Net Income Per Common Share (Ant-Dilutive Schedule) (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock awards excluded because exercise prices were greater than average market price of shares	2,029,000	814,000	1,497,000	570,000
Minimum | Share-based Payment Arrangement, Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Net Income, Per Outstanding Unit, Amount	$ 39.10	$ 67.53	$ 49.51	$ 67.53
Maximum | Share-based Payment Arrangement, Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Net Income, Per Outstanding Unit, Amount	$ 95.25	$ 95.25	$ 95.25	$ 95.25