Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands		12 Months Ended
	Nov. 28, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Capitalized interest		$ 1,444	$ 1,372	$ 2,488
Number of units authorized (in shares)		2,600,000
Common stock distributed (in shares)	27,968,000	27,968,000	0	0
Common Units | Stock Compensation Plan
Property, Plant and Equipment [Line Items]
Number of units authorized (in shares)		2,300,000
Software and Software Development Costs
Property, Plant and Equipment [Line Items]
Estimated useful life		7 years