Debt Guarantees (Details) In Millions, unless otherwise specified	3 Months Ended				3 Months Ended
	Mar. 31, 2013 USD ($) guarantees	Mar. 31, 2013 ZAR	Mar. 31, 2013 CAD	Dec. 31, 2012 USD ($)	Mar. 31, 2013 Geo Amey USD ($)	Mar. 31, 2013 Geo Amey GBP (£)
Line of Credit Facility [Line Items]
Remaining Guarantee under Letter of Credit	$ 3.8	34.8
Maximum Loan Amount under Stand by Facility	2.2	20.0
Potential Estimated Exposure of tax obligations	2.5		2.5
Liability Related to Potential Tax Exposure	2.2			2.0
Number of letters of guarantee outstanding under separate international facilities relating to performance guarantees	8	8
Letters of Guarantee Outstanding Relating to Performance Guarantees	12.7
Variable Interest Entity Ownership Percentage in Joint Venture	50.00%	50.00%
Working Capital Line of Credit	18.3					12.0
Line of Credit Facility, Amount Outstanding					18.6	12.2
Line of Credit Facility, Increase, Accrued Interest					$ 0.4