Benefit Plans (Details Textual) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended			12 Months Ended												12 Months Ended
	Apr. 30, 2011	Jul. 31, 2010	Mar. 31, 2010	Dec. 31, 2012	Dec. 31, 2011 Company Y Employee Plan	Dec. 31, 2010 Plan	Dec. 31, 2009	Dec. 31, 2011 Pension Plans [Member]	Dec. 31, 2010 Pension Plans [Member]	Dec. 31, 2009 Pension Plans [Member]	Dec. 31, 2011 Postretirement Plans [Member]	Dec. 31, 2010 Postretirement Plans [Member]	Dec. 31, 2009 Postretirement Plans [Member]	Dec. 31, 2011 Nonqualified Pension Plans [Member]	Dec. 31, 2010 Nonqualified Pension Plans [Member]	Dec. 31, 2008 Investment at Westridge Capital Management [Member]	Apr. 30, 2011 Investment at Westridge Capital Management [Member]
Benefit Plans (Textual)
Accumulated plan assets exceeded the benefit obligation								$ 812,346	$ 719,447					$ 76,795	$ 72,000
Estimated net actuarial loss and prior service cost that will be amortized from accumulated other comprehensive income								19,443			1,086
Estimated prior service cost that will be amortized from accumulated other comprehensive income								274			(674)
Expected return on plan assets								49,480	50,122	46,505
Expected return on plan assets					8.00%	8.00%	8.25%	8.00%	8.25%	8.25%
Target allocation minimum range for equity securities								50.00%
Target allocation maximum range for equity securities								77.00%
Target allocation minimum range for debt securities								15.00%
Target allocation maximum range for debt securities								27.00%
Target allocation minimum range for specialty investments								10.00%
Target allocation maximum range for specialty investments								20.00%
Target allocation minimum range for cash reserves								0.00%
Target allocation maximum range for cash reserves								5.00%
Fair value of pension plan assets								636,648	630,303	493,646	0	0	0	0	0	59,245	11,227
Write-down in estimated fair value of assets																48,018
Number of funded, noncontributory defined benefit pension plans					3
Normal retirement age					65
Assets in the Chemicals Hourly Plan						85,178
Amount plan assets of Chemical Plan exceeds accumulated benefit obligation						2,272
Amount plan assets of Chemical Plan exceeds projected benefit obligation						1,083
Partial distribution amount released by court-appointed receiver	22,041					6,555
Insurance settlement amount received by the Master Pension Trust related to the WCM loss						15,000
Return on plan assets	10,814							40,293	94,629		0	0
Total contributions (cash and stock) to qualified pension plans			72,500
Contributions to pension plans in cash			18,636
Contributions to pension plans in stock			53,864,000
Number of shares contributed to pension plans			1,190,000
Value per share of shares contributed to pension plans			$ 45.26
Additional contribution to pension plan		1,300
Contributions to non-qualified pension plans					4,906	4,559
Expected contributions to non-qualified pension plans				4,880
Minimum number of unrelated companies that are subject to collective bargaining					2
Percentage of contributions to individual multiemployer pension funds					5.00%
Percentage of domestic hourly labor force covered by collective bargaining agreements					15.00%
Percentage of domestic hourly labor force covered by collective bargaining agreements expiring in 2011					19.00%
Number of union employees in Mexico					228
Unfunded, nonqualified pension plan obligation					8,400	9,000
Number of participants in multiemployer pension plans					1
Number of unfunded supplemental retirement plans					1	1
Accrued costs for the supplemental retirement plan					1,293	1,381
Eligibility age for early retirement coverage					62
Termination age for other group insurance coverage					65
Minimum discount rate					4.15%
Maximum discount rate					5.08%
Healthcare cost trend rate assumed for next year					7.50%						7.50%	8.00%	8.50%
Ultimate health care cost trend rate					5.00%						5.00%	5.00%	5.00%
Year reaching ultimate trend rate					2017						2017	2017	2017
Projected weighted average rate of compensation					3.50%
Number of defined contribution plans					3
Expense recognized relate to defined contribution plans					$ 16,057	$ 15,273	$ 13,361