Long-Term Debt and Related Matters (Narrative - United Kingdom) (Details) £ in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017 GBP (£)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Line of Credit Facility [Line Items]
Line of Credit Facility, Amount Outstanding		$ 125,367	$ 127,073
NatWest Bank [Member] | Foreign Line of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	£ 1,500	1,882
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.
Line of Credit Facility, Interest Rate Description	. The interest rate on this facility is the financial institution's base rate plus 2.50%.
Line of Credit Facility, Amount Outstanding		0
Line of Credit Facility, Current Borrowing Capacity		1,861
NatWest Bank Outstanding Guarantees [Member] | Foreign Line of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Amount Outstanding		$ 21