Subsequent Events (Narrative) (Details) - USD ($)	1 Months Ended		6 Months Ended
	Jul. 31, 2016	Jan. 31, 2015	Jun. 30, 2015	Jun. 30, 2016	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
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
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
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