Stock-Based Compensation (Narrative) (Details)	3 Months Ended
Mar. 31, 2020 $ / shares shares
Stock Options And SOSARs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	106,000
Granted, Weighted-Average Exercise Price \| $ / shares	$ 857.00
Stock option exercises (shares)	149,000
Units forfeited	12,000
Weighted-average grant date fair value \| $ / shares	$ 224.58
Stock Options And SOSARs [Member] \| Vesting Period 1 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years
Stock Options And SOSARs [Member] \| Vesting Period 2 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	32,000
Units forfeited	4,000
Weighted-average grant date fair value \| $ / shares	$ 857.50
Units released	54,000
Restricted Stock Units [Member] \| Vesting Period 1 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years
Restricted Stock Units [Member] \| Vesting Period 2 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units vested	71,000
Units forfeited	2,000
Performance shares granted	27,000
Weighted-average grant date fair value \| $ / shares	$ 857.00
Performance and market measurement period	3 years
Performance Shares [Member] \| Defined Minimum Targets Not Met [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units vested	0
Minimum [Member] \| Performance Shares [Member] \| Vesting Period 1 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	0.00%
Maximum [Member] \| Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target number of shares to be earned if certain criteria is met	100.00%
Maximum [Member] \| Performance Shares [Member] \| Vesting Period 1 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	300.00%

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