Stock-Based Compensation (Details) - USD ($) shares in Millions, $ in Millions		6 Months Ended
	Dec. 31, 2014	Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total payments for employees' tax obligations		$ 2.9	$ 0.0
PSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of target shares earned	200.00%
Shares withheld to satisfy tax withholding obligation		0.2
Total payments for employees' tax obligations		$ 2.9