Investments (Tables)

12 Months Ended

Dec. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Amortized cost and fair values

The following tables present cost or amortized cost and fair values of investments at December 31, 2020 and 2019, respectively ($ in millions):

	Cost or Amortized Cost		Gross Unrealized				Fair Value
			Gains		Losses
December 31, 2020
U.S. Government obligations	$	6.4	$	0.2	$	—	$	6.6
Total	$	6.4	$	0.2	$	—	$	6.6
December 31, 2019
U.S. Government obligations	$	5.8	$	0.1	$	—	$	5.9
Total	$	5.8	$	0.1	$	—	$	5.9

Contractual maturities of bonds

The following table presents the cost or amortized cost and estimated fair value of bonds as of December 31, 2020 by contractual maturity ($ in millions). Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.

	December 31, 2020
	Cost or Amortized Cost		Fair Value
Due in one year or less	$	—	$	—
Due after one year through five years	6.4		6.6
Due after five years through ten years	—		—
Due after ten years	—		—
Total	$	6.4	$	6.6

Aging of gross unrealized losses

The following tables present the gross unrealized losses and related fair values for the Company's available-for-sale bond securities, grouped by duration of time in a continuous unrealized loss position, as of December 31, 2020 and 2019 ($ in millions):

	Less than 12 Months				12 Months or More				Total
	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
December 31, 2020
U.S. Government obligations	$	—	$	—	$	—	$	—	$	—	$	—
Total	$	—	$	—	$	—	$	—	$	—	$	—
December 31, 2019
U.S. Government obligations	$	0.2	$	—	$	2.2	$	—	$	2.4	$	—
Total	$	0.2	$	—	$	2.2	$	—	$	2.4	$	—

Special deposits

The carrying value of bonds deposited with each respective state is as follows ($ in millions):

	December 31,
U.S. State	2020		2019
New York	$	2.8	$	2.1
Washington	1.2		1.1
Colorado	1.1		1.1
North Carolina	0.3		0.3
New Mexico	0.3		0.3
Virginia	0.3		0.3
Florida	0.2		—
Nevada	0.2		0.2
Arkansas	—		0.1
Massachusetts	0.1		0.1
Total	$	6.5	$	5.6

Net investment income

An analysis of net investment income follows ($ in millions):

	December 31,
	2020		2019		2018
Interest on cash and cash equivalents	$	1.0	$	2.8	$	1.0
Bonds	0.1		0.1		0.1
Short-term investments	0.4		0.5		0.2
Net investment income	$	1.5	$	3.4	$	1.3