Insurance Matters (Details) (USD $)	3 Months Ended										12 Months Ended			1 Months Ended	3 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Sep. 30, 2009	Jun. 30, 2009	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Sep. 30, 2008 Hurricane [Member]	Jun. 30, 2009 Hurricane [Member]	Dec. 31, 2011 Catastrophic Bond [Member]	Sep. 30, 2011 Catastrophic Bond [Member]	Dec. 31, 2010 Catastrophic Bond [Member]	Sep. 30, 2010 Catastrophic Bond [Member]	Dec. 31, 2009 Catastrophic Bond [Member]	Sep. 30, 2009 Catastrophic Bond [Member]	Jun. 30, 2011 Catastrophic Bond [Member]	Jun. 30, 2010 Catastrophic Bond [Member]	Jun. 30, 2009 Catastrophic Bond [Member]
Supplementary Insurance Information, by Segment [Line Items]
Aggregate deductibles														$ 6,000,000
Hurricane-related repair costs												4,700,000	25,800,000		8,100,000
Insurance proceeds											5,000,000				102,600,000
Reduction in cost of sales															43,000,000
Insurance expense																2,000,000	8,400,000	2,300,000	9,400,000	2,400,000	10,400,000
Hurricane-related impairment charges															51,500,000
Oil and gas impairments	107,500,000	2,400,000	22,700,000	0	9,200,000	900,000	159,900,000	11,100,000	64,600,000	48,200,000	132,603,000	181,083,000	120,550,000		43,800,000
Prepaid insurance	$ 12,701,000				$ 12,375,000						$ 12,701,000	$ 12,375,000										$ 10,600,000	$ 11,900,000	$ 13,100,000