Shareholders' (Deficit) Equity (Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019	Jan. 01, 2018
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Beginning balance	$ (7,783)	$ 5,684	$ (3,142)
Cumulative impact of accounting changes			384	$ 776
Other comprehensive income before reclassifications	(3,423)	(3,311)	11,915
Amounts reclassified from accumulated other comprehensive loss	(1,649)	72	279
Exchange of common stock of JPHI Holdings, Inc. for common stock of Jason Industries, Inc.			(1,884)
Ending balance	(90,859)	(7,783)	5,684
Acoustics Europe | Disposal Group, Held-for-sale, Not Discontinued Operations
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Amounts reclassified from accumulated other comprehensive loss			(900)
Employee retirement plan adjustments
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Beginning balance	(1,831)	(1,517)	(1,777)
Cumulative impact of accounting changes					$ (137)
Other comprehensive income before reclassifications	(526)	(223)	365
Amounts reclassified from accumulated other comprehensive loss	125	(46)	8
Exchange of common stock of JPHI Holdings, Inc. for common stock of Jason Industries, Inc.			(113)
Ending balance	(2,232)	(1,831)	(1,517)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Beginning balance	(23,151)	(18,596)	(27,404)
Cumulative impact of accounting changes					0
Other comprehensive income before reclassifications	(1,950)	(4,555)	11,394
Amounts reclassified from accumulated other comprehensive loss	(1,112)	0	(888)
Exchange of common stock of JPHI Holdings, Inc. for common stock of Jason Industries, Inc.			(1,698)
Ending balance	(26,213)	(23,151)	(18,596)
Foreign currency translation adjustments | Disposal Of U.K. Entities
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Amounts reclassified from accumulated other comprehensive loss	(800)
Foreign currency translation adjustments | North American Fiber Solutions
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Amounts reclassified from accumulated other comprehensive loss	(300)
Net unrealized gains (losses) on cash flow hedges
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Beginning balance	1,411	51	(1,191)
Cumulative impact of accounting changes					11
Other comprehensive income before reclassifications	(947)	1,467	156
Amounts reclassified from accumulated other comprehensive loss	(662)	118	1,159
Exchange of common stock of JPHI Holdings, Inc. for common stock of Jason Industries, Inc.			(73)
Ending balance	(198)	1,411	51
Total
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Beginning balance	(23,571)	(20,062)	(30,372)
Cumulative impact of accounting changes			(126)		$ (126)
Ending balance	$ (28,643)	$ (23,571)	$ (20,062)