Earnings Per Share (Narrative) (Details) $ / shares in Units, $ in Millions	1 Months Ended		9 Months Ended	12 Months Ended
	Jan. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($)	Sep. 30, 2015 $ / shares shares	Dec. 31, 2014 USD ($)
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Proceeds from issuance of shares | $	$ 2,300
Bridge Loan [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Bridge loan | $		$ 4,500		$ 4,500
Debt instrument, term		364 days		364 days
Common Stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Shares issued	30,000,000
Share price | $ / shares	$ 23.00
Proceeds from issuance of shares | $	$ 669
Depositary Shares [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Shares issued	34,500,000
Proceeds from issuance of shares | $	$ 1,700
Depositary shares conversion rate	0.05
Liquidation preference per share | $ / shares	$ 50
Series B Preferred Stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Liquidation preference per share | $ / shares	$ 1,000		$ 1,000
Trading day period			20 days
Senior Notes [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Proceeds from issuance of debt | $	$ 2,200
Minimum [Member] | Depositary Shares [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Shares issued upon conversion			1.85014
Minimum [Member] | Series B Preferred Stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Shares issued upon conversion			37.0028
Maximum [Member] | Depositary Shares [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Shares issued upon conversion			2.17391
Maximum [Member] | Series B Preferred Stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Shares issued upon conversion			43.4782