Investments In Unconsolidated Affiliates - Narrative (Details) - USD ($)		3 Months Ended			9 Months Ended
	Jul. 06, 2020	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Investment amount			$ 392,600,000		$ 100,000,000.0	$ 392,600,000
Equity interests acquired							18.10%
Equity in earnings (losses) of unconsolidated affiliates, net of tax		$ 86,600,000		$ (11,900,000)	66,200,000	(37,900,000)
Tax on noncash gain		(29,800,000)			(29,800,000)
Gain on sale of equity investments					5,000,000.0
Proceeds from sale of equity method investment					8,400,000	0
Receivable from sale of equity investment, noncurrent		$ 1,800,000			$ 1,800,000
DNB Investment
Schedule of Equity Method Investments [Line Items]
Equity interests acquired	13.00%
Payments to acquire interest in affiliate	$ 100,000,000.0
Investment acquired (shares)	54,800,000
Ownership interest (percent)	13.00%	20.00%			20.00%
Share price (in dollars per share)		$ 25.66			$ 25.66
Fair value of investment		$ 1,407,500,000			$ 1,407,500,000
Equity in earnings (losses) of unconsolidated affiliates, net of tax		86,600,000		(11,800,000)	61,200,000	(37,800,000)
Tax benefit		(29,300,000)		$ 4,200,000	(20,700,000)	$ 13,300,000
Noncash gain as a result of the DNB IPO		$ 88,200,000			$ 88,200,000
DNB Investment | IPO
Schedule of Equity Method Investments [Line Items]
Issuance of stock, IPO (shares)	90,000,000.0
Price per share (in USD per share)	$ 22.00
Proceeds from issuance of initial public offering	$ 2,400,000,000
DNB Investment | Underwriters' Option
Schedule of Equity Method Investments [Line Items]
Issuance of stock, IPO (shares)	11,700,000
DNB Investment | Private Placement
Schedule of Equity Method Investments [Line Items]
Proceeds from issuance of initial public offering	$ 400,000,000.0