Employee Benefit Plans with Related Party (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Employee Benefit Plans with Related Party
Curtailment gain recognized		$ 469,000
Projected benefit obligation	19,246,000	23,096,000
Fair value of plan assets	18,267,000	17,158,000
Net unfunded pension liability	979,000	5,938,000
Pension Plans
Employee Benefit Plans with Related Party
Change in the net unfunded pension liability	5,000,000
Change in the net unfunded pension liability recorded in other comprehensive income	4,400,000
Actual return on plan assets	2,700,000	1,700,000
Net periodic pension costs related to pension plans	32,000	75,000	83,000
Global Pension Plan
Employee Benefit Plans with Related Party
Normal retirement age of employees	65
Projected benefit obligation	15,057,000	17,317,000
Fair value of plan assets	14,435,000	12,980,000
Net unfunded pension liability	622,000	4,337,000
Discount rate for the Plans (as a percent)	4.40%	3.50%
Expected long-term rate of return for the Plans (as a percent)	7.50%	8.00%
Contributions made by the General Partner, the Partnership and its subsidiaries to the Pension Plans	500,000	500,000	1,700,000
GMG Pension Plan
Employee Benefit Plans with Related Party
Normal retirement age of employees	65
Curtailment gain recognized		500,000
Curtailment gain consisted of change in benefit obligation		2,800,000
Curtailment gain consisted of unrecognized net actuarial loss		2,300,000
Projected benefit obligation	4,189,000	5,779,000
Fair value of plan assets	3,832,000	4,178,000
Net unfunded pension liability	357,000	1,601,000
Discount rate for the Plans (as a percent)	4.40%	3.50%
Expected long-term rate of return for the Plans (as a percent)	7.00%	8.00%
Contributions made by the General Partner, the Partnership and its subsidiaries to the Pension Plans	$ 500,000	$ 500,000