Subsequent Events (Details) $ in Thousands				12 Months Ended
	Jan. 11, 2018 USD ($)	Jan. 05, 2018 USD ($) building	Oct. 06, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Subsequent Event [Line Items]
Secured Debt				$ 245,000
Assets Held-for-sale, Not Part of Disposal Group, Current				146,644	$ 0
Proceeds from issuance of Revolving Credit Facility			$ 10,000	$ 10,000	$ 0	$ 0
Subsequent Event
Subsequent Event [Line Items]
Proceeds from Sale of Property, Plant, and Equipment		$ 146,600
Sale Leaseback Transaction, Number Of Buildings | building		2
Sale Leaseback Transaction, Lease Terms		P15Y
Repayments of Debt	$ 100,000
Secured Debt	145,000
Repayments of Lines of Credit	$ 10,000