Earnings Per Share (Narrative) (Details) - USD ($)		1 Months Ended				6 Months Ended		12 Months Ended
	Jul. 15, 2016	Jul. 31, 2016	Nov. 30, 2015	Jan. 31, 2015	Dec. 31, 2014	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Payments on long-term debt							$ 500,000,000
Debt Instrument						$ 5,807,000,000		$ 4,733,000,000
Bridge Loan [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Bridge loan				$ 4,500,000,000	$ 4,500,000,000			$ 4,500,000,000
Debt instrument, term				364 days	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
Price per share				$ 23.00
Proceeds from issuance of shares				$ 669,000,000
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				$ 1,700,000,000
Depositary shares conversion rate				5.00%
Liquidation preference per share				$ 50
Series B Preferred Stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Liquidation preference per share				$ 1,000		$ 1,000		$ 1,000
Trading day period						20 days
Long-term Debt [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Debt Instrument						$ 5,806,000,000		$ 4,732,000,000
Long-term Debt [Member] | Term Loan due November 2018 [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Debt Instrument						$ 750,000,000		$ 750,000,000
Debt instrument, term			3 years
Senior Notes [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Proceeds from issuance of debt				$ 2,200,000,000
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
Potential number of shares issued upon conversion						63,829,830
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
Potential number of shares issued upon conversion						74,999,895
Subsequent Event [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Common stock, shares issued as stock dividend	2,100,119
Subsequent Event [Member] | Common Stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Shares issued		98,900,000
Price per share		$ 13.00
Proceeds from issuance of shares		$ 1,247,000,000
Subsequent Event [Member] | Long-term Debt [Member] | Term Loan due November 2018 [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Payments on long-term debt		375,000,000
Subsequent Event [Member] | Senior Notes [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Purchase of note principal		$ 700,000,000