Debt (Senior Secured Credit Facility) (Terms, Guarantees and Covenants) (Narrative) (Details) - Credit Facility [Member]	12 Months Ended
	Dec. 31, 2016
Debt Instrument [Line Items]
Line of credit facility, description of variable rate	Outstanding revolving loans and the Term Loan under the Credit Facility bear interest, at the Company’s option, at a rate equal to either (a) a Eurocurrency Rate, as defined in the Credit Facility, plus a margin of 1.00% to 2.00% or (b) a Base Rate, plus a margin of 0.00% to 1.00%. The Base Rate equals the highest of (i) the Federal Funds Rate, as defined in the Credit Facility, plus 0.50%, (ii) Bank of America’s prime rate and (iii) the Eurocurrency Rate plus 1.00%
Line of credit facility, commitment fee description	The Company must also pay a commitment fee to the lenders of 0.20% to 0.40% on any unused availability under the Credit Facility.
Line of credit facility, covenant terms	The Credit Facility provides for a maximum Consolidated Leverage Ratio, as defined in the Credit Facility, of up to 3.50 (subject to the Acquisition Adjustment described below). The Credit Facility also requires that the Company maintain a minimum Consolidated Interest Coverage Ratio, as defined in the Credit Facility, of 3.00. The Credit Facility provides that, for purposes of calculating the Consolidated Leverage Ratio, certain cash charges may be added back to the calculation of Consolidated EBITDA, as defined in the Credit Facility, and funded indebtedness excludes undrawn standby performance letters of credit. Additionally, notwithstanding the terms discussed above, subject to certain conditions, if a permitted acquisition or series of permitted acquisitions having consideration exceeding $50 million occurs during a fiscal quarter, the Consolidated Leverage Ratio may be temporarily increased to up to 3.75 during such fiscal quarter and the subsequent two fiscal quarters (the “Acquisition Adjustment”). Such right may be exercised no more than two times during the term of the Credit Facility.
Line of credit facility, collateral	The Credit Facility is guaranteed by certain subsidiaries of the Company (the “Guarantor Subsidiaries”) and the obligations under the Credit Facility are secured by substantially all of the Company’s and the Guarantor Subsidiaries’ respective assets, subject to certain exceptions. Under the Credit Facility, if the “Loan Party EBITDA,” as defined in the Credit Facility, as of the last four consecutive fiscal quarters does not represent at least 70% of the “Adjusted Consolidated EBITDA,” as defined in the Credit Facility, for such period, then the Company must designate additional subsidiaries as Guarantor Subsidiaries, and cause them to join the applicable guaranty and security agreements to the Credit Facility. Additionally, any domestic subsidiary with consolidated EBITDA of at least 15% of the Adjusted Consolidated EBITDA must become a Guarantor Subsidiary and join the applicable guaranty and security agreements.
Letters of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate description, letters of credit	Financial standby letters of credit and commercial letters of credit issued under the Credit Facility are subject to a letter of credit fee of 1.00% to 2.00%, and performance standby letters of credit are subject to a letter of credit fee of 0.50% to 1.00%.