Share-Based Compensation (Summary of PSU Activity) (Details) - PSUs	3 Months Ended
	Mar. 31, 2020 $ / shares shares
One-Year Program
Number of Awards
Unvested balances at beginning of period (in shares) | shares	317,251
Granted (in shares) | shares	26,780
Vested (in shares) | shares	(3,668)
Forfeited (in shares) | shares	(12,833)
Unvested balances at end of period (in shares) | shares	327,530
Weighted-Average Grant Date Fair Value
Unvested balances at beginning of period (in dollars per share) | $ / shares	$ 80.87
Granted (in dollars per share) | $ / shares	84.17
Vested (in dollars per share) | $ / shares	66.12
Forfeited (in dollars per share) | $ / shares	82.40
Unvested balances at end of period (in dollars per share) | $ / shares	$ 81.24
Three-Year Program
Number of Awards
Unvested balances at beginning of period (in shares) | shares	797,451
Granted (in shares) | shares	45,091
Vested (in shares) | shares	(300,767)
Forfeited (in shares) | shares	(6,079)
Unvested balances at end of period (in shares) | shares	535,696
Weighted-Average Grant Date Fair Value
Unvested balances at beginning of period (in dollars per share) | $ / shares	$ 98.31
Granted (in dollars per share) | $ / shares	82.91
Vested (in dollars per share) | $ / shares	81.57
Forfeited (in dollars per share) | $ / shares	96.22
Unvested balances at end of period (in dollars per share) | $ / shares	$ 106.43