CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Accounts receivable, (net of allowance for credit losses of $1.7 and $6.8, respectively)	$ 1.7	$ 6.8
Shareholders’ equity:
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	38,955,848	38,906,221
Common stock, shares outstanding (in shares)	37,552,055	37,678,539
Treasury stock at cost (in shares)	1,403,793	1,227,682