EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net earnings	$ 56.1	$ 10.6	$ (11.8)	$ 7.6	$ 51.0	$ 12.8	$ (7.6)	$ 12.6	$ 62.5	$ 68.8	$ 42.7
Less: net earnings allocated to participating securities									(1.1)	(0.5)	(0.5)
Net earnings available to common shareholders									$ 61.4	$ 68.3	$ 42.2
Denominator:
Weighted average common shares outstanding, shares for basic earnings per share (in shares)	33,886	33,884	33,883	33,874	33,853	33,851	33,850	33,836	33,882	33,848	33,819
Weighted average equity awards outstanding (in shares)									0	0	1
Shares for diluted earnings per share (in shares)	33,886	33,884	33,883	33,874	33,853	33,851	33,850	33,836	33,882	33,848	33,820
Net earnings per common share, basic (in dollars per share)	$ 1.64	$ 0.31	$ (0.36)	$ 0.22	$ 1.50	$ 0.37	$ (0.23)	$ 0.37	$ 1.82	$ 2.02	$ 1.25
Net earnings per common share, diluted (in dollars per share)	$ 1.63	$ 0.31	$ (0.36)	$ 0.22	$ 1.50	$ 0.37	$ (0.23)	$ 0.37	$ 1.81	$ 2.02	$ 1.25
Net earnings allocated to participating securities (in shares)									307	186	166
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive weighted options outstanding (in shares)									1,067	788	640