Employee Benefit Plan Employee Benefit Plan (Details) employee in Thousands, $ in Millions		12 Months Ended
	Jul. 31, 2016	Dec. 31, 2018 USD ($) employee	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Vesting percentage of employer contribution	100.00%
Costs recognized | $		$ 1.4	$ 0.2	$ 0.1
Number of participants | employee		1
Range one
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contribution, percent match on employee contribution	50.00%
Range two | Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer matching contribution on salary of employee	4.00%