CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - shares	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Treasury Stock - Common [Member]
Purchase of shares for company benefit plans, shares	1,189,813	22,810
Release of shares from company benefit plans, shares	73,990	157,514
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