Employee Benefits

3 Months Ended

Mar. 31, 2013

Employee Benefits [Abstract]

Employee Benefits

11. EMPLOYEE BENEFITS 

In conjunction with the acquisition of the coal operations of American Electric Power on April 16, 2004, the Operating Company acquired a postretirement benefit plan providing healthcare to eligible employees at its Hopedale operations. The Partnership has no other postretirement plans.

Net periodic benefit cost for the three months ended March 31, 2013 and 2012 are as follows:

	Three months ended March 31,
	2013	2012
	(in thousands)
Service costs	$                           96	$                           95
Interest cost	46	58
Amortization of (gain)	(36)	(74)
Total	$                         106	$                           79

 For the three months ended March 31, 2013 and 2012, the amortization of actuarial gain included in the table above is included in Cost of operations in the Partnership’s unaudited condensed consolidated statements of operations and comprehensive income.

401(k) Plans—The Operating Company and certain subsidiaries sponsor defined contribution savings plans for all employees. Under one defined contribution savings plan, the Operating Company matches voluntary contributions of participants up to a maximum contribution based upon a percentage of a participant’s salary with an additional matching contribution possible at the Operating Company’s discretion. The expense under these plans for the three months ended March 31, 2013 and 2012 was as follows:  

	Three months ended March 31,
	2013	2012
	(in thousands)
401(k) plan expense	$                         580	$                         603