Investments In Unconsolidated Affiliates - D&B IPO and Private Placement (Details) - Subsequent Event $ / shares in Units, shares in Millions, $ in Millions	Jul. 06, 2020 USD ($) $ / shares shares
DNB Investment
Schedule of Equity Method Investments [Line Items]
Payments to acquire interest in affiliate | $	$ 100.0
Investment acquired (shares) | shares	54.8
Ownership interest (percent)	13.00%
IPO [Member] | DNB Investment
Schedule of Equity Method Investments [Line Items]
Issuance of common stock, net of underwriters' discount and issuance costs (shares) | shares	90.0
Price per share (in USD per share) | $ / shares	$ 22.00
Proceeds from issuance of initial public offering | $	$ 2,400.0
Underwriters' Option [Member] | DNB Investment
Schedule of Equity Method Investments [Line Items]
Issuance of common stock, net of underwriters' discount and issuance costs (shares) | shares	11.7
Private Placement [Member] | DNB Investment
Schedule of Equity Method Investments [Line Items]
Proceeds from issuance of initial public offering | $	$ 400.0
Senior Unsecured Notes Outstanding due 2027 [Member]
Schedule of Equity Method Investments [Line Items]
Stated rate	10.25%