Accumulated Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Accumulated Other Comprehensive Income (Loss)
As at January 1, 2013			$ 86.9
Net current period other comprehensive income - Available for sale securities	0.2	1.2		7.2
Net current period other comprehensive income			14.4
As at September 30, 2013	101.3		101.3
Foreign currency translation adjustment
Accumulated Other Comprehensive Income (Loss)
As at January 1, 2013			85.1
Other Comprehensive income before reclassification			14.4
Amounts reclassified from accumulated other comprehensive income			0
Net current period other comprehensive income- Foreign Currency			14.4
As at September 30, 2013	99.5		99.5
Unrealized holding gain/(loss) on available-for-sale securities
Accumulated Other Comprehensive Income (Loss)
As at January 1, 2013			1.8
Other Comprehensive income before reclassification			2.2
Net current period other comprehensive income - Available for sale securities			0
Gain recognized in the income statement (within Other (expense)/income) on disposal of available-for-sale securities			(2.2)
As at September 30, 2013	1.8		1.8
Accumulated other comprehensive income
Accumulated Other Comprehensive Income (Loss)
As at January 1, 2013			86.9
Other Comprehensive income before reclassification			16.6
Gain recognized in the income statement (within Other (expense)/income) on disposal of available-for-sale securities			(2.2)
Net current period other comprehensive income			14.4
As at September 30, 2013	$ 101.3		$ 101.3