Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Uncertain income tax positions		$ 0	$ 249
Basis in partnerships	$ 10,947	13,377
Deferred tax assets	17,628	32,611
Deferred Tax Assets, Valuation Allowance	$ 1,063	1,346	$ 1,147
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward		2,000
Operating loss carryforward, expiration date	Dec. 31, 2029
State
Operating Loss Carryforwards [Line Items]
Operating loss carryforward, expiration date	Dec. 31, 2023
Minnesota and Nebraska | State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward		$ 13,700