Stockholders' (Deficit) Equity (Details)	12 Months Ended
	Dec. 31, 2016 class $ / shares shares	Dec. 31, 2015 shares	Dec. 31, 2014 shares	Dec. 31, 2016 $ / shares shares
Schedule of Capitalization, Equity [Line Items]
Number of classes of preferred stock | class	2
Preferred stock, dividend rate	4.00%	4.00%
Stock
Shares reserved for issuance under stock plans, dividend reinvestment program and conversion of Preferred and Preference Stock				32,453,416
Preferred Stock
Schedule of Capitalization, Equity [Line Items]
Preferred stock, dividend rate	4.00%
Dividends | $ / shares	$ 2
Shares issued upon conversion				24.24
Redemption price per share | $ / shares				$ 50
Shares authorized to be issued				600,000
Shares outstanding	12	12		12
Stock
Shares outstanding	12
Shares outstanding	12	12
Preference Stock
Schedule of Capitalization, Equity [Line Items]
Dividends | $ / shares	$ 2.12
Shares issued upon conversion				16.53
Redemption price per share | $ / shares				$ 28
Shares authorized to be issued				5,000,000
Shares outstanding	18,660	18,660		17,832
Stock
Shares outstanding	18,660
Shares outstanding	17,832	18,660
Common Stock
Schedule of Capitalization, Equity [Line Items]
Shares outstanding	195,521,208	201,027,964	202,082,522	185,668,718
Stock
Shares outstanding	195,521,208	201,027,964	202,082,522
Repurchases of common stock	(10,633,235)	(6,476,796)	(1,863,262)
Issuance of common stock	767,060	943,686	781,032
Conversions to common stock	13,685	26,354	27,672
Shares outstanding	185,668,718	195,521,208	201,027,964
Treasury Stock
Schedule of Capitalization, Equity [Line Items]
Shares outstanding	127,816,704	122,309,948	121,255,390	137,669,194
Stock
Shares outstanding	127,816,704	122,309,948	121,255,390
Repurchases of common stock	(10,633,235)	(6,476,796)	(1,863,262)
Issuance of common stock	767,060	943,686	781,032
Conversions to common stock	13,685	26,354	27,672
Shares outstanding	137,669,194	127,816,704	122,309,948