Operating Restructuring Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Write down of assets	$ 1,300
Operations restructuring costs	4,655	$ 0	$ 4,655	$ 0
Accrued Expenses and Other Current Liabilities
Restructuring Cost and Reserve [Line Items]
Restructuring charges	3,400
Other Operating Expense
Restructuring Cost and Reserve [Line Items]
Operations restructuring costs	$ 3,900	$ 9,100	$ 10,800	$ 16,800