Share-Based Compensation Arrangements (Details Textual) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Stock Appreciation Rights And Phantom Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense	$ 0.3	$ (0.2)	$ (2.1)	$ (1.6)
Share-Based Compensation Arrangements (Textual) [Abstract]
Employee Service Share-based Compensation, Cash Flow Effect, Cash Used to Settle Awards			1.6	0.1
Phantom Share Units (PSUs) [Member]
Share-Based Compensation Arrangements (Textual) [Abstract]
Share based compensation, unrecognized liability	1.0		1.0		0.8
DSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense	0.2	0	(0.8)	(0.6)
Share-Based Compensation Arrangements (Textual) [Abstract]
Employee Service Share-based Compensation, Cash Flow Effect, Cash Used to Settle Awards			0.2	0
Other Deferred Compensation Arrangements, Liability, Current	$ 1.2		$ 1.2		$ 0.6
Common Class A [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock price	$ 8.95		$ 8.95		$ 4.62