Other Assets (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended			1 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Oct. 31, 2011 Olefins [Member] years	Oct. 31, 2011 Minimum [Member]	Oct. 31, 2011 Maximum [Member]
Other Assets [Line Items]
Amortization expense of other assets	$ 22,812	$ 25,142	$ 24,327
Future amortization expense, 2012	3,292
Future amortization expense, 2013	3,246
Future amortization expense, 2014	2,707
Future amortization expense, 2015	2,707
Future amortization expense, 2016	2,653
Discounted cash flow projections period					2012	2020
Number of years forecasted to test for impairment of goodwill				9
Rate used to discount future cash flows for goodwill impairment test				8.80%
Percentage future cash flows of segment could decrease by and not be impaired				20.00%
Unrealized gain on available for sale securities	1,185
Tax expenses, unrealized gain on available for sale securities	$ 663