Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Schedule of minimum required payments for operating leases and unconditional purchase obligations

The minimum required payments for operating leases and unconditional purchase obligations are as follows:

Year Ending December 31,	Operating Leases		Unconditional Purchase  Obligations
	(in thousands)
2017	$	4,304	$	25,982
2018	3,452		14,289
2019	2,836		11,419
2020	2,310		6,426
2021	2,130		4,643
Thereafter	2,605		32,436
	$	17,637	$	95,195

Long-term Purchase Commitments

Commitments for natural gas purchases consist of the following:

	December 31, 2016
	(in thousands, except weighted average rate)
MMBtus under fixed-price contracts	1,539
Commitments to purchase natural gas (1)	$	5,324
Weighted average rate per MMBtu (1)	$	3.46

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(1)Commitments and weighted average rate per MMBtu is based on the fixed rates applicable to each contract, exclusive of transportation costs.