Severance (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Chief Executive Officer
Restructuring Cost and Reserve [Line Items]
Severance expense	$ 1.3
Chief Operating Officer
Restructuring Cost and Reserve [Line Items]
Severance expense	1.2
Non-executive employees
Restructuring Cost and Reserve [Line Items]
Severance expense	$ 0.7