Investment Portfolio (Tables)

12 Months Ended

Dec. 31, 2020

Investments [Abstract]

Components of Investment Portfolio

The following table shows the components of the investment portfolio as of December 31:

(Amounts in millions)	2020		2019
Cash	$	2,076.8	$	1,675.4
Money market securities	2.5		2.5
Cash and cash equivalents (1)	2,079.3		1,677.9
Interest-bearing investments	991.2		985.9
Available-for-sale investments	3.5		4.5
Total investment portfolio	$	3,074.0	$	2,668.3

(1) For purposes of the disclosure of the investment portfolio as a whole, the cash and cash equivalents balance includes settlement cash and cash equivalents.

Available for Sale Investments (Substantially Restricted)

The following table is a summary of the amortized cost and fair value of available-for-sale investments:

(Amounts in millions)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
December 31, 2020
Residential mortgage-backed securities	$	2.6	$	0.4	$	—	$	3.0
Asset-backed and other securities	0.2		0.5		(0.2)		0.5
Total	$	2.8	$	0.9	$	(0.2)	$	3.5
December 31, 2019
Residential mortgage-backed securities	$	3.3	$	0.3	$	—	$	3.6
Asset-backed and other securities	0.2		0.7		—		0.9
Total	$	3.5	$	1.0	$	—	$	4.5

Schedule of Investment Ratings

Investment grade is defined as a security having a Moody's equivalent rating of Aaa, Aa, A or Baa or an S&P or Fitch equivalent rating of AAA, AA, A or BBB. The Company's investments consisted of the following ratings as of December 31:

	2020					2019
(Amounts in millions, except percentages)	Number of Securities	Fair Value		Percent of Investments		Number of Securities	Fair Value		Percent of Investments
Investment grade	9	$	3.0	86	%	10	$	3.6	80	%
Below investment grade	35	0.5		14	%	35	0.9		20	%
Total	44	$	3.5	100	%	45	$	4.5	100	%