Commitments, Guarantees and Contingencies - Leasing Agreements (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Leasing Agreements [Line Items]
Operating Leases, Future Minimum Payments, Current	$ 11.5
Operating Leases, Future Minimum Payments, Due in Two Years	11.7
Operating Leases, Future Minimum Payments, Due in Three Years	11.4
Operating Leases, Future Minimum Payments, Due in Four Years	9.3
Operating Leases, Future Minimum Payments, Due in Five Years	8.5
Operating Leases, Future Minimum Payments, Due Thereafter	35.0
Operating Leases, Rent Expense	11.5	9.4	9.4
BNI Dragline [Member]
Leasing Agreements [Line Items]
Termination Fee	3.0
Operating Leases, Future Minimum Payments, Current	$ 2.8