Customer Trust Funds (Tables)

9 Months Ended

Sep. 30, 2018

Investments Debt And Equity Securities [Abstract]

Schedule of Amortized Cost and Fair Values of Investments of Customer Trust Funds Available for Sale

Investments of Customer Trust Funds at September 30, 2018

	Amortized		Gross Unrealized					Fair
	Cost		Gain		Loss			Value
Money market securities, investments carried at cost and    other cash equivalents	$	1,697.9	$	—	$	—		$	1,697.9
Available for sale investments:
U.S. government and agency securities		548.6		—		(19.1	)		529.5
Canadian and provincial government securities		414.6		2.1		(2.7	)		414.0
Corporate debt securities		513.1		0.2		(6.8	)		506.5
Asset-backed securities		249.6		—		(3.6	)		246.0
Mortgage-backed securities		9.7		—		(0.3	)		9.4
Other securities		14.9		—		(0.2	)		14.7
Total available for sale investments		1,750.5		2.3		(32.7	)		1,720.1
Invested customer trust funds		3,448.4	$	2.3	$	(32.7	)		3,418.0
Trust receivables		8.6							8.6
Total customer trust funds	$	3,457.0						$	3,426.6

Investments of Customer Trust Funds at December 31, 2017

	Amortized		Gross Unrealized					Fair
	Cost		Gain		Loss			Value
Money market securities, investments carried at cost and    other cash equivalents	$	2,309.3	$	—	$	—		$	2,309.3
Available for sale investments:
U.S. government and agency securities		584.6		0.1		(7.1	)		577.6
Canadian and provincial government securities		418.2		6.6		(1.5	)		423.3
Corporate debt securities		472.3		0.8		(2.5	)		470.6
Asset-backed securities		280.8		—		(1.8	)		279.0
Mortgage-backed securities		15.0		—		(0.2	)		14.8
Other securities		17.0		—		(0.2	)		16.8
Total available for sale investments		1,787.9		7.5		(13.3	)		1,782.1
Invested customer trust funds		4,097.2	$	7.5	$	(13.3	)		4,091.4
Trust receivables		8.3							8.3
Total customer trust funds	$	4,105.5						$	4,099.7

Schedule of Unrealized Losses and Fair Value

The following represents the gross unrealized losses and the related fair value of the investments of customer trust funds available for sale, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position at September 30, 2018.

	Less than 12 months					12 months or more					Total
	Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value
U.S. government and agency securities	$	(8.0	)	$	257.9	$	(11.1	)	$	268.7	$	(19.1	)	$	526.6
Canadian and provincial government securities		(0.9	)		86.9		(1.8	)		100.8		(2.7	)		187.7
Corporate debt securities		(3.7	)		271.1		(3.1	)		145.9		(6.8	)		417.0
Asset-backed securities		(1.1	)		97.4		(2.5	)		129.8		(3.6	)		227.2
Mortgage-backed securities	(a)				1.2		(0.3	)		8.0		(0.3	)		9.2
Other securities		(0.1	)		4.0		(0.1	)		10.5		(0.2	)		14.5
Total available for sale investments	$	(13.8	)	$	718.5	$	(18.9	)	$	663.7	$	(32.7	)	$	1,382.2

(a) These investments have been in an unrealized loss position; however, the amount of unrealized loss is less than $0.05.

Schedule of Amortized Cost and Fair Value of Investment Securities Available for Sale by Contractual Maturity

The amortized cost and fair value of investment securities available for sale at September 30, 2018, by contractual maturity are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to call or to prepay obligations with or without call or prepayment penalties.

	September 30, 2018
	Cost		Fair Value
Due in one year or less	$	2,024.4	$	2,023.9
Due in one to three years		565.6		556.5
Due in three to five years		565.5		557.6
Due after five years		292.9		280.0
Invested customer trust funds	$	3,448.4	$	3,418.0