Long Term Debt and Financing Arrangements - Narrative (Details) - USD ($)		1 Months Ended			3 Months Ended		9 Months Ended
	Sep. 30, 2020	Jul. 31, 2020	Apr. 30, 2020	Mar. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Debt Instrument [Line Items]
Line of credit facility, borrowings							$ 225,000,000.0	$ 0
Long-term debt repayments							331,300,000	$ 18,800,000
Short-term debt outstanding	$ 21,900,000				$ 21,900,000		$ 21,900,000		$ 65,400,000
Term loan
Debt Instrument [Line Items]
Long-term debt repayments					90,700,000
Long-term debt repayments, principal					90,600,000
Long-term debt repayments, accrued interest					100,000
Loss on extinguishment of debt					200,000
2018 Credit Facility | Line of Credit | Credit Agreement
Debt Instrument [Line Items]
Debt term							5 years
Line of credit, maximum borrowing capacity	750,000,000				750,000,000		$ 750,000,000
Line of credit facility, accordion feature, higher borrowing capacity option	1,250,000,000				1,250,000,000		$ 1,250,000,000
Line of credit facility covenants maximum debt to capitalization percentage							65.00%
Line of credit facility, borrowings	0		$ 125,000,000.0	$ 100,000,000.0
Line of credit facility, repayments		$ 125,000,000.0				$ 100,000,000.0
Line of credit facility, borrowing capacity	$ 750,000,000.0				$ 750,000,000.0		$ 750,000,000.0