Compensation Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
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	$ 31,000,000	$ 27,000,000	$ 29,000,000
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	13,107,000	10,220,000	10,189,000
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	0	5,119,000
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		23,000,000
LTIP Expense	5,742,000	4,600,000	5,070,000
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		13,000,000
LTIP Expense	$ 7,365,000	$ 5,620,000	$ 0