Shareholders' Equity (Deficit) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Authorized shares	300,000,000	300,000,000
Par value of common stock (in dollars per share)	$ 0.01	$ 0.01
Shares reserved for issuance of stock options	6,595,567
Stock options exercised	388,174	243,502	386,300
Common stock activity roll forward
Common stock outstanding at the beginning of the period (in shares)	66,792,968	67,780,410	68,309,431
Stock options exercised	388,174	243,502	386,300
Shares issued	94,796	72,590	49,897
Shares forfeited through net share exercise	(130,256)	(132,393)	(29,783)
Shares repurchased	(409,769)	(1,171,141)	(935,435)
Common stock outstanding at the end of the period (in shares)	66,735,913	66,792,968	67,780,410
Proceeds from exercise of stock options	$ 19.1	$ 6.7	$ 16.4
Net share settlement [Member]
Common stock activity roll forward
Shares issued	820
Share-based Payment Arrangement, Nonemployee [Member]
Common stock activity roll forward
Shares issued	13,788
Share-based Payment Arrangement, Employee [Member]
Common stock activity roll forward
Shares issued	80,188