Quarterly Results of Operations (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net revenues	$ 178.9	$ 196.9	$ 339.3	$ 167.5	$ 161.8	$ 181.0	$ 313.3	$ 166.3	$ 882.6	$ 822.4	$ 798.6
Operating income (loss)	(12.8)	26.8	123.3	8.4	32.4	14.0	113.6	12.5	145.7	172.5	126.3
Income from continuing operations, net of tax	34.4	12.9	72.9	2.2	19.4	3.4	66.8	7.1	122.4	96.7	70.8
(Loss) income from discontinued operations, net of tax	$ 3.8	$ 3.8	$ 5.4	$ 5.1	$ 7.4	$ 5.3	$ 3.0	$ (4.3)	$ 18.1	$ 11.4	$ (5.6)
Net income (loss) per common share data - basic:
Continuing operations (in dollars per share)	$ 2.25	$ 0.85	$ 4.52	$ 0.13	$ 1.17	$ 0.20	$ 3.97	$ 0.43	$ 7.76	$ 5.83	$ 4.08
Discontinued operations (in dollars per share)	0.25	0.24	0.34	0.31	0.45	0.32	0.19	(0.26)	1.15	0.69	(0.33)
Net income per common share - basic (in dollars per share)	2.50	1.09	4.86	0.44	1.62	0.52	4.16	0.17	8.91	6.52	3.75
Net income (loss) per common share data - diluted:
Continuing operations (in dollars per share)	2.22	0.84	4.47	0.13	1.16	0.20	3.93	0.42	7.64	5.74	4.03
Discontinued operations (in dollars per share)	0.24	0.24	0.34	0.31	0.44	0.32	0.18	(0.26)	1.13	0.68	(0.32)
Net income per common share - diluted (in dollars per share)	$ 2.46	$ 1.08	$ 4.81	$ 0.44	$ 1.60	$ 0.52	$ 4.11	$ 0.16	$ 8.77	$ 6.42	$ 3.71
Impairment of tangible and other intangible assets									$ 21.7	$ 0.0	$ 0.0
Loss on extinguishment of debt									(20.7)	0.0	0.0
Benefit from change in enacted tax rates									57.7
Gain (loss) on sale of land					$ 23.7				$ 0.0	$ 23.7	$ 0.0