Share-Based Payments (Nonvested restricted stock activity) (Details) - Restricted Stock Units (RSUs)	12 Months Ended
	Dec. 31, 2020 $ / shares shares
RSUs
Nonvested, Beginning Balance (in shares) | shares	1,460,535
Granted (in shares) | shares	239,745
Vested (in shares) | shares	(627,818)
Reinvested dividend equivalents (in shares) | shares	6,511
Forfeited (in shares) | shares	(95,507)
Nonvested, Ending Balance (in shares) | shares	983,466
Weighted Average Grant Date Fair Value Per Share
Nonvested, Beginning Balance (in dollars per share) | $ / shares	$ 72.93
Granted (in dollars per share) | $ / shares	144.06
Vested (in dollars per share) | $ / shares	61.94
Reinvested dividend equivalents (in dollars per share) | $ / shares	83.26
Forfeited (in dollars per share) | $ / shares	88.69
Nonvested, Ending Balance (in dollars per share) | $ / shares	$ 95.82