Income Taxes Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred Tax Assets, Gross [Abstract]
Warranty, insurance and other accruals	$ 8,078	$ 12,738
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost	3,250	5,482
Inventory	4,720	8,223
State taxes	160	219
Net operating loss carryforward	6,193	8,483
Deferred charges	506	1,812
Total deferred tax assets	22,907	36,957
Deferred Tax Liabilities, Gross [Abstract]
Federal effect of state deferred taxes	1,777	3,879
Depreciation	2,382	1,947
Prepaid expenses	310	256
Total deferred tax liabilities	4,469	6,082
Deferred Tax Assets, Net of Valuation Allowance	$ 18,438	$ 30,875