CASH, CASH EQUIVALENTS AND INVESTMENTS

Under the terms of the agreements with certain of our workers' compensation and health benefit insurance carriers, we are required to maintain collateral in trust accounts for the benefit of specified insurance carriers and to reimburse the carriers’ claim payments within our deductible layer. We invest a portion of the collateral amounts in marketable securities. We report the current and noncurrent portions of these trust accounts as restricted cash, cash equivalents and investments on the consolidated balance sheets.

We require our clients to prefund their payroll and related taxes and other withholding liabilities before payroll is processed or due for payment. This prefund is included in restricted cash, cash equivalents and investments as payroll funds collected, which is designated to pay pending payrolls and other WSE-related liabilities.

Our total cash, cash equivalents and investments are summarized below:



	June 30, 2018								December 31, 2017
(in millions)	Cash and cash equivalents		Available-for-sale marketable securities		Certificate of deposits		Total		Cash and cash equivalents		Available-for-sale marketable securities		Certificate of deposits		Total
Cash and cash equivalents	$	202	$	—	$	—	$	202	$	336	$	—	$	—	$	336
Investments	—		29		—		29		—		—		—		—
Restricted cash, cash equivalents and investments
Insurance carriers security deposits	15		—		—		15		15		—		—		15
Payroll funds collected	449		—		—		449		1,095		—		—		1,095
Collateral for health benefits claims	75		—		—		75		69		—		—		69
Collateral for workers' compensation claims	87		1		—		88		98		1		—		99
Collateral to secure standby letter of credit	—		—		2		2		—		—		2		2
Total restricted cash, cash equivalents and investments	626		1		2		629		1,277		1		2		1,280
Investments, noncurrent	—		133		—		133		—		—		—		—
Restricted cash, cash equivalents and investments, noncurrent
Collateral for workers' compensation claims	165		14		—		179		125		37		—		162
Total	$	993	$	177	$	2	$	1,172	$	1,738	$	38	$	2	$	1,778