Investments (Tables)

3 Months Ended

Mar. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Investments in Short and Long-Term Classified as Available-for-Sale Securities

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

Cost and Fair Value of Available-for-Sale Fixed-Maturity Securities by Contractual Maturity

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