Income Taxes - Tax Credit Carryforwards (Details) $ in Millions	Dec. 31, 2016 USD ($)
Tax Credit Carryforward [Line Items]
Taxable income required for full realization of deferred tax assets	$ 226.2
Federal | Research and development tax credit carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward	8.5
State | Research and development tax credit carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforward	$ 5.8