The Company - Additional Information (Detail) $ in Thousands	1 Months Ended	6 Months Ended
	Jun. 30, 2018 USD ($)	Aug. 04, 2018 USD ($) Gallery Store State Showroom
Organization Consolidation and Presentation of Financial Statements [Line Items]
Number of retail Galleries | Gallery		85
Number of outlet stores | Store		36
Number of states | State		32
Number of waterworks showrooms | Showroom		15
Total cost of convertible note hedge transactions		$ 91,857
Cash proceeds from sale of warrants		51,021
Total cash proceeds, net of discounts upon original issuance and offering costs	$ 287,800
Discounts upon original issuance and offering costs	6,300
Convertible Senior Notes Due 2023 [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Debt instrument, principal amount		$ 335,000
Cash proceeds from sale of warrants	51,000
Convertible Senior Notes Due 2023 [Member] | Convertible Bond Hedge and Warrant Transactions [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Total cost of convertible note hedge transactions	91,900
Private Placement [Member] | Convertible Senior Notes Due 2023 [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Debt instrument, principal amount	$ 300,000
Debt instrument, interest rate	0.00%
Over Allotment Option in Private Placement [Member] | Convertible Senior Notes Due 2023 [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Debt instrument, principal amount	$ 35,000