Employee Incentive Plans, LTI Compensation Expense Table (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Incentive Compensation Expense Allocation In Financial Statements
Total non-cash compensation expense in connection with the Equity Incentive Plan	$ 1.2	$ 1.0	$ 3.8	$ 3.9
Service-based vested and non-vested common shares and restricted stock units [Member]
Incentive Compensation Expense Allocation In Financial Statements
Total non-cash compensation expense in connection with the Equity Incentive Plan	0.8	0.8	2.7	2.8
Performance Shares [Member]
Incentive Compensation Expense Allocation In Financial Statements
Total non-cash compensation expense in connection with the Equity Incentive Plan	0.4	0.2	1.1	1.0
Service-based stock options [Member]
Incentive Compensation Expense Allocation In Financial Statements
Total non-cash compensation expense in connection with the Equity Incentive Plan	0	0	0	0.1
Fabricated Products [Member]
Incentive Compensation Expense Allocation In Financial Statements
Total non-cash compensation expense in connection with the Equity Incentive Plan	0.4	0.4	1.2	1.3
All Other [Member]
Incentive Compensation Expense Allocation In Financial Statements
Total non-cash compensation expense in connection with the Equity Incentive Plan	$ 0.8	$ 0.6	$ 2.6	$ 2.6