Other Assets (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended			1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Oct. 31, 2012 Olefins [Member] years	Oct. 31, 2012 Minimum [Member]	Oct. 31, 2012 Maximum [Member]
Other Assets [Line Items]
Amortization expense of other assets	$ 25,131	$ 22,812	$ 25,142
Future amortization expense, 2013	3,298
Future amortization expense, 2014	2,707
Future amortization expense, 2015	2,707
Future amortization expense, 2016	2,652
Future amortization expense, 2017	1,811
Number of years forecasted to test for impairment of goodwill				9
Discounted cash flow projections period					2013	2021
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