Condensed Consolidated Statement of Shareholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings (Accumulated Deficit) [Member]
Beginning Balance at Dec. 31, 2019	$ 42.9	$ 0.3	$ 48.2	$ (5.6)
Net income (loss)	(8.9)			(8.9)
Stock compensation expense	0.3		0.3
Ending Balance at Mar. 31, 2020	34.3	0.3	48.5	(14.5)
Beginning Balance at Dec. 31, 2019	42.9	0.3	48.2	(5.6)
Net income (loss)	(1.2)
Ending Balance at Sep. 30, 2020	42.7	0.3	49.2	(6.8)
Beginning Balance at Mar. 31, 2020	34.3	0.3	48.5	(14.5)
Net income (loss)	1.6			1.6
Stock compensation expense	0.3		0.3
Ending Balance at Jun. 30, 2020	36.2	0.3	48.8	(12.9)
Net income (loss)	6.1			6.1
Stock compensation expense	0.4		0.4
Ending Balance at Sep. 30, 2020	42.7	0.3	49.2	(6.8)
Beginning Balance at Dec. 31, 2020	43.3	0.3	49.5	(6.5)
Net income (loss)	8.1			8.1
Payment for taxes related to sharesettlement of equity awards	(0.2)		(0.2)
Stock compensation expense	0.4		0.4
Ending Balance at Mar. 31, 2021	51.6	0.3	49.7	1.6
Beginning Balance at Dec. 31, 2020	43.3	0.3	49.5	(6.5)
Net income (loss)	41.7
Ending Balance at Sep. 30, 2021	86.0	0.3	50.5	35.2
Beginning Balance at Mar. 31, 2021	51.6	0.3	49.7	1.6
Net income (loss)	14.9			14.9
Stock compensation expense	0.4		0.4
Ending Balance at Jun. 30, 2021	66.9	0.3	50.1	16.5
Net income (loss)	18.7			18.7
Stock compensation expense	0.4		0.4
Ending Balance at Sep. 30, 2021	$ 86.0	$ 0.3	$ 50.5	$ 35.2