Employee Incentive Plans (Details 1) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Incentive Compensation Expense Allocation In Financial Statements
Total expense recorded in connection with the Equity Incentive Plan	$ 1.2	$ 1.3	$ 2.6	$ 2.9
Service-based vested and non-vested common shares and restricted stock units [Member]
Incentive Compensation Expense Allocation In Financial Statements
Total expense recorded in connection with the Equity Incentive Plan	0.9	1.0	1.9	2.0
Service-based stock options [Member]
Incentive Compensation Expense Allocation In Financial Statements
Total expense recorded in connection with the Equity Incentive Plan				0.1
Performance Shares [Member]
Incentive Compensation Expense Allocation In Financial Statements
Total expense recorded in connection with the Equity Incentive Plan	0.3	0.3	0.7	0.8
Fabricated Products [Member]
Incentive Compensation Expense Allocation In Financial Statements
Total expense recorded in connection with the Equity Incentive Plan	0.4	0.4	0.8	0.9
All Other [Member]
Incentive Compensation Expense Allocation In Financial Statements
Total expense recorded in connection with the Equity Incentive Plan	$ 0.8	$ 0.9	$ 1.8	$ 2.0