Summary of Significant Accounting Policies (Foreign Currency Exchange) (Details) In Millions, unless otherwise specified	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2012 SEK	Dec. 31, 2011 SEK	Dec. 31, 2010 SEK	Dec. 31, 2012 GBP GBP (£)	Dec. 31, 2011 GBP GBP (£)	Dec. 31, 2010 GBP GBP (£)	Dec. 31, 2012 Canada, Dollars CAD	Dec. 31, 2011 Canada, Dollars CAD	Dec. 31, 2010 Canada, Dollars CAD
Significant Transactions
Foreign currency exchange rate			6.4973	6.8645	6.7030	0.6154	0.6434	0.6420	0.9955	1.0193	0.9981
Net unrealized foreign currency translation gains	$ 85.7	$ 46.1