Acquisitions (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Mar. 31, 2011
Business Acquisition [Line Items]
Cash paid for acquisitions			$ 2,812,000
Gain on acquisitions	2,700,000		2,666,000
Basis for estimation of earnout liability payable		% of certain defined cash flow of the business through 2018
Payment due for remaining shares acquired				0
Zwicky Denmark And Sweden [Member]
Business Acquisition [Line Items]
Percentage of outstanding capital stock acquired			100.00%
Hyde Marine, Inc. [Member]
Business Acquisition [Line Items]
Percentage of outstanding capital stock acquired			100.00%
Gain on acquisitions			300,000
Estimated earnout liability payable			900,000
Percentage of certain defined cash flow used to calculate earnout liability			5.00%
Zwicky Denmark And Sweden And Hyde Marine [Member]
Business Acquisition [Line Items]
Purchase price of acquisitions			4,300,000
Deferred payments and earnouts			1,500,000
Calgon Mitsubishi Chemical Corporation [Member]
Business Acquisition [Line Items]
Percentage of outstanding capital stock acquired	80.00%
Purchase price of acquisitions			7,700,000
Gain on acquisitions	2,700,000		2,400,000
Former equity interest in joint venture	49.00%
Fair value of equity interest	9,800,000
Calgon Mitsubishi Chemical Corporation Redeemable Noncontrolling Interest [Member]
Business Acquisition [Line Items]
Purchase price of acquisitions			2,400,000
Reduction in final payment related to working capital and other adjustments			2,100,000
Gain in other expense - net		$ 300,000