Acquisitions - Critical Infrastructure Business (Details) (Critical Infrastructure Business, USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 25, 2011	Dec. 30, 2011
Critical Infrastructure Business
Business Acquisition [Line Items]
Consideration transferred		$ 18.8
Recurring Critical Infrastructure Business revenues, percentage	15.00%
Business Combination, Acquired Receivables [Abstract]
Acquired accounts receivable, gross		24.4
Acquired accounts receivable, estimated uncollectible		$ (1.0)

For receivables acquired in a business combination, excluding certain loans and debt securities acquired in a transfer (as defined), this element represents the best estimate at the acquisition date of the contractual cash flows not expected to be collected, by major class of receivable, such as loans, direct finance leases (as defined), and any other class of receivables.

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For receivables acquired in a business combination, excluding certain loans and debt securities acquired in a transfer (as defined), this element represents the gross contractual amounts receivable, by major class of receivable, such as loans, direct finance leases (as defined), and any other class of receivables.

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- Definition

This element represents the acquisition-date fair value of the total consideration transferred which consists of the sum of the acquisition-date fair values of the assets transferred by the acquirer, the liabilities incurred by the acquirer to former owners of the acquiree, and the equity interests issued by the acquirer.

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