Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2019	Jun. 30, 2018
Other Commitments [Line Items]
Actual cash expenditures	$ 4,790	$ 1,985	$ 5,780	$ 3,296
Network1 [Member]
Other Commitments [Line Items]
Cash held in escrow	$ 17,900		$ 17,900			$ 24,100
Scenario, Forecast [Member] | Minimum [Member]
Other Commitments [Line Items]
Actual cash expenditures					$ 10,000
Scenario, Forecast [Member] | Maximum [Member]
Other Commitments [Line Items]
Actual cash expenditures					$ 15,000