Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Trade receivables	$ 178,182	$ 198,435
Less: Allowance for doubtful accounts	(8,984)	(6,751)
Net trade receivables	169,198	191,684
Other receivables	13,040	23,802
Total accounts receivable	182,238	215,486
Refundable alternative minimum tax credits	$ 8,100	$ 16,000