Commitments and Contingencies, Leases (Details) - Office Space and Other Equipment - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Leases [Abstract]
Total expenses under operating lease obligations	$ 1.3	$ 1.2	$ 1.2
Operating Leases, Future Minimum Payments Due [Abstract]
2019	1.0
2020	0.9
2021	0.8
2022	0.8
2023	0.8
Thereafter	3.8
Total	$ 8.1