Accounts Receivable (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Accounts Receivable, Net
Trade receivables	$ 415.9	$ 258.0
Other	9.1	10.6
Less: allowance for doubtful accounts	(4.3)	(1.4)
Accounts receivable, net	420.7	267.2
Unbilled Contracts Receivable	25.6	17.4
Accounts receivable held in retainage by customer	$ 102.0	$ 39.7

Amounts due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer) for goods or services (including trade receivables) that have been delivered or sold in the normal course of business.

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-Number 210

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-Publisher FASB

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- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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- Definition

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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Amounts due for services rendered or to be rendered, actions taken or to be taken, or a promise to refrain from taking certain actions in accordance with the terms of a legally binding agreement between the Entity and, at a minimum, one other party, which amounts are withheld by the contracting party pending the Entity's compliance or performance in conformity with the terms of the contract. Such billed but unpaid amounts are generally expected to be collected upon complying with certain contractual terms or satisfaction and release by the contracting party.

+ References

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- Definition

The sum of amounts currently receivable other than from customers. For classified balance sheets, represents the current amount receivable, that is amounts expected to be collected within one year or the normal operating cycle, if longer.

+ References

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- Definition

Unbilled amounts due for services rendered or to be rendered, actions taken or to be taken, or a promise to refrain from taking certain actions in accordance with the terms of a legally binding agreement between the entity and, at a minimum, one other party. An example would be amounts associated with contracts or programs where the recognized revenue for performance thereunder exceeds the amounts billed under the terms thereof as of the date of the balance sheet.

+ References

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-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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