Summary of Significant Accounting Policies (Narrative) (Details) $ in Thousands, a in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) a	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Principle Accounting Policies [Line Items]
Timber And Timberlands Acres Owned | a	1.9
Restricted cash included in other long-term assets	$ 944	$ 2,802
Restricted Cash, Noncurrent, Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent	us-gaap:OtherAssetsNoncurrent	us-gaap:OtherAssetsNoncurrent
Loss on disposal of property	$ 900	$ 700	$ 200
Defined benefit obligation of plan assets description	amortization of cumulative unrecognized net actuarial gains and losses – generally in excess of 10 percent of the greater of the benefit obligation or market-related value of plan assets at the beginning of the year – over the average remaining service period of the active employee group covered by the plan.
Operating lease, right of use asset	$ 15,772
Operating lease, liability	15,773
ASU 2016-02 [Member]
Principle Accounting Policies [Line Items]
Operating lease, right of use asset	14,000
Operating lease, liability	$ 14,000
Intangible Assets, Amortization Period [Member] | Customer Relationships [Member]
Principle Accounting Policies [Line Items]
Finite-lived intangible asset, useful life	10 years
Intangible Assets, Amortization Period [Member] | Trade Names [Member]
Principle Accounting Policies [Line Items]
Finite-lived intangible asset, useful life	20 years
Maximum [Member]
Principle Accounting Policies [Line Items]
Business combination measurement period	1 year
Operating leases, options to extend leases term	5 years
Maximum [Member] | Timber and Timberlands [Member]
Principle Accounting Policies [Line Items]
Timber volume estimate, review period	10 years
Property, plant and equipment, useful life	20 years
Minimum [Member]
Principle Accounting Policies [Line Items]
Operating leases, options to extend leases term	1 year
Minimum [Member] | Timber and Timberlands [Member]
Principle Accounting Policies [Line Items]
Timber volume estimate, review period	5 years
Property, plant and equipment, useful life	5 years