Acquisitions (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended			3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Mar. 31, 2012 Terphane [Member]	Dec. 31, 2011 Terphane [Member]	Oct. 24, 2011 Terphane [Member]	Jun. 30, 2013 AACOA [Member]	Jun. 30, 2013 AACOA [Member]	Oct. 01, 2012 AACOA [Member]
Business Acquisition [Line Items]
Percentage of outstanding equity interests acquired							100.00%			100.00%
Total purchase price					$ 182,700,000					$ 54,065,000
Cash received from seller								600,000	600,000
Post-closing adjustment paid					3,300,000
Available cash used to fund purchase price						57,700,000
Financing used to fund purchase price						125,000,000
Financing used to fund purchase price from existing credit facility										350,000,000
Sales	243,530,000	215,859,000	485,056,000	432,502,000				22,500,000	44,700,000
Net income	$ 1,290,000	$ 7,353,000	$ 5,567,000	$ 10,351,000				$ 700,000	$ 1,300,000