Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Schedule of Accrued Liabilities

Accrued liabilities consisted of the following as of December 31, 2017 and 2016:

	As of December 31,
	2017		2016
Accrued liabilities:	(in thousands)
Accrued capital expenditures	$	28,711	$	17,775
Accrued incentive compensation	16,503		20,898
Accrued property taxes	4,090		3,175
Accrued other	3,327		9,104
Total accrued liabilities	$	52,631	$	50,952