Acquisitions and divestitures (Details Textuals) (USD $)	6 Months Ended	12 Months Ended
	Dec. 31, 2011	Jul. 02, 2011 Unidux [Member]
Business Acquisition [Line Items]
Approximate annualized revenues of acquired businesses	$ 335,000,000	$ 370,000,000
Purchase price of the business acquired	118,507,000
Gain on bargain purchase		30,990,000
Gain on bargain purchase per share on a diluted basis		$ 0.20
Recognized Loss From Other Activities Before Tax	1,400,000
Recognized Loss From Other Activities Net Of Tax	$ 900,000
Recognized loss from other activities per diluted share	$ 0.01