Employee Incentive Plan (Details Textuals) (USD $)	0 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended			0 Months Ended		1 Months Ended	6 Months Ended	1 Months Ended
	May 09, 2013 Restricted Stock [Member]	Jun. 30, 2013 Restricted Stock [Member]	Jun. 30, 2012 Restricted Stock [Member]	Jun. 30, 2013 Restricted Stock [Member]	Jun. 30, 2012 Restricted Stock [Member]	Jun. 30, 2013 Restricted Stock Units (RSUs) [Member]	Jun. 30, 2012 Restricted Stock Units (RSUs) [Member]	Jun. 30, 2013 Restricted Stock Units (RSUs) [Member]		Jun. 30, 2012 Restricted Stock Units (RSUs) [Member]	May 09, 2013 CELP Restricted Units [Member] Common Units [Member]	Jun. 30, 2013 CELP Restricted Units [Member] Common Units [Member]	Mar. 31, 2013 Restricted Stock [Member]	Jun. 30, 2013 Restricted Stock [Member]	Mar. 31, 2013 Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted units vested and issued				281,145				277,404	[1]				60,018		57,897
Fair value of units vested		$ 217,000	$ 260,000	$ 2,184,000	$ 1,266,000	$ 222,000	$ 281,000	$ 2,496,000		$ 1,608,000			$ 1,000,000		$ 1,000,000
Unrecognized compensation cost related to non-vested restricted units		$ 9,800,000		$ 9,800,000		$ 9,800,000		$ 9,800,000
Unrecognized compensation cost, period for recognition				1 year 5 months				1 year 6 months
Number of additional shares authorized	1,785,000										3,470,000
Number of shares authorized		4,385,000		4,385,000								9,070,000
Award vesting period														3 years

[1] Vested units include 81,321 units withheld for payroll taxes paid on behalf of employees.