Income Taxes Income Tax Eff Rate Recon (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Tax Cuts And Jobs Act Of 2017, Deferred Tax Asset, Change In Tax Rate, Provisional Adjustment									$ (148)	$ 3,190
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent									21.00%	35.00%
Pretax income (loss)	$ (22,376)	$ 3,400	$ 182	$ (1,511)	$ 21,692	$ 6,974	$ 2,505	$ 1,360	$ (20,305)	$ 32,531	$ 33,950
(Provision) benefit for income taxes at federal statutory rate									4,264	(11,386)	(11,883)
Tax rate change									0	(3,190)	0
State income taxes, net of federal benefit									1,396	(1,860)	(1,977)
Manufacturing deduction									0	958	1,142
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Amount									388	159	(145)
Other									(121)	(71)	(161)
Provision for income taxes									$ 6,075	$ (15,390)	$ (13,024)
Effective tax rate									29.90%	47.30%	38.40%
Scenario, Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent									21.00%