Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		12 Months Ended
	Mar. 31, 2019 USD ($) Obligation	Apr. 01, 2018 USD ($)	Dec. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Accounting Policies [Line Items]
Reporting period, minimum	364 days
Reporting period, maximum	371 days
Operating lease, right-of-use asset	$ 254,605,000
Operating lease, liability	$ 266,199,000
Number of performance obligation | Obligation	1
Stored value card redemption revenue recognized	$ 2,100,000	$ 2,300,000
Outstanding stored value card liabilities	$ 6,200,000		$ 7,000,000
Stored value cards redeemed period	2 years
Long-lived assets to be held and used	$ 500,000
Transitional asset impairment adjustment				$ 300,000
Impairment charges	0	0
Merchandise [Member]
Accounting Policies [Line Items]
Estimated right of return related to estimated sales returns	900,000		1,400,000
Allowance for sales returns reserve	1,700,000		$ 2,600,000
Stored Value Card Breakage Revenue [Member]
Accounting Policies [Line Items]
Recognized stored value card breakage revenue	$ 100,000	$ 100,000
ASC 842 [Member]
Accounting Policies [Line Items]
Operating lease, right-of-use asset				262,900,000
Operating lease, liability				$ 279,700,000
First Quarter [Member]
Accounting Policies [Line Items]
Interim reporting periods	91 days		91 days
Second Quarter [Member]
Accounting Policies [Line Items]
Interim reporting periods	91 days		91 days
Third Quarter [Member]
Accounting Policies [Line Items]
Interim reporting periods	91 days		91 days
Fourth Quarter [Member]
Accounting Policies [Line Items]
Interim reporting periods	91 days		91 days