Commitments and Contingencies (Future Minimum Lease Commitments) (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Operating and Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] [Abstract]
Sublease income netted with future minimum lease commitments	$ 1,400
2018	8,633
2019	9,225
2020	9,270
2021	9,192
2022	8,915
Thereafter	33,497
Total	$ 78,732