Stock-Based Compensation Plans (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Percentage Of Share Of Non Vested Stock Considered As Call Option	85.00%		85.00%
Stock Authorized Shares Employee Stock Purchase Plans			1.5
Shares available for grant	6.7		6.7
Compensation cost related to restricted shares	$ 1.8	$ 1.9	$ 5.5	$ 6.8
Share Based Payment Award Value	4.2		4.2		5.2
Compensation expense	2.5	0.4	6.1	5.0
Liability long-term incentive compensation plan	10.5		10.5		9.9
Liability long-term incentive compensation plan variable portion	9.5		9.5		8.5
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized			4.3
Allocated Share-based Compensation Expense	$ 0.1		$ 0.1
Maximum Shares As Incentive Options Member
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares available for grant	2.0		2.0