CONDENSED CONSOLIDATED BALANCE SHEETS CONDENSED CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowance for trade receivables	$ 0.3	$ 0.3
Accumulated depreciation	$ 209.4	$ 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)	146,360,433	146,085,696
Common stock, outstanding (in shares)	146,251,597	145,981,684
Treasury stock, at cost (in shares)	108,836	104,012