Note 4 - Workers’ Compensation Claims

The following table summarizes the aggregate workers’ compensation reserve activity (in thousands):


	Three Months Ended
	March 31,
	2016		2015
			(As Restated)
Balance at January 1,
Workers’ compensation claims liabilities	$	255,675	$	225,300

Claims expense accrual:
Current period		31,155		27,777
Prior periods		848		(2,897	)

		32,003		24,880

Claim payments related to:
Current period		1,271		898
Prior periods		21,264		17,559

		22,535		18,457

Balance at March 31,
Workers’ compensation claims liabilities	$	265,143	$	231,723

Incurred but not reported (IBNR)	$	132,879	$	115,661

The states of California, Oregon, Maryland, Washington, Delaware and Colorado require us to maintain specified investment balances or other financial instruments totaling $158.2 million at March 31, 2016 to cover potential workers’ compensation claims losses related to the Company’s current and former status as a self-insured employer. In partial satisfaction of these requirements, at March 31, 2016, we have provided surety bonds and standby letters of credit totaling $152.0 million, including a California requirement of $147.2 million.

As part of its fronted workers’ compensation insurance program with ACE Group (“ACE”) in the states of California, Delaware, Virginia, Pennsylvania and the District of Columbia, the Company makes payments into a trust account (“the ACE trust account”) to be used for the payment of future claims. The balance in the ACE trust account was $190.2 million and $166.6 million at March 31, 2016 and December 31, 2015. The ACE trust account balances are included as a component of the current and long-term restricted marketable securities and workers’ compensation deposits in the Company’s consolidated balance sheets.