Our healthcare benefit expense (net of employee contributions) for all plans was approximately $4.8 million and $4.4 million for the three months ended March 31, 2019 and 2018, respectively. An accrual for estimated healthcare claims incurred but not reported (“IBNR”) is included within accrued compensation on the Condensed Consolidated Balance Sheets and was $2.7 million and $2.3 million as of March 31, 2019 and December 31, 2018, respectively.

Workers’ compensation expense totaled $4.2 million and $3.8 million for the three months ended March 31, 2019 and 2018, respectively. Workers’ compensation known claims and IBNR reserves included on the Condensed Consolidated Balance Sheets were as follows (in thousands):

	March 31, 2019		December 31, 2018
Included in other current liabilities	$	5,201	$	5,795
Included in other long-term liabilities		11,138		9,447
	$	16,339	$	15,242

We also had an insurance receivable for claims that exceeded the stop loss limit included on the Condensed Consolidated Balance Sheets. This receivable offsets an equal liability included within the reserve amounts noted above and was as follows (in thousands):

We participate in multiple 401(k) plans, whereby we provide a matching contribution of wages deferred by employees and can also make discretionary contributions to each plan. Certain plans allow for discretionary employer contributions only. These plans cover substantially all our eligible employees. We recognized 401(k) plan expenses of $0.6 million and $0.4 million during the three months ended March 31, 2019 and 2018, respectively. These expenses are included in administrative expenses on the accompanying Condensed Consolidated Statements of Operations and Comprehensive Income.

We periodically grant shares of our common stock to our board of directors and our employees. We did not grant any such shares to our board of directors during the three months ended March 31, 2019 or 2018, however we recorded $0.1 million of compensation expense during the three months ended March 31, 2019 related to prior grants to our board of directors. During the three months ended March 31, 2019 and 2018, we granted approximately 11 thousand and approximately eight thousand shares of our common stock, respectively, to employees and recorded $1.1 million and $0.9 million, respectively, of compensation expense associated with non-performance-based awards issued to employees.

During the three months ended March 31, 2019 and 2018, our employees surrendered approximately two hundred and one thousand shares of our common stock, respectively, to satisfy tax withholding obligations arising in connection with the vesting of common stock awards issued under our 2014 Omnibus Incentive Plan. We recognized excess tax benefits of $0.1 million within the income tax provision in the Condensed Consolidated Statements of Operations and Comprehensive Income for the three months ended March 31, 2018.

As of March 31, 2019, we had $4.5 million of unrecognized compensation expense related to these nonvested common stock awards issued to the board of directors and our employees. This expense is subject to future adjustments for forfeitures and is expected to be recognized on a straight-line basis over the remaining weighted-average period of 1.8 years. Shares forfeited are returned as treasury shares and available for future issuances. See the table below for changes in shares and related weighted average fair market value per share.

During the three months ended March 31, 2019, we issued under our 2014 Omnibus Incentive Plan approximately 46 thousand shares of our common stock to certain officers, which vest in two equal installments on each of April 20, 2020 and April 20, 2021. In addition, during the three months ended March 31, 2019, we established, and our Board of Directors approved, performance-based targets in connection with common stock awards to be issued to certain officers in 2020 contingent upon achievement of these targets. Share-based compensation expense associated with these performance-based awards and prior performance-based grants was $0.7 million and $0.4 million for the three months ended March 31, 2019 and 2018, respectively.

As of March 31, 2019, we had $5.8 million of unrecognized compensation expense related to nonvested performance-based common stock awards. This expense is subject to future adjustments for forfeitures and is expected to be recognized over the remaining weighted-average period of 2.1 years using the graded-vesting method. See the table below for changes in shares and related weighted average fair market value per share.

During 2018, we established, and our board of directors approved, performance-based restricted stock units in connection with common stock awards to be issued to certain employees in 2019 based upon achievement of a performance target. These units will be accounted for as equity-based awards that will be settled with a fixed number of common shares. We recorded $0.1 million and $0.9 million in compensation expense associated with these performance-based units during the three months ended March 31, 2019 and 2018, respectively.

As of March 31, 2019, we had $34 thousand of unrecognized compensation expense related to nonvested performance-based common stock units. This expense is subject to future adjustments for forfeitures and is expected to be recognized on a straight-line basis over the remaining weighted-average period of 0.1 years. See the table below for changes in shares and related weighted average fair market value per share.

	Common Stock Awards					Performance-Based Stock Awards					Performance-Based Restricted Stock Units
	Awards			Weighted Average Fair Market Value Per Share		Awards			Weighted Average Fair Market Value Per Share		Units			Weighted Average Fair Market Value Per Share
Nonvested awards/units at December 31, 2018		173,189		$	47.40		115,698		$	52.25		13,248		$	56.05
Granted		10,800			45.65		82,692			45.65		—			—
Vested		(564	)		54.98		—			—		—			—
Forfeited/Cancelled		(445	)		56.05		(6,697	)		65.60		(440	)		56.05
Nonvested awards/units at March 31, 2019		182,980		$	47.25		191,693		$	48.93		12,808		$	56.05

Administrative stock compensation expense includes all stock compensation earned by our administrative personnel, while cost of sales and selling stock compensation represents all stock compensation earned by our installation and sales employees, respectively.