Long-Term Debt (Details) (USD $)														12 Months Ended						12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Buildings [Member]	Dec. 31, 2012 Buildings [Member]	Dec. 31, 2013 Vehicles [Member]	Dec. 31, 2012 Vehicles [Member]	Dec. 31, 2013 Machinery and Equipment [Member]	Dec. 31, 2012 Machinery and Equipment [Member]	Dec. 31, 2013 Capital Leases Member	Dec. 31, 2013 Other Long-term Debt Member	Dec. 31, 2013 Revolving Facility [Member]	Dec. 31, 2012 Revolving Facility [Member]	Dec. 31, 2013 Private Placement [Member]	Dec. 31, 2012 Private Placement [Member]	Dec. 31, 2013 Private Placement [Member] Private Placement Notes Seriesa [Member]	Dec. 31, 2013 Private Placement [Member] Private Placement Notes Series B [Member]	Dec. 31, 2013 Other Non-US Dollar-denominated Facilities [Member]	Dec. 31, 2012 Other Non-US Dollar-denominated Facilities [Member]	Dec. 31, 2013 Dominion Terminal Associates Bonds [Member]	Dec. 31, 2012 Dominion Terminal Associates Bonds [Member]	Dec. 31, 2013 Captial Lease Interest Rate Information [Member]	Dec. 31, 2012 Captial Lease Interest Rate Information [Member]
Long-term Debt Types [Abstract]
Bank Credit Facility												$ 120,600,000	$ 107,200,000	$ 100,000,000	$ 100,000,000			$ 14,900,000	$ 20,900,000
Dominion Terminal Associates Bonds																				43,200,000	43,200,000
Captial lease arrangments	5,500,000	18,100,000	43,000,000																			76,400,000	91,300,000
Total Long-Term Debt	355,100,000	362,600,000
Long Term Debt By Current And Noncurrent [Abstract]
Current maturities of long-term debt	24,600,000	27,000,000
Long-term debt	330,500,000	335,600,000
Total Long-Term Debt	355,100,000	362,600,000
Interest Rate And Other Disclosures [Abstract]
Average Interest Rate												1.60%	1.50%			4.60%	5.20%	5.70%	7.70%	6.00%		3.70%	4.20%
Debt Due Date														Jan. 01, 2021						Jan. 01, 2033
Minimum Repayments of Long-term Debt [Line Items]
2013	24,600									20,500	4,100
2014	34,400									20,700	13,700
2015	22,800									13,700	9,100
2016	140,100									10,400	129,700
2017	13,500									6,400	7,100
Later years	119,700									4,700	115,000
Borrowed Funds	355,100									76,400	278,700
Captial Leases [Line Items]
Capital Leased Assets Gross	138,100	149,600		2,600	4,900	103,700	108,200	31,800	36,500
Accumulated Amortization	57,600	47,400
Total	$ 80,500	$ 102,200