Changes in Consolidated Shareholders' Equity (Parenthetical) (Parentheticals) - shares	3 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Common shares issued from treasury stock for stock-based compensation (in shares)		11,139,748	4,164,134	2,931,595
Common shares repurchased (in shares)	19,600,000	0	0	25,841,608