total financing leases including interest	33,095
Less: Amounts representing interest	4,074
Present value of minimum lease principal payments	29,021
Less: Current portion of lease liabilities - financing leases	9,209		$ 8,617
Noncurrent portion of lease liabilities - financing leases	19,812		$ 26,631
Total Operating and Financing Leases [Member]
Lessee Disclosure [Line Items]
Total future minimum payments due remainder of 2019	7,168
Total future minimum payments due in 2020	29,998
Total future minimum payments due in 2021	23,601
Total future minimum payments due in 2022	16,659
Total future minimum payments due in 2023	14,452
Total future minimum payments due, in Thereafter	86,756
Total minimum lease payments including interest	178,634
Less: Amounts representing interest	32,800
Present value of minimum lease principal payments	145,834
Less: Current portion of lease liabilities - operating and financing leases	24,138
Noncurrent portion of lease liabilities - operating and financing leases	$ 121,696