Derivative Contracts (Details) (FX Forward Contracts [Member], USD $) In Millions, unless otherwise specified	Mar. 31, 2013
Buy Euros [Member]
Derivative [Line Items]
Notional Amount	$ 319.9
Buy Pound Sterling [Member]
Derivative [Line Items]
Notional Amount	163.6
Buy Norwegian Kroners [Member]
Derivative [Line Items]
Notional Amount	1,525.5
Buy Singapore Dollars [Member]
Derivative [Line Items]
Notional Amount	0.6
Buy U.S. Dollars [Member]
Derivative [Line Items]
Notional Amount	65.6
Sell Euros [Member]
Derivative [Line Items]
Notional Amount	(25.2)
Sell Pound Sterling [Member]
Derivative [Line Items]
Notional Amount	(25.4)
Sell Norwegian Kroners [Member]
Derivative [Line Items]
Notional Amount	(327.1)
Sell Singapore Dollars [Member]
Derivative [Line Items]
Notional Amount	0
Sell U.S. Dollars [Member]
Derivative [Line Items]
Notional Amount	(253.7)
2013 [Member] | Buy Euros [Member]
Derivative [Line Items]
Notional Amount	247.8
2013 [Member] | Buy Pound Sterling [Member]
Derivative [Line Items]
Notional Amount	163.5
2013 [Member] | Buy Norwegian Kroners [Member]
Derivative [Line Items]
Notional Amount	975.8
2013 [Member] | Buy Singapore Dollars [Member]
Derivative [Line Items]
Notional Amount	0.6
2013 [Member] | Buy U.S. Dollars [Member]
Derivative [Line Items]
Notional Amount	64.2
2013 [Member] | Sell Euros [Member]
Derivative [Line Items]
Notional Amount	(23.7)
2013 [Member] | Sell Pound Sterling [Member]
Derivative [Line Items]
Notional Amount	(25.1)
2013 [Member] | Sell Norwegian Kroners [Member]
Derivative [Line Items]
Notional Amount	(326.7)
2013 [Member] | Sell Singapore Dollars [Member]
Derivative [Line Items]
Notional Amount	0
2013 [Member] | Sell U.S. Dollars [Member]
Derivative [Line Items]
Notional Amount	(239.8)
2014 [Member] | Buy Euros [Member]
Derivative [Line Items]
Notional Amount	72.1
2014 [Member] | Buy Pound Sterling [Member]
Derivative [Line Items]
Notional Amount	0.1
2014 [Member] | Buy Norwegian Kroners [Member]
Derivative [Line Items]
Notional Amount	496.6
2014 [Member] | Buy Singapore Dollars [Member]
Derivative [Line Items]
Notional Amount	0
2014 [Member] | Buy U.S. Dollars [Member]
Derivative [Line Items]
Notional Amount	1.4
2014 [Member] | Sell Euros [Member]
Derivative [Line Items]
Notional Amount	(1.5)
2014 [Member] | Sell Pound Sterling [Member]
Derivative [Line Items]
Notional Amount	(0.3)
2014 [Member] | Sell Norwegian Kroners [Member]
Derivative [Line Items]
Notional Amount	(0.4)
2014 [Member] | Sell Singapore Dollars [Member]
Derivative [Line Items]
Notional Amount	0
2014 [Member] | Sell U.S. Dollars [Member]
Derivative [Line Items]
Notional Amount	(13.4)
2015 [Member] | Buy Euros [Member]
Derivative [Line Items]
Notional Amount	0
2015 [Member] | Buy Pound Sterling [Member]
Derivative [Line Items]
Notional Amount	0
2015 [Member] | Buy Norwegian Kroners [Member]
Derivative [Line Items]
Notional Amount	53.1
2015 [Member] | Buy Singapore Dollars [Member]
Derivative [Line Items]
Notional Amount	0
2015 [Member] | Buy U.S. Dollars [Member]
Derivative [Line Items]
Notional Amount	0
2015 [Member] | Sell Euros [Member]
Derivative [Line Items]
Notional Amount	0
2015 [Member] | Sell Pound Sterling [Member]
Derivative [Line Items]
Notional Amount	0
2015 [Member] | Sell Norwegian Kroners [Member]
Derivative [Line Items]
Notional Amount	0
2015 [Member] | Sell Singapore Dollars [Member]
Derivative [Line Items]
Notional Amount	0
2015 [Member] | Sell U.S. Dollars [Member]
Derivative [Line Items]
Notional Amount	$ (0.5)