Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 30, 2016
Income Tax Examination [Line Items]
Reported effective tax rate									39.40%	35.80%	19.30%
Deferred tax asset reduction									$ (13,900)
Change in valuation allowance									(13,900)	$ (15,300)
Alternative minimum tax credit	$ 155								155
Valuation allowance	34,776				$ 50,114				34,776	50,114
Gross deferred tax assets	42,064				61,219				42,064	61,219
Credit to tax expense	(526)	$ (930)	$ (879)	$ (627)	(1,263)	$ 685	$ (460)	$ (204)	(2,962)	(1,242)	$ (369)
Loss carry-forwards	17,161				33,087				17,161	33,087
U.S. federal
Income Tax Examination [Line Items]
Loss carry-forwards	81,700								81,700			$ 87,300
State
Income Tax Examination [Line Items]
Loss carry-forwards	65,000								65,000
Foreign subsidiary
Income Tax Examination [Line Items]
Gross deferred tax assets	$ 900				$ 8,400				900	8,400	1,500
Credit to tax expense									$ 200	$ 1,700	$ 500