Compensation Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Compensation Plans [Abstract]
Profit Sharing Plan Minimum Contribution, Percent	5.00%
Profit Sharing Plan, Contributions Vesting Immediately, Percent	40.00%
Profit Sharing Plan, Contributions Vesting Based on Years of Service, Percent	60.00%
Profit Sharing Expense	$ 27,000,000	$ 29,000,000	$ 25,000,000
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Period of Measurement for Book Value Per Share	5 years
LTIP Expense	10,241,000	10,189,000	7,563,000
2006 grant [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Long-Term Incentive Compensation Plan, Earned	30,700,000
Number of years long-term compensation was earned		5 years
LTIP Expense	0	5,119,000	3,816,000
2008 grant [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Long-Term Incentive Compensation Plan, Number of Units Oustanding	158,500
Long-Term Incentive Compensation Plan, Maximum Value	39,600,000
Long-Term Incentive Compensation Plan, Earned	17,300,000
Number of years long-term compensation was earned	4 years
LTIP Expense	4,597,000	5,070,000	3,747,000
2011 grant [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Long-Term Incentive Compensation Plan, Number of Units Oustanding	193,600
Long-Term Incentive Compensation Plan, Maximum Value	48,400,000
Long-Term Incentive Compensation Plan, Earned	5,600,000
LTIP Expense	$ 5,644,000	$ 0	$ 0