Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income	$ 261,952	$ 62,273	$ 39,301
Other comprehensive (loss) income:
Adjustment to pension liability	(7,410)	(592)	5,783
Income tax (benefit) expense	(2,890)	(231)	2,255
Other comprehensive (loss) income	(4,520)	(361)	3,528
Comprehensive income	$ 257,432	$ 61,912	$ 42,829