Share-Based Payments (Performance Share Awards (PSAs) Activity) (Details) - PSUs	12 Months Ended
	Dec. 31, 2020 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Issued | shares	276,199
RSUs
Nonvested, Beginning Balance (in shares) | shares	419,396
Granted (in shares) | shares	85,279
Vested (in shares) | shares	(141,594)
Reinvested dividend equivalents (in shares) | shares	2,671
Forfeited (in shares) | shares	(21,481)
Nonvested, Ending Balance (in shares) | shares	344,271
Weighted Average Grant Date Fair Value Per Share
Nonvested, Beginning Balance (in dollars per share) | $ / shares	$ 93.19
Granted (in dollars per share) | $ / shares	217.49
Vested (in dollars per share) | $ / shares	77.69
Reinvested dividend equivalents (in dollars per share) | $ / shares	106.27
Forfeited (in dollars per share) | $ / shares	110.43
Nonvested, Ending Balance (in dollars per share) | $ / shares	129.38
Share-based Compensation Arrangement by Share-based Payment Award, Per Share Weighted Average Price of Shares Purchased | $ / shares	$ 74.32