Fair Value Measurement Fair Value Measurement - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset retirement obligations adjustments	$ (462)	$ (2,058)	$ (200)
Restructuring gains	(2,411)	(1,925)	(6,003)
Derivative Asset	1,400	800
Commodity Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Gain (Loss) on Derivative, Net			(400)
Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Gain (Loss) on Derivative, Net		$ 300	1,500
Cash Flow Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap initial notional amount	$ 98,800
Cash flow hedge fixed rate	1.47%
Noncontrolling Interest [Member] | Restructuring Type, Real Estate Asset Impairment [Member] | Enterprise Improvement Plan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring gains			$ (3,300)