Long-Term Debt and Related Matters (Narrative) (Details) In Thousands, unless otherwise specified					12 Months Ended	0 Months Ended	12 Months Ended			12 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2014 Letter of Credit [Member] USD ($)	Dec. 31, 2013 Letter of Credit [Member] USD ($)	Dec. 31, 2013 Prior Revolving Credit Facility [Member] USD ($)	Sep. 23, 2014 PNC Bank, N.A., Bank of America, N.A., Wells Fargo Bank, N.A. and Citizens Bank of Pennsylvania [Member] Revolving Credit Facility [Member] USD ($)	Dec. 31, 2014 PNC Bank, N.A., Bank of America, N.A., Wells Fargo Bank, N.A. and Citizens Bank of Pennsylvania [Member] Revolving Credit Facility [Member] USD ($)	Sep. 23, 2014 PNC Bank, N.A., Bank of America, N.A., Wells Fargo Bank, N.A. and Citizens Bank of Pennsylvania [Member] Revolving Credit Facility [Member] USD ($)	Dec. 31, 2014 PNC Bank, N.A., Bank of America, N.A., Wells Fargo Bank, N.A. and Citizens Bank of Pennsylvania [Member] Revolving Credit Facility Available To Canadian Borrowers [Member] USD ($)	Dec. 31, 2014 NatWest Bank [Member] Foreign Line of Credit [Member] USD ($)	Dec. 31, 2014 NatWest Bank [Member] Foreign Line of Credit [Member] GBP (£)	Dec. 31, 2013 NatWest Bank [Member] Foreign Line of Credit [Member] USD ($)	Dec. 31, 2014 NatWest Bank Outstanding Guarantees [Member] Foreign Line of Credit [Member] USD ($)	Dec. 31, 2013 NatWest Bank Outstanding Guarantees [Member] Foreign Line of Credit [Member] USD ($)
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity					$ 125,000			$ 200,000	$ 25,000	$ 2,337	£ 1,500
Debt Instrument, Term						5 years
Line of Credit Facility, Description										A subsidiary of the Company has a working capital facility with NatWest Bank for its United Kingdom operations which includes an overdraft availability of £1,500 pounds sterling (approximately $2,337 at December 31, 2014). This credit facility supports the subsidiary's working capital requirements and is collateralized by substantially all of the assets of its United Kingdom operations	A subsidiary of the Company has a working capital facility with NatWest Bank for its United Kingdom operations which includes an overdraft availability of £1,500 pounds sterling (approximately $2,337 at December 31, 2014). This credit facility supports the subsidiary's working capital requirements and is collateralized by substantially all of the assets of its United Kingdom operations
Line of Credit Facility, Provision for Increase in Capacity					50,000	100,000
Line of Credit Facility, Capacity Available for Trade Purchases					20,000			30,000
Line of Credit Facility, Interest Rate Description						Borrowings under the Amended Credit Agreement will bear interest at rates based upon either the base rate or Euro-rate plus applicable margins. Applicable margins are dictated by the ratio of the Company's indebtedness less cash on hand to the Company's consolidated EBITDA, as defined in the underlying Amended Credit Agreement. The base rate is the highest of (a) PNC Bank's prime rate, (b) the Federal Funds Rate plus 0.50% or (c) the daily Euro-rate (as defined in the Amended Credit Agreement) plus 1.00%. The base rate and Euro-rate spreads range from 0.00% to 1.00% and 1.00% to 2.00%, respectively.				. The interest rate on this facility is the financial institution's base rate plus 1.50%.	. The interest rate on this facility is the financial institution's base rate plus 1.50%.
Line of Credit Facility, Covenant Terms						The Amended Credit Agreement includes two financial covenants: (a) Leverage Ratio, defined as the Company's indebtedness less cash on hand, in excess of $15,000, divided by the Company's consolidated EBITDA, which must not exceed 3.25 to 1.00 and (b) Minimum Interest Coverage, defined as consolidated EBITDA less capital expenditures divided by consolidated interest expense, which must be no less than 3.00 to 1.00.
Line of Credit Facility, Dividend Restrictions						The Amended Credit Agreement permits the Company to pay dividends, distributions, and make redemptions with respect to its stock provided no event of default or potential default (as defined in the Amended Credit Agreement) has occurred prior to or after giving effect to the dividend, distribution, or redemption. Dividends, distributions, and redemptions are capped at $25,000 per year when funds are drawn on the facility. If no drawings on the facility exist, dividends, distributions, and redemptions in excess of $25,000 per year are subjected to a limitation of $75,000 in the aggregate. The $75,000 aggregate limitation also permits certain loans, investments, and acquisitions.
Line of Credit Facility, Amount Outstanding	24,200	0	425	814	0		24,200						0	60
Line of Credit Facility, Current Borrowing Capacity					$ 124,186		$ 175,375			$ 2,337		$ 2,424
Line of Credit Facility, Collateral										This credit facility supports the subsidiary's working capital requirements and is collateralized by substantially all of the assets of its United Kingdom operations.	This credit facility supports the subsidiary's working capital requirements and is collateralized by substantially all of the assets of its United Kingdom operations.
Line of Credit Facility, Covenant Compliance							As of December 31, 2014, the Company was in compliance with the Amended Credit Agreement's covenants			The United Kingdom loan agreements contain certain financial covenants that require that subsidiary to maintain senior interest and cash flow coverage ratios. The subsidiary was in compliance with these financial covenants as of December 31, 2014 a	The United Kingdom loan agreements contain certain financial covenants that require that subsidiary to maintain senior interest and cash flow coverage ratios. The subsidiary was in compliance with these financial covenants as of December 31, 2014 a