Revenues Revenues - ASU 2014-09 Inititial Adoption (Details) $ in Thousands	Jan. 01, 2018 USD ($)
Trade accounts and notes receivable
New Accounting Pronouncements or Change in Accounting Principle
New accounting pronouncement, effect of adoption ASU 2014-09	$ 765
Inventory
New Accounting Pronouncements or Change in Accounting Principle
New accounting pronouncement, effect of adoption ASU 2014-09	(223)
Other accrued liabilities
New Accounting Pronouncements or Change in Accounting Principle
New accounting pronouncement, effect of adoption ASU 2014-09	1,276
Deferred tax liabilities and other noncurrent tax liabilities
New Accounting Pronouncements or Change in Accounting Principle
New accounting pronouncement, effect of adoption ASU 2014-09	(144)
Retained earnings
New Accounting Pronouncements or Change in Accounting Principle
New accounting pronouncement, effect of adoption ASU 2014-09	$ (590)