Common Stock Treasury Shares (Details) - shares	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Jun. 29, 2010
Share-based Compensation Arrangement by Share-based Payment Award
Common stock, shares authorized	150,000,000	150,000,000	3,000,000
Treasury stock acquired, and available for reissuance	10,397
Common Stock, Shares Held in Employee Trust, Shares		18,366
Treasury Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award
Treasury stock acquired, and available for reissuance	41,523
Treasury Stock, Shares, Acquired	80,572
Treasury stock acquired and reissued	49,446