Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2021	May 17, 2021	Dec. 31, 2020	Apr. 29, 2020
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	$ 1,248.9		$ 1,127.6
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	$ 1,198.7		$ 1,049.3
Senior Notes | 2.625% Senior Notes, due June 2031
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	2.625%	2.625%
Senior Notes | 3.00% Senior Notes, due May 2030
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	3.00%			3.00%
Senior Notes | 3.20% Senior Notes, due June 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	3.20%		3.20%
Senior Notes | 3.37% Senior Notes, due June 2025
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	3.37%		3.37%
Senior Notes | 4.20% Senior Notes, due December 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	4.20%		4.20%