v2.4.0.6
Fair value of financial instruments (Details ) (USD $)
In Millions, unless otherwise specified
3 Months Ended 3 Months Ended 12 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Dec. 31, 2012
Mar. 31, 2013
Credit valuation adjustments
Dec. 31, 2012
Credit valuation adjustments
Dec. 31, 2012
Credit valuation adjustments
Foreign currency forward contracts
Mar. 31, 2013
Recurring
Level 1
Dec. 31, 2012
Recurring
Level 1
Mar. 31, 2013
Recurring
Level 2
Dec. 31, 2012
Recurring
Level 2
Mar. 31, 2013
Recurring
Total
Dec. 31, 2012
Recurring
Total
Assets:                        
Cash and cash equivalents             $ 85.7 $ 60.2     $ 85.7 $ 60.2
Restricted cash 43.5   28.6       43.5 28.6     43.5 28.6
Derivative instruments asset                 14.8 20.6 14.8 20.6
Total             129.2 88.8 14.8 20.6 144.0 109.4
Liabilities:                        
Derivative instruments liability                 136.1 151.1 136.1 151.1
Total                 136.1 151.1 136.1 151.1
Net increase in fair value       16.7 18.4              
Pre-tax increase in other comprehensive income       0.9 1.1              
Increase in change in fair value of derivatives       15.8 13.8              
Foreign exchange loss (gain) $ (7.5) $ 1.0       $ 3.6