Supplemental Quarterly Information (Unaudited) - (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Significant items for the results of operations on a quarterly basis
Revenues	$ 577,264	$ 626,983	$ 535,103	$ 418,893	$ 560,421	$ 624,640	$ 558,301	$ 297,870	$ 2,158,243	$ 2,041,232	$ 1,387,344
Gross profit (loss)	20,049	14,795	31,454	17,283	81,920	47,350	24,862	17,384	83,581	171,516	110,543
Selling, general, and administrative expenses including research and development expense	25,379	29,639	25,993	26,505	31,864	25,604	25,277	23,703
Impairment of property, plant and equipment	48,532	0	1,341	0	17,893	0	0	0	49,873	17,893	0
Net income (loss) from operations	(53,862)	(14,844)	4,120	(9,222)	32,163	21,746	(415)	(6,319)	(73,808)	47,175	(154,733)
Other income (expense), net	3,469	3,356	(36,969)	(5,617)	(6,343)	558	7,432	159	(35,761)	1,806	(5,678)
Net income (loss) attributable to the Company	$ (16,983)	$ (11,373)	$ (34,809)	$ (15,914)	$ 20,197	$ 23,442	$ 7,606	$ (6,918)	$ (79,079)	$ 44,327	$ (151,392)
Net income (loss) per share attributable to common stockholders - basic (in dollars per share)	$ (0.44)	$ (0.29)	$ (0.90)	$ (0.41)	$ 0.51	$ 0.59	$ 0.18	$ (0.16)	$ (2.04)	$ 1.06	$ (3.44)
Net income (loss) per share attributable to common stockholders - diluted (in dollars per share)	$ (0.44)	$ (0.29)	$ (0.90)	$ (0.41)	$ 0.51	$ 0.59	$ 0.18	$ (0.14)	$ (2.04)	$ 1.06	$ (3.44)