Equity Equity - Preferred Stock Conversion Terms Table (Details) (USD $)	12 Months Ended
	Dec. 31, 2013
5.75% Cumulative Convertible Preferred Stock
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.75%
5.75% Cumulative Convertible Preferred Stock | Preferred Stock
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Conversion of Stock, Stock Issue Date	May and June 2010
Preferred Stock, Liquidation Preference Per Share	$ 1,000
Conversion of Stock, Holders Conversion Right	Any time
Preferred Stock Conversion Rate	37.185%
Conversion of Stock, Conversion Price	$ 26.8926
Conversion of Stock, Company Conversion Right, Date	May 17, 2015
Trigger Price For Time Period	$ 34.9604
Debt Instrument, Interest Rate, Stated Percentage	5.75%
5.75% Cumulative Convertible Preferred Stock Series A | Preferred Stock
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Conversion of Stock, Stock Issue Date	May 2010
Preferred Stock, Liquidation Preference Per Share	$ 1,000
Conversion of Stock, Holders Conversion Right	Any time
Preferred Stock Conversion Rate	35.9339%
Conversion of Stock, Conversion Price	$ 27.8289
Conversion of Stock, Company Conversion Right, Date	May 17, 2015
Trigger Price For Time Period	36.1776
Debt Instrument, Interest Rate, Stated Percentage	5.75%
4.50% Cumulative Convertible Preferred Stock [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.50%
4.50% Cumulative Convertible Preferred Stock [Member] | Preferred Stock
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Conversion of Stock, Stock Issue Date	September 2005
Preferred Stock, Liquidation Preference Per Share	$ 100
Conversion of Stock, Holders Conversion Right	Any time
Preferred Stock Conversion Rate	2.2969%
Conversion of Stock, Conversion Price	$ 43.5375
Conversion of Stock, Company Conversion Right, Date	September 15, 2010
Trigger Price For Time Period	56.5988
Debt Instrument, Interest Rate, Stated Percentage	4.50%
5.0% Cumulative Convertible Preferred Stock Series Two Thousand And Five B [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.00%
5.0% Cumulative Convertible Preferred Stock Series Two Thousand And Five B [Member] | Preferred Stock
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Conversion of Stock, Stock Issue Date	November 2005
Preferred Stock, Liquidation Preference Per Share	$ 100
Conversion of Stock, Holders Conversion Right	Any time
Preferred Stock Conversion Rate	2.599%
Conversion of Stock, Conversion Price	$ 38.4757
Conversion of Stock, Company Conversion Right, Date	November 15, 2010
Trigger Price For Time Period	$ 50.0184
Debt Instrument, Interest Rate, Stated Percentage	5.00%
Minimum | 5.75% Cumulative Convertible Preferred Stock Series A | Preferred Stock
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Conversion of Stock, Company Market Trigger	25,000
Minimum | 4.50% Cumulative Convertible Preferred Stock [Member] | Preferred Stock
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Conversion of Stock, Company Market Trigger	250,000