Significant Accounting Policies (Narrative) (Details) - USD ($)		12 Months Ended
	Jan. 24, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2019
Property, Plant and Equipment [Line Items]
Capitalized interest		$ 6,033,000	$ 1,444,000	$ 1,372,000
Impairment of long-lived assets		$ 0	$ 0	$ 0
Number of units authorized (in shares)		2,600,000
Common stock distributed (in shares)		27,928,245	27,968,188	27,967,509
Preferred stock (in shares)		500,000
Preferred stock issued (in shares)		0
Preferred stock outstanding (in shares)		0
Restricted cash		$ 29,258,000	$ 0
Common Units | Stock Compensation Plan
Property, Plant and Equipment [Line Items]
Number of units authorized (in shares)		2,300,000
Accounting Standards Update 2018-02 | Retained Earnings
Property, Plant and Equipment [Line Items]
Cumulative effect of adjustments		$ 84,729,000
Subsequent Event
Property, Plant and Equipment [Line Items]
Cash distributions declared per unit (in dollars per share)	$ 0.5125
Scenario, Forecast | Accounting Standards Update 2018-11 | Minimum
Property, Plant and Equipment [Line Items]
Initial lease liability					$ 75,000,000
Right of use asset					75,000,000
Scenario, Forecast | Accounting Standards Update 2018-11 | Maximum
Property, Plant and Equipment [Line Items]
Initial lease liability					100,000,000
Right of use asset					$ 100,000,000