CONDENSED CONSOLIDATED BALANCE SHEETS CONDENSED CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowance for trade receivables	$ 0.3	$ 0.3
Accumulated depreciation	$ 217.1	$ 202.2
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	2,000,000,000	2,000,000,000
Common stock, shares issued (in shares)	146,410,139	146,085,696
Common stock, outstanding (in shares)	146,302,517	145,981,684
Treasury stock, at cost (in shares)	107,622	104,012