Restructuring Plans - (Additional Information) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended		9 Months Ended	15 Months Ended
	Jan. 03, 2021	Oct. 04, 2020	Sep. 30, 2019	Oct. 04, 2020	Sep. 30, 2019	Dec. 31, 2019	Jul. 05, 2020	Jun. 30, 2020	Mar. 31, 2020
Restructuring Cost and Reserve [Line Items]
Expected remaining cost		$ 5,500		$ 5,500
Restructuring and other exit charges		3,119	$ 6,282	4,506	$ 8,654
Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1,503		2,906
Exit charges		1,616		1,600
Restructuring and other exit charges		3,119		4,506
Restructuring costs incurred				4,068
Energy Systems | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1,331		1,843
Exit charges		0		0
Restructuring and other exit charges		1,331		1,843
Motive Power | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		172		934
Exit charges		1,509		1,509
Restructuring and other exit charges		1,681		2,443
Specialty | Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0		129
Exit charges		107		91
Restructuring and other exit charges		107		220
Closure Of Facility In Targovishte Bulgaria
Restructuring Cost and Reserve [Line Items]
Expected remaining cost									$ 30,000
Restructuring and other exit charges						$ 20,242
Richmond Kentucky Battery Formation Area Fire
Restructuring Cost and Reserve [Line Items]
Restructuring and other exit charges		15,316			17,037			$ 32,353
Expected additional restructuring charges		45,000		45,000
Prepaid Insurance		18,144		$ 18,144					$ 12,000
Restructuring costs incurred		5,156			$ 5,000		$ 10,156	$ 30,144
Richmond Kentucky Battery Formation Area Fire | Subsequent Event
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	$ 2,000
Strategy To Exit Manufacture Of Batteries For Diesel-Electric Submarines
Restructuring Cost and Reserve [Line Items]
Proceeds for sale of certain licenses and assets		2,031
Gain on sale of assets		892
Fixed Asset Write-Off, Kentucky And Tennessee Plants
Restructuring Cost and Reserve [Line Items]
Restructuring and other exit charges		$ 5,441