Segment Information (Details) (USD $)	3 Months Ended
	Mar. 30, 2013 segment business	Mar. 31, 2012
Segment Information
Number of primary businesses	2
Financial information relating to the reportable segments
Number of reportable segments	3
Total net sales to external customers	$ 163,513,000	$ 173,705,000
Operating income	23,379,000	37,138,000
Interest expense, net	9,791,000	8,791,000
Foreign currency and other	619,000	451,000
Income before income taxes	12,969,000	27,896,000
Depreciation and amortization	14,325,000	13,532,000
Reportable segments
Financial information relating to the reportable segments
Total net sales to external customers	163,513,000	173,705,000
Operating income	28,327,000	41,976,000
Energy Storage
Financial information relating to the reportable segments
Total net sales to external customers	118,060,000	128,590,000
Operating income	18,836,000	36,809,000
Depreciation and amortization	7,882,000	6,062,000
Electronics and EDVs
Financial information relating to the reportable segments
Total net sales to external customers	24,375,000	42,388,000
Operating income	(2,519,000)	16,795,000
Depreciation and amortization	4,401,000	3,161,000
Transportation and industrial
Financial information relating to the reportable segments
Total net sales to external customers	93,685,000	86,202,000
Operating income	21,355,000	20,014,000
Depreciation and amortization	3,481,000	2,901,000
Separations Media
Financial information relating to the reportable segments
Total net sales to external customers	45,453,000	45,115,000
Operating income	15,509,000	13,863,000
Depreciation and amortization	3,436,000	3,322,000
Healthcare
Financial information relating to the reportable segments
Total net sales to external customers	29,498,000	27,545,000
Filtration and specialty
Financial information relating to the reportable segments
Total net sales to external customers	15,955,000	17,570,000
Corporate and other
Financial information relating to the reportable segments
Operating income	(6,018,000)	(8,696,000)
Depreciation and amortization	3,007,000	4,148,000
Unallocated amount to segment
Financial information relating to the reportable segments
Stock-based compensation	4,467,000	4,270,000
Non-recurring and other costs	$ 481,000	$ 568,000