Leases (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Finance lease obligation	$ 4,814	$ 4,814	$ 5,049
Finance lease right-of-use assets	6,529	6,529	6,750
Operating lease right-of-use assets	6,285	6,285	0
Operating lease, liability	6,304	6,304	0
Germany
Lessee, Lease, Description [Line Items]
Finance lease obligation	4,800	4,800	5,000
Finance lease right-of-use assets	6,500	6,500	6,700
Finance lease, right-of-use asset, amortization		3,700	$ 3,500
Accounting Standards Update 2016-02
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets				$ 6,200
Operating lease, liability				$ 6,200
Additional operating lease asset recognized	100	800
Additional operating lease liability recognized	100	800
Scenario, Adjustment
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets	7,000	7,000
Operating lease, liability	$ 7,000	$ 7,000