Derivative Instruments (Tables)

3 Months Ended

Mar. 31, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Derivative Instruments in Statement of Financial Position, Fair Value

The fair value of all derivatives is recorded as assets or liabilities on a gross basis in our Consolidated Balance Sheets. As of March 31, 2018 and December 31, 2017, respectively, the fair value of our derivatives and their respective balance sheet locations are presented in the following table:

	Asset Derivatives			Liability Derivatives
	Location	Fair  Value		Location	Fair  Value
As of March 31, 2018	(Dollars in thousands)
Derivatives designated as cash flow hedges:
Commodity derivative contracts	Prepaid and other current assets	$	2,436	Other accrued liabilities	$	285
	Other long-term assets	1,862		Other long-term obligations	5,888
Total fair value		$	4,298		$	6,173
As of December 31, 2017
Derivatives designated as cash flow hedges:
Commodity derivative contracts	Prepaid and other current assets	$	2,518	Other accrued liabilities	$	—
	Other long-term assets	2,808		Other long-term obligations	581
Total fair value		$	5,326		$	581