Guarantor Financial Information - Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
ASSETS
Cash and cash equivalents	$ 56.2	$ 52.0	$ 32.2	$ 36.2
Receivables, less allowances	221.5	165.2
Intercompany receivables	0.0	0.0
Intercompany short-term note receivable-net	0.0	0.0
Inventories	13.8	23.3
Prepaid expenses and other current assets	16.4	29.6
Total current assets	307.9	270.1
Property, plant and equipment-net	31.7	34.7
Goodwill	437.5	447.4
Other intangible assets-net	29.3	39.9
Software-net	46.4	41.1
Deferred income taxes	14.0	22.2
Intercompany long-term note receivable	0.0
Other noncurrent assets	46.6	38.1
Investments in consolidated subsidiaries	0.0	0.0
Total assets	913.4	893.5	933.7
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	67.5	67.8
Intercompany payables	0.0	0.0
Intercompany short-term note payable-net	0.0	0.0
Accrued liabilities	137.3	119.2
Total current liabilities	204.8	187.0
Long-term debt	397.2	458.3
Intercompany long-term note payable	0.0
Deferred compensation liabilities	21.7	22.8
Pension and other postretirement benefits plan liabilities	47.7	52.5
Other noncurrent liabilities	10.3	23.5
Total liabilities	681.7	744.1
Total equity	231.7	149.4	173.6	111.1
Total liabilities and equity	913.4	893.5
Eliminations
ASSETS
Cash and cash equivalents	0.0	0.0	0.0	(2.4)
Receivables, less allowances	0.0	0.0
Intercompany receivables	(116.1)	(146.4)
Intercompany short-term note receivable-net	(45.0)	(30.0)
Inventories	0.0	0.0
Prepaid expenses and other current assets	0.0	(25.1)
Total current assets	(161.1)	(201.5)
Property, plant and equipment-net	0.0	0.0
Goodwill	0.0	0.0
Other intangible assets-net	0.0	0.0
Software-net	0.0	0.0
Deferred income taxes	(23.4)	(21.7)
Intercompany long-term note receivable	(326.0)
Other noncurrent assets	0.0	0.0
Investments in consolidated subsidiaries	(565.2)	(813.6)
Total assets	(1,075.7)	(1,036.8)
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	0.0	0.0
Intercompany payables	(116.1)	(146.4)
Intercompany short-term note payable-net	(45.0)	(30.0)
Accrued liabilities	0.0	(25.1)
Total current liabilities	(161.1)	(201.5)
Long-term debt	0.0	0.0
Intercompany long-term note payable	(326.0)
Deferred compensation liabilities	0.0	0.0
Pension and other postretirement benefits plan liabilities	0.0	0.0
Other noncurrent liabilities	(23.4)	(21.7)
Total liabilities	(510.5)	(223.2)
Total equity	(565.2)	(813.6)
Total liabilities and equity	(1,075.7)	(1,036.8)
Parent
ASSETS
Cash and cash equivalents	20.5	8.3	0.2	0.0
Receivables, less allowances	0.0	0.0
Intercompany receivables	0.0	0.0
Intercompany short-term note receivable-net	0.0	0.0
Inventories	0.0	0.0
Prepaid expenses and other current assets	0.0	37.1
Total current assets	20.5	45.4
Property, plant and equipment-net	0.0	0.0
Goodwill	0.0	0.0
Other intangible assets-net	0.0	0.0
Software-net	0.0	0.0
Deferred income taxes	0.0	0.0
Intercompany long-term note receivable	326.0
Other noncurrent assets	2.7	3.4
Investments in consolidated subsidiaries	456.2	728.4
Total assets	805.4	777.2
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	0.0	0.0
Intercompany payables	111.1	139.5
Intercompany short-term note payable-net	45.0	30.0
Accrued liabilities	18.1	0.0
Total current liabilities	174.2	169.5
Long-term debt	397.2	458.3
Intercompany long-term note payable	0.0
Deferred compensation liabilities	0.0	0.0
Pension and other postretirement benefits plan liabilities	0.0	0.0
Other noncurrent liabilities	2.3	0.0
Total liabilities	573.7	627.8
Total equity	231.7	149.4
Total liabilities and equity	805.4	777.2
Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	5.6	27.9	21.3	21.8
Receivables, less allowances	183.5	131.3
Intercompany receivables	116.1	146.4
Intercompany short-term note receivable-net	0.0	0.0
Inventories	10.9	21.3
Prepaid expenses and other current assets	14.1	14.8
Total current assets	330.2	341.7
Property, plant and equipment-net	28.7	31.2
Goodwill	425.7	429.2
Other intangible assets-net	24.0	32.4
Software-net	46.4	40.6
Deferred income taxes	34.6	40.5
Intercompany long-term note receivable	0.0
Other noncurrent assets	37.8	30.0
Investments in consolidated subsidiaries	109.0	85.2
Total assets	1,036.4	1,030.8
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	53.1	57.9
Intercompany payables	0.0	0.0
Intercompany short-term note payable-net	0.0	0.0
Accrued liabilities	103.3	127.6
Total current liabilities	156.4	185.5
Long-term debt	0.0	0.0
Intercompany long-term note payable	326.0
Deferred compensation liabilities	21.7	22.8
Pension and other postretirement benefits plan liabilities	46.6	51.3
Other noncurrent liabilities	29.5	42.8
Total liabilities	580.2	302.4
Total equity	456.2	728.4
Total liabilities and equity	1,036.4	1,030.8
Non-guarantor Subsidiaries
ASSETS
Cash and cash equivalents	30.1	15.8	$ 10.7	$ 16.8
Receivables, less allowances	38.0	33.9
Intercompany receivables	0.0	0.0
Intercompany short-term note receivable-net	45.0	30.0
Inventories	2.9	2.0
Prepaid expenses and other current assets	2.3	2.8
Total current assets	118.3	84.5
Property, plant and equipment-net	3.0	3.5
Goodwill	11.8	18.2
Other intangible assets-net	5.3	7.5
Software-net	0.0	0.5
Deferred income taxes	2.8	3.4
Intercompany long-term note receivable	0.0
Other noncurrent assets	6.1	4.7
Investments in consolidated subsidiaries	0.0	0.0
Total assets	147.3	122.3
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	14.4	9.9
Intercompany payables	5.0	6.9
Intercompany short-term note payable-net	0.0	0.0
Accrued liabilities	15.9	16.7
Total current liabilities	35.3	33.5
Long-term debt	0.0	0.0
Intercompany long-term note payable	0.0
Deferred compensation liabilities	0.0	0.0
Pension and other postretirement benefits plan liabilities	1.1	1.2
Other noncurrent liabilities	1.9	2.4
Total liabilities	38.3	37.1
Total equity	109.0	85.2
Total liabilities and equity	$ 147.3	$ 122.3