Employee Benefits and Share-Based Compensation - Stock Repurchase Program (Details) - USD ($)	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Aug. 02, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares acquired (in shares)	0	0
The 2016 Repurchase Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase, authorized amount			$ 50,000,000.0
2016 and 2014 Share Repurchase Programs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase, remaining authorized repurchase amount	$ 54,900,000