Long-term Equity-based Compensation - Option and SAR Activity (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
Shares Subject to Awards
Outstanding at Beginning of the Year (in shares) | shares	1,808,815
Granted (in shares) | shares	375,534
Exercised (in shares) | shares	(215,700)
Forfeited or Expired (in shares) | shares	(67,692)
Outstanding at December 31, 2019 (in shares) | shares	1,900,957
Vested and Expected to Vest at December 31, 2019 (in shares) | shares	1,823,133
Exercisable at December 31, 2019 (in shares) | shares	1,045,250
Weighted- average Exercise Price Per Share ($)
Outstanding at Beginning of the Year (in dollars per share) | $ / shares	$ 56.53
Granted (in dollars per share) | $ / shares	75.91
Exercised (in dollars per share) | $ / shares	45.64
Forfeited or Expired (in dollars per share) | $ / shares	73.88
Outstanding at December 31, 2019 (in dollars per share) | $ / shares	60.97
Vested and Expected to Vest at December 31, 2019 (in dollars per share) | $ / shares	60.47
Exercisable at December 31, 2019 (in dollars per share) | $ / shares	$ 50.78
Weighted- average Remaining Contractual Life (in Years)
Outstanding at December 31, 2020	7 years 1 month 9 days
Vested and Expected to Vest at December 31, 2020	7 years 21 days
Exercisable at December 31, 2020	6 years 21 days
Aggregate Intrinsic Value ($ In Millions)
Outstanding at December 31, 2020 | $	$ 30.6
Vested and Expected to Vest at December 31, 2020 | $	30.3
Exercisable at December 31, 2020 | $	$ 27.4