Condensed Consolidated Statements of Earnings and Comprehensive Earnings - USD ($) shares in Millions, $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Revenues		$ 293.1		$ 294.9		$ 583.8	$ 578.0
Expenses:
Operating expenses		155.5		159.4		317.9	319.4
Depreciation and amortization		58.6		57.5		116.3	114.4
Transition and integration costs		2.5		1.0		4.9	1.9
Total expenses		216.6		217.9		439.1	435.7
Operating income (loss)		76.5		77.0		144.7	142.3
Other income and expense:
Interest expense		(13.0)		(16.7)		(27.7)	(31.7)
Other income (expense), net		18.8		(0.5)		18.0	(0.8)
Total other income (expense), net		5.8		(17.2)		(9.7)	(32.5)
Earnings before income taxes and equity in losses of unconsolidated affiliates		82.3		59.8		135.0	109.8
Income tax expense		17.2		14.5		25.4	25.2
Earnings before equity in losses of unconsolidated affiliates		65.1		45.3		109.6	84.6
Equity in losses of unconsolidated affiliates, net of tax		(26.0)		(12.7)		(20.4)	(26.0)
Net earnings		39.1		32.6		89.2	58.6
Unrealized holding losses, net of tax(1)	[1]	(2.6)		(11.8)		(24.2)	(18.0)
Reclassification adjustments for losses (gains) included in net earnings, net of tax(2)	[2]	(3.2)		0.3		(4.4)	1.0
Reclassification adjustments for losses (gains) included in net earnings, net of tax(2)		0.6		(12.1)		(19.8)	(19.0)
Foreign currency translation adjustment	[3]	0.0		0.0		(0.2)	0.0
Unrealized loss on investments in unconsolidated affiliates	[4]	(1.5)		(2.2)		(1.7)	(2.4)
Other comprehensive losses		(0.9)		(14.3)		(21.7)	(21.4)
Comprehensive earnings		$ 38.2		$ 18.3		$ 67.5	$ 37.2
Net earnings per share:
Basic (in dollars per share)		$ 0.26		$ 0.22		$ 0.60	$ 0.40
Diluted (in dollars per share)		$ 0.26		$ 0.22		$ 0.60	$ 0.39
Weighted average shares of common stock outstanding (Note 4):
Basic (in shares)		149.2	[4]	147.7	[4]	148.6	147.6
Diluted (in shares)		150.0	[4]	148.5	[4]	149.3	148.4
Derivatives qualifying as hedges, tax		$ (0.9)		$ (4.1)		$ (8.2)	$ (6.3)
Reclassification adjustment from AOCI on derivatives, tax		(1.1)		0.1		(1.5)	0.4
Foreign currency translation adjustment, tax benefit						0.1
Unrealized loss on investments in unconsolidated affiliates, tax benefit		$ (0.5)		$ (0.8)		$ (0.6)	$ (0.9)

[1] Net of income tax benefit of $0.9 million and $8.2 million for the three and six months ended June 30, 2020, respectively, and $4.1 million and $6.3 million for the three and six months ended June 30, 2019, respectively.

[2] Amounts reclassified to net earnings relate to losses (gains) on interest rate swaps and are included in Interest expense, net above. Amounts are net of income tax benefit of $1.1 million and $1.5 million for the three and six months ended June 30, 2020, respectively, and net of income tax expense of $0.1 million and $0.4 million for the three and six months ended June 30, 2019, respectively.

[3] Net of income tax benefit of $0.1 million for the six months ended June 30, 2020

[4] Net of income tax benefit of $0.5 million and $0.6 million for the three and six months ended June 30, 2020, respectively, and $0.8 million and $0.9 million for the three and six months ended June 30, 2019, respectively.