Stock Options and SARs (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Dividends, Per Share, Declared					$ 43.40
Proceeds from Stock Options Exercised	$ 1	$ 3	$ 2
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	1	2	1
Unrecognized compensation expense	17
Allocated Share-based Compensation Expense	$ 17	$ 8	$ 12
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 79.61	$ 123.52	$ 94.73
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	290,000
Price Range One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	7,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	2 years 1 month 6 days
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning Balance	$ 54.80
Price Range Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	48,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	3 years 3 months 18 days
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning Balance	$ 72.89
Price Range Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	166,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	5 years 3 months 18 days
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning Balance	$ 87.40
Price Range Four [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Outstanding Options	69,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	5 years 3 months 18 days
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price, Beginning Balance	$ 124.35
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Unrecognized compensation expense	$ 8
Allocated Share-based Compensation Expense	$ 6	$ (2)	$ 6
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 111.98	$ 124.90	$ 110.66
Expected volatility	31.20%	24.10%
Risk-free interest rate	2.43%	2.33%
Expected dividend yield	0.00%	0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Forfeited or expired Options Weighted Average Exercise Price	$ 118.87	$ 33.85	$ 103.72
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested at beginning of period	195,000	461,000	414,000
Granted	71,000	87,000	78,000
Exercised	(73,000)	(63,000)	(16,000)
Forfeited	(23,000)	(290,000)	(15,000)
Non-vested at end of period	170,000	195,000	461,000	414,000
Restricted Stock Units Equity Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 8
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1 year 6 months
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 79.88	$ 123.52	$ 94.51
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Granted	133,000	70,000	76,000
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 8
Allocated Share-based Compensation Expense	$ 9	$ 8	$ 11
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested at beginning of period	164,000	230,000	170,000
Granted	141,000	70,000	99,000
Exercised	(71,000)	(102,000)	(29,000)
Forfeited	(18,000)	(34,000)	(10,000)
Non-vested at end of period	216,000	164,000	230,000	170,000
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Awards other than Options, Exerciable, Weighted-Average Exercisable Price	$ 70.05
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1 year
Expected Term			5 years
Expected volatility			27.31%
Risk-free interest rate			2.03%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested at beginning of period	7,000	8,000	13,000
Granted			2,000
Exercised		(1,000)	(7,000)
Non-vested at end of period	7,000	7,000	8,000	13,000
Non-vested SARS Weighted Average Exercise Price	$ 72.84	$ 72.84	$ 69.21	$ 51.10
Granted SARS Weighted Average Exercise Price	0		94.77
Exercised SARs Weighted Average Exercise Price	$ 0	$ 51.25	44.33
Forfeited or expired SARs Weighted Average Exercise Price			$ 59.59
Share-based Compensation Arangements by Share-based Payment Award, Equity Awards other than options, excercisable, number	6,000
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 1
Allocated Share-based Compensation Expense	$ 2	$ 2	$ 2
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1 year 6 months
Expected Term	5 years		5 years	5 years
Expected volatility	27.69%		22.95%	27.31%
Risk-free interest rate	2.43%		2.58%	2.03%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding Options Beginning Period	213,000	166,000	115,000
Granted	106,000	78,000	84,000
Exercised	(4,000)	(31,000)	(26,000)
Forfeited or expired	(32,000)		(7,000)
Outstanding Options Ending Period	283,000	213,000	166,000	115,000
Outstanding Options Weighted Average Exercise Price	$ 93.51	$ 99.36	$ 81.72	$ 68.37
Granted Options Weighted Average Exercise Price	80.97	124.35	94.77
Exercised Options Weighted Average Exercise Price	59.37	$ 68.02	65.79
Forfeited or expired Options Weighted Average Exercise Price	$ 96.02		77.36
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	129,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 91.65
Restricted Stock Units Liability Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	1 year 7 months 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 75.02		$ 95.45
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Granted	8,000		23,000
Maximum [Member] | Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 1
Maximum [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Date	10 years
Maximum [Member] | Restricted Stock Units Liability Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 1
Minimum [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Date	7 years