Share-Based Compensation Share-Based Compensation - Options (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding beginning of the period (in shares)	1,989,137
Grants (in shares)	10,000
Exercises (in shares)	(10,147)	(122,327)
Canceled and forfeited (in shares)	(4,129)
Outstanding end of the period (in shares)	1,984,861
Exercisable end of the period (in shares)	1,527,184
Available for grant end of the period (in shares)	4,038,811
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding beginning of the period (in dollars per share)	$ 16.99
Grants (in dollars per share)	17.35
Exercises (in dollars per share)	7.16
Canceled and forfeited (in dollars per share)	29.81
Outstanding end of the period (in dollars per share)	17.01
Exercisable end of the period (in dollars per share)	$ 13.46
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding, weighted average remaining contractual term (in years)	5 years 6 months
Exercisable, weighted average remaining contractual term (in years)	4 years 8 months 12 days
Outstanding, aggregate intrinsic value	$ 15.1
Exercisable, aggregate intrinsic value	15.0
Intrinsic value of options exercised	$ 0.1	$ 3.5