CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - shares	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Treasury Stock - Common [Member]
Purchase of shares for company benefit plans, shares	1,194,986	33,955
Release of shares from company benefit plans, shares	92,015	182,092
Preferred Stock, Exchanged for Shares of Common Stock [Member] | Preferred Stock [Member]
Conversion of Stock, Shares Converted	236,048	25,802
Preferred Stock, Exchanged for Shares of Common Stock [Member] | Additional Paid-in Capital [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities	9,965,835	1,021,506
Contingent Convertible Senior Notes Exchanged for Shares of Common Stock [Member] | Additional Paid-in Capital [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities	0	55,427,782
Senior Notes Exchanged for Shares of Common Stock [Member] | Additional Paid-in Capital [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities	0	53,923,925