Employee Benefits and Share-Based Compensation - Employee Stock Purchase Plan (ESPP) Activity (Details) - Nineteen Ninety Seven Employee Stock Purchase Plan - Employee Stock Purchase Plan $ in Millions	9 Months Ended
	Sep. 30, 2016 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	$ 5.2
Weighted average period of compensation cost recognized	21 months 95 days