Stock-Based Compensation

6 Months Ended

Jun. 30, 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 June 30, 2017, there were 1,480,137 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	5,447		95.37		—		—		—	—		—		—
Exercised/vested	(6,098	)	62.29		(1,730	)	76.07		—	—		(744,247	)	59.32
Forfeited/expired	—		—		(870	)	76.07		—	—		(33,492	)	69.35
Balance, June 30, 2017	53,008		$	64.87	254,250		$	73.40	43,860	$	69.70	3,311,289		$	63.36

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   June 30,				Six Months Ended   June 30,
	2017		2016		2017		2016
New shares issued from available authorized shares	310,021		—		593,363		—
Issued from available treasury stock	—		65,200		158,712		67,075
Total	310,021		65,200		752,075		67,075
Proceeds from stock option exercises	$	19,402	$	3,490	$	44,149	$	3,586

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   June 30,				Six Months Ended   June 30,
	2017		2016		2017		2016
Stock options	$	1,573	$	2,117	$	3,360	$	4,242
Non-vested stock awards/stock units	901		358		1,934		715
Director deferred stock units	519		520		519		520
Performance stock units	195		—		478		—
Total	$	3,188	$	2,995	$	6,291	$	5,477
Income tax benefit	$	1,116	$	1,048	$	2,202	$	1,917

Unrecognized stock-based compensation expense at June 30, 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	$	8,694
Non-vested stock awards/stock units	8,413
Performance stock units	2,579
Total	$	19,686