Capital Preferred Stock (Additional Information) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Nov. 30, 2017	May 31, 2017	Nov. 30, 2014	Dec. 31, 2011	Sep. 22, 2011	Dec. 31, 2008	Sep. 30, 2006
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	50,000,000	50,000,000
Preferred Stock, Shares Outstanding	20,000	25,000
Payments for Repurchase of Warrants	$ 0	$ 0	$ 24,000,000
Stock Warrants Expired	7,445
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized										5,000
Preferred Stock, Shares Issued										5,000
Preferred Stock, Shares Outstanding	1,725
Preferred Stock, No Par Value										$ 0
Preferred Stock, Liquidation Preference, Value										$ 100,000
Declared And Accrued Preferred Stock Dividend Basis Spread on Variable Rate	0.53%
Declared And Accrued Preferred Stock Dividend Fixed Rate	4.00%
Preferred Stock, Redemption Price Per Share										$ 100,000
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized							5,010
Preferred Stock, Shares Issued							1,025
Preferred Stock, Shares Outstanding	1,025
Preferred Stock, No Par Value							$ 0
Preferred Stock, Liquidation Preference, Value							$ 100,000
Declared And Accrued Preferred Stock Dividend Basis Spread on Variable Rate	0.645%
Declared And Accrued Preferred Stock Dividend Fixed Rate	4.00%
Preferred Stock, Redemption Price Per Share							$ 100,000
Series C Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Issued									35,000
Series D Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Issued									13,500
Series F Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized						5,000
Preferred Stock, Shares Issued						5,000
Preferred Stock, Shares Outstanding	5,000
Preferred Stock, No Par Value						$ 0
Preferred Stock, Liquidation Preference, Value						$ 100,000
Declared And Accrued Preferred Stock Dividend Basis Spread on Variable Rate	3.86%
Declared And Accrued Preferred Stock Dividend Fixed Rate	5.625%
Preferred Stock, Redemption Price Per Share						$ 100,000
Series G Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized					7,500
Preferred Stock, Shares Issued					7,500
Preferred Stock, Shares Outstanding	7,500
Preferred Stock, No Par Value					$ 0
Preferred Stock, Liquidation Preference, Value					$ 100,000
Declared And Accrued Preferred Stock Dividend Basis Spread on Variable Rate	3.102%
Declared And Accrued Preferred Stock Dividend Fixed Rate	5.05%
Preferred Stock, Redemption Price Per Share					$ 100,000
Series H Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized				5,000
Preferred Stock, Shares Issued				5,000
Preferred Stock, Shares Outstanding	5,000
Preferred Stock, No Par Value				$ 0
Preferred Stock, Liquidation Preference, Value				$ 100,000
Declared And Accrued Preferred Stock Dividend Basis Spread on Variable Rate	2.786%
Declared And Accrued Preferred Stock Dividend Fixed Rate	5.125%
Preferred Stock, Redemption Price Per Share				$ 100,000
Warrant [Member]
Class of Stock [Line Items]
Class of Warrant or Right, Outstanding									17,900,000
Series A [Member]
Class of Stock [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights								4,000,000	6,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights								$ 11,000,000	$ 33.70
warrants purchased		1,100,000
Series B [Member]
Class of Stock [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights									11,900,000
Class of Warrant or Right, Exercise Price of Warrants or Rights									$ 44.15
warrants purchased		5,400,000
Parent Company [Member]
Class of Stock [Line Items]
Payments for Repurchase of Warrants	$ 0	$ 0	$ 24,000,000
Common Stock [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, Other	3,000,000