Acquisitions (Narrative) (Details)	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]
Business combination, provisional information, initial accounting incomplete, items	As of September 30, 2013, the allocations of purchase prices to the fair values of tangible and intangible assets and liabilities, including the estimated values of contingent earn-out obligations and the estimated useful lives of acquired assets for these acquisitions, are provisional and remain preliminary as management continues to assess the valuation of these items and any ultimate purchase price adjustments that may result based on the final net assets and net working capital of the acquired businesses, as prescribed in the corresponding purchase agreements.
Business combination, provisional information, initial accounting incomplete, nature of adjustments	During the three and nine month periods ended September 30, 2013, the Company revised its preliminary allocations for certain of the 2013 and 2012 acquisitions based on new information about the facts and circumstances existing as of the respective dates of such acquisitions, or, for purchase price adjustments, based on the final net assets and net working capital of the businesses acquired, as prescribed in the relevant purchase agreements. These adjustments resulted in the recognition of, or adjusted the fair values of, certain acquired assets and assumed liabilities, which, for the 2012 acquisitions, resulted in the revision of comparative prior period financial information. Such measurement period adjustments are presented as if the adjustments had been taken into account as of the dates of the respective acquisitions. All changes that do not qualify as measurement period adjustments are included in current period earnings.