Commitments and Contingencies (Leases Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Lessee, Lease, Description [Line Items]
Operating lease right-of-use asset	$ 14,817
Operating lease liabilities	$ 18,793
Operating leases, weighted average remaining lease term (in years)	3 years 3 months 8 days
Operating leases, weighted average discount rate (percent)	7.00%
Cash payments for operating leases	$ 1,500
Rental expense for operating leases	$ 2,900	$ 2,600
Minimum
Lessee, Lease, Description [Line Items]
Operating leases, initial lease terms	2 years
Maximum
Lessee, Lease, Description [Line Items]
Operating leases, initial lease terms	13 years