Condensed Consolidated Statements of Equity (UNAUDITED) - USD ($) $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-in-Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Balance at Dec. 31, 2017	$ 149.4	$ 0.3	$ (0.9)	$ 205.7	$ 8.9	$ (64.6)
Balance (in shares) at Dec. 31, 2017		33,800,000	0
Net earnings	74.6	$ 0.0	$ 0.0	0.0	74.6	0.0
Other comprehensive income (loss)	(0.9)	0.0	0.0	0.0	0.0	(0.9)
Adoption of ASU 2014-09	0.9	0.0	0.0	0.0	0.9	0.0
Share-based compensation	7.2	0.0	0.0	7.2	0.0	0.0
Issuance of share-based awards, net of withholdings and other	0.5	$ 0.0	$ (0.8)	1.3	0.0	0.0
Issuance of share-based awards, net of withholdings and other (in shares)		300,000	100,000
Balance at Sep. 30, 2018	231.7	$ 0.3	$ (1.7)	214.2	84.4	(65.5)
Balance (in shares) at Sep. 30, 2018		34,100,000	100,000
Balance at Jun. 30, 2018	180.8	$ 0.3	$ (1.7)	212.1	36.4	(66.3)
Balance (in shares) at Jun. 30, 2018		34,100,000	100,000
Net earnings	48.0	$ 0.0	$ 0.0	0.0	48.0	0.0
Other comprehensive income (loss)	0.8	0.0	0.0	0.0	0.0	0.8
Share-based compensation	2.1	0.0	0.0	2.1	0.0	0.0
Balance at Sep. 30, 2018	231.7	$ 0.3	$ (1.7)	214.2	84.4	(65.5)
Balance (in shares) at Sep. 30, 2018		34,100,000	100,000
Balance at Dec. 31, 2018	$ 226.0	$ 0.3	$ (2.4)	216.5	94.3	(82.7)
Balance (in shares) at Dec. 31, 2018	34,200,000	34,200,000	100,000
Net earnings	$ 30.6	$ 0.0	$ 0.0	0.0	30.6	0.0
Other comprehensive income (loss)	3.3	0.0	0.0	0.0	0.0	3.3
Share-based compensation	7.7	0.0	0.0	7.7	0.0	0.0
Issuance of share-based awards, net of withholdings and other	(1.5)	$ 0.0	$ (1.3)	(0.2)	0.0	0.0
Issuance of share-based awards, net of withholdings and other (in shares)		300,000	100,000
Balance at Sep. 30, 2019	$ 266.1	$ 0.3	$ (3.7)	224.0	124.9	(79.4)
Balance (in shares) at Sep. 30, 2019	34,500,000	34,500,000	200,000
Balance at Jun. 30, 2019	$ 249.1	$ 0.3	$ (3.7)	221.6	110.2	(79.3)
Balance (in shares) at Jun. 30, 2019		34,500,000	200,000
Net earnings	14.7	$ 0.0	$ 0.0	0.0	14.7	0.0
Other comprehensive income (loss)	(0.1)	0.0	0.0	0.0	0.0	(0.1)
Share-based compensation	2.6	0.0	0.0	2.6	0.0	0.0
Issuance of share-based awards, net of withholdings and other	(0.2)	$ 0.0	0.0	(0.2)	0.0	0.0
Issuance of share-based awards, net of withholdings and other (in shares)		0
Balance at Sep. 30, 2019	$ 266.1	$ 0.3	$ (3.7)	$ 224.0	$ 124.9	$ (79.4)
Balance (in shares) at Sep. 30, 2019	34,500,000	34,500,000	200,000