Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2016

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

Summary of Activity in Corporation's Active Stock Plans

A combined summary of activity in our active stock-based compensation plans is presented in the following table.

		Director Deferred Stock Units Outstanding			Non-Vested Stock Awards/Stock Units Outstanding			Stock Options Outstanding
	Shares Available for Grant	Number of Shares	Weighted- Average Grant-Date Fair Value		Number of Shares	Weighted- Average Grant-Date Fair Value		Number of Shares		Weighted- Average Exercise Price
Balance, January 1, 2016	1,589,727	45,443	$	61.35	173,180	$	66.05	5,612,240		$	60.30
Authorized	—	—	—		—	—		—		—
Granted	—	—	—		—	—		—		—
Stock options exercised	—	—	—		—	—		(1,875	)	51.21
Stock awards/units vested	—	—	—		—	—		—		—
Forfeited/expired	26,775	—	—		—	—		(26,775	)	70.55
Balance, March 31, 2016	1,616,502	45,443	$	61.35	173,180	$	66.05	5,583,590		$	60.26

Shares Issued in Connection with Stock Compensation Awards

Shares issued in connection with stock compensation awards along with other related information were as follows:

	Three Months Ended   March 31,
	2016		2015
New shares issued from available authorized shares	—		—
Issued from available treasury stock	1,875		14,350
Total	1,875		14,350
Proceeds from stock option exercises	$	96	$	728

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]

Stock-based compensation expense was as follows:

	Three Months Ended   March 31,
	2016		2015
Stock options	$	2,125	$	2,166
Non-vested stock awards/stock units	357		396
Deferred stock units	—		—
Total	$	2,482	$	2,562

Unrecognized Stock-Based Compensation Expense

Unrecognized stock-based compensation expense at March 31, 2016 was as follows:

Stock options	$	18,759
Non-vested stock awards/stock units	2,998
Total	$	21,757