Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net income	$ 210,803	$ 261,952	$ 62,273
Other comprehensive income (loss):
Adjustment to pension liability	1,056	(7,410)	(592)
Income tax expense (benefit)	268	(2,890)	(231)
Other comprehensive income (loss)	788	(4,520)	(361)
Comprehensive income	$ 211,591	$ 257,432	$ 61,912