CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS Statement - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net loss	$ (45,835)	$ (39,911)	$ (47,041)
Other comprehensive income (loss):
Reclassification of other post-retirement benefits loss to net income	0	1,082	0
Other post-retirement benefits income (loss)	2,196	(636)	(446)
Total other comprehensive income (loss)	2,196	446	(446)
Comprehensive loss	$ (43,639)	$ (39,465)	$ (47,487)