CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Common Class A Common Stock	Common Class B Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Total
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2017	$ 52	$ 24	$ 2,215,109	$ (1,970,097)	$ (449,369)	$ (51)	$ (204,332)
Changes in stockholders' equity
Net loss				(38,941)			(38,941)
Other comprehensive income					5,550		5,550
Issuance of shares	1		(1)
Stock compensation expense			741				741
Purchase of shares of treasury stock						(307)	(307)
Stockholders' Equity Attributable to Parent, Ending Balance at Apr. 01, 2018	53	24	2,215,849	(2,011,706)	(443,819)	(358)	(239,957)
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2017	52	24	2,215,109	(1,970,097)	(449,369)	(51)	(204,332)
Changes in stockholders' equity
Net loss							(52,268)
Stockholders' Equity Attributable to Parent, Ending Balance at Sep. 30, 2018	54	24	2,216,926	(2,025,033)	(432,720)	(475)	(241,224)
Changes in stockholders' equity
Cumulative effect adjustment of new accounting pronouncement | ASU 2014-09				(2,668)			(2,668)
Stockholders' Equity Attributable to Parent, Beginning Balance at Apr. 01, 2018	53	24	2,215,849	(2,011,706)	(443,819)	(358)	(239,957)
Changes in stockholders' equity
Net loss				(20,365)			(20,365)
Other comprehensive income					5,549		5,549
Issuance of shares	1		(1)
Stock compensation expense			320				320
Purchase of shares of treasury stock						(64)	(64)
Stockholders' Equity Attributable to Parent, Ending Balance at Jul. 01, 2018	54	24	2,216,168	(2,032,071)	(438,270)	(422)	(254,517)
Changes in stockholders' equity
Net loss				7,038			7,038
Other comprehensive income					5,550		5,550
Stock compensation expense			758				758
Purchase of shares of treasury stock						(53)	(53)
Stockholders' Equity Attributable to Parent, Ending Balance at Sep. 30, 2018	54	24	2,216,926	(2,025,033)	(432,720)	(475)	(241,224)
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 30, 2018	53	24	2,216,681	(1,954,132)	(604,289)	(2)	(341,665)
Changes in stockholders' equity
Net loss				(41,956)			(41,956)
Other comprehensive income					22,552		22,552
Issuance of shares	2		(2)
Stock compensation expense			663				663
Purchase of shares of treasury stock						(268)	(268)
Stockholders' Equity Attributable to Parent, Ending Balance at Mar. 31, 2019	55	24	2,217,342	(1,996,065)	(581,737)	(270)	(360,651)
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 30, 2018	53	24	2,216,681	(1,954,132)	(604,289)	(2)	(341,665)
Changes in stockholders' equity
Net loss							(364,190)
Stockholders' Equity Attributable to Parent, Ending Balance at Sep. 29, 2019	56	24	2,217,898	(2,318,299)	(570,855)	(360)	(671,536)
Changes in stockholders' equity
Cumulative effect adjustment of new accounting pronouncement | ASU 2016-02				23			23
Stockholders' Equity Attributable to Parent, Beginning Balance at Mar. 31, 2019	55	24	2,217,342	(1,996,065)	(581,737)	(270)	(360,651)
Changes in stockholders' equity
Net loss				(17,531)			(17,531)
Other comprehensive income					5,441		5,441
Issuance of shares	1		(1)
Stock compensation expense			303				303
Purchase of shares of treasury stock						(85)	(85)
Stockholders' Equity Attributable to Parent, Ending Balance at Jun. 30, 2019	56	24	2,217,644	(2,013,596)	(576,296)	(355)	(372,523)
Changes in stockholders' equity
Net loss				(304,703)			(304,703)
Other comprehensive income					5,441		5,441
Stock compensation expense			254				254
Purchase of shares of treasury stock						(5)	(5)
Stockholders' Equity Attributable to Parent, Ending Balance at Sep. 29, 2019	$ 56	$ 24	$ 2,217,898	$ (2,318,299)	$ (570,855)	$ (360)	$ (671,536)