Share-based Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Mar. 01, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock authorized for issuance under the plan (in shares)	30,200,000
Capital shares reserved for future issuance (in shares)	3,500,000
Share-based payment award, expiration period	10 years
Tax benefit from compensation expense	$ 5.4	$ 4.8	$ 7.4
Share-based compensation expense, after-tax	20.2	17.7	13.7
Cash related stock options exercises	$ 50.7	10.7	22.5
Stock Options Outstanding, Weighted Average Exercise Price (dollars per share) [Abstract]
Conversion impact from Livent spin (in dollars per share)	$ 53.09
Livent
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock owned (in shares)					123,000,000
Discontinued operations, net of income taxes
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense, after-tax	$ 0.1	4.0	4.4
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vesting period	3 years
Share-based payment award, expiration period	10 years
Tax benefit from compensation expense	$ 1.5	1.3	2.4
Share-based compensation expense, after-tax	$ 5.7	$ 4.9	$ 4.5
Fair value assumptions, forfeiture rate	4.00%
Black Scholes valuation assumptions for stock option grants [Abstract]
Expected dividend yield	1.83%	0.77%	1.15%
Expected volatility	26.07%	26.85%	27.04%
Expected life (in years)	6 years 6 months	6 years 6 months	6 years 6 months
Risk-free interest rate	2.53%	2.79%	2.10%
Options granted, weighted-average grant-date fair value (in dollars per share)	$ 18.66	$ 25.70	$ 15.66
Stock Option Outstanding (shares) [Roll Forward]
Options exercisable (in shares)	628,000	1,044,000	920,000	1,292,000
Options vested and expected to vest (in shares)	835,000	1,287,000	1,452,000	1,373,000
Beginning (in shares)	2,364,000	2,435,000	2,749,000
Granted (in shares)	380,000	250,000	370,000
Impacts of conversion (in shares)	210,000
Exercised (in shares)	(1,414,000)	(260,000)	(590,000)
Forfeited (in shares)	(36,000)	(61,000)	(94,000)
Ending (in shares)	1,504,000	2,364,000	2,435,000	2,749,000
Options outstanding, weighted-average remaining contractual life (in years)	6 years 6 months	6 years	6 years 3 months 18 days	6 years 1 month 6 days
Stock Options Outstanding, Weighted Average Exercise Price (dollars per share) [Abstract]
Beginning (in dollars per share)	$ 52.87	$ 48.37	$ 45.34
Granted (in dollars per share)	75.76	85.19	57.63
Exercised (in dollars per share)	39.17	41.80	39.93
Forfeited (in dollars per share)	67.82	52.51	49.10
Ending (in dollars per share)	$ 58.06	$ 52.87	$ 48.37	$ 45.34
Options outstanding, aggregate intrinsic value	$ 62.8	$ 52.5	$ 112.7	$ 37.6
Options exercised, aggregate intrinsic value	67.2	$ 11.7	20.1
Stock Option Additional Disclosures [Abstract]
Options exercisable, intrinsic value	$ 33.2
Options exercisable, weighted-average remaining contractual term (in years)	4 years 2 months 12 days
Options exercisable, weighted-average exercise price per share (in dollars per share)	$ 47.02
Unrecognized compensation cost	$ 3.9
Unrecognized compensation cost, weighted-average period of recognition (in years)	1 year 9 months 14 days
Restricted Stock Units (RSUs) related to Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock credited to directors' accounts for RSUs (in shares)	276,145	248,465
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vesting period	3 years
Tax benefit from compensation expense	$ 2.2	$ 2.3	3.5
Share-based compensation expense, after-tax	$ 8.2	$ 8.4	$ 6.4
Fair value assumptions, forfeiture rate	2.00%
Stock Option Additional Disclosures [Abstract]
Unrecognized compensation cost	$ 10.0
Unrecognized compensation cost, weighted-average period of recognition (in years)	1 year 9 months 7 days
Nonvested Restricted Awards (shares) [Roll Forward]
Nonvested awards, beginning (in shares)	459,000	489,000	496,000
Granted (in shares)	108,000	137,000	121,000
Conversion impact from Livent spin (in shares)	(29,000)
Vested (in shares)	(223,000)	(154,000)	(98,000)
Forfeited (in shares)	(13,000)	(13,000)	(30,000)
Nonvested awards, ending (in shares)	302,000	459,000	489,000	496,000
Nonvested Awards, Weighted Average Grant Date Fair Value (dollars per share) [Abstract]
Nonvested awards, beginning (in dollars per share)	$ 55.75	$ 47.63	$ 48.56
Granted (in dollars per share)	76.22	84.94	57.66
Conversion impact from Livent spin (in dollars per share)	67.46
Vested (in dollars per share)	37.54	55.14	64.75
Forfeited (in dollars per share)	69.69	65.39	47.60
Nonvested awards, ending (in dollars per share)	$ 67.89	$ 55.75	$ 47.63	$ 48.56
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Tax benefit from compensation expense	$ 1.7	$ 1.2	$ 1.5
Share-based compensation expense, after-tax	$ 6.3	$ 4.4	$ 2.8
Nonvested Restricted Awards (shares) [Roll Forward]
Nonvested awards, beginning (in shares)	335,000	260,000	158,000
Granted (in shares)	106,000	133,000	105,000
Conversion impact from Livent spin (in shares)	(12,000)
Vested (in shares)	(222,000)	(58,000)	0
Forfeited (in shares)	(1,000)	0	(3,000)
Nonvested awards, ending (in shares)	206,000	335,000	260,000	158,000
Nonvested Awards, Weighted Average Grant Date Fair Value (dollars per share) [Abstract]
Nonvested awards, beginning (in dollars per share)	$ 56.42	$ 53.36	$ 49.55
Granted (in dollars per share)	83.89	88.65	66.93
Conversion impact from Livent spin (in dollars per share)	84.58
Vested (in dollars per share)	42.18	81.15	0
Forfeited (in dollars per share)	78.92	0	52.74
Nonvested awards, ending (in dollars per share)	$ 72.06	$ 56.42	$ 53.36	$ 49.55