Supplemental Cash Flow and Other Information (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Significant Noncash Transactions [Line Items]
Accrual for capital expenditures	$ 2,700	$ 2,000	$ 3,900
Accrued liabilities	68,248	31,152
Accrued liabilities current [Member]
Other Significant Noncash Transactions [Line Items]
Accrued liabilities	68,200	31,200
Employee-related liabilities	31,400	$ 11,900
Litigation settlement	$ 14,000