Commitments and Contingencies Loss Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Loss Contingencies [Line Items]
Accrued litigation settlement	$ 59,600	$ 0
Legal proceedings recorded as a liability under other noncurrent liabilities	7,600	$ 6,500
Strack royalty payment litigation [Member]
Loss Contingencies [Line Items]
Damages sought related to contingency matter	200,000
Accrued litigation settlement	$ 59,600