Segment and geographic information (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Revenue and Assets
Project Revenue	$ 140.2	$ 118.7
Property, plant, and equipment, net	2,020.0		2,055.5
United States
Revenue and Assets
Project Revenue	72.7	55.4
Property, plant, and equipment, net	1,489.5		1,504.8
Canada
Revenue and Assets
Project Revenue	67.5	63.3
Property, plant, and equipment, net	$ 530.5		$ 550.7

Amount, net of accumulated depreciation, depletion and amortization, of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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