Common and Preferred Shares and Warrants (Details 1) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) shares
Series B
Preferred Shares [Line Items]
Issuance Date	Nov. 10, 2014
Securities issued	750
Depositary shares, issued	750,000
Aggregate Liquidation Preference | $	$ 750
Fixed dividend rate per annum	5.20%
Semi-annual fixed dividend, payment dates	Beginning May 15, 2015
Floating dividend rate per annum	3 month LIBOR+ 3.428%
Quarterly floating dividend, Payment Dates	Beginning February 15, 2020
Fixed to floating rate, conversion date	Nov. 15, 2019
Series C
Preferred Shares [Line Items]
Issuance Date	Mar. 02, 2015
Securities issued	850
Depositary shares, issued	850,000
Aggregate Liquidation Preference | $	$ 850
Fixed dividend rate per annum	4.90%
Semi-annual fixed dividend, payment dates	Beginning September 15, 2015
Floating dividend rate per annum	3 month LIBOR+ 3.285%
Quarterly floating dividend, Payment Dates	Beginning June 15, 2020
Fixed to floating rate, conversion date	Mar. 15, 2020