Investments

3 Months Ended

Mar. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Investments

6. Investments

We invest in short and long-term investments classified as available-for-sale securities. Information regarding our investments is as follows (in millions):

	Amortized Cost		Gross Unrealized
			Gains		Losses			Fair Value
As of March 31, 2016
Corporate debt securities	$	49.9	$	0.1	$	(0.1	)	$	49.9
As of December 31, 2015
Corporate debt securities	$	245.7	$	0.1	$	(0.4	)	$	245.4
U.S. government and agency debt securities		21.6		—		(0.1	)		21.5
Commercial paper		4.2		—		—			4.2
Certificates of deposit		2.0		—		—			2.0
Total short and long-term investments	$	273.5	$	0.1	$	(0.5	)	$	273.1

The unrealized losses on our investments in corporate debt securities were caused by increases in interest yields in the global credit markets. We believe the unrealized losses associated with these securities as of March 31, 2016 are temporary because we do not intend to sell these investments, and we do not believe we will be required to sell them before recovery of their amortized cost basis.

The amortized cost and fair value of our available-for-sale fixed-maturity securities by contractual maturity are as follows (in millions):

	March 31, 2016
	Amortized Cost		Fair Value
Due in one year or less	$	13.4	$	13.4
Due after one year through two years		36.5		36.5
Total	$	49.9	$	49.9