Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 2.6	$ 2.1
Accumulated depreciation and amortization	$ 263.4	$ 214.8
Common Stock, No Par Value	$ 0	$ 0
Common Stock, Shares Authorized	200,000,000	200,000,000
Common Stock, Shares, Outstanding	42,529,709	42,932,994
Treasury Stock, Shares	10,627,537	10,106,249