Stock-Based Compensation

3 Months Ended

Mar. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

The Corporation measures stock-based compensation expense at grant date, based on the fair value of the award, and recognizes expense over the employees' requisite service periods. Stock-based compensation expense is the cost of stock options and time-based restricted stock units issued under the approved stock-based compensation plans and shares issued under the approved member stock purchase plans. The following table summarizes expense associated with these plans (in thousands):



	Three Months Ended
	March 31, 2018		April 1, 2017
Compensation cost	$	3,712	$	4,671

The options and units granted by the Corporation had fair values as follows (in thousands):



	Three Months Ended
	March 31, 2018		April 1, 2017
Stock options	$	6,611	$	7,206

The following table summarizes unrecognized compensation expense and the weighted-average remaining service period for non-vested stock options and restricted stock units as of March 31, 2018:



	Unrecognized Compensation Expense (in thousands)		Weighted-Average Remaining Service Period (years)
Non-vested stock options	$	5,543	1.3
Non-vested restricted stock units	$	238	0.7