Guarantor Financial Information - Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
ASSETS
Cash and cash equivalents	$ 32.1		$ 47.3
Receivables, less allowances	201.2		172.9
Intercompany receivables	0.0		0.0
Intercompany short-term note receivable-net			0.0
Inventories	13.7		12.1
Prepaid expenses and other current assets	21.0		16.7
Total current assets	268.0		249.0
Property, plant and equipment-net	25.0		32.2
Right-of-use assets	85.7		0.0
Software-net	53.6		47.8
Goodwill	450.2		450.0
Other intangible assets-net	26.3		37.2
Deferred income taxes	10.8		9.7
Intercompany long-term note receivable	0.0		0.0
Other noncurrent assets	42.7		42.8
Investments in consolidated subsidiaries	0.0		0.0
Total assets	962.3		868.7	$ 913.4
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	50.6		72.4
Intercompany payables	0.0		0.0
Intercompany short-term note payable-net			0.0
Accrued liabilities	142.9		126.0
Total current liabilities	193.5		198.4
Long-term debt	364.1		362.7
Intercompany long-term note payable	0.0		0.0
Deferred compensation liabilities	19.8		19.5
Pension and other postretirement benefits plan liabilities	47.7		51.3
Noncurrent lease liabilities	63.2		0.0
Other noncurrent liabilities	7.9		10.8
Total liabilities	696.2		642.7
Total equity	266.1	$ 249.1	226.0	$ 231.7	$ 180.8	$ 149.4
Total liabilities and equity	962.3		868.7
Eliminations
ASSETS
Cash and cash equivalents	0.0		0.0
Receivables, less allowances	0.0		0.0
Intercompany receivables	(121.1)		(123.6)
Intercompany short-term note receivable-net			(60.5)
Inventories	0.0		0.0
Prepaid expenses and other current assets	0.0		0.0
Total current assets	(121.1)		(184.1)
Property, plant and equipment-net	0.0		0.0
Right-of-use assets	0.0
Software-net	0.0		0.0
Goodwill	0.0		0.0
Other intangible assets-net	0.0		0.0
Deferred income taxes	(1.7)		(29.9)
Intercompany long-term note receivable	(298.0)		(298.0)
Other noncurrent assets	0.0		0.0
Investments in consolidated subsidiaries	(487.5)		(551.9)
Total assets	(908.3)		(1,063.9)
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	0.0		0.0
Intercompany payables	(121.1)		(123.6)
Intercompany short-term note payable-net			(60.5)
Accrued liabilities	0.0		0.0
Total current liabilities	(121.1)		(184.1)
Long-term debt	0.0		0.0
Intercompany long-term note payable	(298.0)		(298.0)
Deferred compensation liabilities	0.0		0.0
Pension and other postretirement benefits plan liabilities	0.0		0.0
Noncurrent lease liabilities	0.0
Other noncurrent liabilities	(1.7)		(29.9)
Total liabilities	(420.8)		(512.0)
Total equity	(487.5)		(551.9)
Total liabilities and equity	(908.3)		(1,063.9)
Parent
ASSETS
Cash and cash equivalents	17.4		24.9
Receivables, less allowances	0.0		0.0
Intercompany receivables	0.0		0.0
Intercompany short-term note receivable-net			0.0
Inventories	0.0		0.0
Prepaid expenses and other current assets	4.5		0.0
Total current assets	21.9		24.9
Property, plant and equipment-net	0.0		0.0
Right-of-use assets	0.0
Software-net	0.0		0.0
Goodwill	0.0		0.0
Other intangible assets-net	0.0		0.0
Deferred income taxes	0.0		0.0
Intercompany long-term note receivable	298.0		298.0
Other noncurrent assets	3.3		3.6
Investments in consolidated subsidiaries	434.2		445.9
Total assets	757.4		772.4
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	0.0		0.0
Intercompany payables	118.9		120.9
Intercompany short-term note payable-net			60.0
Accrued liabilities	5.6		0.1
Total current liabilities	124.5		181.0
Long-term debt	364.1		362.7
Intercompany long-term note payable	0.0		0.0
Deferred compensation liabilities	0.0		0.0
Pension and other postretirement benefits plan liabilities	0.0		0.0
Noncurrent lease liabilities	0.0
Other noncurrent liabilities	2.7		2.7
Total liabilities	491.3		546.4
Total equity	266.1		226.0
Total liabilities and equity	757.4		772.4
Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	2.6		5.0
Receivables, less allowances	166.6		141.6
Intercompany receivables	121.1		123.6
Intercompany short-term note receivable-net			0.0
Inventories	11.1		10.4
Prepaid expenses and other current assets	13.8		13.5
Total current assets	315.2		294.1
Property, plant and equipment-net	23.0		29.3
Right-of-use assets	72.2
Software-net	53.6		47.8
Goodwill	438.6		438.5
Other intangible assets-net	23.6		32.6
Deferred income taxes	10.0		37.2
Intercompany long-term note receivable	0.0		0.0
Other noncurrent assets	35.4		35.1
Investments in consolidated subsidiaries	53.3		106.0
Total assets	1,024.9		1,020.6
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	42.5		61.0
Intercompany payables	0.0		0.0
Intercompany short-term note payable-net			0.5
Accrued liabilities	122.8		109.2
Total current liabilities	165.3		170.7
Long-term debt	0.0		0.0
Intercompany long-term note payable	298.0		298.0
Deferred compensation liabilities	19.8		19.5
Pension and other postretirement benefits plan liabilities	46.7		50.3
Noncurrent lease liabilities	54.8
Other noncurrent liabilities	6.1		36.2
Total liabilities	590.7		574.7
Total equity	434.2		445.9
Total liabilities and equity	1,024.9		1,020.6
Non-guarantor Subsidiaries
ASSETS
Cash and cash equivalents	12.1		17.4
Receivables, less allowances	34.6		31.3
Intercompany receivables	0.0		0.0
Intercompany short-term note receivable-net			60.5
Inventories	2.6		1.7
Prepaid expenses and other current assets	2.7		3.2
Total current assets	52.0		114.1
Property, plant and equipment-net	2.0		2.9
Right-of-use assets	13.5
Software-net	0.0		0.0
Goodwill	11.6		11.5
Other intangible assets-net	2.7		4.6
Deferred income taxes	2.5		2.4
Intercompany long-term note receivable	0.0		0.0
Other noncurrent assets	4.0		4.1
Investments in consolidated subsidiaries	0.0		0.0
Total assets	88.3		139.6
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	8.1		11.4
Intercompany payables	2.2		2.7
Intercompany short-term note payable-net			0.0
Accrued liabilities	14.5		16.7
Total current liabilities	24.8		30.8
Long-term debt	0.0		0.0
Intercompany long-term note payable	0.0		0.0
Deferred compensation liabilities	0.0		0.0
Pension and other postretirement benefits plan liabilities	1.0		1.0
Noncurrent lease liabilities	8.4
Other noncurrent liabilities	0.8		1.8
Total liabilities	35.0		33.6
Total equity	53.3		106.0
Total liabilities and equity	$ 88.3		$ 139.6