Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Narrative) (Details) $ / shares in Units, shares in Thousands	2 Months Ended	12 Months Ended
	Feb. 27, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) shares	Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jan. 01, 2019 USD ($)
Organization Consolidation And Presentation [Line Items]
Cash equivalents		$ 146,100,000	$ 146,100,000	$ 146,100,000	$ 146,100,000	$ 146,100,000	$ 146,100,000	$ 0
Revenue recognized for performance obligations satisfied over time					26.00%
Selling, general and administrative expenses				680,273,000				619,546,000	$ 571,799,000
Depreciation expense				39,627,000				43,022,000	38,441,000
Number of reportable segments					1		1
Number of operating segments					5
Amount authorized for share repurchase program		$ 75,000,000	75,000,000	75,000,000	$ 75,000,000	75,000,000	$ 75,000,000
Share repurchase program expiration date		Nov. 20, 2019
Payments for Repurchase of Common Stock				2,891,000				0	0
Shares repurchased				2,891,000
Amount remaining under repurchase program		$ 72,100,000	72,100,000	72,100,000	72,100,000	72,100,000	72,100,000
Aggregate maximum obligation of reinsurer									17,500,000
Insurance reserves related to reinsurance claims		3,700,000	3,700,000	3,700,000	3,700,000	3,700,000	3,700,000	4,500,000
Debt issuance cost		6,400,000	6,400,000	6,400,000	6,400,000	6,400,000	6,400,000	8,100,000
Amortization of debt issuance costs				1,684,000				1,684,000	3,114,000
Deferred Tax Benefit, 2017 Tax Act				500,000				3,600,000
Shipping and Handling [Member]
Organization Consolidation And Presentation [Line Items]
Selling, general and administrative expenses				189,600,000				172,200,000	152,700,000
Depreciation expense				22,900,000				24,800,000	20,900,000
Selling, general and administrative expenses [Member]
Organization Consolidation And Presentation [Line Items]
Retirement savings expense recorded				5,900,000				5,200,000	4,600,000
Advertising expense				4,900,000				5,800,000	3,700,000
Interest expense [Member]
Organization Consolidation And Presentation [Line Items]
Amortization of debt issuance costs				1,684,000				1,684,000	$ 3,114,000
Prepaid expenses and other current assets [Member]
Organization Consolidation And Presentation [Line Items]
Rebates receivable		18,000,000	18,000,000	18,000,000	18,000,000	18,000,000	18,000,000	23,300,000
Other long-term assets [Member]
Organization Consolidation And Presentation [Line Items]
Assets held for sale		1,300,000	1,300,000	1,300,000	1,300,000	1,300,000	1,300,000	2,300,000
Accounts payable [Member]
Organization Consolidation And Presentation [Line Items]
Book overdrafts		(100,000)	(100,000)	(100,000)	(100,000)	(100,000)	(100,000)	(100,000)
Accrued expenses and other liabilities [Member]
Organization Consolidation And Presentation [Line Items]
Warranty liabilities		2,900,000	2,900,000	2,900,000	2,900,000	2,900,000	2,900,000	2,500,000
Accrued expenses and other liabilities and other long-term liabilities [Member]
Organization Consolidation And Presentation [Line Items]
Deferred rent liability		$ 5,000,000	$ 5,000,000	$ 5,000,000	$ 5,000,000	$ 5,000,000	$ 5,000,000	$ 4,200,000
Subsequent Event [Member]
Organization Consolidation And Presentation [Line Items]
Shares repurchased (shares) | shares	700
Weighted average price | $ / shares	$ 16.82
Shares repurchased	$ 11,500,000
FY18 Repurchase Program 75M [Member]
Organization Consolidation And Presentation [Line Items]
Shares repurchased (shares) | shares			182
Weighted average price | $ / shares						$ 15.91
Minimum [Member] | Subsequent Event [Member]
Organization Consolidation And Presentation [Line Items]
Operating lease liability										$ 110,000,000
Current operating lease liability										22,000,000
ROU Asset										105,000,000
Maximum [Member] | Subsequent Event [Member]
Organization Consolidation And Presentation [Line Items]
Operating lease liability										125,000,000
Current operating lease liability										37,000,000
ROU Asset										$ 120,000,000