Commitments and Contingencies - Lease Commitments (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) renewal_option	Sep. 30, 2016 USD ($)
Operating Leased Assets [Line Items]
Operating leases, rent expense | $	$ 1.1	$ 0.2	$ 2.9	$ 0.6
Minimum
Operating Leased Assets [Line Items]
Operating leases, renewal term			3 years
Maximum
Operating Leased Assets [Line Items]
Operating leases, renewal term			30 years
Corporate Headquarters, Office Lease
Operating Leased Assets [Line Items]
Operating leases, renewal term			5 years
Operating lease term			83 months
Operating lease, number of renewal options | renewal_option			3