Stock-Based Compensation (Narrative) (Details)	9 Months Ended
Sep. 30, 2020 $ / shares shares
Stock Options And SOSARs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	112,000
Granted, weighted-average exercise price \| $ / shares	$ 859.20
Stock option exercises (shares)	438,000
Units forfeited	25,000
Weighted-average grant date fair value \| $ / shares	$ 227.08
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	42,000
Units forfeited	9,000
Weighted-average grant date fair value \| $ / shares	$ 904.87
Units released	58,000
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	$ 853.03
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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