Stock-Based Compensation

3 Months Ended

Mar. 31, 2017

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

Stock-Based Compensation

Stock-Based Compensation

A combined summary of activity in our active stock plans is presented in the table. Performance stock units outstanding are presented assuming attainment of the maximum payout rate as set forth by the performance criteria. The target award level for performance stock units granted in 2016 was 29,240.As of March 31, 2017, there were 1,472,138 shares remaining available for grant for future stock-based compensation awards.

	Director Deferred Stock Units Outstanding				Non-Vested Stock Awards/Stock Units Outstanding				Performance Stock Units Outstanding		Stock Options Outstanding
	Number of Units		Weighted- Average Fair Value at Grant		Number of Shares/Units		Weighted- Average Fair Value at Grant		Number of Units	Weighted- Average Fair Value at Grant	Number of Shares		Weighted- Average Exercise Price
Balance, January 1, 2017	53,659		$	61.48	256,850		$	73.43	43,860	69.70	4,089,028		$	62.67
Authorized	—		—		—		—		—	—	—		—
Granted	—		—		—		—		—	—	—		—
Exercised/vested	(1,180	)	67.75		(1,730	)	76.07		—	—	(439,144	)	56.35
Forfeited/expired	—		—		(260	)	76.07		—	—	(20,656	)	67.47
Balance, March 31, 2017	52,479		$	61.34	254,860		$	73.41	43,860	69.70	3,629,228		$	63.41

Shares issued in connection with stock compensation awards are issued from available treasury shares. If no treasury shares are available, new shares are issued from available authorized shares. Shares issued in connection with stock compensation awards along with other related information were as follows:

	Three Months Ended   March 31,
	2017		2016
New shares issued from available authorized shares	283,342		—
Issued from available treasury stock	158,712		1,875
Total	442,054		1,875
Proceeds from stock option exercises	$	24,747	$	97

Stock-based compensation expense is recognized ratably over the requisite service period for all awards. For most stock option awards, the service period generally matches the vesting period. For stock options granted to certain executive officers and for non-vested stock units granted to all participants, the service period does not extend past the date the participant reaches 65 years of age. Deferred stock units granted to non-employee directors generally have immediate vesting and the related expense is fully recognized on the date of grant. For performance stock units, the service period generally matches the three-year performance period specified by the award, however, the service period does not extend past the date the participant reaches 65 years of age. Expense recognized each period is dependent upon our estimate of the number of shares that will ultimately be issued.

Stock-based compensation expense and the related income tax benefit is presented in the following table.

	Three Months Ended   March 31,
	2017		2016
Stock options	$	1,787	$	2,125
Non-vested stock awards/stock units	1,033		357
Director deferred stock units	—		—
Performance stock units	283		—
Total	$	3,103	$	2,482
Income tax benefit	$	1,086	$	869

Unrecognized stock-based compensation expense at March 31, 2017 is presented in the table below. Unrecognized stock-based compensation expense related to performance stock units is presented assuming attainment of the maximum payout rate as set forth by the performance criteria.

Stock options	$	10,439
Non-vested stock awards/stock units	9,360
Performance stock units	2,774
Total	$	22,573