Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2016

Stockholders' Equity [Abstract]

Schedule of Common Stock Outstanding Roll Forward [Table Text Block]

	Common Stock
Share Activity	Treasury	Outstanding
	(Number of Shares)
Balance at end of 2013	927,258	10,188,521
Issued for share-based compensation plans	(53,884)	53,884
Balance at end of 2014	873,374	10,242,405
Issued for share-based compensation plans	(59,113)	59,113
Repurchased common shares	80,512	(80,512)
Balance at end of 2015	894,773	10,221,006
Issued for share-based compensation plans	(96,619)	96,619
Repurchased common shares	5,000	(5,000)
Balance at end of 2016	803,154	10,312,625