Income Taxes - Carryforwards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Research Tax Credit Carryforward
Operating loss and tax credit carryforwards
Tax credit carryforwards	$ 2.6	$ 2.3
Tax Credit Carryforward, Expiration Date	Dec. 31, 2027
Federal
Operating loss and tax credit carryforwards
Net operating loss carryforwards	$ 96.0	84.0
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2028
State
Operating loss and tax credit carryforwards
Net operating loss carryforwards	$ 103.8	$ 84.1
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2028	Dec. 31, 2027
Foreign | Australian Taxation Office
Operating loss and tax credit carryforwards
Net operating loss carryforwards	$ 1.0	$ 1.2