Leases - Summary of Future Minimum Lease Payments For Noncancelable Operating And Financing Leases (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Dec. 30, 2018
Lessee Disclosure [Line Items]
Operating Leases, Remainder of 2019	$ 8,751
Operating Leases, 2020	18,652
Operating Leases, 2021	16,658
Operating Leases, 2022	13,551
Operating Leases, 2023	11,698
Operating Leases, Thereafter	54,384
Total operating leases including interest	123,694
Less: Amounts representing interest	21,119
Present value of minimum lease principal payments	102,575	$ 88,200
Less: Current portion of lease liabilities - operating leases	14,771
Noncurrent portion of lease liabilities - operating leases	87,804
Financing Leases, Remainder of 2019	5,222
Financing Leases, 2020	10,611
Financing Leases, 2021	6,215
Financing Leases, 2022	2,694
Financing Leases, 2023	2,750
Financing Leases, Thereafter	8,214
Total financing leases including interest	35,706
Less: Amounts representing interest	4,505
Present value of minimum lease principal payments	31,201
Less: Current portion of lease liabilities - financing leases	9,019		$ 8,617
Noncurrent portion of lease liabilities - financing leases	22,182		$ 26,631
Total Operating and Financing Leases [Member]
Lessee Disclosure [Line Items]
Total future minimum payments due remainder of 2019	13,973
Total future minimum payments due in 2020	29,263
Total future minimum payments due in 2021	22,873
Total future minimum payments due in 2022	16,245
Total future minimum payments due in 2023	14,448
Total future minimum payments due, in Thereafter	62,598
Total minimum lease payments including interest	159,400
Less: Amounts representing interest	25,624
Present value of minimum lease principal payments	133,776
Less: Current portion of lease liabilities - operating and financing leases	23,790
Noncurrent portion of lease liabilities - operating and financing leases	$ 109,986