Net Income Per Common Share (Ant-Dilutive Schedule) (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 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	2,056,133	470,162	1,633,078	446,610
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	$ 79.01	$ 39.10	$ 79.01
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