Parent Only Statements - Balance Sheets (Additional Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Preferred stock, stated value (in dollars per share)	$ 0.20	$ 0.20
Preferred stock, shares authorized	20,000,000	20,000,000
Common stock, par value (in dollars per share)	$ 0.20	$ 0.20
Common stock, shares authorized	1,125,000,000.000	1,125,000,000.000
Common stock, shares issued	430,700,000	424,800,000
Accumulated other comprehensive loss tax benefit	$ (9,949)	$ (7,186)
Common stock held in treasury	4,400,000	1,400,000
Series A Preferred Stock
Condensed Financial Statements, Captions [Line Items]
Preferred stock, stated value (in dollars per share)	$ 50	$ 50
Series B Preferred Stock
Condensed Financial Statements, Captions [Line Items]
Preferred stock, stated value (in dollars per share)	100	100
Parent Company
Condensed Financial Statements, Captions [Line Items]
Preferred stock, stated value (in dollars per share)	$ 0.20	$ 0.20
Preferred stock, shares authorized	20,000,000	20,000,000
Common stock, par value (in dollars per share)	$ 0.20	$ 0.20
Common stock, shares authorized	1,125,000,000.000	1,125,000,000.000
Common stock, shares issued	431,000,000	425,000,000
Accumulated other comprehensive loss tax benefit	$ 9,949	$ 7,186
Common stock held in treasury	4,000,000	1,000,000
Parent Company | Series A Preferred Stock
Condensed Financial Statements, Captions [Line Items]
Preferred stock, stated value (in dollars per share)	$ 50	$ 50
Preferred stock, shares issued	3,300,000	3,300,000
Parent Company | Series B Preferred Stock
Condensed Financial Statements, Captions [Line Items]
Preferred stock, stated value (in dollars per share)	$ 100	$ 100
Preferred stock, shares issued	4,000,000	4,000,000