Investments (Tables)

12 Months Ended

Dec. 31, 2020

Investments classified as short-term consist of the following:

	Years Ended December 31,
	2020		2019
Available-for-sale investments:
Time deposits and certificates of deposit	$	0.7	$	13.1
Bankers’ acceptance drafts		3.8		4.0
Commercial paper		—		61.2
U.S. treasury obligations		223.2		5.0
U.S. agency obligations		—		26.1
	$	227.7	$	109.4

Investments classified as long-term consist of the following:

	Years Ended December 31,
	2020		2019
Available-for-sale investments:
Group insurance contracts	$	6.5	$	5.8

The following table shows the gross unrealized gains and (losses) aggregated by investment category for available-for-sale investments:

As of December 31, 2020:	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)		Estimated Fair Value
Short-term investments:
Available-for-sale investments:
Time deposits and certificates of deposit	$	0.7	$	—	$	—	$	0.7
Bankers' acceptance drafts		3.8		—		—		3.8
U.S. treasury obligations		223.2		—		—		223.2
	$	227.7	$	—	$	—	$	227.7

As of December 31, 2020:	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)		Estimated Fair Value
Long-term investments:
Available-for-sale investments:
Group insurance contracts	$	5.6	$	0.9	$	—	$	6.5

As of December 31, 2019:	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Estimated Fair Value
Short-term investments:
Available-for-sale investments:
Time deposits and certificates of deposit	$	13.1	$	—	$	—		$	13.1
Bankers' acceptance drafts		4.0		—		—			4.0
Commercial paper		61.5		—		(0.3	)		61.2
U.S. treasury obligations		5.0		—		—			5.0
U.S. agency obligations		26.1		—		—			26.1
	$	109.7	$	—	$	(0.3	)	$	109.4

As of December 31, 2019:	Cost		Gross Unrealized Gains		Gross Unrealized (Losses)		Estimated Fair Value
Long-term investments:
Available-for-sale investments:
Group insurance contracts	$	5.2	$	0.6	$	—	$	5.8